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Research about Everglades National Park

Source-linked reports with geographic coverage including Everglades National Park.

At least 55 records · Page 3Linked to original sources
USGS2011

Recovery of native treefrogs after removal of nonindigenous Cuban Treefrogs, Osteopilus septentrionalis

Florida is home to several introduced animal species, especially in the southern portion of the state. Most introduced species are restricted to the urban and suburban areas along the coasts, but some species, like the Cuban Treefrog ( Osteopilus septentrionalis ), are locally abundant in natural protected areas. Although Cuban Treefrogs are known predators of native treefrog species as both adults and larvae, no study has demonstrated a negative effect of Cuban Treefrogs on native treefrog survival, abundance, or occupancy rate. We monitored survival, capture probability, abundance, and proportion of sites occupied by Cuban Treefrogs and two native species, Green Treefrogs ( Hyla cinerea ) and Squirrel Treefrogs ( Hyla squirella ), at four sites in Everglades National Park in southern Florida with the use of capture–mark–recapture techniques. After at least 5 mo of monitoring all species at each site we began removing every Cuban Treefrog captured. We continued to estimate survival, abundance, and occupancy rates of native treefrogs for 1 yr after the commencement of Cuban Treefrog removal. Mark–recapture models that included the effect of Cuban Treefrog removal on native treefrog survival did not have considerable Akaike's Information Criterion (AIC) weight, although capture rates of native species were generally very low prior to Cuban Treefrog removal. Estimated abundance of native treefrogs did increase after commencement of Cuban Treefrog removal, but also varied with the season of the year. The best models of native treefrog occupancy included a Cuban Treefrog removal effect at sites with high initial densities of Cuban Treefrogs. This study demonstrates that an introduced predator can have population-level effects on similar native species.

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USGS2010

Controls on mangrove forest‐atmosphere carbon dioxide exchanges in western Everglades National Park

We report on net ecosystem production (NEP) and key environmental controls on net ecosystem exchange (NEE) of carbon dioxide (CO 2 ) between a mangrove forest and the atmosphere in the coastal Florida Everglades. An eddy covariance system deployed above the canopy was used to determine NEE during January 2004 through August 2005. Maximum daytime NEE ranged from −20 to −25 μ mol (CO 2 ) m −2 s −1 between March and May. Respiration (R d ) was highly variable (2.81 ± 2.41 μ mol (CO 2 ) m −2 s −1 ), reaching peak values during the summer wet season. During the winter dry season, forest CO 2 assimilation increased with the proportion of diffuse solar irradiance in response to greater radiative transfer in the forest canopy. Surface water salinity and tidal activity were also important controls on NEE. Daily light use efficiency was reduced at high (>34 parts per thousand (ppt)) compared to low (<17 ppt) salinity by 46%. Tidal inundation lowered daytime R d by ∼0.9 μ mol (CO 2 ) m −2 s −1 and nighttime R d by ∼0.5 μ mol (CO 2 ) m −2 s −1 . The forest was a sink for atmospheric CO 2 , with an annual NEP of 1170 ± 127 g C m −2 during 2004. This unusually high NEP was attributed to year‐round productivity and low ecosystem respiration which reached a maximum of only 3 g C m −2 d −1 . Tidal export of dissolved inorganic carbon derived from belowground respiration likely lowered the estimates of mangrove forest respiration. These results suggest that carbon balance in mangrove coastal systems will change in response to variable salinity and inundation patterns, possibly resulting from secular sea level rise and climate change.

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USGS2010

Measurement-derived heat-budget approaches for simulating coastal wetland temperature with a hydrodynamic model

Numerical modeling is needed to predict environmental temperatures, which affect a number of biota in southern Florida, U.S.A., such as the West Indian manatee (Trichechus manatus), which uses thermal basins for refuge from lethal winter cold fronts. To numerically simulate heat-transport through a dynamic coastal wetland region, an algorithm was developed for the FTLOADDS coupled hydrodynamic surface-water/ground-water model that uses formulations and coefficients suited to the coastal wetland thermal environment. In this study, two field sites provided atmospheric data to develop coefficients for the heat flux terms representing this particular study area. Several methods were examined to represent the heat-flux components used to compute temperature. A Dalton equation was compared with a Penman formulation for latent heat computations, producing similar daily-average temperatures. Simulation of heat-transport in the southern Everglades indicates that the model represents the daily fluctuation in coastal temperatures better than at inland locations; possibly due to the lack of information on the spatial variations in heat-transport parameters such as soil heat capacity and surface albedo. These simulation results indicate that the new formulation is suitable for defining the existing thermohydrologic system and evaluating the ecological effect of proposed restoration efforts in the southern Everglades of Florida.

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USGS2010

Development of inferential sensors for real-time quality control of water-level data for the Everglades Depth Estimation Network

The Everglades Depth Estimation Network (EDEN) is an integrated network of real-time water-level gaging stations, ground-elevation models, and watersurface models designed to provide scientists, engineers, and water-resource managers with current (2000-present) water-depth information for the entire freshwater portion of the greater Everglades. The generation of EDEN waterlevel surfaces is derived from real-time data. Real-time data are automatically checked for outliers using minimum, maximum, and rate-of-change thresholds for each station. Smaller errors in the real-time data, such as gradual drift of malfunctioning pressure transducers, are more difficult to immediately identify with visual inspection of time-series plots and may only be identified during on-site inspections of the gages. Correcting smaller errors in the data often is time consuming and water-level data may not be finalized for several months. To provide water-level surfaces on a daily basis, EDEN needed an automated process to identify errors in water-level data and to provide estimates for missing or erroneous waterlevel data. A technology often used for industrial applications is &ldquo;inferential sensor.&rdquo; Rather than installing a redundant sensor to measure a process, such as an additional waterlevel gage, an inferential sensor, or virtual sensor, is developed that estimates the processes measured by the physical sensor. The advantage of an inferential sensor is that it provides a redundant signal to the sensor in the field but without exposure to environmental threats. In the event that a gage does malfunction, the inferential sensor provides an estimate for the period of missing data. The inferential sensor also can be used in the quality assurance and quality control of the data. Inferential sensors for gages in the EDEN network are currently (2010) under development. The inferential sensors will be automated so that the real-time EDEN data will continuously be compared to the inferential sensor signal and digital reports of the status of the real-time data will be sent periodically to the appropriate support personnel. The development and application of inferential sensors is easily transferable to other real-time hydrologic monitoring networks.

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USGS2009

Hurricane Wilma's impact on overall soil elevation and zones within the soil profile in a mangrove forest

Soil elevation affects tidal inundation period, inundation frequency, and overall hydroperiod, all of which are important ecological factors affecting species recruitment, composition, and survival in wetlands. Hurricanes can dramatically affect a site's soil elevation. We assessed the impact of Hurricane Wilma (2005) on soil elevation at a mangrove forest location along the Shark River in Everglades National Park, Florida, USA. Using multiple depth surface elevation tables (SETs) and marker horizons we measured soil accretion, erosion, and soil elevation. We partitioned the effect of Hurricane Wilma's storm deposit into four constituent soil zones: surface (accretion) zone, shallow zone (0–0.35 m), middle zone (0.35–4 m), and deep zone (4–6 m). We report expansion and contraction of each soil zone. Hurricane Wilma deposited 37.0 (± 3.0 SE) mm of material; however, the absolute soil elevation change was + 42.8 mm due to expansion in the shallow soil zone. One year post-hurricane, the soil profile had lost 10.0 mm in soil elevation, with 8.5 mm of the loss due to erosion. The remaining soil elevation loss was due to compaction from shallow subsidence. We found prolific growth of new fine rootlets (209 ± 34 SE g m −2 ) in the storm deposited material suggesting that deposits may become more stable in the near future (i.e., erosion rate will decrease). Surficial erosion and belowground processes both played an important role in determining the overall soil elevation. Expansion and contraction in the shallow soil zone may be due to hydrology, and in the middle and bottom soil zones due to shallow subsidence. Findings thus far indicate that soil elevation has made substantial gains compared to site specific relative sea-level rise, but data trends suggest that belowground processes, which differ by soil zone, may come to dominate the long term ecological impact of storm deposit.

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USGS2008

Estimation of water surface elevations for the Everglades, Florida

The Everglades Depth Estimation Network (EDEN) is an integrated network of real-time water-level monitoring gages and modeling methods that provides scientists and managers with current (2000–present) online water surface and water depth information for the freshwater domain of the Greater Everglades. This integrated system presents data on a 400-m square grid to assist in (1) large-scale field operations; (2) integration of hydrologic and ecologic responses; (3) supporting biological and ecological assessment of the implementation of the Comprehensive Everglades Restoration Plan (CERP); and (4) assessing trophic-level responses to hydrodynamic changes in the Everglades. This paper investigates the radial basis function multiquadric method of interpolation to obtain a continuous freshwater surface across the entire Everglades using radio-transmitted data from a network of water-level gages managed by the US Geological Survey (USGS), the South Florida Water Management District (SFWMD), and the Everglades National Park (ENP). Since the hydrological connection is interrupted by canals and levees across the study area, boundary conditions were simulated by linearly interpolating along those features and integrating the results together with the data from marsh stations to obtain a continuous water surface through multiquadric interpolation. The absolute cross-validation errors greater than 5 cm correlate well with the local outliers and the minimum distance between the closest stations within 2000-m radius, but seem to be independent of vegetation or season.

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USGS2008

Tracking sea turtles in the Everglades

The U.S. Geological Survey (USGS) has a long history of conducting research on threatened, endangered, and at-risk species inhabiting both terrestrial and marine environments, particularly those found within national parks and protected areas. In the coastal Gulf of Mexico region, for example, USGS scientist Donna Shaver at Padre Island National Seashore in Texas has focused on “headstarting” hatchlings of the rare Kemp’s ridley sea turtle (Lepidochelys kempii). She is also analyzing trends in sea turtle strandings onshore and interactions with Gulf shrimp fisheries. Along south Florida’s Gulf coast, the USGS has focused on research and monitoring for managing the greater Everglades ecosystem. One novel project involves the endangered green sea turtle (Chelonia mydas). The ecology and movements of adult green turtles are reasonably well understood, largely due to decades of nesting beach monitoring by a network of researchers and volunteers. In contrast, relatively little is known about the habitat requirements and movements of juvenile and subadult sea turtles of any species in their aquatic environment.

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USGS2006

Descriptions and preliminary report on sediment cores from the southwest coastal area, Part II: Collected July 2005, Everglades National Park, Florida

Twelve cores were collected from six sites in the southwest coastal area of Everglades National Park, Florida, in July 2005. These six sites create transects up three river systems that are part of the complex network of channels and bays that form the mangrove and coastal glades – Lostmans River system, Harney River system, and Shark River system. The three transects are linked to two cores collected in 2004 from Big Lostmans Bay and Tarpon Bay. A preliminary model of changes in flow through the southwest coastal zone is proposed based on an examination of the sediments and an initial assessment of key indicator species of mollusks within the cores. Throughout the time period recorded by deposition of these cores, flow to the southwest coastal area has been predominantly through the Shark River channels, diminishing to the north toward the Lostmans River system. The Lostmans system was less influenced by freshwater flow and more emergent than the two systems to the south. Freshwater flow has periodically reached the mouths of the Harney and Shark River systems, but these areas have persistently been zones of mixed estuarine environments, typical of transition zones. Evidence for a substantial change in the flow regime is found in the mid-system cores from the Harney and Shark Rivers. The lower portions of both cores were deposited in freshwater environments, with no indication of estuarine influence; however, a shift towards more estuarine conditions occurs in the upper portions of the cores and a loss of the larger freshwater fauna. These results are preliminary. The next step will be to develop age models and to conduct quantitative analyses of the fauna, flora, and sediment geochemistry at these sites. Results of the quantitative analyses will provide information on the natural and anthropogenic changes that have occurred in the southwest coastal system that will allow resource managers to set targets for restoration.

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USGS2006

Spatial patterns of fish communities along two estuarine gradients in southern Florida

In tropical and subtropical estuaries, gradients of primary productivity and salinity are generally invoked to explain patterns in community structure and standing crops of fishes. We documented spatial and temporal patterns in fish community structure and standing crops along salinity and nutrient gradients in two subtropical drainages of Everglades National Park, USA. The Shark River drains into the Gulf of Mexico and experiences diurnal tides carrying relatively nutrient enriched waters, while Taylor River is more hydrologically isolated by the oligohaline Florida Bay and experiences no discernable lunar tides. We hypothesized that the more nutrient enriched system would support higher standing crops of fishes in its mangrove zone. We collected 50 species of fish from January 2000 to April 2004 at six sampling sites spanning fresh to brackish salinities in both the Shark and Taylor River drainages. Contrary to expectations, we observed lower standing crops and density of fishes in the more nutrient rich tidal mangrove forest of the Shark River than in the less nutrient rich mangrove habitats bordering the Taylor River. Tidal mangrove habitats in the Shark River were dominated by salt-tolerant fish and displayed lower species richness than mangrove communities in the Taylor River, which included more freshwater taxa and yielded relatively higher richness. These differences were maintained even after controlling for salinity at the time of sampling. Small-scale topographic relief differs between these two systems, possibly created by tidal action in the Shark River. We propose that this difference in topography limits movement of fishes from upstream marshes into the fringing mangrove forest in the Shark River system, but not the Taylor River system. Understanding the influence of habitat structure, including connectivity, on aquatic communities is important to anticipate effects of construction and operational alternatives associated with restoration of the Everglades ecosystem.

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USGS2005

Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida

Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measures and targets for salinity and other water quality and quantity quality measures. Preliminary examination of the cores indicates significant changes have taken place over the last 1000-2000 years. The cores collected from the inner bays — the most landward bays — are distinctly different from other estuarine sediment cores examined in Florida Bay and Biscayne Bay. Peats in the inner-bay cores from Big Lostmans Bay, Broad River Bay, and Tarpon Bay were deposited at least 1000 years before present (BP) based on radiocarbon analyses. The peats are overlain by poorly sorted organic muds and sands containing species indicative of deposition in a freshwater to very low salinity environment. The Alligator Bay core, the most northern inner-bay core, is almost entirely sand; no detailed faunal analyses or radiometric dating has been completed on this core. The Roberts River core, taken from the mouth of the River where it empties into Whitewater Bay, is lithologically and faunally similar to previously examined cores from Biscayne and Florida Bays; however, the basal unit was deposited ~2000 years before the present based on radiocarbon analyses. A definite trend of increasing salinity over time is seen in the Roberts River core, from sediments representing a terrestrially dominated freshwater environment at the bottom of the core to those representing an estuarine environment with a strong freshwater influence at the top. The changes seen at Roberts River could represent a combination of factors including rising sea-level and changes in freshwater supply, but the timing and extent of the changes needs to be determined. The preliminary information on the cores collected in 2004 will be combined with data from cores collected in July 2005. The 2005 cores were collected along transects moving from the inner bays out towards the coast. These transects, combining information from the 2004 and 2005 cores, will allow us to examine long term trends in freshwater supply, sea-level rise, and potentially the impact of storms on the coastal ecosystem.

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USGS2005

Cascading ecological effects of low-level phosphorus enrichment in the Florida Everglades

Few studies have examined long-term ecological effects of sustained low-level nutrient enhancement on wetland biota. To determine sustained effects of phosphorus (P) addition on Everglades marshes we added P at low levels (5, 15, and 30 μg L −1 above ambient) for 5 yr to triplicate 100-m flow-through channels in pristine marsh. A cascade of ecological responses occurred in similar sequence among treatments. Although the rate of change increased with dosing level, treatments converged to similar enriched endpoints, characterized most notably by a doubling of plant biomass and elimination of native, calcareous periphyton mats. The full sequence of biological changes occurred without an increase in water total P concentration, which remained near ambient levels until Year 5. This study indicates that Everglades marshes have a near-zero assimilative capacity for P without a state change, that ecosystem responses to enrichment accumulate over time, and that downstream P transport mainly occurs through biota rather than the water column.

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USGS2004

Isotopic views of food web structure in the Florida Everglades

Introduction Nearly one million acres of the Everglades are under a health advisory that discourages the human consumption of largemouth bass and several other fish because of high mercury contents. Food web structure (base of food web, number of trophic steps) plays a potentially critical role in determining the patterns of mercury contamination of the Everglades ecosystem. Methylmercury (MeHg) is present in low concentrations in water, yet after entering the base of the food web it biomagnifies to toxic concentrations in organisms that occupy higher trophic positions (like bass). One of the main research questions under investigation by a multi-agency task force in the Everglades is how MeHg bioaccumulates up the food chain in this complex aquatic ecosystem. Understanding variations in food web structure may help explain mercury patterns in the Everglades and ultimately lead to more effective restoration of Everglades ecosystems.

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USGS2004

Water flow and nutrient flux from five estuarine rivers along the southwest coast of the Everglades National Park, Florida, 1997-2001

Discharge and nutrient fluxes for five tidally affected streams were monitored and evaluated as a part of the U.S. Geological Survey Place-Based Studies Initiative and the U.S. Department of the Interior Critical Ecosystem Studies Initiative. Locations on Lostmans Creek, and Broad, Harney, Shark, and North Rivers were selected using the criterion that a large amount of the water that flows through Shark River Slough must pass these sites. Discharge and nutrient-concentration data collection started at the Broad, Harney, and Shark River stations in January 1997 and ended in early 2001. Discharge and nutrient-concentration data collection started at the Lostmans Creek and North River stations in April 1999 and ended in early 2001. Each station was equipped with a vertically oriented acoustic-velocity sensor, water-level pressure transducer, bottom water-temperature thermistor, and specific conductance four-electrode sensor. Data collected using a vessel-mounted acoustic discharge measurement system were used to calibrate regression models of the mean river velocities and the in-situ index velocities. Information from these stations, in conjunction with data from other ongoing studies, will help to determine environmental effects on the southwest coast estuaries as changes in water management of the Everglades National Park continue. Discharges from the Lostmans Creek, and Broad, Harney, Shark, and North River stations are influenced by semidiurnal tides, meteorological events, and surface- and ground-water inflow. Each of the five rivers is usually well mixed, having no greater than 500 microSiemens per centimeter at 25? Celsius difference in specific conductance from top to bottom during flood and ebb tides. Instantaneous flood discharges (water moving upstream) are typically of greater magnitude and shorter duration than instantaneous ebb discharges (water moving downstream). Instantaneous discharge data were filtered using a low-pass filter to remove predominant tidal frequencies, and the filtered data were used to compute daily mean and monthly mean residual discharges. Lostmans Creek, and Broad, Harney and Shark Rivers each contributed from 20 to 27 percent of the total measured discharge to the Gulf of Mexico, whereas North River contributed approximately 4 percent. The main discharge region of the Shark River Slough extends from as far north as Lostmans Creek to as far south as North River. North River discharge has similar response characteristics to the other four rivers measured, but with a lesser magnitude of discharge. Comparisons of monthly mean discharges from the Tamiami Canal flow control structures S-12-A, B, C, and D located on U.S. Highway 41 (Tamiami Trail) to the five station total monthly mean discharges indicate that the discharges from the five rivers are approximately 2 to 3 times the S-12-A, B, C, D discharges, and that the measured southwest coast discharge peaks lead the S-12-A, B, C, D discharge peaks by approximately 1 month. Residual total nitrogen and total phosphorus fluxes were estimated using linear regression models of discharge and flux. Monthly mean total nitrogen residual fluxes for the five southwest coast rivers ranged from approximately 0 to 390 short tons, whereas monthly mean total phosphorus residual fluxes ranged from approximately 0 to 6 short tons. Total nitrogen and total phosphorus residual fluxes at Lostmans Creek, and Broad, Harney, and Shark Rivers were similar in magnitude, each accounting for between 20 to 29 percent of the total measured residual flux. North River contributed between 3 to 4 percent of the total nitrogen and total phosphorus residual flux from the five rivers.

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USGS2002

Flow-velocity, water-temperature and conductivity data collected in Shark River Slough, Everglades National Park, during 1999-2000 and 2000-2001 wet seasons

A project within the U. S. Geological Survey Place- Based Studies Program is focused on investigation of ?Forcing Effects on Flow Structure in Vegetated Wetlands of the Everglades.? Data-collection efforts conducted within this project at three locations in Shark River Slough, Everglades National Park, during the 1999-2000 and 2000-2001 wet seasons are described in this report. Techniques for collecting and processing the data and summaries of daily mean flowvelocity, water-temperature, and conductivity data are presented. The quality-checked and edited data have been compiled and stored on the USGS South Florida Information Access website.

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USGS2002

The road to flamingo: An evaluation of flow pattern alterations and salinity intrusion in the lower glades, Everglades National Park

Introduction This report describes the history of roads through the Lower Glades of Everglades National Park, Florida and their influence on salinity intrusion. The chronology that lead to this work is interesting. The U.S. Geological Survey flew a series of helicopter electromagnetic surveys over portions of Everglades National Park to map saltwater intrusion starting in 1994 (Fitterman et al., 1995; Fitterman, 1996; Fitterman and Deszcz-Pan, 1998, 2002). These surveys identified variations in the electrical resistivity that were associated with changes in ground-water quality. The patterns of ground-water quality have been traced to natural saltwater intrusion, such as the effect of tidal rivers on lowering hydrologic heads far inland, and the influence of man-made structures, such as canals and roadways on surface water flow. These latter effects are of interest as they represent variations from the natural state of affairs in the park. Previous investigations had been done by Everglades National Park staff on the influence of some roads and canals on the near surface hydrology. This information was scattered through a number of National Park Service publications. In an effort to bring these materials together in an easily located reference, along with new data on flows through culverts beneath the main park road, this report was written.

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USGS2001

Molluscan fauna from core 25B, Whipray Basin, central Florida Bay, Everglades National Park

Molluscan assemblages preserved in an 80-cm core from Whipray Basin in central Florida Bay, Everglades National Park, illustrate changes in the environmental conditions within the basin over the last two centuries. Salinity remained polyhaline to euhaline throughout the time of deposition (1800-1997), with alternating periods of stability and increased fluctuations. Since 1800, a Brachidontes assemblage has characterized Whipray Basin and the dominant faunal components have remained the same in terms of presence and absence of species. However, patterns of dominance and diversity within the Brachidontes assemblage have changed and these changes indicate fluctuations in the environment. The period from 1815 to 1857 was distinguished by an abundance of molluscs dwelling on seagrass and sub-aquatic vegetation. Faunal richness and abundance were high and stable, and epiphytic molluscs flourished. Polyhaline conditions existed, although periods of slightly lower salinities occurred. The period from 1862 to 1894 appears unstable based on fluctuations in molluscan faunal richness, abundance, and dominant species. The epiphytic molluscs experienced significant shifts (? >30%) associated with changes in sub-aquatic vegetation. The changes in epiphytic molluscs from 1871 to 1913 may be indicative of a seagrass die-off. The period from 1899 to 1950 was the most stable section of the core in terms of changes in the molluscan fauna. Faunal richness and abundance reached highs of 31 groups and 726 individuals per sample during this period and epiphytic molluscs were prevalent. Beginning in 1955, faunal groups experienced high amplitude fluctuations in abundance; this pattern continued through the second half of the 20th century. Fluctuating salinity, changes in vegetation, and reduced water quality (low O2, increased nutrients and/or reduced clarity) oxygen supply) have characterized the past 50 years. These changes preceded a seagrass die-off in 1987-88 and may be related to the causes of the die-off. Whether the cause of the changes seen in Whipray Basin is natural or a combination of natural and anthropogenic factors, the amount of change in the molluscan fauna in the last 50 years clearly exceeds the preceding 150 years.

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