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Research about Florida

Source-linked reports with geographic coverage including Florida.

At least 163 records · Page 9Linked to original sources
USGS2023

Accuracy and precision of sea-finding orientation as a function of dune proximity in hatchlings of two species of sea turtles

Context: Sea turtle hatchlings generally emerge at night from nests on sand beaches and immediately orient using visual cues, which are believed to entail the difference in brightness between the light seen in the seaward direction and that seen in the duneward direction. Aim: The aim of this study was to understand how dune proximity affected hatchling orientations in two sea turtle species that share a nesting beach 15 km long and 25.3 ± 9.4 m ( N = 215) from dune to waterline, with low to moderate artificial light nearby. Methods: For hatchling loggerhead and green turtles, we measured accuracy and precision of orientation, tested differences in distance from nest to dune, and investigated the effect of dune proximity on hatchling orientation. Key results: We found a significant decrease in hatchling orientation accuracy and precision in both species as the distance increased from nests to dune. Loggerhead and green turtles showed similar orientation ability when in the same proximity to the dune. Conclusions: We conclude that dune features provide important cues for hatchling orientation on sea turtle nesting beaches. Implications: Restoring and maintaining natural beach profiles, especially dune systems, is likely to increase the accuracy and precision of sea finding in hatchling sea turtles.

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USGS2023

Quantifying uncertainty in coastal salinity regime for biological application using quantile regression

Salinity regimes in coastal ecosystems are highly dynamic and driven by complex geomorphic and hydrological processes. Estuarine biota are generally adapted to salinity fluctuation, but are vulnerable to salinity extremes. Characterizing coastal salinity regime for ecological studies therefore requires representing extremes of salinity ranges at time scales relevant to ecology (e.g., daily, monthly, and seasonally). Here, we propose a framework for modeling coastal salinity with these overall goals: (1) quantify uncertainty in salinity associated with important terrestrial and oceanographic drivers, (2) examine time scales of salinity response to river streamflow events, and (3) predict salinity continuously over space at key time scales. Salinity is modeled as quantile surfaces related to river discharge, tidal dynamics, wind, and spatial location, applied to Suwannee Sound estuary, FL, USA, where salinity has been monitored spatially since 1981. Each quantile level is regressed independently, and together they comprise a distribution of salinity uncertainty across space, with upper and lower quantiles describing salinity extremes. Effects of physical drivers on salinity are compared through four base models with various combinations of tide and wind variables, each including spatial coordinates and a single streamflow metric (in cubic meters per second). Multiple time scales of streamflow are considered by taking means across various periods, from 1 to 12 days, and at various lagged intervals prior to salinity sample, totaling 144 streamflow metrics. We found that the Suwannee coastal salinity regime is dynamic at multiple time scales and varies nonlinearly across space from the river effluence outward. Salinity increases nonlinearly with decreasing river flow rates below 200 m 3 /s, most prominently in the lower quantiles of salinity (τ = 0.05–0.25). Wind appears to have a stronger influence on salinity than astronomic tides for this estuary. The regression approach developed here can be applied to any coastal system that has sufficient spatial and temporal monitoring coverage to capture multiple flood and drought events. It is implemented with a simple R routine, and is less computationally-intensive than finite difference hydrodynamic modeling. The characterizations of salinity uncertainty developed in these analyses can be directly applied to future studies of fish and wildlife responses to changes in watershed management.

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USGS2023

Survey evaluation of Florida’s freshwater fisheries long-term monitoring program

Natural resource monitoring programs benefit from routine evaluation. Here, Florida’s statewide Freshwater Fisheries Long-Term Monitoring (LTM) program is used to show how stakeholder surveys can be integral to this process. In 2022, an online questionnaire was sent to internal stakeholders, i.e., state agency personnel who collect, enter, or use freshwater fisheries data for fisheries and habitat management purposes. The survey’s primary objective was to evaluate the program at its 15-year mark; secondary objectives were to compare results with a similar survey conducted at the 4-year mark, compare results among respondents based on experience and functional role, and develop recommendations for strategic initiatives to further improve the program. The survey consisted of 43 questions across six sections of program evaluation: demographics; field sampling; data entry, summary, and reporting; management decision support; programmatic views; and additional input. Respondents generally had positive views of the LTM program, but the survey revealed differences among respondents with different functional roles (e.g., fisheries researchers and managers viewed the decisional value, priority, and sample sizes of LTM data more favorably than habitat managers) while highlighting high-priority future initiatives (e.g., database development). Our results demonstrate the utility of stakeholder surveys as an important step in evaluating monitoring programs.

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USGS2023

How do ambient conditions and management actions affect manatee movements and habitat use?

Kings Bay in northwest Florida, USA, is an important winter home of the largest aggregation of Florida manatee ( Trichechus manatus latirostris ), and the only location in the United States where visitors legally swim and interact with manatees. In addition to ambient conditions, visitors to the area and management actions have the potential to influence manatee behaviors. We tracked 32 manatees with satellite-linked global position system (GPS) telemetry tags in Kings Bay from 2006 to 2018. Also, personnel at Crystal River National Wildlife Refuge collected manatee counts at Three Sisters Springs from 2014 to 2017. Our objectives were to document the use of springs and other habitat components in Kings Bay relative to ambient water temperature, time of day, tide stage, and management actions within Three Sisters Springs and other manatee sanctuaries in the bay. Manatees that we tagged in Kings Bay spent a median 87% of the winter within the local study area, compared to 47% for animals that we tagged in the Florida Panhandle. Manatees showed preferences for King and Magnolia springs basins at low tide, indicating that they function as tidal refuges, when other locations may be less accessible; we also recorded within spring basin movements. Magnolia Spring Basin showed a significant diel pattern overall, and within basins, King Spring, Tarpon Hole, and Three Sisters Springs were used more during the night than during the day. All areas outside Kings Bay were used more at warmer ambient gulf water temperatures, while all of the springs basins were used more when gulf temperature was colder, especially Three Sisters Springs Basin. Management of Three Sisters Springs had an influence on manatee use during times of cold ambient gulf water temperatures; manatees used the springs more when the spring was closed to visitors, versus when the springs were completely open or when the spring lobes alone were closed. Manatee decisions were consistent with avoiding human interactions.

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USGS2023

The Everglades vulnerability analysis: Linking ecological models to support ecosystem restoration

Understanding of the Everglades’ ecological vulnerabilities and restoration needs has advanced over the past decade but has not been applied in an integrated manner. To address this need, we developed the Everglades Vulnerability Analysis (EVA), a decision support tool that uses modular Bayesian networks to predict the ecological outcomes of a subset of the ecosystem’s health indicators. This tool takes advantage of the extensive modeling work already done in the Everglades and synthesizes information across indicators of ecosystem health to forecast long-term, landscape-scale changes. In addition, the tool can predict indicator vulnerability through comparison to user-defined ideal system states that can vary in the level of certainty of outcomes. An integrated understanding of the Everglades system is essential for evaluation of trade-offs at local, regional, and system-wide scales. Through EVA, Everglades restoration decision makers can provide effective guidance during restoration planning and implementation processes to mitigate unintended consequences that could result in further damage to the Everglades system.

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USGS2023

Environmental formation of methylmercury is controlled by synergy of inorganic mercury bioavailability and microbial mercury-methylation capacity

Methylmercury (MeHg) production is controlled by the bioavailability of inorganic divalent mercury (Hg(II) i ) and Hg-methylation capacity of the microbial community (conferred by the hgcAB gene cluster). However, the relative importance of these factors and their interaction in the environment remain poorly understood. Here, metagenomic sequencing and a full-factorial MeHg formation experiment were conducted across a wetland sulfate gradient with different microbial communities and pore water chemistries. From this experiment, the relative importance of each factor on MeHg formation was isolated. Hg(II) i bioavailability correlated with the dissolved organic matter composition, while the microbial Hg-methylation capacity correlated with the abundance of hgcA genes. MeHg formation responded synergistically to both factors. Notably, hgcA sequences were from diverse taxonomic groups, none of which contained genes for dissimilatory sulfate reduction. This work expands our understanding of the geochemical and microbial constraints on MeHg formation in situ and provides an experimental framework for further mechanistic studies.

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USGS2023

Maximum clutch size of an invasive Burmese Python (Python bivittatus) in Florida, USA

Native to southeastern Asia, the Burmese Python (Python bivittatus Kuhl 1820) is an invasive species established in southern Florida (Snow et al. 2007; Krysko et al. 2016; Krysko et al. 2019). Pythons are documented as having negative effects on the Greater Everglades Ecosystem and they have proven to be a complex problem for managers trying to control populations (Guzy et al. 2023). This species can move long distances (Pittman et al. 2014; Hart et al. 2015), use diverse habitats (Hart et al. 2015; Walters et al. 2016; Bartoszek et al. 2021a), consume a wide range of vertebrate prey items (Romagosa et al. 2022; Guzy et al. 2023 and citations therein), and has few documented predators (Bartoszek et al. 2021b; Mccollister et al. 2021; Currylow et al. 2023). Another factor that likely has contributed to the success of Burmese Pythons as an invasive species is their reproductive output (Reed et al. 2012). Though data are limited, clutch sizes of pythons in Florida range from 22–84 (mean = 49; see Currylow et al. 2022a and citations therein). Herein we report, to the best of our knowledge, the largest number of eggs in a single wild python nest recorded to date in Florida.

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USGS2023

Reconstructing the geomorphic evolution and sediment budget history of a dynamic barrier island: Anclote Key, Florida

Decadal to centennial variations in sediment availability are a primary driver of coastal change within barrier systems. Models help explore how barrier morphology relates to past changes in magnitude of sediment availability, but this requires insights and validation from field efforts. In this study, we investigate the progradation of Anclote Key via its morphostratigraphy, a presently dynamic barrier on the Central Florida Gulf Coast. The results of our field efforts, including vibracores, ground-penetrating radar scans, and optically stimulated luminescence dating of sediments, reveal that Anclote Key has gone through at least two phases of sustained island-scale progradation, with an intervening episode of transgression followed by relative stability. We show that these shifts were likely driven by relatively small changes in shoreface sediment availability owing to the island’s limited accommodation and suggest that Anclote Key may have been relatively isolated from the alongshore sediment supply of nearby barriers prior to the late 20 th century.

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USGS2023

Bluegill population demographics as related to abiotic and biotic factors in Florida lakes

Research on Bluegills, Lepomis macrochirus R., is abundant but typically focuses on water bodies with similar environmental conditions. We assessed Bluegill density, relative abundance (catch per unit effort [CPUE] by electrofishing), growth, and size structure in 60 lakes with wide-ranging surface areas (2–12,412 ha), trophic states (oligotrophic–hypereutrophic), and macrophyte abundances (0.3–100 percent of lake volume inhabited [PVI]) across Florida, USA. Bluegill density and CPUE increased with lake productivity and decreased with macrophyte abundance. Bluegill growth increased with lake productivity and CPUE of stock-length Florida Bass, Micropterus floridanus L., a Bluegill predator. Bluegill size structure increased with lake productivity and decreased with Bluegill density. Results indicate that Bluegill fisheries with abundant individuals of quality size (≥150 mm) require productive (>25 μg/L chlorophyll- a concentration) lakes with moderate to high macrophyte coverage (PVI 50–100), abundant stock-length Florida Bass (>40 fish/h of electrofishing), and Bluegill densities <300 fish/ha. This study provides an approach to predict Bluegill population demographics based on abiotic and biotic factors, establish fisheries management expectations, and develop regional and lake-specific management tools.

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USGS2023

Continuous stream discharge, salinity, and associated data collected in the lower St. Johns River and its tributaries, Florida, 2021

The U.S. Army Corps of Engineers, Jacksonville District, is deepening the St. Johns River channel in Jacksonville, Florida, by 7 feet along 13 miles of the river channel beginning at the mouth of the river at the Atlantic Ocean, in order to accommodate larger, fully loaded cargo vessels. The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, monitored stage, discharge, and (or) water temperature and salinity at 26 continuous data collection stations in the St. Johns River and its tributaries. This is the sixth annual report by the U.S. Geological Survey on data collection for the Jacksonville Harbor deepening project. Prior reports in this series documented data collected from October 2015 to September 2020. This report contains information pertinent to data collection during the 2021 water year, from October 2020 to September 2021. There were no modifications this year to the previously installed monitoring network. Data at each station were compared for the length of the project and on a yearly basis to show the annual variability of discharge and salinity in the project area. Discharge and salinity varied widely during the 2021 water year data collection period, which included above-average rainfall for four of the five counties in the study area. Total annual rainfall for all counties ranked third among the annual totals computed for the 6 years considered for this study. Annual mean discharge at Durbin Creek was highest among the tributaries, followed by Trout River, Clapboard Creek, Ortega River, Pottsburg Creek at U.S. 90, Julington Creek, Pottsburg Creek near South Jacksonville, Dunn Creek, Cedar River, and Broward River, whose annual mean discharge was lowest. Annual mean discharge at 7 of the 10 tributary monitoring sites was higher for the 2021 water year than for the 2020 water year, and the computed annual mean flow at Clapboard Creek was the highest over the 6 years considered for this study. The annual mean discharge for each of the main-stem sites was higher for the 2021 water year than for the 2020 water year and ranked second among the annual totals computed for the 6 years considered for this study. Among the tributary sites, annual mean salinity was highest at Clapboard Creek, the site closest to the Atlantic Ocean, and was lowest at Durbin Creek, the site farthest from the ocean. Annual mean salinity data from the main-stem sites on the St. Johns River indicate that salinity decreased with distance upstream from the ocean, which was expected. Relative to annual mean salinity calculated for the 2020 water year, annual mean salinity at all monitoring locations was lower for the 2021 water year except at the tributary site of Durbin Creek, which remained the same. The 2021 annual mean salinity at all sites ranked second lowest since the beginning of the study in 2016 except at Julington Creek and Racy Point, which tied for lowest, and Durbin Creek, which had the same value for each year.

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USGS2023

Nest-site selection model for endangered Everglade snail kites to inform ecosystem restoration

dictors of nesting for snail kites in south Florida. The results of our modeling indicate that hydrology, percent canopy cover, and proximity to recently burned areas were the most important factors associated with nest-site selection for snail kites. Water depths between 75 and 100 cm, water recession rates between 0 and 1.25 cm/day, percent canopy covers <20%, and areas <10 km from recently burned habitat were associated with the greatest likelihood of nest-site selection. KiteNest is applicable to natural resource management decisions in the Everglades and may be useful independently or in conjunction with other ecological models for restoration decision support.

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USGS2023

Sea level rise may pose conservation challenges for the endangered Cape Sable seaside sparrow

Biodiversity conservation under a changing climate is a challenging endeavor. Landscapes are shifting as a result of climate change and sea level rise but plant communities in particular may not keep up with the pace of change. Predictive ecological models can help decision makers understand how species are likely to respond to change and then adjust management actions to align with desired future conditions. Florida’s Everglades is a wetland ecosystem that is host to many species, including a large number of endangered and endemic species. Everglades ecosystem restoration has been ongoing for decades, but consideration of sea level rise impacts in restoration planning is more recent. Incorporating potential impacts from sea level rise into restoration planning should benefit species and their coastal habitats, most notably at the southern Florida peninsula. The endangered Cape Sable seaside sparrow ( Ammospiza maritima mirabilis ) occurs in marl prairie habitat at the southern end of the Everglades. The locations of three of its six subpopulations are proximate to the coast. We used a spatially explicit predictive model, EverSparrow, to estimate probability of sparrow presence considering both hydrologic change from restoration and sea level rise. We found that the probability of sparrow presence decreased with increasing sea level rise. Within approximately 50 years, probability of presence significantly decreased for all three coastal subpopulation areas, with areas above 40% probability increasingly limited. Given the exceptionally low dispersal ability of this species and the geographic restrictions for habitat expansion, our results highlight the importance of freshwater flow into the southern Everglades marl prairie for habitat conservation.

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USGS2023

Burmese pythons in Florida: A synthesis of biology, impacts, and management tools

Burmese pythons ( Python molurus bivittatus ) are native to southeastern Asia, however, there is an established invasive population inhabiting much of southern Florida throughout the Greater Everglades Ecosystem. Pythons have severely impacted native species and ecosystems in Florida and represent one of the most intractable invasive-species management issues across the globe. The difficulty stems from a unique combination of inaccessible habitat and the cryptic and resilient nature of pythons that thrive in the subtropical environment of southern Florida, rendering them extremely challenging to detect. Here we provide a comprehensive review and synthesis of the science relevant to managing invasive Burmese pythons. We describe existing control tools and review challenges to productive research, identifying key knowledge gaps that would improve future research and decision making for python control.

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USGS2023

Green turtle movements in the Gulf of Mexico: Tracking reveals new migration corridor and habitat use suggestive of MPA expansion

Globally, Marine Protected Areas are an important tool in the conservation of large marine vertebrates. Recent studies have highlighted the use of protected areas by imperiled green turtles ( Chelonia mydas ) in the southern Gulf of Mexico. To identify and characterize inter-nesting, migratory, and foraging areas for green turtles that nest in the northern Gulf of Mexico, we deployed 14 satellite tags on 13 individual green turtles after nesting in Northwest Florida. We used switching state-space modeling to highlight turtle use in the Florida Keys National Marine Sanctuary and in habitat outside of protected areas such as near Cape Sable, Florida and off the Yucatán Peninsula, Mexico. Turtles were tracked for 21–217 days and migrated for a mean of 22 days. Five individuals used stopover sites during migration; these sites were in areas of dense seagrass habitat, often within boundaries of existing Aquatic Preserves. Turtles established mean foraging home ranges of 118.0 km 2 (50% kernel density estimate) with foraging centroids that were 0.33–7.3 km apart. The area off Cape Sable, Florida, which lies outside of currently protected area boundaries, appears to be a hotspot for green turtles that nest throughout the Gulf of Mexico. While protected areas in the Gulf of Mexico are used by this subset of nesting green turtles, several key sites remain unprotected. These findings are relevant when considering expansion of currently protected areas and in defining critical habitat for this species.

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USGS2023

The sands of time: Predicting sea level rise impacts to barrier island habitats

Coastal beach ecosystems support critical habitat for numerous species and are vulnerable to sea level rise. Sand beaches are spatially and temporally dynamic, making it difficult to accurately predict future habitat loss – estimates that are crucial as species are being assessed for protection. We mapped sand beach habitat on 12 focal barrier islands and low-lying beaches off the Gulf Coast of Florida, USA using two methods for comparison - a remotely sensed land cover and hand-digitized aerial imagery that was collected concurrently with digital elevation data. We then compared estimates of beach habitat lost to sea level rise between the two methods and compared this sensitivity to control mangrove islands. Predictions suggest that most of the beach habitat in our study areas will be underwater within the next century. These beaches represent critical nesting habitat for vulnerable vertebrate species such as the snowy plover ( Charadrius nivosus ) and the loggerhead turtle ( Caretta caretta ). Importantly, we found that for some islands, using remotely sensed land cover data led us to under- or over-estimate the amount of beach habitat lost to sea level rise relative to the digitized data because of the temporal mismatch between land cover and elevation data. In contrast, we found relatively little difference between methods in the amount of mangrove forest lost to sea level rise on nearby control islands. We suggest that using land cover data collected at the same time as elevation data can produce more accurate predictions of beach habitat inundation from sea level rise.

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USGS2023

Precipitation, submarine groundwater discharge of nitrogen, and red tides along the southwest Florida Gulf coast

Blooms of the dinoflagellate Karenia brevis occur almost every year along the southwest Florida Gulf coast. Long-duration blooms with especially high concentrations of K. brevis , known as red tides, destroy marine life through production of neurotoxins. Current hypotheses are that red tides originate in oligotrophic waters far offshore using nitrogen (N) from upwelling bottom water or, alternatively, from blooms of Trichodesmium , followed by advection to nearshore waters. But the amount of N available from terrestrial sources does not appear to be adequate to maintain a nearshore red tide. To explain this discrepancy, we hypothesize that contemporary red tides are associated with release of N from offshore submarine groundwater discharge (SGD) that has accumulated in benthic sediment biomass by dissimilatory nitrate reduction to ammonium (DNRA). The release occurs when sediment labile organic carbon (LOC), used as the electron donor in DNRA, is exhausted. Detritus from the resulting destruction of marine life restores the sediment LOC to continue the cycle of red tides. The severity of individual red tides increases with increased bloom-year precipitation in the geographic region where the SGD originates, while the severity of ordinary blooms is relatively unaffected.

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