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Aiken, G.R., Gilmour, C.C., Krabbenhoft, D.P. and Orem, W. (2011) Dissolved Organic Matter in the Florida Everglades: Implications for Ecosystem Restoration. Critical Reviews in Environmental Science and Technology 41, 217-48.

 

ABSTRACT
Dissolved organic matter (DOM) in the Florida Everglades controls a number of environmental processes important for ecosystem function including the absorption of light, mineral dissolution/precipitation, transport of hydrophobic compounds (e.g., pesticides), and the transport and reactivity of metals, such as mercury. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the present transport of DOM from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. In part, the restoration plan calls for increasing water flow throughout the Everglades by removing some of the manmade barriers to flow in place today. The land- and water-use practices associated with the plan will likely result in changes in the quality, quantity, and reactivity of DOM throughout the greater Everglades ecosystem. The authors discuss the factors controlling DOM concentrations and chemistry, present distribution of DOM throughout the Everglades, the potential effects of DOM on key water-quality issues, and the potential utility of dissolved organic matter as an indicator of success of restoration efforts.

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Anonymous (2011) Wind Across the Everglades. Sight and Sound 21(9), 88-89.

 

 

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Bao, K.S., Zhao, H.M., Xing, W., Lu, X.G., McLaughlin, N.B. and Wang, G.P. (2011) Carbon Accumulation in Temperate Wetlands of Sanjiang Plain, Northeast China. Soil Science Society of America Journal 75(6), 2386-97.

 

ABSTRACT
Wetland ecosystems contain large C stocks and are considered to play an important role in global C cycling, thus having potential implications for global climate change. The Sanjiang Plain wetland is the largest freshwater marsh in China and a principle element of the Wetlands of International Importance with three Ramsar wetland sites (Xingkai Lake, Sanjiang, and Honghe) since 2002. Nevertheless, little is known about organic C storage, and no data combining both long-and short-term C accumulation rates have been reported for this region. We used 10 cores collected from previous investigations to determine radiocarbon age and long-term (apparent) rate of C accumulation (LORCA) based on dry bulk density and organic C content; we used five recent cores representing the three main wetland types in Sanjiang Plain to estimate the recent (apparent) rate of C accumulation (RERCA) inferred from (210)Pb dating. The LORCA ranged from 5 to 61 g C m(-2) yr(-1) with an average of 22 +/- 5 g C m(-2) yr(-1) (+/- SE), and the RERCA ranged from 170 to 384 g C m(-2) yr(-1) with a mean of 264 +/- 45 g C m(-2) yr(-1) (+/- SE). Th e average C flux was 0.05 Tg C yr(-1) for herbaceous peatland, 0.02 Tg C yr(-1) for humus marsh, and 0.03 Tg C yr(-1) for marshy meadow and the total soil C pool in Sanjiang Plain wetlands was estimated to be 0.36 Pg C. Our results are in good agreement with other published relevant data and may be useful for predicting global climate change. Th e Sanjiang Plain wetlands deserve more attention in wetland protection and restoration of the wetland ecosystem and wise use of wetlands for agricultural development.

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Barrios, B., Arellano, G. and Koptur, S. (2011) The effects of fire and fragmentation on occurrence and flowering of a rare perennial plant. Plant Ecology 212(6), 1057-67.

 

ABSTRACT
The pine rocklands of southern Florida are a fire-dependent forest associated with outcroppings of limestone. Pine rockland plants have several adaptations to fire, and for many species burns increase plant growth, flowering, and seedling establishment. The pine rockland forest has been reduced and fragmented in recent decades. Outside of Everglades National Park, only two percent of the original pine rocklands remain, and are in the form of small fragments. Habitat fragmentation may have a negative effect on the biology of plants; we investigated the effects of both fire and fragmentation on Angadenia berteroi (A.DC.) Miers, a threatened species of the southern Florida pine rockland. We estimated the density and flowering of A. berteroi using adaptive cluster sampling in six study sites with different fire and disturbance histories. A. berteroi is more abundant in the largest fragments, and those having experienced fire most recently. However, fragmentation and lack of fire did not appear to have a great impact on flowering or fruit production. Insights from this threatened species may provide impetus not only to conserve, but to properly manage remaining pine rocklands in south Florida.

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Beckage, B., Gross, L.J. and Platt, W.J. (2011) Grass feedbacks on fire stabilize savannas. Ecological Modelling 222(14), 2227-33.

 

ABSTRACT
Savannas commonly consist of a discontinuous cover of overstory trees and a groundcover of grasses. Savanna models have previously demonstrated that vegetation feedbacks on fire frequency can limit the density of overstory trees, thereby maintaining savannas. Positive feedbacks of either savanna trees alone or trees and grasses together on fire frequency have been shown to result in a stable savanna equilibrium. Grass feedbacks on fire frequency, in contrast, have resulted in stable equilibria in either a grassland or forest state, but not in a savanna. These results, however, were derived from a system of differential equations that assumes that fire occurrence is strictly deterministic and that vegetation losses due to fire are continuous in time. We develop an alternative formulation of the grass-fire feedback model that assumes that fires are discrete and occur stochastically in time to examine the influence of these assumptions on the predicted state of the system. We show that incorporating fire as a discrete event can produce a recurring temporal refuge in which both grass and trees co-occur in a stable, bounded savanna. In our model, tree abundance is limited without invoking demographic bottlenecks in the transition from fire-sensitive to fire-resistant life history stages. An increasing strength of grass feedback on fire results in regular, predictable fires, which suggests that the system can also be modeled using a set of difference equations. We implement this discrete system using modified Leslie/Gower difference equations and demonstrate the existence of a bounded savanna state in this model framework. Our results confirm the potential for grass feedbacks to result in stable savannas, and indicate the importance of modeling fire as a discrete event rather than as a loss rate that is continuous in time.

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Beganyi, S.R. and Batzer, D.P. (2011) Wildfire induced changes in aquatic invertebrate communities and mercury bioaccumulation in the Okefenokee Swamp. Hydrobiologia 669(1), 237-47.

 

ABSTRACT
Fire is an important natural disturbance in the Okefenokee Swamp. From April-June 2007, wildfire burned 75% of the wetland area. With the existence of extensive pre-fire data sets on community structure and total mercury of invertebrates, the fire presented an opportunity to assess impacts of wildfire on invertebrates. Post-fire collection of samples occurred in September, December, and May, 2007-2009. Sample sites included 13 burned and 8 non-burned (reference) sites. Comparisons of data among pre-fire, post-fire reference, and post-fire burned sites revealed that the major difference between pre-fire communities and post-fire communities was a decrease in the number of water mites. We also found a decrease in mercury concentrations in amphipods, odonates, and crayfish post-fire. The differences between pre-fire and post-fire samples may be confounded by drought conditions during the baseline study. NMDS ordinations and ANOSIM tests suggested that habitat was an important factor; communities in burned cypress differed from reference cypress. Unexpectedly, burned sites had lower mercury concentrations in odonates and crayfish, with variation again being greatest in cypress stands. These findings and others suggest mercury levels do not follow a predictable pattern but can vary with pre-fire concentrations, variation in water levels, and burn intensity. We found that wildfire in the Okefenokee had little impact on invertebrates in prairies and scrub-shrub thickets, but can affect indicator organisms (Oecetis, Ischnura, and Sigara) in cypress stands. Our study suggests that vegetation type and burn intensity may have impacts on the invertebrate communities and mercury concentrations of organisms.

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Belila, A., Ghrabi, A. and Hassen, A. (2011) Molecular analysis of the spatial distribution of sulfate-reducing bacteria in three eutrophicated wastewater stabilization ponds. Annals of Microbiology 61(3), 563-73.

 

ABSTRACT
The spatial distribution of sulfate-reducing bacteria (SRB) within three eutrophicated wastewater stabilization ponds (anaerobic, facultative and maturation) was assessed by terminal restriction fragment (TRF) polymorphism targeting the dissimilatory (bi) sulfite reductase (dsrAB) gene. High sulfate reducing diversity was confirmed through the 93 and 78 TRFs found using Sau3A1 and Taq alpha 1 restriction enzymes. Statistical analysis using Simpson (D) and Shannon (H') diversity index and principal coordinate analysis revealed differential distribution of SRB at each treatment stage and between waste and sediment samples. Inversely to the distribution of purple phototrophic bacteria, the diversity of SRB decreased within sediment and increased within the water phase downstream of the plant.

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Bernhardt, C. (2011) Native Americans, regional drought and tree island evolution in the Florida Everglades. Holocene 21(6), 967-78.

 

ABSTRACT
This study uses palynologic data to determine the effects of regional climate variability and human activity on the formation and development of tree islands during the last similar to 4000 years. Although prolonged periods of aridity have been invoked as one mechanism for their formation, Native American land use has also been hypothesized as a driver of tree island development. Using pollen assemblages from head and near tail sediments collected on two tree islands and documented archeological data, the relative roles of Native Americans, climate variability, and recent water-management practices in forming and structuring Everglades tree islands are examined. The timing of changes recorded in the pollen record indicates that tree islands developed from sawgrass marshes similar to 3800 cal. yr BP, prior to human occupation. Major tree island expansion, recorded near tail sediments, occurred similar to 1000 years after initial tree island formation. Comparison of the timing of pollen assemblages with other proxy records indicates that tree island expansion is related to regional and global aridity correlated with southward migration of the Intertropical Convergence Zone. Local fire associated with droughts may also have influenced tree island expansion. This work suggests that Native American occupation did not significantly influence tree island formation and that the most important factors governing tree island expansion are extreme hydrologic events due to droughts and intense twentieth century water management.

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Bernhardt, C.E., Stanley, J.D. and Horton, B.P. (2011) Wetland Vegetation in Manzala Lagoon, Nile Delta Coast, Egypt: Rapid Responses of Pollen to Altered Nile Hydrology and Land Use. Journal of Coastal Research 27(4), 731-37.

 

ABSTRACT
The pollen record in a sediment core from Manzala lagoon on the Nile delta coastal margin of Egypt, deposited from ca. AD 1860 to 1990, indicates rapid coastal wetland vegetation responses to two primary periods of human activity. These are associated with artificially altered Nile hydrologic regimes in proximal areas and distal sectors located to similar to 1200 km south of Manzala. Freshwater wetland plants that were dominant, such as Typha and Phragmites, decreased rapidly, whereas in the early 1900s, brackish water wetland species (e.g., Amaranthaceae) increased. This change occurred after closure of the Aswan Low Dam in 1902. The second major modification in the pollen record occurred in the early 1970s, after Aswan High Dam closure from 1965 to 1970, when Typha pollen abundance increased rapidly. Massive population growth occurred along the Nile during the 130 years represented by the core section. During this time, the total volume of lagoon water decreased because of conversion of wetland areas to agricultural land, and input of organic-rich sediment, sewage (municipal, agricultural, industrial), and fertilizer in Manzala lagoon increased markedly. Although the wetland plant community has continued to respond to increasingly intensified and varied human-induced pressures in proximal sectors, the two most marked changes in Manzala pollen best correlate with distal events (i.e., closure of the two dams at Aswan). The study also shows that the two major vegetation changes in Manzala lagoon each occurred less than 10 years after closure upriver of the Low and High dams that markedly altered the Nile regime from Upper Egypt to the coast.

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Bloetscher, F., Heimlich, B. and Meeroff, D.E. (2011) Development of an adaptation toolbox to protect southeast Florida water supplies from climate change. Environmental Reviews 19, 397-417.

 

ABSTRACT
Sea level rise and changes in precipitation patterns due to climate change present a challenge to water resources engineers and planners in southeast Florida with regard to sustainable water supplies and Everglades restoration. Because over half of the urban areas of Miami-Dade and Broward counties, as well as portions of Palm Beach County (home to 5 million people), are at an elevation below 5 ft national geodetic vertical datum (ngvd), protection against sea level rise and coastal migration presents a challenge. Current approaches to water supply will not protect the resilience and prolong the sustainability of the region's water resources. In this paper, the authors outline the potential effects of sea level rise scenarios for coastal southeast Florida and develop a toolbox of options for adaptation for water, wastewater, and stormwater utilities to apply. Any given option may not be appropriate for all utilities, and any given utility may deem there to be benefits to pursuing multiple strategies on a timeline in keeping with the latest estimates of sea level rise. The authors also developed milestones to trigger infrastructure investments, as climate changes may occur more rapidly or more slowly than currently projected. While applied to southeast Florida, many of these same toolbox items may be useful for other utilities located in coastal areas with low elevation, high water tables, and significant wet and dry seasons.

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Bohlen, P.J. and Villapando, O.R. (2011) Controlling Runoff from Subtropical Pastures Has Differential Effects on Nitrogen and Phosphorus Loads. Journal of Environmental Quality 40(3), 989-98.

 

ABSTRACT
A 4-yr (2005-2008) study was conducted to evaluate the potential of pasture water management for controlling nutrient losses in surface runoff in the Northern Everglades. Two pasture water management treatments were investigated on Bahia grass (Paspalum notatum Flugge) pastures: reduced flow and unobstructed flow. The reduced flow treatment was applied to four of eight 20.23-ha pastures by installing water control structures in pasture drainage ditches with flashboards set at a predetermined height. Four other pastures received the unobstructed-flow treatment, in which surface runoff exited pastures unimpeded. Automated instruments measured runoff volume and collected surface water samples for nutrient analysis. In analyzing data for before-after treatment analysis, the 2005 results were removed because of structural failure in water control structures and the 2007 results were removed because of drought conditions. Pasture water retention significantly reduced annual total nitrogen (TN) loads, which were 11.28 kg ha(-1) and 6.28 kg ha(-1), respectively, in pastures with unobstructed and reduced flow. Total phosphorus (TP) loads were 27% lower in pastures with reduced flow than in pastures with unobstructed flow, but this difference was not statistically significant. Concentrations of available soil P were significantly greater in pastures with reduced flow. Pasture water retention appears to be an effective approach for reducing runoff volume and TN loads from cattle pastures in the Northern Everglades, but the potential to reduce TP loads may be diminished if higher water table conditions cause increased P release from soils, which could result in higher P concentration in surface runoff.

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Bohnsack, J.A. (2011) Impacts of Florida coastal protected areas on recreational world records for spotted seatrout, red drum, black drum, and common snook. Bulletin of Marine Science 87(4), 939-70.

 

ABSTRACT
The present study examines the influence of coastal marine protected areas (MPAs) and statewide fishing regulations on recreational trophy fisheries for four important estuarine game fishes in Florida, where similar to 59% of the mainland coast consists of MPAs. The distribution of International Game Fish Association (IGFA) recreational world records achieved over 70 years (1939-2009) were correlated with the strength and duration of fishery restrictions in MPAs. No difference in record density was detected between coastal areas inside and outside of MPAs where fishing was managed by statewide regulations. However, 74% (n = 143) of all records for three species were concentrated near the two MPAs that had additional fishery restrictions. The highest concentration was along similar to 11% of the mainland coast at Cape Canaveral (CAN) near MPAs closed to all fishing since 1962. It included 42% of spotted seatrout [Cynoscion nebulosus (Cuvier in Cuvier and Valenciennes, 1830)1, 55% of red drum [Sciaenops ocellatus (Linnaeus, 1766)], and 69% of black drum [Pogonias cromis (Linnaeus, 1766)] Florida records. Everglades National Park (ENP) had the second highest concentration with 7% of spotted seatrout, 32% of red drum, and 24% of black drum records caught along similar to 9% of the mainland coast. ENP partially limited fishing starting in 1980 by establishing a closed area, daily bag limits, and eliminating commercial fishing. Common snook [Centropomus undecimalis (Bloch, 1792)] records did not increase significantly at CAN or ENP. Recreational fishery statistics corroborated IGFA record patterns. Total recreational catch and catch per trip (CPUE) increased significantly for spotted seatrout, red drum, and black drum in northeast and southwest Florida, the two regions with the most protective MPAs, and either declined or were unchanged in the northeast and southeast, which did not have MPAs with fishing restrictions. Both datasets supported predictions of marine reserve theory that MPAs can benefit fisheries by increasing the abundance and size of exploited species. Data did not support other alternative hypotheses proposed to explain record patterns. In conclusion, evidence indicates that Florida coastal estuarine MPAs with fishery restrictions allowed recreational anglers to increase their total catch and CPUE, and achieve more game fish world records than would have occurred if all coastal areas had been regulated by existing statewide fishing regulations.

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Boulton, R.L., Baiser, B., Davis, M.J., Virzi, T. and Lockwood, J.L. (2011) Variation in laying date and clutch size: The Everglades environment and the endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis). Auk 128(2), 374-81.

 

ABSTRACT
When to commence breeding is a fundamental decision made by individuals that inhabit seasonal environments. Although photoperiod determines the timing of breeding in most temperate zones, other abiotic conditions can also play a significant role by influencing food availability and, consequently, reproductive performance throughout a breeding cycle. This study used the multibrooded endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis) to test whether water conditions (rainfall and groundwater levels) influenced breeding variables in a subtropical environment, the Florida Everglades. Timing of breeding was related to rainfall preceding the breeding season, with females initiating nesting up to 1 month earlier in years with greater rainfall. Clutch size averaged 3.4 eggs, and females showed an increase in clutch size as the breeding season progressed and in response to higher groundwater levels during the laying period. This effect was more apparent for first nesting attempts, with drier conditions limiting clutch size. Although wetter conditions favored earlier breeding and larger clutch sizes, annual nest survival (range: 12-36%) was negatively associated with high average rainfall late in the breeding season. Clutch-size variation and high nest survival in Cape Sable Seaside Sparrows' first nesting attempts suggests that food-mediated processes affect their reproductive decisions early in the breeding season, whereas predator-mediated processes drove overall reproductive output, possibly through increased activity of major nest predators during wetter conditions.

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Brasseur, B., Semah, F., Semah, A.M. and Djubiantono, T. (2011) Paleopedological approach of the environment of fossil hominids from the Sangiran dome (central Java, Indonesia). Quaternaire 22(1), 13-34.

 

ABSTRACT
The thick fossiliferous volcano-sedimentary series of the Sangiran dome area (Kalibeng, Pucangan, Grenzbank, Kabuh and Notopuro) from central Java (Indonesia) were deposited throughout the Quaternary and represent a succession of coastal, marine and finally continental terrestrial environments. Palaeosoils from these series of Southeast Asia are good indicators of the successive landscapes in which early hominids lived and migrated during the Lower and early Middle Pleistocene. This palaeopedological study deals with seven localities distributed over an area of ca. 50 km(2). Six palaeosoil orders (histosol, gleysol, vertisol, argillisol, protosol, oxisol) are characterised and include 19 pedotypes. We investigated the south-eastern and northwestern fossiliferous regions, which show very different sedimentary sequences. The characterisation of successive pedoclimatic contexts and toposequences enables us to reconstruct the local palaeogeography and informs about the climate (mainly influenced by south-eastern Asia monsoon cycles) that prevailed during the periods of palaeosoil development. The first fully terrestrial levels were identified at the base of the upper Pucangan unit, corresponding to the development of an open landscape on earlier sites of wide coastal swamps. Higher up in the series, environments are indicative of a contrasted seasonal climate with a long dry season, alternate with periods of more humid palustrine conditions. Recurrent aridity proxies are then found in the overlying Grenzbank and Kabuh series (both have yield the most abundant hominid fossils). Soils from these series reflect a long dry season and an open vegetation landscape, in agreement with stratigraphical and palynological observations.

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Carol, E.S., Kruse, E.E. and Pousa, J.L. (2011) Influence of the geologic and geomorphologic characteristics and of crab burrows on the interrelation between surface water and groundwater in an estuarine coastal wetland. Journal of Hydrology 403(3-4), 234-41.

 

ABSTRACT
The interrelation between surface water and groundwater in intertidal flats is often studied through mathematical models. In many cases these models need to be supported by an integral analysis of the geologic, geomorphologic, hydrologic and biological characteristics of the environment that are to be obtained from field surveys. The marshy environment of the River Ajo in the Samborombon Bay wetland, Argentina, is a typical example of an estuarine coastal zone. Geologic and geomorphologic surveys were carried out, as well as measurements of surface water and groundwater level changes as a response of the aquifer to tidal forcing. The banks of the River Ajo are either scarped with storm flats, or mildly sloped with intertidal flats and numerous crab burrows. Sediments are mainly silty-clayey with low permeability, and lie over silty-sandy layers. At the erosion scarps the tidal wave enters the aquifer as a sub-horizontal flow through the pore space of the sediments. The tidal range in the aquifer depends on the lithological characteristics of the sediments and on the side changes of their hydraulic conductivity. The rise of the water table at high water and its subsequent fall are nearly sinusoidal, with a period similar to that of the tide at the river. At the intertidal flats, instead, the tidal wave enters the aquifer mainly as a sub-vertical flow through the crab burrows. As the crab burrows are not interconnected, they are not distinct pathways for preferential flow. Therefore, the groundwater flux into the river is very slow during low water, and the recovery of the water table takes a long time. The tidal influence upon the water table on both kinds of banks affects only a narrow strip of the aquifer. Not only are the characteristics of the marshy environment of the River Ajo representative of most of the Samborombon Bay wetland; they can also be extended to other similar coastal wetlands to help preserve these invaluable environments.

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Chin, D.A. (2011) Hydraulic Resistance versus Flow Depth in Everglades Hardwood Halos. Wetlands 31(5), 989-1002.

 

ABSTRACT
The variation of the Manning roughness with flow depth in two hardwood-dominated vegetation halos that surround water-delivery structures in Everglades National Park was investigated. The results show that the hydraulic resistance of the halos decreases approximately linearly with increasing flow depth. For flow depths less than 15-20 cm, the hydraulic resistance is similarly high in both the halo and the downstream marsh vegetation, however, as the flow depth increases the hydraulic resistance in the halo decreases to below that in the downstream marsh. As a consequence, for increased stages at the delivery structure, the halo vegetation will become less restrictive relative to the marsh vegetation in controlling water deliveries.

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Chin, D.A., Kelly, P.M., Kiger, R.T. and Sonenshein, R.S. (2011) Assessing the Effectiveness of Spreader Canals in Delivering Water to Marshes.
Journal of Hydrologic Engineering 16(10), 829-36.

 

ABSTRACT
Single-species flow-through toxicity tests were conducted to determine the times-to-death of two indigenous fish to South Florida-least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis)-from acute exposure to endosulfan sulfate. Mortalities were recorded within 8-h periods from test initiation to termination at 96 h. The 96-h LC(50)s for least killifish and mosquitofish estimated using the trimmed-Spearman-Karber method were 2.0 and 2.3 mu g/l, respectively. An accelerated failure time model was used to estimate times to death at selected concentrations. Data were fit to log-normal, log-logistic, and Weibull distributions. Acute toxicity data fit to the Weibull distribution produced a better relative fit than log-normal or log-logistic distributions for both toxicity tests. The survival-time profiles and associated statistics illustrate the benefit of considering exposure duration as well as concentration when predicting acute risk to species' populations. Both toxicity tests had similar outcomes from exposure to endosulfan sulfate, with least killifish being slightly more likely to die at lower concentrations and shorter time periods than mosquitofish. From the models generated by the toxicity tests, times-to-death for least killifish and mosquitofish were estimated for environmentally relevant concentrations of total endosulfan at a site of concern in South Florida. When the results from the current toxicity tests were compared to environmental concentrations from previous screening-level ecological risk assessments, the durations necessary to potentially kill 10% or more of the populations of the two native south Florida fish species were estimated to be 77 and 96 h for least killifish and mosquitofish, respectively. However, the exposure values included the alpha and beta isomers as well as endosulfan sulfate; therefore, an understanding of their toxicity might be important in understanding the survival dynamics of fish species in endosulfan sulfate-contaminated sites
KEYWORDS:
south Florida; pesticides; sediment; everglades; mortality; canals

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Chin, D.A., Kelly, P.M., Kiger, R.T. and Sonenshein, R.S. (2011) Assessing the Effectiveness of Spreader Canals in Delivering Water to Marshes. Journal of Hydrologic Engineering 16(10), 829-36.

 

ABSTRACT
Hydrodynamic modeling is usually necessary for predicting water deliveries to marshes from source reservoirs. A novel approach is developed that decouples the delivery structure hydraulics from the marsh hydrodynamics, allowing these components to be analyzed both separately and in combination. This approach is applied to assess the effectiveness of incorporating spreader canals into water delivery systems in Everglades National Park. The results show that Manning's n in the marsh can be reasonably approximated as a function of VR, in which V is the flow velocity and R is the hydraulic radius; spreader canals can provide substantial percentage increases in water deliveries compared to the smaller structure tailwater pools, and spreader canal outflows can be linear functions of the length of the spreader canal. DOI: 10.1061/(ASCE)HE.1943-5584.0000369.

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Chui, T.F.M., Low, S.Y. and Liong, S.Y. (2011) An ecohydrological model for studying groundwater-vegetation interactions in wetlands. Journal of Hydrology 409(1-2), 291-304.

 

ABSTRACT
Despite their importance to the natural environment, wetlands worldwide face drastic degradation from changes in land use and climatic patterns. To help preservation efforts and guide conservation strategies, a clear understanding of the dynamic relationship between coupled hydrology and vegetation systems in wetlands, and their responses to engineering works and climate change, is needed. An ecohydrological model was developed in this study to address this issue. The model combines a hydrology component based on the Richards' equation for characterizing variably saturated groundwater flow, with a vegetation component described by Lotka-Volterra equations tailored for plant growth. Vegetation is represented by two characteristic wetland herbaceous plant types which differ in their flood and drought resistances. Validation of the model on a study site in the Everglades demonstrated the capability of the model in capturing field-measured water table and transpiration dynamics. The model was next applied on a section of the Nee Soon swamp forest, a tropical wetland in Singapore, for studying the impact of possible drainage works on the groundwater hydrology and native vegetation. Drainage of 10 m downstream of the wetland resulted in a localized zone of influence within half a kilometer from the drainage site with significant adverse impacts on groundwater and biomass levels, indicating a strong need for conservation. Simulated water table-plant biomass relationships demonstrated the capability of the model in capturing the time-lag in biomass response to water table changes. To test the significance of taking plant growth into consideration, the performance of the model was compared to one that substituted the vegetation component with a pre-specified evapotranspiration rate. Unlike its revised counterpart, the original ecohydrological model explicitly accounted for the drainage-induced plant biomass decrease and translated the resulting reduced transpiration toll back to the groundwater hydrology for a more accurate soil water balance. This study represents, to our knowledge, the first development of an ecohydrological model for wetland ecosystems that characterizes the coupled relationship between variably-saturated groundwater flow and plant growth dynamics.

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Chumchal, M.M., Rainwater, T.R., Osborn, S.C., Roberts, A.P., Abel, M.T., Cobb, G.P., Smith, P.N. and Bailey, F.C. (2011) Mercury speciation and biomagnification in the food web of caddo lake, Texas and Louisiana, USA, a subtropical freshwater ecosystem. Environmental Toxicology and Chemistry 30(5), 1153-62.

 

ABSTRACT
We studied the biomagnification of total mercury and methylmercury in a subtropical freshwater lake, Caddo Lake, Texas and Louisiana, USA. The present study is unique in that it not only included invertebrates (seven species) and fish (six species) but also an amphibian (one species), reptiles (three species), and mammals (three species). Nonfish vertebrates such as those included in the present study are often not included in assessments of trophic transfer of Hg. Mean trophic position (determined using stable isotopes of nitrogen) ranged from 2.0 (indicative of a primary consumer) to 3.8 (indicative of a tertiary consumer). Mean total Hg concentrations ranged from 36 to 3,292 ng/g dry weight in muscle and whole body and from 150 to 30,171 ng/g dry weight in liver. Most of the Hg in muscle and whole-body tissue was found as methylmercury, and at least 50% of the Hg found in liver was in the inorganic form (with the exception of largemouth bass, Micropterus salmoides). Mercury concentrations were positively correlated with trophic position, indicating that biomagnification occurs in the food web of Caddo Lake. The food web magnification factors (FWMFs; slope of the relationship between mean Hg concentration and trophic position) for both total Hg and methylmercury were similar to those observed in other studies. Because most of the total Hg in consumers was methylmercury, the FWMF for methylmercury was not significantly different from the FWMF for total Hg. Some vertebrates examined in the present study had low Hg concentrations in their tissues similar to those observed in invertebrates, whereas others had concentrations of Hg in their tissues that in previous studies have been associated with negative health consequences in fish.

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Ci, Z.J., Zhang, X.S., Wang, Z.W. and Niu, Z.C. (2011) Phase speciation of mercury (Hg) in coastal water of the Yellow Sea, China. Marine Chemistry 126(1-4), 250-55.

 

ABSTRACT
The objective of this study is to investigate the phase distribution of mercury (Hg) in water and the relative importance of processes affecting its distribution and behavior at a coastal site of the Yellow Sea with high tidal current speeds in the eastern continental margin of China. Total Hg (THg) and reactive Hg (RHg) were measured in unfiltered and filtered (0.45 mu m) water in four different seasons at 1-3 h intervals using ultra-trace Hg techniques. The Hg in this coastal water showed typical Hg-unpolluted coastal region levels. Mean (+/- SD) concentrations of THg in unfiltered water were 13.4 +/- 3.9 pM with a range of 6.7 to 27.5 pM and a considerable RHg fraction (%RHg/THg = 36.9%). Particulate Hg (PHg) was the dominant phase in unfiltered water samples (%PHg/THg = 70 +/- 11%), and the distribution coefficient (Log K(d)) of Hg in particulate and dissolved (0.45 mu m) phases averaged 4.96 +/- 0.20 with a range of 4.26 to 5.38. Enhanced suspended particulate matter (SPM) in water induced by wind and tidal mixing probably explained most of the variation in the unfiltered THg. In the dissolved phase, RHg accounted for a major fraction of THg (%RHg/THg = 86 +/- 16%). The weak correlation between dissolved organic carbon (DOC) and THg in the dissolved phase indicated that Hg in this study region might primarily originate from atmospheric deposition and also reflected the importance of other competing ligands (e.g., Cl(-)) in the water column. Interestingly, measurements covering four different seasons showed no seasonality in these Hg species. Although there was some uncertainty in the measurements, using the difference of RHg between unfiltered and dissolved samples revealed that a considerable fraction (28 +/- 19%) of RHg could bind to SPM.

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Clement, B.M., Javier, J., Sah, J.P. and Ross, M.S. (2011) The effects of wildfires on the magnetic properties of soils in the Everglades. Earth Surface Processes and Landforms 36(4), 460-66.

 

ABSTRACT
We present results of a rock-magnetic study of soils that were affected by wildfires that burned portions of the Everglades in the Spring of 2008. Soils at sites that were extensively burned exhibit a pronounced surface magnetic enhancement effect with magnetizations of surface samples up to 16 times greater than that observed at depth (>7 cm) at these sites. The increase in magnetization results from an increased abundance of a low-coercivity phase (maghemite) that occurs at the expense of the abundance of a high-coercivity phase (goethite). These results indicate that fire-induced heating caused goethite in the surface soils to convert into a more magnetic, low-coercivity phase, such as maghemite. Goethite is an excellent adsorber of phosphorus, and therefore we hypothesize that the destruction of goethite as a result of burning may have important implications for phosphorus cycling in the Everglades ecosystem.

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Cohen, M.J., Watts, D.L., Heffernan, J.B. and Osborne, T.Z. (2011) Reciprocal Biotic Control on Hydrology, Nutrient Gradients, and Landform in the Greater Everglades. Critical Reviews in Environmental Science and Technology 41, 395-429.

 

ABSTRACT
Restoration can be viewed as the process of reestablishing both exogenous drivers and internal feedbacks that maintain ecosystems in a desirable state. Correcting exogenous and abiotic drivers is clearly necessary, but may be insufficient to achieve desired outcomes in systems with self-organizing biotic feedbacks that substantially influence ecological stability and timing of responses. Evidence from a broad suite of systems demonstrates the prevalence of biotic control over key ecosystem attributes such as hydroperiod, nutrient gradients, and landform that are most commonly conceived of as exogenously controlled. While a general theory to predict conditions under which biotic controls exert such strong feedbacks is still nascent, it appears clear that the Greater Everglades/South Florida landscape has a high density of such effects. The authors focus on three examples of biotic control over abiotic processes: hydroperiod and discharge controls exerted by peat accretion in the ridge-slough landscape; phosphorus (P) gradients that emerge, at least in part, from interactions between accelerated peat accretion rates, vegetation structure and fauna; and reinforcing feedbacks among land elevation, aquatic respiration, and carbonate dissolution that produce local and landscape basin structure. The authors propose that the unifying theme of biogeomorphic landforms in South Florida is low extant topographic variability, which allows reciprocal biotic modification of local site conditions via mechanisms of peat accretion (including via effects of landscape P redistribution on primary production) or limestone dissolution. Coupling these local positive feedbacks, which drive patch expansion, with inhibitory or negative feedbacks on site suitability at distance, which serve to constrain patch expansion, provide the mechanistic basis for landscape pattern formation. The spatial attributes (range and isotropy) of the distal negative feedback, in particular, control pattern geometry; elucidating the mechanisms and properties of these distal feedbacks is critical to restoration planning.

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Collado-Vides, L., Mazzei, V., Thyberg, T. and Lirman, D. (2011) Spatio-temporal patterns and nutrient status of macroalgae in a heavily managed region of Biscayne Bay, Florida, USA. Botanica Marina 54(4), 377-90.

 

ABSTRACT
The coastal bays of South Florida are located downstream of the Florida Everglades, where a comprehensive restoration plan will strongly impact the hydrology of the region. Submerged aquatic vegetation communities are common components of benthic habitats of Biscayne Bay, and will be directly affected by changes in water quality. This study explores community structure, spatio-temporal dynamics, and tissue nutrient content of macroalgae to detect and describe relationships with water quality. The macroalgal community responded to strong variability in salinity; three distinctive macroalgal assemblages were correlated with salinity as follows: (1) low-salinity, dominated by Chara hor-nemannii and a mix of filamentous algae; (2) brackish, dominated by Penicillus capitatus, Batophora oerstedii, and Acetabularia schenckii; and (3) marine, dominated by Halimeda incrassata and Anadyomene stellata. Tissue-nutrient content was variable in space and time but tissues at all sites had high nitrogen and N:P values, demonstrating high nitrogen availability and phosphorus limitation in this region. This study clearly shows that distinct macroalgal assemblages are related to specific water quality conditions, and that macroalgal assemblages can be used as community-level indicators within an adaptive management framework to evaluate performance and restoration impacts in Biscayne Bay and other regions where both freshwater and nutrient inputs are modified by water management decisions.

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Corrales, J., Naja, G.M., Dziuba, C., Rivero, R.G. and Orem, W. (2011) Sulfate threshold target to control methylmercury levels in wetland ecosystems. Science of the Total Environment 409(11), 2156-62.

 

ABSTRACT
Sulfate contamination has a significant environmental implication through the stimulation of toxic hydrogen sulfide and methylmercury (MeHg) production. High levels of MeHg are a serious problem in many wetland ecosystems worldwide. In the Florida Everglades, it has been demonstrated that increasing MeHg occurrence is due to a sulfate contamination problem. A promising strategy of lowering the MeHg occurrence is to reduce the amount of sulfate entering the ecosystem. High surface water sulfate concentrations in the Everglades are mainly due to discharges from the Everglades Agricultural Area (EAA) canals. Water and total sulfur mass balances indicated that total sulfur released by soil oxidation. Lake Okeechobee and agricultural application were the major sources contributing 49,169, 35,217 and 11,775 mtons year(-1), respectively. Total sulfur loads from groundwater, levees, and atmospheric deposition contributed to a lesser extent: 4055: 5858 and 4229 mtons year(-1) respectively. Total sulfur leaving the EAA into Water Conservation Areas (WCAs) through canal discharge was estimated at 116,360 mtons year(-1), and total sulfur removed by sugarcane harvest accounted for 23,182 mtons year(-1). Furthermore, a rise in the mineral content and pH of the EAA soil over time, suggested that the current rates of sulfur application would increase as the buffer capacity of the soil increases. Therefore, a site specific numeric criterion for sulfate of 1 mg L(-1) was recommended for the protection of the Everglades; above this level, mercury methylation is enhanced. In parallel, sulfide concentrations in the EAA exceeded the 2 mu g L(-1) criterion for surface water already established by the U.S. Environmental Protection Agency (EPA).

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Crescenzo, D.L. (2011) An Everglades Providence: Marjory Stoneman Douglas and the American Environmental Century. Organization & Environment 24(1), 92-94.

 

ABSTRACT (none)

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Criales, M.M., Robblee, M.B., Browder, J.A., Cardenas, H. and Jackson, T.L. (2011) Observation on selective tidal-stream transport for postlarval and juvenile pink shrimp in Florida Bay. Journal of Crustacean Biology 31(1), 26-33.

 

ABSTRACT
Post larvae and juveniles of pink shrimp were collected in the summers of 2005 and 2006 at three stations in northwestern Florida Bay. the main nursery ground of this species in South Florida. Collections were made at one- or two-hour intervals during three full moon nights and two new moon nights at depth intervals in the water column. Results of the five collections were consistent with the assumption that postlarvae use a flood-tide transport (FTT) to advance into the estuary by ascending in the water column during the dark-flood tide and resting near the bottom during the ebb tide. Evidence of a FTT were higher numbers of postlarvae per hour collected during the flood tide vs. ebb tide and the large number of postlarvae collected with highest velocity flood tide currents. ANOVA indicated significant differences in the number of postlarvae collected between tidal stages and moon phases, but not among depths. Post larvae were more abundant during new moon than full moon. We also found different patterns of postlarval distribution between the new and full moon. During the new moon, a large peak of postlarvae occurred coincident with highest current speeds, whereas, with one exception, during the full moon postlarvae were more abundant in the second half of the flood period near the slack tide. In contrast, juveniles exhibited a behavior and migratory pattern opposite to that of postlarvae. ANOVA indicated significant differences between the number of juveniles captured between tidal stages and among depths, but not between moon phases. Juveniles were found almost exclusively near the surface on the ebb tide. Significantly larger juveniles were captured on the dark-ebb rather than on the dark-flood tide during both moon phases, suggesting that older juveniles were leaving the Bay on the ebb tide.

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Daroub, S.H., Van Horn, S., Lang, T.A. and Diaz, O.A. (2011) Best Management Practices and Long-Term Water Quality Trends in the Everglades Agricultural Area. Critical Reviews in Environmental Science and Technology 41, 608-32.

 

ABSTRACT
The Everglades Agricultural Area (EAA) in South Florida, part of the historical Everglades, was initially drained in the early 20th century for agriculture and flood protection. The organic soils have been subject to subsidence caused by organic matter oxidation. Soils are deeper east of Lake Okeechobee compared to soils south of the lake. The area is mostly planted to sugarcane and other crops such as rice, vegetables, and sod. Concerns about quality of water leaving the EAA led to a regulatory program for mandatory best management practices (BMP) since 1995 to reduce phosphorus (P) loads out of the EAA by 25% compared to historical levels. The program is highly successful, with 100% grower participation and exceeding P load reduction required by law. Trend analysis conducted on selected EAA farms, subbasins, and whole basin show, in general, decreasing trends in P concentrations, drainage flow, and P loads. Differences are noted between farms and subbasins due to factors that include rainfall distribution, water management practices, irrigation water quality, soil type/depth, and cropping systems. Water management practices were the dominant factors affecting P loads out of the EAA. Water management research that targets farms with deeper soils is recommended to achieve additional P load reductions. Other practices to improve BMP performance include minimizing generation and transport of sediments from farm canals. The quality of irrigation water from Lake Okeechobee is of concern of its impact on BMP performance.

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DeBusk, T.A., Kharbanda, M., Jackson, S.D., Grace, K.A., Hileman, K. and Dierberg, F.E. (2011) Water, vegetation and sediment gradients in submerged aquatic vegetation mesocosms used for low-level phosphorus removal. Science of the Total Environment 409(23), 5046-56.

 

ABSTRACT
Gradients in phosphorus (P) removal and storage were investigated over 6 years using mesocosms (each consisting of three tanks in series) containing submerged aquatic vegetation (SAV) grown on muck and limerock (LR) substrates. Mean inflow total P concentrations (TP) of 32 mu g L(-1) were reduced to 15 and 17 mu g L(-1) in the muck and LR mesocosms, respectively. Mesocosm P loading rates (mean = 1.75 g m(-2) year(-1)) varied widely during the study and were not correlated with outflow TP, which instead varied seasonally with lowest monthly mean values in December and January. The mesocosms initially were stocked with Najas guadalupensis, Ceratophyllum demersum, and Chara zeylanica, but became dominated by C zeylanica. At the end of the study, highest vegetative biomass (1.1 and 1.4 kg m(-2) for muck and LR substrates) and tissue P content (1775 and 1160 mg kg(-1)) occurred in the first tank in series, and lowest biomass (1.0 and 02 kg m(-2)) and tissue P (147 and 120 mg kg(-1)) in the third tank Sediment accretion rates (2.5, 1.9 and 0.9 cm yr(-1) on muck substrates), accrued sediment TP (378, 309 and 272 mg kg(-1)), and porewater soluble reactive P (SRP) concentrations (40, 6 and 4 mu g L(-1)) in the first, second and third tanks, respectively, exhibited a similar decreasing spatial trend. Plant tissue calcium (Ca) near mesocosm inflow (19-30% dry weight) and outflow (23-26%) were not significantly different, and sediment Ca was also similar (range of 24 to 28%) among sequential tanks. Well-defined vegetation and sediment enrichment gradients developed in SAV wetlands operated under low TP conditions. While the mesocosm data did not reflect deterioration in treatment performance over 6 years, accumulation of P-enriched sediments near the inflow could eventually compromise hydraulic storage and P removal effectiveness of these shallow systems.

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Deonarine, A., Lau, B.L.T., Aiken, G.R., Ryan, J.N. and Hsu-Kim, H. (2011) Effects of Humic Substances on Precipitation and Aggregation of Zinc Sulfide Nanoparticles. Environmental Science & Technology 45(8), 3217-23.

 

ABSTRACT
Nanoparticulate metal sulfides such as ZnS can influence the transport and bioavailability of pollutant metals in anaerobic environments. The aim of this work was to investigate how the composition of dissolved natural organic matter (NOM) influences the stability of zinc sulfide nanoparticles as they nucleate and aggregate in water with dissolved NOM. We compared NOM fractions that were isolated from several surface waters and represented a range of characteristics including molecular weight, type of carbon, and ligand density. Dynamic light scattering was employed to monitor the growth and aggregation of Zn-S-NOM nanoparticles in supersaturated solutions containing dissolved aquatic humic substances. The NOM was observed to reduce particle growth rates, depending on solution variables such as type and concentration of NOM, monovalent electrolyte concentration, and pH. The rates of growth increased with increasing ionic strength, indicating that observed growth rates primarily represented aggregation of charged Zn-S-NOM particles. Furthermore, the observed rates decreased with increasing molecular weight and aromatic content of the NOM fractions, while carboxylate and reduced sulfur content had little effect. Differences between NOM were likely due to properties that increased electrosteric hindrances for aggregation. Overall, results of this study suggest that the composition and source of NOM are key factors that contribute to the stabilization and persistence of zinc, sulfide nanoparticles in the aquatic environment.

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Dierberg, F.E., DeBusk, T.A., Larson, N.R., Kharbanda, M.D., Chan, N. and Gabriel, M.C. (2011) Effects of sulfate amendments on mineralization and phosphorus release from South Florida (USA) wetland soils under anaerobic conditions. Soil Biology & Biochemistry 43(1), 31-45.

 

ABSTRACT
We investigated the potential effects of elevated water-column sulfate (SO(4)) levels on heterotrophic microbial respiration and net phosphorus (P) release for soils collected from impacted and unimpacted Everglades wetlands in south Florida. Soils from three sites, ranging from low P and low SO(4) to high P and high SO(4) environments, were examined under controlled laboratory conditions. The soils were subjected to anaerobic incubations to evaluate net P release and organic matter decomposition in response to SO(4) amendments of 32 or 96 mg l(-1) (0.33 and 1.0 mM). Three processes have been described in the literature to explain why SO(4) enrichment may lead to P release from soils under anaerobic conditions. First, alkalinization can lead to a more favorable pH environment for decomposition. For the soils examined here, alkalinization due to the hydrogen ion-consuming reaction of SO(4) reduction was not a prominent mechanism. We found that pH decreased in the incubation vessels, and that increases in alkalinity were more likely attributable to calcium carbonate dissolution than SO(4) reduction. Moreover, all the soils exhibited near circum-neutral pH levels, with moderate to high concentrations of native alkalinity. Second, formation of iron sulfide (FeS(x)) compounds has been shown to mobilize iron (Fe)-associated P. Soils from only one of the study sites had Fe concentrations that would be expected to be high enough to influence P mobility. Relatively high porewater Fe:soluble reactive P (SRP) ratios (>83:1) were observed at this site, which suggests that Fe could theoretically exert control over the release of P from the soil. However, soil P levels at this site were too low to measure any substantial influence of Fe on net P mobilization. Finally, availability of electron acceptors such as SO(4) is a major determinant of decomposition rate, and thus rate of organic P release. Amending the soils with SO(4) did not result in either more heterotrophic microbial respiration as measured by carbon dioxide (CO(2)) and methane (CH(4)) production, or increased net P mobilization. In two of the Sal-amended soils where post-incubation total sulfide concentrations were as high as 23.4 mg l(-1). SO(4) addition reduced production of respiratory carbon end products, suggesting hydrogen sulfide inhibition. Moreover, limitations imposed by substrate quality and low P contributed to the lack of meaningful enhanced decomposition of organic matter with the addition of 32 or 96 mg SO(4) l(-1) to the oligotrophic wetland soils. Even though P release did occur under anaerobic conditions for the more enriched site, addition of SO(4) did not enhance P release.

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Dixon, A.D., Cox, W.R., Everham III, E.M. and Ceilley, D.W. (2011) Anurans as Biological Indicators of Restoration Success in the Greater Everglades Ecosystem. Southeastern Naturalist 10(4), 629-46.

  ABSTRACT
The Picayune Strand Restoration Project is being conducted as part of the Comprehensive Everglades Restoration Plan to restore hydrology and habitat in Southwest Florida. This study evaluated the success of the restoration activities by examining anuran species richness and relative abundance in relation to various restoration treatments, which included restored areas, un-restored areas, and natural wetlands. Anuran observations were conducted using nocturnal audible call surveys and dip netting. Univariate results indicated that: the lowest species richness and relative abundance values occurred within the un-restored areas, richness signifi cantly increased in all restored areas relative to un-restored areas, abundance increased in some restored areas but not others, and highest richness and abundance were documented in the natural wetlands. Multivariate analysis confi rmed these patterns and also indicated that the anuran species assemblages were signifi cantly different between restoration treatments. Furthermore, the presence or absence of Lithobates sphenocephalus utricularius (Southern Leopard Frog), Gastrophryne carolinensis (Eastern Narrow-mouthed Toad), and Hyla femoralis (Pine Woods Treefrog) may be used to document restoration success or hydrologic disturbance, respectively. These fi ndings suggest that the restoration activities can be effective and that anurans could be used as performance

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D'Odorico, P., Engel, V., Carr, J.A., Oberbauer, S.F., Ross, M.S. and Sah, J.P. (2011) Tree-Grass Coexistence in the Everglades Freshwater System. Ecosystems 14(2), 298-310.

 

ABSTRACT
Mosaic freshwater landscapes exhibit tree-dominated patches -or tree islands-interspersed in a background of marshes and wet prairies. In the Florida Everglades, these patterned landscapes provide habitat for a variety of plant and animal species and are hotspots of biodiversity. Even though the emergence of patchy freshwater systems has been associated with climate histories, fluctuating hydrologic conditions, and internal feedbacks, a process-based quantitative understanding of the underlying dynamics is still missing. Here, we develop a mechanistic framework that relates the dynamics of vegetation, nutrients and soil accretion/loss through ecogeomorphic feedbacks and interactions with hydrologic drivers. We show that the stable coexistence of tree islands and marshes results as an effect of their both being (meta-) stable states of the system. However, tree islands are found to have only a limited resilience, in that changes in hydrologic conditions or vegetation cover may cause an abrupt shift to a stable marsh state. The inherent non-linear and discontinuous dynamics determining the stability and resilience of tree islands should be accounted for in efforts aiming at the management, conservation and restoration of these features.

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Dong, W.M., Bian, Y.R., Liang, L.Y. and Gu, B.H. (2011) Binding Constants of Mercury and Dissolved Organic Matter Determined by a Modified Ion Exchange Technique. Environmental Science & Technology 45(8), 3576-83.

 

ABSTRACT
Ion-exchange techniques have been widely used for determining the conditional stability constants (logK) between dissolved organic matter (DOM) and various metal ions in aqueous solution. An exception is mercuric ion, Hg(2+), whose exceedingly strong binding with reduced sulfur or thiol-like functional groups in DOM makes the ion exchange reactions difficult. Using a Hg-selective thiol resin, we have developed a modified ion-exchange technique which overcomes this limitation. This technique allows not only the determination of binding constants between Hg(2+) and DOM of varying origins, but also the discrimination of complexes with varying coordination numbers [i.e., 1:1 and 1:2 Hg:thiol-ligand (HgL) complexes]. Measured logK values of four selected DOM isolates varied slightly from 21.9 to 23.6 for 1:1 HgL complexes, and from 30.1 to 31.6 for 1:2 HgL(2) complexes. These results suggest similar binding modes that are likely occurring between Hg(2+) and key thiolate functional groups in DOM particularly at a relatively low Hg to DOM ratio. Future studies should further elucidate the nature and precise stoichiometries of binding between Hg(2+) and DOM at environmentally relevant concentrations.

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Dorcas, M.E., Willson, J.D. and Gibbons, J.W. (2011) Can invasive Burmese pythons inhabit temperate regions of the southeastern United States? Biological Invasions 13(4), 793-802.

 

ABSTRACT
Understanding potential for range expansion is critical when evaluating the risk posed by invasive species. Burmese pythons (Python molurus bivittatus) are established in southern Florida and pose a significant threat to native ecosystems. Recent studies indicate that climate suitable for the species P. molurus exists throughout much of the southern United States. We examined survivorship, thermal biology, and behavior of Burmese pythons from South Florida in a semi-natural enclosure in South Carolina, where winters are appreciably cooler than in Florida, but within the predicted region of suitable climate. All pythons acclimated to the enclosure, but most died after failing to seek appropriate refugia during sub-freezing weather. The remaining snakes used refugia but died during an unusually cold period in January 2010. Although all snakes died during the study, most survived extended periods at temperatures below those typical of southern Florida and none exhibited obvious signs of disease. Our study represents a first step in evaluating the results of climate matching models and we address factors that may affect range expansion in this invasive species.

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Dorn, N.J., Cook, M.I., Herring, G., Boyle, R.A., Nelson, J. and Gawlik, D.E. (2011) Aquatic prey switching and urban foraging by the White Ibis Eudocimus albus are determined by wetland hydrological conditions. Ibis 153(2), 323-35.

 

ABSTRACT
Prey availability is known to limit reproduction of some species of nesting birds, but identifying the primary prey types of a species with a flexible diet can be challenging. For the White Ibis Eudocimus albus, a tactile feeding, medium-sized wading bird, nestling prey composition is suggested to depend on landscape water depths/availability of foraging habitat at the time of nesting and on historical drying events affecting prey production. We collected and compared inter- and intra-annual diet variation of White Ibis chicks reared in the Everglades over two years that were independently identified as being relatively good (2006) and poor (2007) nesting seasons. We collected 127 nestling boluses and analysed the temporal variation in biomass of eight functional prey groups using multivariate techniques. The boluses from 2006 in the central Everglades were dominated by fish, but in 2007, after fish had been reduced by the previous year of drying, the boluses from the same region were more variable and dominated by garbage (i.e. scavenging). Analysis of five different collections taken from a different colony in the northern Everglades indicated that boluses were characterized by crayfish and had fewer fish or less garbage when landscape water depths were relatively higher and more preferred habitat was available. At lower landscape water depths in 2007 the bolus composition shifted away from crayfish towards small fish and urban food (terrestrial insects and garbage). Our results support the suggestion of depth-dependent diets; prey composition depends on the current landscape water levels around the colonies, and also suggests that previous drying events can lead to increased reliance on alternative food sources. White Ibis partially compensated for unavailable aquatic prey with alternative urban foods, but their nesting success appears to have suffered.

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Dove, C.J., Snow, R.W., Rochford, M.R. and Mazzotti, F.J. (2011) Birds consumed by the invasive burmese python (Python molurus bivittatus) in Everglades National Park, Florida, USA. Wilson Journal of Ornithology 123(1), 126-31.

 

ABSTRACT
We identified 25 species of birds representing nine avian Orders from remains in digestive tracts of 85 Burmese pythons (Python molurus bivittatus) collected in Everglades National Park, Florida, USA, from 2003 to 2008. Four species of birds identified in this study are of special concern in Florida and a fifth, the Wood Stork (Mycteria americana), is listed as federally endangered. This represents the first detailed analysis of the avian component of the diet of the introduced Burmese python, now established in Everglades National Park, Florida and highlights the potential for considerable negative impact of this invasive species on native bird populations.

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Dunlop-Hayden, K.L. and Rehage, J.S. (2011) Antipredator behavior and cue recognition by multiple Everglades prey to a novel cichlid predator. Behaviour 148(7), 795-823.

 

ABSTRACT
Novel predator introductions are thought to have a high impact on native prey, especially in freshwater systems. Prey may fail to recognize predators as a threat, or show inappropriate or ineffective responses. The ability of prey to recognize and respond appropriately to novel predators may depend on the prey's use of general or specific cues to detect predation threats. We used laboratory experiments to examine the ability of three native Everglades prey species (Eastern mosquitofish, flagfish and riverine grass shrimp) to respond to the presence, as well as to the chemical and visual cues of a native predator (warmouth) and a recently-introduced non-native predator (African jewelfish). We used prey from populations that had not previously encountered jewelfish. Despite this novelty, the native warmouth and non-native jewel fish had overall similar predatory effects, except on mosquitofish, which suffered higher warmouth predation. When predators were present, the three prey taxa showed consistent and strong responses to the non-native jewelfish, which were similar in magnitude to the responses exhibited to the native warmouth. When cues were presented, fish prey responded largely to chemical cues, while shrimp showed no response to either chemical or visual cues. Overall, responses by mosquitofish and flagfish to chemical cues indicated low differentiation among cue types, with similar responses to general and specific cues. The fact that antipredator behaviours were similar toward native and non-native predators suggests that the susceptibility to a novel fish predator may be similar to that of native fishes, and prey may overcome predator novelty, at least when predators are confamilial to other common and longer-established non-native threats.

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Espinar, J.L., Ross, M.S. and Sah, J.P. (2011) Pattern of nutrient availability and plant community assemblage in Everglades Tree Islands, Florida, USA. Hydrobiologia 667(1), 89-99.

 

ABSTRACT
We address the relative importance of nutrient availability in relation to other physical and biological factors in determining plant community assemblages around Everglades Tree Islands (Everglades National Park, Florida, USA). We carried out a one-time survey of elevation, soil, water level and vegetation structure and composition at 138 plots located along transects in three tree islands in the Park's major drainage basin. We used an RDA variance partitioning technique to assess the relative importance of nutrient availability (soil N and P) and other factors in explaining herb and tree assemblages of tree island tail and surrounded marshes. The upland areas of the tree islands accumulate P and show low N concentration, producing a strong island-wide gradient in soil N:P ratio. While soil N:P ratio plays a significant role in determining herb layer and tree layer community assemblage in tree island tails, nevertheless part of its variance is shared with hydrology. The total species variance explained by the predictors is very low. We define a strong gradient in nutrient availability (soil N:P ratio) closely related to hydrology. Hydrology and nutrient availability are both factors influencing community assemblages around tree islands, nevertheless both seem to be acting together and in a complex mechanism. Future research should be focused on segregating these two factors in order to determine whether nutrient leaching from tree islands is a factor determining community assemblages and local landscape pattern in the Everglades, and how this process might be affected by water management.

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Fan, X.H., Gu, B.H., Hanlon, E.A., Li, Y.C., Migliaccio, K. and Dreschel, T.W. (2011) Investigation of long-term trends in selected physical and chemical parameters of inflows to Everglades National Park, 1977-2005. Environmental Monitoring and Assessment 178(1-4), 525-36.

 

ABSTRACT
Data of seven water-quality parameters from inflows to the Everglades National Park were collected at three monitoring stations and analyzed for temporal trends. The best-fit models for the existence of trends were evaluated. The Kolmogorov-Smirnov test was used to select the theoretical distribution which best fit the data. Simple regression was used to examine the parameters for concentration-discharge relationships. The power and linear models were found to better describe the concentration-discharge relationships. Loess trend lines indicated a similar trend period of color value change during the selected period at three stations. The sharp decrease in color after 1990 at each station is consistent with the beneficial impacts of control measures, which include Best Management Practices implementation in the Everglades Agricultural Area, water management improvement, and the construction of additional stormwater treatment areas. The existence of trend analysis was performed by using the uncensored seasonal Kendall test. Conductivity and color decreased significantly at two (S12A and S333) of three stations. Alkalinity decreased significantly at S333. A "best-fit" model was selected to describe a trend change with statistical significance; the second-order equation provides a better description of the trend. This study also indicates that by using the routinely measured water-quality parameters, it may be easier to quantify the changes in water quality to aid in making water resources management decisions.

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Fell, J.W., Statzell-Tallman, A., Scorzetti, G. and Gutierrez, M.H. (2011) Five new species of yeasts from fresh water and marine habitats in the Florida Everglades. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology 99(3), 533-49.

 

ABSTRACT
Yeast populations in the Shark River Slough of the Florida Everglades, USA, were examined during a 3-year period (2002-2005) at six locations ranging from fresh water marshes to marine mangroves. Seventy-four described species (33 ascomycetes and 41 basidiomycetes) and an approximately equal number of undescribed species were isolated during the course of the investigation. Serious human pathogens, such as Candida tropicalis, were not observed, which indicates that their presence in coastal waters is due to sources of pollution. Some of the observed species were widespread throughout the fresh water and marine habitats, whereas others appeared to be habitat restricted. Species occurrence ranged from prevalent to rare. Five representative unknown species were selected for formal description. The five species comprise two ascomycetes: Candida sharkiensis sp. nov. (CBS 11368(T)) and Candida rhizophoriensis sp. nov. (CBS 11402(T)) (Saccharomycetales, Metschnikowiaceae), and three basidiomycetes: Rhodotorula cladiensis sp. nov. (CBS 10878(T)) in the Sakaguchia clade (Cystobasidiomycetes), Rhodotorula evergladiensis sp. nov. (CBS 10880(T)) in the Rhodosporidium toruloides clade (Microbotryomycetes, Sporidiobolales) and Cryptococcus mangaliensis sp. nov. (CBS 10870(T)) in the Bulleromyces clade (Agaricomycotina, Tremellales).

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Fitz, H.C., Kiker, G.A. and Kim, J.B. (2011) Integrated Ecological Modeling and Decision Analysis Within the Everglades Landscape. Critical Reviews in Environmental Science and Technology 41, 517-47.

 

ABSTRACT
Planning for complex ecosystem restoration projects involves integrating ecological modeling with analysis of performance trade-offs among restoration alternatives. The authors used the Everglades Landscape Model and Multi-Criteria Decision Analysis to explore the effect of simulated ecosystem performance, risk preferences, and criteria weights on the ranking of three alternatives to restoring overland sheet flow in the Everglades. The ecological model outputs included both hydrologic and water quality criteria. Results were scored in the decision analysis framework, highlighting the trade-offs between hydrologic restoration and water quality constraints. Given equal weighting of performance measures, the alternative with more homogenous sheet flow was preferred over other alternatives, despite evidence of some localized eutrophication risk.

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Frankovich, T.A., Morrison, D. and Fourqurean, J.W. (2011) Benthic Macrophyte Distribution and Abundance in Estuarine Mangrove Lakes and Estuaries: Relationships to Environmental Variables. Estuaries and Coasts 34(1), 20-31.

 

ABSTRACT
Annual mean salinity, light availability, and sediment depth to bedrock structured the submerged aquatic vegetation (SAV) communities in subtropical mangrove-lined estuaries. Three distinct SAV communities (i.e., Chara group, Halodule group, and Low SAV coverage group) were identified along the Everglades-Florida Bay ecotone and related to water quality using a discriminant function model that predicted the type of plant community at a given site from salinity, light availability, and sediment depth to bedrock. Mean salinity alone was able to correctly classify 78% of the sites and reliably separated the Chara group from the Halodule group. The addition of light availability and sediment depth to bedrock increased model accuracy to 90% and further distinguished the Chara group from the Halodule group. Light availability was uniquely valuable in separating the Chara group from the Low SAV coverage group. Regression analyses identified significant relationships between phosphorus concentration, phytoplankton abundance, and light availability and suggest that a decline in water transparency, associated with increasing salinity, may have also contributed to the historical decline of Chara communities in the region. This investigation applies relationships between environmental variables and SAV distribution and provides a case study into the application of these general principals to ecosystem management.

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Frederick, P. and Jayasena, N. (2011) Altered pairing behaviour and reproductive success in white ibises exposed to environmentally relevant concentrations of methylmercury. Proceedings of the Royal Society B - Biological Sciences 278(1713), 1851-57.

 

ABSTRACT
Methylmercury (MeHg) is the most biologically available and toxic form of mercury, and can act as a powerful teratogen, neurotoxin and endocrine disruptor in vertebrates. However, mechanisms of endocrine impairment and net effects on demography of biota are poorly understood. Here, we report that experimental exposure of an aquatic bird over 3 years to environmentally relevant dietary MeHg concentrations (0.05-0.3 ppm wet weight) resulted in dose-related increases in male-male pairing behaviour (to 55% of males), and decreases in egg productivity (to 30%). Dosed males showed decreased rates of key courtship behaviours, and were approached less by courting females in comparison to control males. Within dosed groups, homosexual males showed a similar reduction when compared with dosed heterosexual males. We found an average 35 per cent decrease in fledgling production in high-dose birds over the study duration. These results are of interest because (i) MeHg exposure is experimentally tied to demographically important reproductive deficits, (ii) these effects were found at low, chronic exposure levels commonly experienced by wildlife, and (iii) effects on reproductive behaviour and sexual preference mediated by endocrine disruption represent a novel and probably under-reported mechanism by which contaminants may influence wild populations of birds.

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Frey, B., Niklaus, P.A., Kremer, J., Luscher, P. and Zimmermann, S. (2011) Heavy-Machinery Traffic Impacts Methane Emissions as Well as Methanogen Abundance and Community Structure in Oxic Forest Soils. Applied and Environmental Microbiology 77(17), 6060-68.

 

ABSTRACT
Temperate forest soils are usually efficient sinks for the greenhouse gas methane, at least in the absence of significant amounts of methanogens. We demonstrate here that trafficking with heavy harvesting machines caused a large reduction in CH(4) consumption and even turned well-aerated forest soils into net methane sources. In addition to studying methane fluxes, we investigated the responses of methanogens after trafficking in two different forest sites. Trafficking generated wheel tracks with different impact (low, moderate, severe, and unaffected). We found that machine passes decreased the soils' macropore space and lowered hydraulic conductivities in wheel tracks. Severely compacted soils yielded high methanogenic abundance, as demonstrated by quantitative PCR analyses of methyl coenzyme M reductase (mcrA) genes, whereas these sequences were undetectable in unaffected soils. Even after a year after traffic compression, methanogen abundance in compacted soils did not decline, indicating a stability of methanogens here over time. Compacted wheel tracks exhibited a relatively constant community structure, since we found several persisting mcrA sequence types continuously present at all sampling times. Phylogenetic analysis revealed a rather large methanogen diversity in the compacted soil, and most mcrA gene sequences were mostly similar to known sequences from wetlands. The majority of mcrA gene sequences belonged either to the order Methanosarcinales or Methanomicrobiales, whereas both sites were dominated by members of the families Methanomicrobiaceae Fencluster, with similar sequences obtained from peatland environments. The results show that compacting wet forest soils by heavy machinery causes increases in methane production and release.

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Fujisaki, I., Mazzotti, F.J., Dorazio, R.M., Rice, K.G., Cherkiss, M. and Jeffery, B. (2011) Estimating Trends in Alligator Populations from Nightlight Survey Data. Wetlands 31(1), 147-55.

 

ABSTRACT
Nightlight surveys are commonly used to evaluate status and trends of crocodilian populations, but imperfect detection caused by survey- and location-specific factors makes it difficult to draw population inferences accurately from uncorrected data. We used a two-stage hierarchical model comprising population abundance and detection probability to examine recent abundance trends of American alligators (Alligator mississippiensis) in subareas of Everglades wetlands in Florida using nightlight survey data. During 2001-2008, there were declining trends in abundance of small and/or medium sized animals in a majority of subareas, whereas abundance of large sized animals had either demonstrated an increased or unclear trend. For small and large sized class animals, estimated detection probability declined as water depth increased. Detection probability of small animals was much lower than for larger size classes. The declining trend of smaller alligators may reflect a natural population response to the fluctuating environment of Everglades wetlands under modified hydrology. It may have negative implications for the future of alligator populations in this region, particularly if habitat conditions do not favor recruitment of offspring in the near term. Our study provides a foundation to improve inferences made from nightlight surveys of other crocodilian populations.

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Fuller, B. (2011) Enabling problem-solving between science and politics in water conflicts: impasses and breakthroughs in the Everglades, Florida, USA. Hydrological Sciences Journal-Journal Des Sciences Hydrologiques 56(4), 576-87.

 

ABSTRACT
Water conflicts, such as the one in the Everglades, Florida, USA, are complex and dynamic, and there is no theory that yet provides a comprehensive and sufficient explanation for when and how science may be more or less effective. Using both the literature and the water conflict in the Everglades, it is argued that science is most influential in political negotiations when it is created with, not for, stakeholders. The stakeholder negotiators need to know, give feedback on, and eventually vet all stages of the scientific process, which is generating data and possible solutions for them. Such close cooperation is not easy, however. Each group has different goals, jargons, objects to represent phenomena and concepts, and different procedures for working through problems. This paper argues that the political negotiations and technical groups need to jointly create "a common playing field," with a shared purpose supported by a negotiated set of concepts, "boundary objects," and procedures and norms that they use to coordinate their work.

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Gaiser, E.E., McCormick, P.V., Hagerthey, S.E. and Gottlieb, A.D. (2011) Landscape Patterns of Periphyton in the Florida Everglades. Critical Reviews in Environmental Science and Technology 41, 92-120.

 

ABSTRACT
Periphyton is an abundant and ubiquitous feature of the Florida Everglades, often forming thick mats that blanket shallow sediments and submersed plants. They are considered to be primary ecosystem engineers in the Everglades by forming and stabilizing soils, controlling concentrations of nutrients and gases, and supplying food and structure for other organisms. Distribution patterns are related to underlying physicochemical gradients as well as those hydrologic changes imposed by water management. Because communities respond rapidly to environmental change, their use has been advocated to provide indication of system degradation or restoration. The authors review studies on the distribution of periphyton in the Everglades, highlighting major findings relevant to water management, and also areas where additional exploration is necessary.

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Gao, E. and Liu, J.S. (2011) Rapid Determination of Mercury Species in Sewage Sludge by High-Performance Liquid Chromatography On-line Coupled with Cold-Vapor Atomic-Fluorescence Spectrometry after Ultrasound-assisted Extraction. Analytical Sciences 27(6), 637-41.

 

ABSTRACT
So far, no research has been focused on the determination of organomercuries in sewage sludge. Here, an ultrasonic extraction method for the rapid determination of methylmercury (MeHg) and ethylmercury (EtHg) in sewage sludge after ultrasound-assisted extraction is proposed. Using TMA (tetramethylammonium hydroxide) as the extractant with 3.0 g copper powder, ultrasonic extraction for 30 min at 70 degrees C demonstrated to be highly efficient, and was shown a satisfied extraction efficiency for MeHg and EtHg from sewage sludge samples. Determination of mercury species was carried out by high-performance liquid chromatography on-line coupled with cold-vapor atomic fluorescence spectrometry (HPLC-CV-AFS). The obtained results from quality control samples were excellent. The proposed method was also validated by the application to five real samples. The results showed that the developed methodology was practicable and highly reliable. Due to the high toxicity of organomercuries and huge amounts of sewage sludge discharged every year, people should pay particular attention to pollutions from sewage sludge.

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Gerbig, C.A., Kim, C.S., Stegemeier, J.P., Ryan, J.N. and Aiken, G.R. (2011) Formation of Nanocolloidal Metacinnabar in Mercury-DOM-Sulfide Systems. Environmental Science & Technology 45(21), 9180-87.

 

ABSTRACT
Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., < 4 nmol Hg (mg DOM)(-1)) by combining solid phase extraction using C(18) resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 mu M total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 +/- 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 angstrom). In the presence of sulfide, mercury showed greater affinity for the C(18) resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury sulfur bonds with a longer interatomic distance (2.51-2.53 angstrom) similar to the mercury-sulfur bond distance in metacinnabar (2.53 angstrom) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg(-1)) mercury was coordinated by 2.3 +/- 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to be considered when addressing mercury biogeochemistry.

top    full text Gerlak, A.K. and Heikkilay, T. (2011) Building a Theory of Learning in Collaboratives: Evidence from the Everglades Restoration Program. Journal of Public Administration Research and Theory 21(4), 619-44.
ABSTRACT
Many of society's most vexing problems must be solved through collaborative arrangements. Growing scholarly interest in collaboratives recognizes that the capacity for collective learning may play a critical role in their success. However, limited theoretical or empirical research exists to explain how learning occurs and the conditions that support learning in this context. In this article, we draw upon a wealth of literature, ranging from organization theory, policy process and change, and network analysis, to establish a framework of collective learning to guide inquiry in learning in collaborative governance settings. We apply our learning framework to a study of learning in a collaborative ecosystem restoration program in the Florida Everglades. We use the framework to guide a study of how learning processes and products are linked within a collaborative using a case-based, inductive approach at two levels of analysis-the larger program level and the subcase level of a learning product case. Our multilevel analysis draws upon survey and interview data to examine how the framework helps diagnose the specific types of learning processes and products that emerge in this setting, as well as the factors that influence these learning processes. In doing so, the analysis illuminates theoretical propositions, not explained by the broader literature on collective learning, around the structural, social, and technological features of the collaborative, which may foster learning.

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Goutner, V., Becker, P.H., Liordos, V. and Tsachalidis, E.P. (2011) Mercury in White Stork (Ciconia ciconia) Chick Feathers from Northeastern Mediterranean Areas in Relation to Age, Brood Size, and Hatching Order. Archives of Environmental Contamination and Toxicology 61(2), 327-36.

 

ABSTRACT
Mercury (Hg) levels in white stork (Ciconia ciconia) feathers collected in the mid-1990s from five northeastern Mediterranean (Greece) areas varied, with mean ranges between 301 ng g(-1) dry weight (dw) (Pinios River) and 1911 ng g(-1) dw (Sperchios Delta). A significant increase of Hg levels in chick feathers with age (surrogated by bill size) was found in the Evros and Pinios River areas, a nonsignificant increase in the Amvrakikos Gulf and the Epirus Region, and a marginally significant decrease in the Sperchios Delta area. For combined data of 1993 and 1995, Hg concentrations did not differ significantly in relation to hatching order among broods but differed significantly in relation to brood size being higher in 4-chick broods than those in 3-chick broods. All 10 areas formed 4 groups with levels mutually significantly different. Highest levels were detected in the Evros, Axios, and Sperchios riverine areas, whereas the lowest levels occurred at Drama plain, which lacks large water bodies in its vicinity. Levels were lower than those associated with intoxication to other ciconiiform species.

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Gusyev, M.A. and Haitjema, H.M. (2011) Modeling flow in wetlands and underlying aquifers using a discharge potential formulation. Journal of Hydrology 408(1-2), 91-99.

 

ABSTRACT
An accurate assessment of water and nutrient balances in large scale wetland systems such as the Florida Everglades requires conjunctive modeling of surface water flow in wetlands and groundwater flow in underlying aquifers. Earlier work was based on the finite difference code MODFLOW with a special "wetlands package." This model treats the wetland flow as laminar with a very high transmissivity that is proportional to the wetland water depth cubed. However, these MODFLOW solutions appear sensitive to this highly non-linear wetland transmissivity, particularly under conditions of low vegetation density when the model may fail to converge. We propose to formulate the governing differential equation in terms of a discharge potential instead of potentiometric heads as done in MODFLOW, but otherwise using the same assumptions as in its wetlands package. We tested our approach on a few cases of one- and two-dimensional flow, both with a constant and a varying wetland bottom elevation. For the latter the discharge potential represents an irrotational part of the flow field which is combined with a component of the flow field that contains the curl. We found that both the robustness and the accuracy of the solution in terms of potentials was superior to the solution in terms of heads. In some cases the latter solution failed altogether, even for simple one-dimensional flow. We applied our method to model the effects of wetland hydrology on the nutrient redistribution in and near tree islands. We found that the subtle velocity distributions near these tree islands, as resulted from our conjunctive wetlands and groundwater flow solution, could help explain the increased nutrient depositions at these islands, particularly at the head of the islands, where, consequently, most of the vegetation occurs.

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Hagerthey, S.E., Bellinger, B.J., Wheeler, K., Gantar, M. and Gaiser, E. (2011) Everglades Periphyton: A Biogeochemical Perspective. Critical Reviews in Environmental Science and Technology 41, 309-43.

 

ABSTRACT
Periphyton is an important component of the Everglades biogeochemical cycle but remains poorly understood. From a biogeochemical perspective, periphyton is a dense aggregation of diverse microorganisms (autotrophic and heterotrophic) and particles (mineral and detrital) imbedded within an extracellular matrix. The authors synthesize Everglades periphyton biogeochemistry and diversity at the ecosystem and community scales. The primary regulator of biogeochemical processes (material flux, transformation, and storage) is photosynthesis, which controls oxidation-reduction potentials and heterotrophic metabolism. Eutrophication and hydrologic alterations have resulted in fundamental periphyton biogeochemical differences. Elucidation of these processes is required to predict and interpret responses to ecosystem restoration.

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Hamelin, S., Amyot, M., Barkay, T., Wang, Y.P. and Planas, D. (2011) Methanogens: Principal Methylators of Mercury in Lake Periphyton. Environmental Science & Technology 45(18), 7693-700.

 

ABSTRACT
Mercury methylation and demethylation rates were measured in periphyton biofilms growing on submerged plants from a shallow fluvial lake located along the St. Lawrence River (Quebec, Canada). Incubations were performed in situ within macrophytes beds using low-level spikes of (199)HgO and Me(200)Hg stable isotopes as tracers. To determine which microbial guilds are playing a role in these processes, methylation/demethylation experiments were performed in the absence and presence of different metabolic inhibitors: chloramphenicol (general bacteriostatic inhibitor), molybdate (sodium molybdate, a sulfate reduction inhibitor), BESA (2-bromoethane sulfonic acid, a methanogenesis inhibitor), and DCMU (3-(3,4-dichlorophenyl)-1,1 dimethyl urea, a photosynthesis inhibitor). Active microbes of the periphytic consortium were also characterized using 16S rRNA gene sequencing. Methylation rates in the absence of inhibitors varied from 0.0015 to 0.0180 d(-1) while demethylation rates ranged from 0.083 to 0.217 d(-1), which corresponds to a net methylmercury balance of - 0.51 to 1.28 ng gDW periphyton(-1) d(-1). Methylation rates were significantly decreased by half by DCMU and chloramphenicol, totally inhibited by BESA, and were highly stimulated by molybdate. This suggests that methanogens rather than sulfate reducing bacteria were likely the primary methylators in the periphyton of a temperate fluvial lake, a conclusion supported by the detection of 16S rRNA gene sequences that were closely related to those of methanogens. This first clear demonstration of methanogens' role in mercury methylation in environmental periphyton samples expands the known diversity of microbial guilds that contribute to the formation of the neurotoxic substance methylmercury.

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Harley, G.L., Grissino-Mayer, H.D. and Horn, S.P. (2011) The dendochronology of Pinus elliottii in the lower Florida Keys: Chronology development and climate response. Tree-Ring Research 67(1), 39-50.

 

ABSTRACT
South Florida slash pine (Pious elliottii var. densa) is the southernmost pine species in the United States and the foundation species of the globally endangered pine rockland communities in south Florida. To test if slash pine produces annual growth rings in the Lower Florida Keys, we counted the number of rings on samples collected from the North Big Pine Key site (NBP), which contained a fire scar from a known wildfire and a known date for hurricane-induced tree mortality (2006 or 2007). In addition, a crossdated tree-ring chronology (1871-2009) was developed from living trees and remnant wood found at the site and compared to divisional climate data to determine how the regional climate regime influences radial growth. Our analyses demonstrated that slash pine forms anatomically distinct, annual growth rings with the consistent year-to-year variability necessary for rigorous dendrochronological studies. Response-function and correlation analysis showed that annual growth of slash pine at NBP is primarily influenced by water availability during the growing season. However, no significant correlations were found between tree growth and the Atlantic Multidecadal Oscillation or the El Nino-Southern Oscillation. Our study reveals the potential of producing high-quality dendrochronological data in southern Florida from slash pine, which should prove useful in further studies on fire history and tree phenology and for assessing the projected impacts of impending climate change on the fragile pine rockland community.

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Harris, W. (2011) Mineral Distribution and Weathering in the Greater Everglades: Implications for Restoration. Critical Reviews in Environmental Science and Technology 41, 4-27.

 

ABSTRACT
The Greater Everglades encompasses two regions of mineralogical contrastthe Lake Okeechobee Basin (LOB) and the region south of the lake that includes the Everglades and Florida Bay. Lake Okeechobee is a transition zone with mineralogical similarities to both regions. Weathering in the LOB is mainly unidirectional and flow driven, whereas in the Everglades it tends to be cyclical and driven by diurnal and seasonal biogeochemical gradients. LOB soils formed in quartz-dominated marine sediments of various ages under diverse landscape, hydrology, vegetation, and weathering intensities. Calcite and quartz are dominant south of the lake, with quartz diminishing southward. Secondary calcite forms via algal photosynthesis to become a major constituent of marl soils and periphyton. Phosphorus immobilized via periphyton formation is mainly in microbial biomass, but calcite is essential to the process. Minerals of lesser abundance can have disproportionate ecological influence. These include phyllosilicates, oxides, sulfates, sulfides, and phosphates, which have roles in turbidity and biogeochemical processes affecting the fate of P, Hg, and possibly As. Mineral-related perturbations of ecological impact include inhibited precipitation of calcite in periphyton mats, enhanced Hg methylation via sulfide formation from agricultural sulfate, and entrainment of readily-suspended minerals via construction of canals. The nature and rate of Ca-P interactions bear on the rate of ecological recovery. Understanding the dynamics of mineral redistributions is critical for effective restoration.

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Harvey, J.W., Noe, G.B., Larsen, L.G., Nowacki, D.J. and McPhillips, L.E. (2011) Field flume reveals aquatic vegetation's role in sediment and particulate phosphorus transport in a shallow aquatic ecosystem. Geomorphology 126(3-4), 297-313.

 

ABSTRACT
Flow interactions with aquatic vegetation and effects on sediment transport and nutrient redistribution are uncertain in shallow aquatic ecosystems. Here we quantified sediment transport in the Everglades by progressively increasing flow velocity in a field flume constructed around undisturbed bed sediment and emergent macrophytes. Suspended sediment < 100 mu m was dominant in the lower range of laminar flow and was supplied by detachment from epiphyton. Sediment flux increased by a factor of four and coarse flocculent sediment > 100 mu m became dominant at higher velocity steps after a threshold shear stress for bed floc entrainment was exceeded. Shedding of vortices that had formed downstream of plant stems also occurred on that velocity step which promoted additional sediment detachment from epiphyton. Modeling determined that the potentially entrainable sediment reservoir, 46 g m(-2), was similar to the reservoir of epiphyton (66 g m(-2)) but smaller than the reservoir of flocculent bed sediment (330 g m(-2)). All suspended sediment was enriched in phosphorus (by approximately twenty times) compared with bulk sediment on the bed surface and on plant stems, indicating that the most easily entrainable sediment is also the most nutrient rich (and likely the most biologically active).

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Henneberry, Y.K., Kraus, T.E.C., Fleck, J.A., Krabbenhoft, D.P., Bachand, P.M. and Horwath, W.R. (2011) Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts. Science of the Total Environment 409(3), 631-37.

 

ABSTRACT
The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however these studies used high concentrations of Hg and did not reflect naturally occurring concentrations of Hg. In this study, water collected from an agricultural drain in the Sacramento-San Joaquin Delta was filtered to isolate the dissolved organic matter (DOM) fraction. The DOM was then treated with a range of coagulant doses to determine the efficacy of removing all forms of Hg from solution. Three industrial-grade coagulants were tested: ferric chloride, ferric sulfate, and polyaluminum chloride. Coagulation removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant regarding large-scale removal of Hg at environmentally relevant concentrations.

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Herbert, D.A., Perry, W.B., Cosby, B.J. and Fourqurean, J.W. (2011) Projected Reorganization of Florida Bay Seagrass Communities in Response to the Increased Freshwater Inflow of Everglades Restoration. Estuaries and Coasts 34(5), 973-92.

 

ABSTRACT
Historic changes in water-use management in the Florida Everglades have caused the quantity of freshwater inflow to Florida Bay to decline by approximately 60% while altering its timing and spatial distribution. Two consequences have been (1) increased salinity throughout the bay, including occurrences of hypersalinity, coupled with a decrease in salinity variability, and (2) change in benthic habitat structure. Restoration goals have been proposed to return the salinity climates (salinity and its variability) of Florida Bay to more estuarine conditions through changes in upstream water management, thereby returning seagrass species cover to a more historic state. To assess the potential for meeting those goals, we used two modeling approaches and long-term monitoring data. First, we applied the hydrological mass balance model FATHOM to predict salinity climate changes in sub-basins throughout the bay in response to a broad range of freshwater inflow from the Everglades. Second, because seagrass species exhibit different sensitivities to salinity climates, we used the FATHOM-modeled salinity climates as input to a statistical discriminant function model that associates eight seagrass community types with water quality variables including salinity, salinity variability, total organic carbon, total phosphorus, nitrate, and ammonium, as well as sediment depth and light reaching the benthos. Salinity climates in the western sub-basins bordering the Gulf of Mexico were insensitive to even the largest (5-fold) modeled increases in freshwater inflow. However, the north, northeastern, and eastern sub-basins were highly sensitive to freshwater inflow and responded to comparatively small increases with decreased salinity and increased salinity variability. The discriminant function model predicted increased occurrences of Halodule wrightii communities and decreased occurrences of Thalassia testudinum communities in response to the more estuarine salinity climates. The shift in community composition represents a return to the historically observed state and suggests that restoration goals for Florida Bay can be achieved through restoration of freshwater inflow from the Everglades.

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Herring, G., Cook, M.I., Gawlik, D.E. and Call, E.M. (2011) Food availability is expressed through physiological stress indicators in nestling white ibis: a food supplementation experiment. Functional Ecology 25(3), 682-90.

 

ABSTRACT
Physiological responses to environmental stress such as adrenocortical hormones and cellular stress proteins have recently emerged as potentially powerful tools for investigating physiological effects of avian food limitation. However, little is known about the physiological stress responses of free-living nestling birds to environmental variation in food availability. 2. We experimentally tested how hydrologically mediated changes in food availability affect the physiological stress responses of juvenile white ibises Eudocimus albus in a fluctuating wetland. We provided supplementary food to free-living nestlings during 2 years with contrasting hydrologic and food availability conditions, and used plasma (PCORT) and faecal (FCORT) corticosterone and heat shock proteins (HSP60 and HSP70) from first-hatched (A-nestlings) and second-hatched (B-nestlings) to detect relatively short- to long-term responses to food limitation. 3. Nestling physiological stress responses were relatively low in all treatments during the year with optimal food availability, but PCORT, FCORT and HSP60 levels increased during the poor food year. FCORT and HSP60 responses were clearly due to nutritional condition as elevated concentrations were evident primarily in control nestlings. Significant year by hatch order interactions for both FCORT and HSP60 revealed that these increases were largely incurred by B-nestlings. FCORT and HSP60 responses were also well developed early in neonatal development and remained elevated for the duration of the experiment suggesting a chronic stress response. PCORT and HSP70 were less informative stress responses. 4. The nutritionally mediated increases in FCORT and HSP60 provide compelling evidence that white ibis nestlings can be physiologically affected by environmental food levels. FCORT and HSP60 are effective indicators of nutritional mediated stress for nestling white ibises and potentially for other species prone to capture or handling stress.

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Herring, H.K. and Gawlik, D.E. (2011) Resource Selection Functions for Wood Stork Foraging Habitat in the Southern Everglades. Waterbirds 34(2), 133-42.

 

ABSTRACT
Modeling habitat selection of species with specific foraging requirements is an effective means to evaluate landscape quality for restoration and conservation purposes. Proportional hazards regression, a discrete choice model, was used to develop resource selection functions for breeding Wood Stork in the southern Everglades during the 2006 nesting season. Wood Storks showed the highest probability of habitat selection in a narrow range of shallow water depths. The quadratic form of water depth (depth+depth(2)) was an important indicator of habitat selection with mean water depths between -25 and 25 cm receiving the highest probability of use (a negative water depth is below average ground elevation). Foraging sites within 20 km of nesting colonies were selected over farther sites. Shrub swamp, mangrove swamp and saltwater marsh vegetation types were used in higher proportions than they occurred in the landscape. Results exemplify the importance of shallow water depths near established stork breeding colonies throughout the breeding season.

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Hoang, T.C., Pryor, R.L., Rand, G.M. and Frakes, R.A. (2011) Bioaccumulation and toxicity of copper in outdoor freshwater microcosms. Ecotoxicology and Environmental Safety 74(4), 1011-20.

 

ABSTRACT
This study characterizes the effects of copper (Cu) on Florida apple snails (Pomacea paludosa) and mosquito fish (Gambusia affinis) using a replicated outdoor microcosm design. Soils used in this study were collected from two Cu-enriched citrus agricultural sites in South Florida (Agler property (AGLR) in St. Lucie County and Sunrise Boys property (SRB) in Palm Beach County) and a reference site (Equus property) in St. Lucie County. The study included a 5-week aging phase, an 11 month exposure phase, and a 3 month post-treatment (exposure) phase. The aging phase was initiated by flooding agricultural soils with rainwater in 4 m(3) fiberglass microcosm tanks. Introducing juvenile apple snails (<= 7 d old) and mosquito fish (2-3 cm) into the microcosm tanks initiated the exposure phase. Survival, growth, and reproduction of apple snails and fish, and Cu uptake in apple snails, fish, and periphyton were determined in this study. Water chemistry (e.g., dissolved Cu concentration, dissolved organic carbon and dissolved oxygen concentrations, pH, hardness, alkalinity, etc.) was measured daily or weekly during the study. Initial soil Cu concentrations in Equus, SRB, and AGLR microcosms were 7, 55, and 99 mg/kg dw, respectively. Dissolved Cu concentrations in Equus, SRB and AGLR microcosms at the beginning of the study were 3, 82, and 43 mu g/L, respectively and decreased to low saturation levels of about <= 9 mu g/L Cu after the first 3 months of the study. The decrease of dissolved Cu concentrations was likely due to the dilution of rainwater. Snail and fish mortality appeared to be higher in SRB microcosms than in Equus and AGLR microcosms. There was no significant difference in growth of the snails between treatments. Snail growth data followed the von Bertalanffy Model. The maximum shell length, shell height, and shell width of the snails calculated by the von Bertalanffy Model (L(infinity)) were 2.76, 2.05, and 2.18 cm, respectively. The maximum wet weight was 9.38 g. Growth rate (k) of the snails increased in order of shell height (0.459), shell length (0.550), and shell weight (0.598). There was no reproduction in the snails in any treatments including the reference during the exposure phase. However, Cu did not affect reproduction of fish during this period. Copper concentrations in periphyton from Equus, SRB, and AGLR microcosms ranged from 2 to 62, 31 to 371, and 13 to 478 mg/kg, respectively. Copper concentrations in fish at the beginning, days 30 and 150 of the study ranged from 3.19 to 7.53 mg/kg and were not significantly different from the different treatments. Average Cu concentrations in the soft tissue of dead snails from SRB and AGLR microcosms were 4602 mg/kg dw (ranged from 2913 to 8370 mg/kg dw) and 2824 mg/kg dw (ranged from 2118 to 3600 mg/kg dw), respectively. The Cu concentrations in the soft tissue of dead snails found in this study were higher than the tissue Cu concentrations in live aquatic organisms reported in the literature. These high Cu concentrations in edible apple snail soft tissue might pose a risk to Florida apple snail predators, including the snail kite. The post-exposure phase, with snails exposed to only water (i.e., no soils) showed depuration of copper from apple snails and reproduction in all treatments.

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Inglett, K.S., Inglett, P.W. and Reddy, K.R. (2011a) Soil Microbial Community Composition in a Restored Calcareous Subtropical Wetland.
Soil Science Society of America Journal
75(5), 1731-40.

 

ABSTRACT
Extreme restoration mechanisms can have important implications in ecosystem development. Complete soil removal during restoration of a freshwater wetland permitted the study of microbial and biogeochemical changes occurring during early development of soils in restored sites of different ages (2-, 5-, 8-, 16-yr old). We examined whether the soil microbial community composition (using phospholipid fatty acid analysis, PLFA) was related to the biogeochemical factors across the restored and the undisturbed native site. We observed (i) with accretion of organic matter there was a general shift from N limitation in younger sites to P limitation in the older sites, (ii) soil microbial communities in restored sites were different from that in the native vegetation site, (iii) seasonal variation (dry vs. wet) in microbial community composition in younger restored sites was greater than relatively older sites. Restored sites were characterized by higher relative abundance of fungal biomarkers and higher ratios of gram negative to gram positive compared to the undisturbed native site. Biomarkers for actinomycetes were positively correlated with P concentrations in soils. There did not appear to be any association between fungal biomarkers and soil P. Our results indicate that extreme restoration processes may influence the ecosystem development processes by affecting the soil microbial community composition.

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Inglett, P.W., Rivera-Monroy, V.H. and Wozniak, J.R. (2011b) Biogeochemistry of Nitrogen Across the Everglades Landscape.
Critical Reviews in Environmental Science and Technology
41, 187-216.

 

ABSTRACT
Compared to phosphorus (P), nitrogen (N) has received little attention across the Everglades landscape. Despite this lack of attention, N plays important roles in many Everglades systems, including being a significant pollutant in Florida Bay and the Gulf of Mexico, the limiting nutrient in highly P-impacted areas, and an important substrate for microbial metabolism. Storage and transport of N throughout the Everglades is dominated by organic forms, including peat soils and dissolved organic N in the water column. In general, N sources are highest in the northern areas; however, atmospheric deposition and active N2 fixation by the periphyton components are a significant N source throughout most systems. Many of the processes involved in the wetland N cycle remain unmeasured for most of the Everglades systems. In particular, the lack of in situ rates for N2 fixation and denitrification prevent the construction of system-level budgets, especially for the Southern mangrove systems where N export into Florida Bay is critical. There is also the potential for several novel N processes (e.g., Anammox) with an as yet undetermined importance for nitrogen cycling and function of the Everglades ecosystem. Phosphorus loading alters the N cycle by stimulating organic N mineralization with resulting flux of ammonium and DON, and at elevated P concentrations, by increasing rates of N2 fixation and N assimilation. Restoration of hydrology has a potential for significantly impacting N cycling in the Everglades both in terms of affecting N transport, but also by altering aerobic-anaerobic transitions at the soil-water interface or in areas with seasonal drawdowns (e.g., marl prairies). Based on the authors' understanding of N processes, much more research is necessary to adequately predict potential impacts from hydrologic restoration, as well as the function of Everglades systems as sinks, sources, and transformers of N in the South Florida landscape.

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Jalali, M. and Tabar, S.S. (2011) Chemical fractionation of phosphorus in calcareous soils of Hamedan, western Iran under different land use. Journal of Plant Nutrition and Soil Science 174(4), 523-31.

 

ABSTRACT
We investigated the effects of land uses on P distribution and availability in selected calcareous soils under different management practices. KCl-P (labile P), NaOH-P (Fe-Al-bound P), HCl-P (Ca-bound P), and residual P (Res-P) fractions at 0-30 cm depth were determined for soils planted to garlic, orchard, pasture, potato, leafy vegetables, and wheat. Trends in P distribution between chemical fractions were similar between land uses. Ca-bound P was the most abundant P fraction in the soils, constituting between 61% and 78% of the total P, whereas P associated with labile was less abundant (<2%). Soils under leafy vegetables and wheat along with pasture presented the highest and lowest values in all fractions of P, respectively. Labile P generally was highest for leafy vegetables and potato. Labile P and Fe-Al-bound P comprised <1.4% and 8% of total P, respectively. Residual P ranged from approximate to 14% (potato and garlic) to 31% (pasture). Long-term fertilization increased P allocation to inorganic fractions, as Ca-bound P contained 78% of total P for potato and garlic and 74% for leafy vegetables but 61% for pasture. A strong positive correlation between labile P and Fe-Al-bound P (r = 0.534, p < 0.01), labile P and Ca-bound P (r = 0.574, p < 0.01), Ca-bound P and Fe-Al-bound P (r = 0.504, p < 0.01), Olsen-P and CaCl(2)-P (r = 0.821, p < 0.01) was found. Principal-component analysis showed that the first four components accounted for most of the variation, 32.5%, 16.9%, 12.9%, and 7.9% of total variation, respectively.

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Jones, J.W. (2011) Remote Sensing of Vegetation Pattern and Condition to Monitor Changes in Everglades Biogeochemistry. Critical Reviews in Environmental Science and Technology 41, 64-91.

 

ABSTRACT
Ground-based studies of biogeochemistry and vegetation patterning yield process understanding, but the amount of information gained by ground-based studies can be greatly enhanced by efficient, synoptic, and temporally resolute monitoring afforded by remote sensing. The variety of presently available Everglades vegetation maps reflects both the wide range of application requirements and the need to balance cost and capability. More effort needs to be applied to documenting and understanding vegetation distribution and condition as indicators of biogeochemistry and contamination. Ground-based and remote sensing studies should be modified to maximize their synergy and utility for adaptive management.

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Juston, J.M. and DeBusk, T.A. (2011) Evidence and implications of the background phosphorus concentration of submerged aquatic vegetation wetlands in Stormwater Treatment Areas for Everglades restoration. Water Resources Research 47.

 

ABSTRACT
The limits of phosphorus (P) removal from the 18,120 ha Stormwater Treatment Areas (STAs) for Everglades restoration depend largely on the performance of submerged aquatic vegetation (SAV) wetlands, as SAV treatment cells now provide final stage treatment for 85% of the STA project. A long-term internal P profile in STA-2 cell 3 (STA2C3), one of the longest-running and best performing SAV cells, demonstrated no further net removal in the back quarter of the cell once total P (TP) levels approached 15 mu g L(-1). Inflow-outflow performance data from STA2C3 were analyzed at monthly and annual scales and were pooled with data from an additional eight STA SAV treatment cells. The pooled data allowed inference of background TP concentrations in SAV treatment cells using existing Bayesian methods. Results showed a central tendency of 16 mu g L(-1)(13 - 17, 90% bounds), insensitivity to P loads less than similar to 1.7 g m(-2) yr(-1), and interannual variability outside these bounds. Internal data from the STA2C3 profile provided validation. Background P concentrations of 7 and 6 mu g L(-1) were identified for dissolved organic and particulate P fractions in the data pool, respectively, again similar to values in the STA2C3 gradient. Existing simulation modeling approaches for STA evaluations were identified as ineffective at or near background TP concentrations. Instead, we use an empirical and probabilistic approach based on full-scale data from STAs that produces annual risk of exceedance statistics and is easy to update. The current analysis suggests tangible risks for exceeding proposed annual discharge criteria from the STAs in the range of 16-20 mu g L(-1).

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Kaplan, D. and Munoz-Carpena, R. (2011) Complementary effects of surface water and groundwater on soil moisture dynamics in a degraded coastal floodplain forest. Journal of Hydrology 398(3-4), 221-34.

 

ABSTRACT
Restoration of degraded floodplain forests requires a robust understanding of surface water, groundwater, and vadose zone hydrology. Soil moisture is of particular importance for seed germination and seedling survival, but is difficult to monitor and often overlooked in wetland restoration studies. This research hypothesizes that the complex effects of surface water and shallow groundwater on the soil moisture dynamics of floodplain wetlands are spatially complementary. To test this hypothesis, 31 long-term (4-year) hydrological time series were collected in the floodplain of the Loxahatchee River (Florida, USA), where watershed modifications have led to reduced freshwater flow, altered hydroperiod and salinity, and a degraded ecosystem. Dynamic factor analysis (DFA), a time series dimension reduction technique, was applied to model temporal and spatia variation in 12 soil moisture time series as linear combinations of common trends (representing shared but unexplained, variability) and explanatory variables (selected from 19 additional candidate hydrological time series). The resulting dynamic factor models yielded good predictions of observed soil moisture series (overall coefficient of efficiency = 0.90) by identifying surface water elevation, groundwater elevation, and net recharge (cumulative rainfall-cumulative evapotranspiration) as important explanatory variables. Strong and complementary linear relationships were found between floodplain elevation and surface water effects (slope = 0.72, R(2) = 0.86, p < 0.001), and between elevation and groundwater effects (slope = -0.71, R(2) = 0.71, p = 0.001), while the effect of net recharge was homogenous across the experimental transect (slope = 0.03, R(2) = 0.05, p = 0.242). This study provides a quantitative insight into the spatial structure of groundwater and surface water effects on soil moisture that will be useful for refining monitoring plans and developing ecosystem restoration and management scenarios in degraded coastal floodplains.

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Kerfoot, J.R., Lorenz, J.J. and Turingan, R.G. (2011) Environmental correlates of the abundance and distribution of Belonesox belizanus in a novel environment. Environmental Biology of Fishes 92(1), 125-39.

 

ABSTRACT
Environmental factors, such as temperature, dissolved oxygen, salinity, and pH may influence the population dynamics of an introduced species by imposing limits to its distribution and abundance. In 1957, the non-indigenous pike killifish, Belonesox belizanus Kner, was released into a Miami-Dade County, Florida, canal, from which it has since spread across most of south Florida. The main goal of this study was to characterize patterns of covariation between B. belizanus density and temporal, spatial, and physicochemical variables, and attempt to identify which physicochemical variables may explain variation in densities of this species. Results of AIC(c) model selection indicated that patterns of physicochemical variables such as pH, salinity, and temperature correlated with annual change in B. belizanus density, and that these physicochemical-density patterns were mesohabitat specific. For the southern most sites, the interaction between temperature and salinity provide the best model to explain B. belizanus density, whereas variability in pH provides the best model at northern sites. These patterns of covariance between density and specific physicochemical variables suggests that specific mesohabitat characteristics may play a role in mediating the physiological, behavioral, and/or ecological performance of this introduced species in Florida and elsewhere. Future studies will test hypotheses on the direct and indirect effects of these physicochemical variables within the context of specific mesohabitats on the behavior and physiology of B. belizanus in its novel environment in South Florida.

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Kim, E.A. and Luthy, R.G. (2011) Partitioning of dissolved organic matter-bound mercury between a hydrophobic surface and polysulfide-rubber polymer. Water Research 45(17), 5441-48.

 

ABSTRACT
This study investigated the role of dissolved organic matter on mercury partitioning between a hydrophobic surface (polyethylene, PE) and a reduced sulfur-rich surface (polysulfide rubber, PSR). Comparative sorption studies employed polyethylene and polyethylene coated with PSR for reactions with DOM-bound mercuric ions. These studies revealed that PSR enhanced the Hg-DOM removal from water when DOM was Suwannee River natural organic matter (NOM), fulvic acid (FA), or humic acid (HA), while the same amount of 1,3-propanedithiol-bound mercuric ion was removed by both PE and PSR-PE. The differences for Hg-DOM removal efficiencies between PE and PSR-PE varied depending on which DOM was bound to mercuric ion as suggested by the PE/water and PSR-PE/water partition coefficients for mercury. The surface concentrations of mercury on PE and PSR-PE with the same DOM measured by x-ray photoelectron spectroscopy were similar, which indicated the comparable amounts of immobilized mercury on PE and PSR-PE being exposed to the aqueous phase. With these observations, two major pathways for the immobilization reactions between PSR-PE and Hg-DOM were examined: 1) adsorption of Hg-DOM on PE by hydrophobic interactions between DOM and PE, and 2) addition reaction of Hg-DOM onto PSR by a complexation reaction between Hg and PSR. The percent contribution of each pathway was derived from a mass balance and the ratios among aqueous mercury, PE-bound Hg-DOM, and PSR-bound Hg-DOM concentrations. The results indicate strong binding of mercuric ion with both dissolved organic matter and PSR polymer. The FT-IR examination of Hg-preloaded-PSR-PEs after the reaction with DOM corroborated a strong interaction between mercuric ion and 1,3-propanedithiol compared to Hg-HA, Hg-FA, or Hg-NOM interactions.

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Kovacs, J.M., Liu, Y.L., Zhang, C.H., Flores-Verdugo, F. and de Santiago, F.F. (2011) A field based statistical approach for validating a remotely sensed mangrove forest classification scheme. Wetlands Ecology and Management 19(5), 409-21.

 

ABSTRACT
Amongst the most threatened ecosystems on Earth, mangrove forests are also one of the more difficult to work in due to their growth in mud and open water coastal zones and their dense tangled stems, branches and prop roots. Consequently, there has been an impetus to employ remotely sensed imagery as a means for rapid inventory of these coastal wetlands. To date, the majority of mangrove maps derived from satellite imagery utilize a simple mangrove classification scheme which does not distinguish mangrove species and may not be useful for conservation and management purposes. Although more elaborate satellite based mangrove classification schemes are being developed, given their enhanced complexity they deserve additional justification for end users. The purpose of this study was to statistically examine the appropriateness of one such classification scheme based on an inventory of field data. In January of 2007 and May of 2008, 61 field sample plots were selected in a stratified random fashion based on a previous classification of a degraded mangrove forest of the Isla La Palma (Sinaloa, Mexico) using Landsat TM5 data. Unlike other previous Landsat TM based classifications of this region, which simply identified the mangrove forests as one class, the mangroves were classified (i.e. mapped) according to four conditions; healthy tall, healthy dwarf, poor condition, and dead mangroves. Within each sample plot, all mangroves of diameter of breast height (dbh) greater than 2.5 cm were identified and their height, condition and dbh recorded. An estimated Leaf Area Index (LAI) value also was obtained for each sample and the shortest distance from the center of each sample plot to open flowing water was determined using a geographic information system (GIS) overlay procedure. These data were then used to calculate mean values for the four classes as well as to determine stem densities, basal areas, and the Shannon-Wiener diversity index. In order to assess the appropriateness of this mangrove classification scheme a discriminant analysis approach was then applied to these field data. The results indicate this forest has undergone severe degradation, with decreasing mean tree heights, mean dbh and species diversity. In regards to the discriminant analysis procedure, further classification of these field plots and cross-validation based on these significant variables provided high classification accuracy thus validating the appropriateness of the satellite based image classification scheme. Moreover, the discriminant analysis indicated that the estimated LAI, mean height, and mean dbh are significant in the separation of the classification of mangrove forest condition along these field sample plots.

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Kritsky, D.C., McAleese, W.J. and Bakenhaster, M.D. (2011) Heteronchoineans (Monogenoidea) from the Gills of Crevalle Jack, Caranx hippos (Perciformes, Carangidae), from Everglades National Park, Florida, with a Redescription of Protomicrocotyle mirabilis (Gastrocotylinea, Protomicrocotylidae). Comparative Parasitology 78(2), 265-74.

 

ABSTRACT
Examination of the gills of 10 crevalle jack, Caranx hippos (Linnaeus) (Carangidae), from the northeastern portion of Florida Bay, Everglades National Park, Florida revealed 3 species of Heteronchoinea (Monogenoidea): Protomicrocotyle mirabilis (MacCallum, 1918) Johnston & Tiegs, 1922 (Gastrocotylinea, Protomicrocotylidae) (prevalence = 80%; intensity = 2-16 parasites/host; mean intensity = 7 parasites/host); Allopyragraphorus hippos (Hargis, 1956) Yamaguti, 1963 (Microcotylinea, Allopyragraphoridae) (80%; 1-8; 3.5); and Cemocotyle noveboracensis Price, 1962 (Microcotylinea, Cemocotylidae) (80%; 1-100; 35.3). Two crevalle jack (standard length 139-140 mm) were uninfected; 3 (standard length 154-183 mm) had mean intensities (all parasite species) of 14.3 (intensity = 5-20) parasites per host; 5 larger hosts (standard length = 312-395 mm) were more heavily infected with the 3 parasite species (mean intensity = 63.8 [intensity = 16-109] parasites per host). Protomicrocotyle mirabilis is redescribed and figured; A. hippos is considered a valid species and distinct from Allopyragraphorus incomparabilis (MacCallum, 1917) Yamaguti, 1963 (previously considered synonyms); and C. noveboracensis is distinguished from congenerics in part by lacking a haptoral lappet.

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Kwon, H.H., Lall, U. and Engel, V. (2011) Predicting foraging wading bird populations in Everglades National Park from seasonal hydrologic statistics under different management scenarios. Water Resources Research 47.

 

ABSTRACT
The ability to map relationships between ecological outcomes and hydrologic conditions in the Everglades National Park (ENP) is a key building block for their restoration program, a primary goal of which is to improve conditions for wading birds. This paper presents a model linking wading bird foraging numbers to hydrologic conditions in the ENP. Seasonal hydrologic statistics derived from a single water level recorder are well correlated with water depths throughout most areas of the ENP, and are effective as predictors of wading bird numbers when using a nonlinear hierarchical Bayesian model to estimate the conditional distribution of bird populations. Model parameters are estimated using a Markov chain Monte Carlo (MCMC) procedure. Parameter and model uncertainty is assessed as a byproduct of the estimation process. Water depths at the beginning of the nesting season, the average dry season water level, and the numbers of reversals from the dry season recession are identified as significant predictors, consistent with the hydrologic conditions considered important in the production and concentration of prey organisms in this system. Long-term hydrologic records at the index location allow for a retrospective analysis (1952-2006) of foraging bird numbers showing low frequency oscillations in response to decadal fluctuations in hydroclimatic conditions. Simulations of water levels at the index location used in the Bayesian model under alternative water management scenarios allow the posterior probability distributions of the number of foraging birds to be compared, thus providing a mechanism for linking management schemes to seasonal rainfall forecasts.

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Land, L., White, J.R. and Gambrell, R.P. (2011) Microbial Response to Potential Soil-Stabilizing Polymer Amendments for Coastal Wetland Restoration. Soil Science Society of America Journal 75(6), 2398-406.

 

ABSTRACT
Microbes release extracellular polymeric substances during metabolism of organic matter, which accumulate to bind particles and increase soil aggregation. On a large scale, hydraulically dredged sediment can be amended with polymer and deposited on subsiding marshes, where the polymer stabilizes the sediment until marsh plants become established. However, adding a simple C source to the soil can potentially affect microbial activity. This study determined the effect of addition of two commercially available natural polymers (xanthan gum and guar gum) on microbial biomass and activity in three types of hydraulically dredged sediments (clay, silty clay, and sandy loam) saturated under a range of salinity regimes (1.49 and 7.46, 7.46 and 14.9, and 22.4 and 37.3 mS cm(-1), respectively) for four time periods (1, 8, 16, and 26 wk). The CO(2) evolved in response to added polymer suggests that microbial communities rapidly degraded the polymers. Addition of polymers provided a readily available source of C that induced a priming effect on the microbial biomass leading to increased activity. Microbial activity accelerated to a much greater rate than background (control) respiration, resulting in up to an 8.7-fold increase in loss of native soil C beyond degradation of the added polymer C. Therefore, polymer additions to stabilized sediments led to a significant increase in native soil C loss with a concomitant decrease in soil quality.

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Langtimm, C.A., Dorazio, R.M., Stith, B.M. and Doyle, T.J. (2011) New Aerial Survey and Hierarchical Model to Estimate Manatee Abundance. Journal of Wildlife Management 75(2), 399-412.

 

ABSTRACT
Monitoring the response of endangered and protected species to hydrological restoration is a major component of the adaptive management framework of the Comprehensive Everglades Restoration Plan. The endangered Florida manatee (Trichechus manatus latirostris) lives at the marine-freshwater interface in southwest Florida and is likely to be affected by hydrologic restoration. To provide managers with prerestoration information on distribution and abundance for postrestoration comparison, we developed and implemented a new aerial survey design and hierarchical statistical model to estimate and map abundance of manatees as a function of patch-specific habitat characteristics, indicative of manatee requirements for offshore forage (seagrass), inland fresh drinking water, and warm-water winter refuge. We estimated the number of groups of manatees from dual-observer counts and estimated the number of individuals within groups by removal sampling. Our model is unique in that we jointly analyzed group and individual counts using assumptions that allow probabilities of group detection to depend on group size. Ours is the first analysis of manatee aerial surveys to model spatial and temporal abundance of manatees in association with habitat type while accounting for imperfect detection. We conducted the study in the Ten Thousand Islands area of southwestern Florida, USA, which was expected to be affected by the Picayune Strand Restoration Project to restore hydrology altered for a failed real-estate development. We conducted 11 surveys in 2006, spanning the cold, dry season and warm, wet season. To examine short-term and seasonal changes in distribution we flew paired surveys 1-2 days apart within a given month during the year. Manatees were sparsely distributed across the landscape in small groups. Probability of detection of a group increased with group size; the magnitude of the relationship between group size and detection probability varied among surveys. Probability of detection of individual manatees within a group also differed among surveys, ranging from a low of 0.27 on 11 January to a high of 0.73 on 8 August. During winter surveys, abundance was always higher inland at Port of the Islands (POI), a manatee warm-water aggregation site, than in the other habitat types. During warm-season surveys, highest abundances were estimated in offshore habitat where manatees forage on seagrass. Manatees continued to use POI in summer, but in lower numbers than in winter, possibly to drink freshwater. Abundance in other inland systems and inshore bays was low compared to POI in winter and summer, possibly because of low availability of freshwater. During cold weather, maps of patch abundance of paired surveys showed daily changes in manatee distribution associated with rapid changes in air and water temperature as manatees sought warm water with falling temperatures and seagrass areas with increasing temperatures. Within a habitat type, some patches had higher manatee abundance suggesting differences in quality, possibly due to freshwater flow. If hydrological restoration alters the location of quality habitat, postrestoration comparisons using our methods will document how manatees adjust to new resources, providing managers with information on spatial needs for further monitoring or management. Total abundance for the entire area was similar among survey dates. Credible intervals however were large on a few surveys, and may limit our ability to statistically detect trends in total abundance. Additional modeling of abundance with time-and patch-secific covariates of salinity, water temperature, and seagrass abundance will directly link manatee abundance with physical and biological changes due to restoration and should decrease uncertainty of estimates.

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Larsen, L., Aumen, N., Bernhardt, C., Engel, V., Givnish, T., Hagerthey, S., Harvey, J., Leonard, L., McCormick, P., McVoy, C., Noe, G., Nungesser, M., Rutchey, K., Sklar, F., Troxler, T., Volin, J. and Willard, D. (2011) Recent and Historic Drivers of Landscape Change in the Everglades Ridge, Slough, and Tree Island Mosaic. Critical Reviews in Environmental Science and Technology 41, 344-81.

 

ABSTRACT
More than half of the original Everglades extent formed a patterned peat mosaic of elevated ridges, lower and more open sloughs, and tree islands aligned parallel to the dominant flow direction. This ecologically important landscape structure remained in a dynamic equilibrium for millennia prior to rapid degradation over the past century in response to human manipulation of the hydrologic system. Restoration of the patterned landscape structure is one of the primary objectives of the Everglades restoration effort. Recent research has revealed that three main drivers regulated feedbacks that initiated and maintained landscape structure: the spatial and temporal distribution of surface water depths, surface and subsurface flow, and phosphorus supply. Causes of recent degradation include but are not limited to perturbations to these historically important controls; shifts in mineral and sulfate supply may have also contributed to degradation. Restoring predrainage hydrologic conditions will likely preserve remaining landscape pattern structure, provided a sufficient supply of surface water with low nutrient and low total dissolved solids content exists to maintain a rainfall-driven water chemistry. However, because of hysteresis in landscape evolution trajectories, restoration of areas with a fully degraded landscape could require additional human intervention.

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Larsen, L.G. and Harvey, J.W. (2011) Modeling of hydroecological feedbacks predicts distinct classes of landscape pattern, process, and restoration potential in shallow aquatic ecosystems. Geomorphology 126(3-4), 279-96.

 

ABSTRACT
It is widely recognized that interactions between vegetation and flow cause the emergence of channel patterns that are distinct from the standard Schumm classification of river channels. Although landscape pattern is known to be linked to ecosystem services such as habitat provision, pollutant removal, and sustaining biodiversity, the mechanisms responsible for the development and stability of different landscape patterns in shallow, vegetated flows have remained poorly understood. Fortunately, recent advances have made possible large-scale models of flow through vegetated environments that can be run over a range of environmental variables and over timescales of millennia. We describe a new, quasi-3D cellular automata model that couples simulations of shallow-water flow, bed shear stresses, sediment transport, and vegetation dynamics in an efficient manner. That efficiency allowed us to apply the model widely in order to determine how different hydroecological feedbacks control landscape pattern and process in various types of wetlands and floodplains. Distinct classes of landscape pattern were uniquely associated with specific types of allogenic and autogenic drivers in wetland flows. Regular, anisotropically patterned wetlands were dominated by allogenic processes (i.e., processes driven by periodic high water levels and flow velocities that redistribute sediment), relative to autogenic processes (e.g., vegetation production, peat accretion, and gravitational erosion). These anistropically patterned wetlands are therefore particularly prone to hydrologic disturbance. Other classes of wetlands that emerged from simulated interactions included maze-patterned, amorphous, and topographically noisy marshes, open marsh with islands, banded string-pool sequences perpendicular to flow, parallel deep and narrow channels flanked by marsh, and ridge-and-slough patterned marsh oriented parallel to flow. Because vegetation both affects and responds to the balance between the transport capacity of the flow and sediment supply, these vegetated systems exhibit a feedback that is not dominant in most rivers. Consequently, unlike in most rivers, it is not possible to predict the "channel pattern" of a vegetated landscape based only on discharge characteristics and sediment supply: the antecedent vegetation pattern and vegetation dynamics must also be known. In general, the stability of different wetland pattern types is most strongly related to factors controlling the erosion and deposition of sediment at vegetation patch edges, the magnitude of sediment redistribution by flow, patch elevation relative to water level, and the variability of erosion rates in vegetation patches with low flow-resistance. As we exemplify in our case-study of the Everglades ridge and slough landscape, feedback between flow and vegetation also causes hysteresis in landscape evolution trajectories that will affect the potential for landscape restoration. Namely, even if the hydrologic conditions that historically produced higher flows are restored, degraded portions of the ridge and slough landscape are unlikely to revert to their former patterning. As wetlands and floodplains worldwide become increasingly threatened by climate change and urbanization, the greater mechanistic understanding of landscape pattern and process that our analysis provides will improve our ability to forecast and manage the behavior of these ecosystems.
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Li, X., Wang, Y., Stern, J. and Cu, B.H. (2011) Isotopic evidence for the source and fate of phosphorus in Everglades wetland ecosystems. Applied Geochemistry 26(5), 688-95.

 

ABSTRACT
Phosphorus has historically been a limiting nutrient in the Florida Everglades. Increased P loading to the Everglades over the past several decades has led to significant changes in water quality and plant communities. Stormwater runoff that drains agricultural lands and enters the Water Conservation Areas (WCAs) are known to contain elevated levels of P. but the exact source of this P has not been fully determined. Here the results of an O isotope study of dissolved inorganic phosphate (DIP) in both polluted and relatively pristine (or reference) areas of the Everglades are reported. The data reveal spatial and temporal variations in the delta(18)O signature of DIP, reflecting the source and the degree of cycling of P. The delta(18)O values of DIP collected from the Everglades National Park were close or equal to the predicted delta(18)O values of DIP formed in situ in equilibrium with ambient water, indicating that P is quickly cycled in the water column in oligotrophic ecosystems with very low P concentrations. However, most DIP samples collected from areas impacted by agricultural runoff yielded delta(18)O values that deviated from the predicted equilibrium DIP-delta(18)O values based on the delta(18)O of water and water temperature, suggesting that biological cycling of P was not rapid enough to remove the fertilizer delta(18)O signature in the DIP pool from areas receiving high P loading. The delta(18)O signature of DIP in impacted areas reflects a mixing of fertilizer P and biologically cycled P. where the relative proportions of biologically cycled vs. fertilizer DIP are controlled by both biological (microbial activities and plant uptake) and hydrologic factors (loading rate and residence time). Using a two-end-member (i.e., fertilizer P and biologically cycled P) mixing model, fertilizers were estimated to contribute about 15-100% of the DIP pool in the highly impacted areas of the northern Everglades, whereas the DIP pool in the reference (i.e., relatively pristine) wetlands in the Everglades National Park was dominated by biologically cycled P. The study shows that O isotopic measurements of dissolved PO(4)(3-) can be a useful tool for tracing the fertilizer P inputs to freshwater ecosystems.

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Lin, L., Webb, J. and Zhang, X.H. (2011) Involvement of Arbuscular Mycorrhizal Symbiosis in the Distribution of Sawgrass and Cattail in Florida Everglades. Wetlands 31(2), 263-72.

 

ABSTRACT
In areas of the Florida Everglades, USA, a massive replacement of the historically predominant sawgrass by native cattail is occurring. Phosphorus enrichment due to runoff and hydrological engineering is considered a major environmental cause. As part of our investigation into the genetic and molecular mechanisms underlying this habitat shift, we examined the possible involvement of arbuscular mycorrhizal (AM) symbiosis in sawgrass and cattail. Laboratory experiments determined that sawgrass, but not cattail, was susceptible to fungal inoculation and formed AM under low phosphate (Pi) conditions. Collection of plants from four representative sites in the Everglades revealed that while all sawgrass plants formed root AM associations, no AM was detected in cattail. We identified a phosphate transporter gene of sawgrass, CjPT4, that was preferentially expressed in roots of fungal inoculated and AM plants. In contrast, cattail PT genes were steadily expressed regardless of Pi levels. Our studies demonstrate a strong possibility that ability to form AM symbiosis is a key genetic distinction between sawgrass and cattail in their adaptive response to the changing phosphorus environment. We propose a mechanistic explanation based on AM symbiosis for the distribution and competition of these two plants in the pre-industrial Pi-deficient and modern Pi-enriched Florida Everglades ecosystems.

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Liu, G.L., Naja, G.M., Kalla, P., Scheidt, D., Gaiser, E. and Cai, Y. (2011) Legacy and Fate of Mercury and Methylmercury in the Florida Everglades. Environmental Science & Technology 45(2), 496-501.

 

ABSTRACT
Mass inventories of total Hg (THg) and methylmercury (MeHg) and mass budgets of Hg newly deposited during the 2005 dry and wet seasons were constructed for the Everglades. As a sink for Hg, the Everglades has accumulated 914, 1138, 4931, and 7602 kg of legacy THg in its 4 management units, namely Water Conservation Area (WCA) 1, 2, 3, and the Everglades National Park (ENP), respectively, with most Hg being stored in soil. The current annual Hg inputs account only for 1-2% of the legacy Hg. Mercury transport across management units during a season amounts to 1% or less of Hg storage, except for WCA 2 where inflow inputs can contribute 4% of total MeHg storage. Mass budget suggests distinct spatiality for cycling of seasonally deposited Hg, with significantly lower THg fluxes entering water and floc in ENP than in the WCAs. Floc in WCAs can retain a considerable fraction (around 16%) of MeHg produced from the newly deposited Hg during the wet season. This work is important for evaluating the magnitude of legacy Hg contamination and for predicting the fate of new Hg in the Everglades, and provides a methodological example for large-scale studies on Hg cycling in wetlands.

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