Geology topics

Research about Florida

Source-linked reports with geographic coverage including Florida.

At least 271 records · Page 15Linked to original sources

USGS2021

Evaluating the use of marine protected areas by endangered species: A habitat selection approach

1. Optimizing the design of marine protected area (MPA) networks for the conservation of migratory marine species and their habitats involves a suite of important considerations, such as appropriate scale requirements and the distribution of anthropogenic impacts. Often, a fundamental component of the conservation planning process is delineating areas of high use or high biodiversity within a region of interest. 2. However, basing conservation strategies off merely the number of individuals in an ecosystem is outdated and potentially subject to arbitrary thresholds. To be effective at protecting marine megafauna, MPAs would ideally encompass habitats used by focal species. Through satellite-tracking studies, evidence of whether species actually use protected areas is emerging. 3. Here, we present a multispecies perspective on habitat selection within existing MPAs throughout the Floridian ecoregion, which encompasses coastal Florida and the Gulf of Mexico. Using an 11-year satellite-tracking dataset on 235 marine turtles, we used integrated step selection analysis to quantify the effects of sea turtle behavioural state (identified by a switching state-space model), protected area status, chlorophyll and bathymetry on habitat selection. 4. Our results show that sea turtles do select for existing protected areas, specifically multi-use zones, while controlling for the effects of depth and primary productivity. However, our analysis revealed that turtles showed no selection for the no-take zones within MPAs, during either transiting or foraging. 5. These findings contribute to the existing literature base of MPA use for highly mobile, imperilled species and could inform management of existing MPAs or changes to zoning, specifically multi-use to no-take. Our use of a robust spatial modelling framework to evaluate habitat selection relative to MPAs could be incorporated into conservation planning to build MPA networks designed to accommodate migratory species.

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USGS2021

Movements of marine and estuarine turtles during Hurricane Michael

Natural disturbances are an important driver of population dynamics. Because it is difficult to observe wildlife during these events, our understanding of the strategies that species use to survive these disturbances is limited. On October 10, 2018, Hurricane Michael made landfall on Florida’s northwest coast. Using satellite and acoustic telemetry, we documented movements of 6 individual turtles: one loggerhead sea turtle, one Kemp’s ridley sea turtle, three green sea turtles and one diamondback terrapin, in a coastal bay located less than 30 km from hurricane landfall. Post-storm survival was confirmed for all but the Kemp’s ridley; the final condition of that individual remains unknown. No obvious movements were observed for the remaining turtles however the loggerhead used a larger home range in the week after the storm. This study highlights the resiliency of turtles in response to extreme weather conditions. However, long-term impacts to these species from habitat changes post-hurricane are unknown.

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USGS2021

The demographic contributions of connectivity versus local dynamics to population growth of an endangered bird

Conservation and management increasingly focus on connectivity, because connectivity driven by variation in immigration rates across landscapes is thought to be crucial for maintaining local population and metapopulation persistence. Yet, efforts to quantify the relative role of immigration on population growth across the entire range of species and over time have been lacking. We assessed whether immigration limited local and range‐wide population growth of the endangered snail kite Rostrhamus sociabilis in Florida, USA, over 18 years using multi‐state, reverse‐time modelling that accounts for imperfect detection of individuals and unobservable states. Demographic contributions of immigration varied depending on the dynamics and geographic position of the local populations, were scale‐dependent and changed over time. By comparing the relative contributions of immigration versus local demography for periods of significant change in local abundance, we found empirical evidence for a disproportionately large role of immigration in facilitating population growth of a centrally located population—a connectivity ‘hub’. The importance of connectivity changed depending of the spatial scale considered, such that immigration was a more important driver of population growth at small versus large spatial scales. Furthermore, the contribution of immigration was much greater during time periods when local population size was small, emphasizing abundance‐dependent rescue effects. Our findings suggest that efforts aimed at improving local breeding habitat will likely be most effective at increasing snail kite population growth. More broadly, our results provide much needed information on the role of connectivity for population growth, suggesting that connectivity conservation may have the greatest benefits when efforts focus on centrally located habitat patches and small populations. Furthermore, our results highlight that connectivity is highly dynamic over time and that interpreting the effects of connectivity at local scales may not transfer to region‐wide dynamics.

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USGS2021

Development and application of surrogate models, calculated loads, and aquatic export of carbon based on specific conductance, Big Cypress National Preserve, south Florida, 2015–17

Understanding the carbon transport within aquatic environments is crucial to quantifying global and local carbon budgets, yet limited empirical data currently (2021) exist. This report documents methodology and provides data for quantifying the aquatic export of carbon from a cypress swamp within Big Cypress National Preserve and is part of a larger carbon budget study. The U.S. Geological Survey operated two continuous monitoring stations, 022889001 and 022909471, that measured flow volume and water quality within the Big Cypress National Preserve in South Florida from September 2015 to October 2017. Station 022889001 represented the flow into the study area and station 022909471 represented the flow out of the study area. Site-specific regression models were developed by using continuously measured specific conductance and concomitant, discretely collected dissolved organic carbon, dissolved inorganic carbon, and particulate carbon samples to calculate total carbon (TC) concentrations at 15-minute intervals. Calculated TC concentrations typically increased as flow was decreasing and decreased as flow was increasing. TC loads were calculated by multiplying concentrations and flow volume, and the difference between the load calculations for input/output locations of the swamp flow system was used to determine the aquatic carbon export from the study area. Calculated monthly TC loads ranged from 0 metric tons in spring 2017 at both stations to 3,145 and 7,821 metric tons in September 2017 at 022889001 and 022909471, respectively. During 2016, the annual loads were 10,479 and 15,243 metric tons at 022889001 and 022909471, respectively. Calculated monthly aquatic TC exports from the study area ranged from −0.7 gram of carbon per square meter in May 2016 to 44.1 grams of carbon per square meter during September 2017. The carbon export from the study area varied monthly, increased as flow increased, and was greatly influenced by Hurricane Irma in September 2017. The aquatic TC export from the Sweetwater Strand study area was 42.0 grams of carbon per square meter per year in 2016, which is substantially (about 15 times) larger than the estimated overall mean riverine carbon export per square meter for the eastern United States; however, it was also less than the monthly export of carbon in September 2017. The monthly aquatic carbon export from the study area in September 2017 alone was greater than the aquatic carbon export from all of 2016, which is largely the result of the substantial increase in flow attributed to Hurricane Irma.

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USGS2021

Variation in species composition, size and fitness of two multi-species sea turtle assemblages using different neritic habitats

The neritic environment is rich in resources and as such plays a crucial role as foraging habitat for multi-species marine assemblages, including sea turtles. However, this habitat also experiences a wide array of anthropogenic threats. To prioritize conservation funds, targeting areas that support multi-species assemblages is ideal. This is particularly important in the Gulf of Mexico where restoration actions are currently ongoing following the Deepwater Horizon oil spill. To better understand these areas in the Gulf of Mexico, we characterized two multi-species aggregations of sea turtles captured in different neritic habitats. We described species composition and size classes of turtles, and calculated body condition index for 642 individuals of three species captured from 2011 to 2019: 13.6% loggerheads (Caretta caretta), 44.9% Kemp’s ridleys (Lepidochelys kempii) and 41.4% green turtles (Chelonia mydas). Species composition differed between the two sites with more loggerheads captured in seagrass and a greater proportion of green turtles captured in sand bottom. Turtles in sand bottom were smaller and weighed less than those captured in seagrass. Although small and large turtles were captured at both sites, the proportions differed between sites. Body condition index of green turtles was lower in sand habitat than seagrass habitat; there was no difference for Kemp’s ridleys or loggerheads. In general, smaller green turtles had a higher body condition index than larger green turtles. We have identified another habitat type used by juvenile sea turtle species in the northern Gulf of Mexico. In addition, we highlight the importance of habitat selection by immature turtles recruiting from the oceanic to the neritic environment, particularly for green turtles.

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USGS2021

Accelerometry to study fine-scale activity of invasive Burmese pythons (Python bivittatus) in the wild

The establishment of Burmese pythons ( Python bivittatus) in Everglades National Park, Florida, USA, has been connected to a > 90% decline in the mesomammal population in the park and is a major threat to native reptile and bird populations. Efforts to control this population are underway, but are hampered by a lack of information about fine-scale activity cycles and ecology of these cryptic animals in the wild. We aimed to establish a technique for monitoring the activity of Burmese pythons in the wild using acceleration data loggers (ADLs), while attempting to identify any behavioral patterns that could be used to help manage this invasive species in the Greater Everglades and South Florida.

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USGS2021

Underwater photographic reconnaissance and habitat data collection in the Florida Keys—A procedure for ground truthing remotely sensed bathymetric data

Bathymetric geoprocessing analyses of the Florida Reef Tract have provided insights into trends of seafloor accretion and seafloor erosion over time and following major storm events. However, bathymetric surveys sometimes capture manmade structures and vegetation, which do not represent the desired bare-earth data. Therefore, ground truthing is essential to maintain the most accurate bathymetric data possible. Field procedures were developed in the Florida Reef Tract in order to quickly and accurately collect consistent imagery and habitat data across variable sites. Areas of significant elevation change were determined through elevation change analyses; these areas were targeted for ground truthing in order to check the reliability of the surveys. This report outlines the standard operating procedures for underwater photographic imagery and habitat data collection, as well as procedures for the storage of these photographs and associated metadata. These standard operating procedures ensure the reproducibility of photographic operations and habitat data collection in future field excursions, enable longitudinal visual comparisons alongside seafloor elevation change analyses, and also have the potential to be applied to similar studies in different coastal environments.

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USGS2021

Forecasting ecological responses for wetland restoration planning in Florida's Everglades

The Everglades wetland was once a river of grass, with water flowing slowly through the sawgrass, southward across the landscape. As developers took hold of south Florida, water was sent away from the heart of the Everglades through canals and levees to protect the former wetland for residential and agricultural development. In the 1990s, planning began to restore the Everglades in what is the largest hydrologic restoration undertaking in the world. With billions of taxpayer dollars at stake, restoration planners benefit from forecasting tools to inform restoration planning. To meet this need, scientists developed predictive ecological models and other decision support tools tailored to this dynamic ecosystem as well as to the needs of restoration planning teams. Predictive modeling has been able to take advantage of well-understood relationships between species of interest and hydrologic dynamics in the Everglades. Recent modeling advances include multi-species approaches that consider interactions among species as well as explicit consideration of trade-offs among species from potential water management actions. Scientists are also starting to look at ecosystem-wide vulnerabilities with explicit consideration of future change such as sea level rise. Modeling tools and approaches continue to be refined to meet decision making needs for Everglades restoration. However, more work is needed to consider additional complexities of this dynamic wetland as well as to consider the broader socio-environmental system.

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USGS2021

Native mammals lack resilience to invasive generalist predator

Invasive predators have caused catastrophic declines in native wildlife across the globe. Though research has focused on the initial establishment, rapid growth, and spread of invasive predators, our understanding of prey resilience to established invasive predators remains limited. As a direct result of invasive Burmese pythons ( Python molurus bivittatus ), medium- to large-bodied native mammals decreased drastically across much of southern Florida as early as 2003. By 2014, most of these mammal species were exceedingly rare within the core invasion area, while pythons expanded outward to newly invaded areas. We used python observations to delineate the core python invasion area from the more recently invaded invasion front, and we compared changes in mammal occurrence from 2014 to 2019 between these two areas. We surveyed mammal communities using camera traps and scat surveys and used these observations to quantify the changes in occurrence among mammal species. As expected, occurrence of medium- and large-bodied mammals declined within the invasion front. However, contrary to our expectation, we observed little evidence of resilience among mammals within the invasion core. Of the 15 species detected in 2019, invasive black rats were the only species to increase in occurrence within the invasion core. Additionally, we observed declines in occurrence among native rodents within the invasion core, which were previously thought to be resistant to the effects of pythons. The continued presence of invasive pythons appears to be shifting the diverse mammal communities of southern Florida to one primarily composed of invasive species.

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USGS2021

Hierarchical models improve the use of alligator abundance as an indicator

Indicator species are species which can be monitored as an index to measure the overall health of an ecosystem. Crocodylians have been shown to be good indicators of wetland condition as they respond to changes in hydrology, can be efficiently monitored, and are a key part of ecosystem trophic relationships. Eye shine surveys at night are a standard method used to sample alligators, but because some individuals that are present in a study area may go undetected and the proportion of individuals counted is not constant over time, appropriate modeling is required to convert counts to estimates of abundance. We analyzed 13 years of American alligator ( Alligator mississippiensis ) survey count data from South Florida using an N -mixture model. Alligator abundance estimates were assigned to quartiles that were then represented as color coded categories of red, yellow, or green to provide a straightforward rating of Everglades restoration based on familiar stoplight coloring. These results were then compared to a previously used method in which unadjusted counts of these same data were assigned to color coded quartile categories. Water depth played a major role in the detection probability of alligators and the stoplight colors between the two methods matched 76% of the time. This suggests that the original stoplight score method provided a good overall snapshot of the trends in alligator abundance in the Everglades; however, the hierarchical models estimate abundance and trends of alligator abundance by incorporating detection probability thus providing unbiased estimates of abundance.

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USGS2021

Landscape-scale drivers of endangered Cape Sable Seaside Sparrow (Ammospiza maritima mirabilis) presence using an ensemble modeling approach

The Florida Everglades is a vast and iconic wetland ecosystem in the southern United States that has undergone dramatic changes from habitat degradation, development encroachment, and water impoundment. Starting in the past few decades, large restoration projects have been undertaken to restore the landscape, including improving conditions for threatened and imperiled taxa. One focus of restoration has been the marl prairie ecosystem, where the federally endangered Cape Sable Seaside Sparrow ( Ammospiza maritima mirabilis ; CSSS) resides. The CSSS is endemic to the Everglades where populations have been steadily declining, signaling the importance of decision support tools for natural resource managers for evaluating water management and restoration scenarios. Here we developed an ensemble logistic regression, combining a frequentist and Bayesian approach, to model CSSS presence and measure how environmental factors such as hydrometrics, fire occurrence, and vegetation structure impact CSSS habitat suitability. This is the first analysis to quantitatively assess the interdependent relationships between a broad range of environmental factors and CSSS presence across the landscape. Our results show that the probability of CSSS presence was highest in areas with dry conditions, hydroperiods between 80 and 120 days, percentages of canopy cover and woody vegetation less than 10%, and more than six years post-fire where 75% or more of the area was burned. Because the frequentist and Bayesian models had nearly identical spatial outputs with the Bayesian model having slightly higher validation metrics, we used the Bayesian approach as our final model (EverSparrow). The results from our analysis can provide a valuable decision support tool as natural resource managers work to restore the Everglades landscape.

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USGS2021

Carbon stock losses and recovery observed for a mangrove ecosystem following a major hurricane in Southwest Florida

Studies integrating mangrove in-situ observations and remote sensing analysis for specific sites often lack precise estimates of carbon stocks over time frames that include disturbance events. This study quantifies change in mangrove area from 1985 to 2018 with Landsat time series analysis, estimates above and belowground stored carbon using field data, and evaluates aboveground carbon stock changes after the 2004 Category 4, Hurricane Charley, in J.N. “Ding” Darling National Wildlife Refuge. Two allometric equation methods yielding similar results were used to estimate aboveground carbon content in three mangrove species found in the refuge. Aboveground carbon contained 67 (SE = 2) MgC ha −1 with a total refuge estimate of 74,504 MgC in 2018. Sediment contained 259 (SE = 28) MgC ha −1 for a total of 288,008 MgC in the refuge. The initial reduction in mangrove area caused by Hurricane Charley was between 0.6% and 5.3%, equivalent to between 427 MgC and 3,599 MgC under three different scenarios of carbon loss. As a result of the hurricane, approximately 61 ha of mangroves were disturbed, of which 24 ha had recovered by 2018, with 37 ha (~3% of the pre-hurricane mangrove area) still not recovered 14 years after the event. The 37 ha of mangroves that have not recovered are located in a tidally restricted area of the refuge. A longer recovery time in this area will likely result in a greater loss of carbon storage than in the rest of the refuge.

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USGS2021

Chronic exposure to glyphosate in Florida manatee

Florida manatees depend on freshwater environments as a source of drinking water and as warm-water refuges. These freshwater environments are in direct contact with human activities were glyphosate-based herbicides are being used. Glyphosate is the most used herbicide worldwide and it is intensively used in Florida as a sugarcane ripener and to control invasive aquatic plants. The objective of the present study was to determine the concentration of glyphosate and its breakdown product, aminomethylphosphonic acid (AMPA), in Florida manatee plasma and assess their exposure to manatees seeking a warm-water refuge in Crystal River (west central Florida), and in South Florida. We analyzed glyphosate’s and AMPA’s concentrations in Florida manatee plasma (n = 105) collected during 2009–2019 using HPLC-MS/MS. We sampled eight Florida water bodies between 2019 and 2020, three times a year: before, during and after the sugarcane harvest using grab samples and molecular imprinted passive Polar Organic Chemical Integrative Samplers (MIP-POCIS). Glyphosate was present in 55.8% of the sampled Florida manatees’ plasma. The concentration of glyphosate has significantly increased in Florida manatee samples from 2009 until 2019. Glyphosate and AMPA were ubiquitous in water bodies. The concentration of glyphosate and AMPA was higher in South Florida than in Crystal River, particularly before and during the sugarcane harvest when Florida manatees depend on warm water refuges. Based on our results, Florida manatees were chronically exposed to glyphosate and AMPA, during and beyond the glyphosate applications to sugarcane, possibly associated with multiple uses of glyphosate-based herbicides for other crops or to control aquatic weeds. This chronic exposure in Florida water bodies may have consequences for Florida manatees’ immune and renal systems which may further be compounded by other environmental exposures such as red tide or cold stress.

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USGS2021

Environmental factors predicting the orientation of sea turtle hatchlings on a naturally lighted beach: A baseline for light-management goals

On sea turtle nesting beaches, artificial lighting associated with human development interferes with hatchling orientation from nest to sea. Although hatchling disorientation has been documented for many beaches, data that managers can use in understanding, predicting, and managing the issue are of limited detail. The present study provides baseline hatchling orientation data that can be compared to those from beaches with artificial lighting to prioritize light-management efforts there. In 2014, the precision of hatchling orientation was quantified for 87 nests on a naturally lighted beach that had little to no artificial lighting. Precision of hatchling orientation was regressed against seven environmental variables: beach slope, distance from nest to dune, dune height, apparent dune silhouette height relative to nest site, moon illumination percentage, cloud cover percentage, and relative humidity. Results favored a regression model that included distance from nest to dune, with shorter distances from the dune predicting a narrower angular range (i.e., greater precision) of hatchling orientation. The study confirmed findings of an earlier laboratory experiment that highlighted the importance to accurate hatchling orientation of a dark silhouette (dune) on the side of the nest site opposite the ocean side. Reducing artificial light and promoting the planting of pioneer plants that assist dune formation can increase hatchling survival.

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USGS2021

Complex sedimentary processes in large coastal embayments and their potential for coastal morphological and paleo tropical cyclone studies: A case study from Choctawhatchee Bay Western Florida, U.S.A

Storminess and sea-level can both have a significant impact on landforms in cyclone-prone coastal regions, although much of our understanding comes from short-timescale modern observations. This study aims to understand the variability of sediment transport and deposition in the Choctawhatchee Bay/Santa Rosa Island in the northern Gulf of Mexico, establishing the dominant sediment transport processes and morphological response of the barrier system to long-term variations in storminess and rising sea-levels. Here, we study the spatial and temporal changes in physicochemical properties of the sedimentary record of Choctawhatchee Bay to examine the character and fidelity of records of storm impacts spanning the Holocene. Proxies for marine and terrestrial conditions in the cores situated closer to the present barrier (proximal) show that sedimentation in coastal areas and marine influence of the bay during the last ~8000 yrs. were mainly determined by barrier response to the Holocene transgression and changes in storminess. In contrast, sedimentation close to the landward shore was governed by terrigenous input. The correlation of grain size and terrigenous proxies with regional hurricane records indicates that hinterland erosion by the rainfall during hurricane events is likely the dominant terrigenous sediment transport mechanism in areas close to the landward shore of the bay. These results suggest that sediment archives in large coastal deposition environments are equally suitable for sea level and cyclone modulated coastal morphological studies and paleo tropical cyclone studies, depending on the location, selected with an understanding of sedimentation processes in the vicinity.

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USGS2021

Stable isotopes used to infer trophic position of green turtles (Chelonia mydas) from Dry Tortugas National Park, Gulf of Mexico, United States

Evaluating resource use patterns for imperiled species is critical for understanding what supports their populations. Here we established stable isotope ( δ 13 "> δ13 C, δ 15 "> δ15 N) values for the endangered green sea turtle ( Chelonia mydas ) population found within the boundaries of Dry Tortugas National Park (DRTO), south Florida, USA. There is little gene flow between turtles sampled at DRTO and in other rookeries in Florida, underscoring the need to study this distinct population. Between 2008 and 2015 we collected multiple sample types (skin [homogenized epidermis/dermis], whole blood, red blood cells, plasma, carapace) from 151 unique green turtles, including 43 nesting females and 108 in-water captures; some individuals were resampled multiple times across years to evaluate consistency of isotope signatures. Isotopic ratios ranged from -27.3 to -5.4 for δ 13 "> δ 13 C and 3.7 to 10.6 for δ 15 "> δ 15 N. Using linear mixed models, we evaluated covariates (sample type, turtle size and year) that best explained the isotope patterns observed in turtle tissues. Predictions from the top model for δ 13 "> δ 13 C indicated a slight decrease over time and for δ 15 "> δ 15 N a slight increase in the middle sampling years (2010–2012); results indicated that turtle size appeared to be the driver behind the range in δ 13 "> δ 13 C and δ 15 "> δ 15 N observed in turtle skin. We found a pattern in stable carbon isotope values that are indicative of an ontogenetic change from an omnivorous diet in smaller turtles to a seagrass-based diet in larger turtles. When we compared the stable carbon and nitrogen isotope values of the samples collected from turtles with that of seagrasses found in DRTO, we found that turtles > 65 cm SCL had similar stable carbon isotope values to the seagrass species present. Results of this study suggest stable isotope analysis coupled with data for available resources can be useful for tracking and detecting future changes in green turtle resource shifts in DRTO.

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USGS2021

Native mammalian predators can depredate adult Burmese Pythons in Florida

Invasive predators are of conservation concern because they contribute to species declines and extinctions worldwide. Interactions of native fauna and invasive predators can be complex, but understanding these relationships can guide management and restoration. Observations of these interactions are especially important for invaders with low detectability like Python bivittatus (Burmese Python) where data are sparse. Here, we provide the first detailed documentation of mammalian attacks on Burmese Pythons in Florida: 1 Lynx rufus (Bobcat) predation of an adult male python and 1 Ursus americanus floridanus (Florida Black Bear) non-lethal attack on an adult female python.

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USGS2021

Genome-wide SNP analysis reveals multiple paternity in Burmese pythons invasive to the Greater Florida Everglades

Reproductive strategies are an essential component of invasion ecology that influence invasion success and rates of population growth. Burmese Pythons ( Python bivittatus ) are large constrictor snakes that were introduced to the Greater Everglades Ecosystem of southern Florida, USA, from Asia. Since their introduction, these giant constrictors have spread throughout wetlands of southern Florida while increasing in abundance and causing declines in the native species upon which they prey. Multiple paternity in reproduction could facilitate invasion success by increasing the genetic diversity produced within each reproductive event. We used Diversity Arrays Technology genome-wide genotyping to assess multiple paternity in the progeny of wild Burmese Pythons in Florida. We analyzed >4,000 single nucleotide polymorphisms from 153 neonates belonging to 4 clutches collected in southwestern Florida. Complementary hierarchical and K -means clustering analyses of the genetic distances within clutches revealed that three clutches were each fertilized by two sires, with a fourth fertilized by a single sire. The proportions of offspring attributable to each sire within multiple paternity clutches ranged from nearly even to highly skewed. Analysis of multivariate dispersion showed significantly increased genetic variability in the multiple paternity clutches. These results improve our understanding of the reproductive strategy and invasion potential of a giant constrictor with significant ecological impacts.

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