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Research about Florida

Source-linked reports with geographic coverage including Florida.

At least 1,027 records · Page 57Linked to original sources
USGS2006

Identifying suitable sites for Florida panther reintroduction

A major objective of the 1995 Florida Panther ( Puma concolor cory ) Recovery Plan is the establishment of 2 additional panther populations within the historic range. Our goal was to identify prospective sites for Florida panther reintroduction within the historic range based on quantitative landscape assessments. First, we delineated 86 panther home ranges using telemetry data collected from 1981 to 2001 in south Florida to develop a Mahalanobis distance (D 2 ) habitat model, using 4 anthropogenic variables and 3 landscape variables mapped at a 500-m resolution. From that analysis, we identified 9 potential reintroduction sites of sufficient size to support a panther population. We then developed a similar D 2 model at a higher spatial resolution to quantify the area of favorable panther habitat at each site. To address potential for the population to expand, we calculated the amount of favorable habitat adjacent to each prospective reintroduction site within a range of dispersal distances of female panthers. We then added those totals to the contiguous patches to estimate the total amount of effective panther habitat at each site. Finally, we developed an expert-assisted model to rank and incorporate potentially important habitat variables that were not appropriate for our empirical analysis (e.g., area of public lands, livestock density). Anthropogenic factors heavily influenced both the landscape and the expert-assisted models. Of the 9 areas we identified, the Okefenokee National Wildlife Refuge, Ozark National Forest, and Felsenthal National Wildlife Refuge regions had the highest combination of effective habitat area and expert opinion scores. Sensitivity analyses indicated that variability among key model parameters did not affect the high ranking of those sites. Those sites should be considered as starting points for the field evaluation of potential reintroduction sites.

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USGS2006

Archive of digital boomer seismic reflection data collected during USGS field activity 04SGI01 in the Withlacoochee River of West-Central Florida, March 2004

In March of 2004, the U.S. Geological Survey conducted a geophysical survey in the Withlacoochee River of west-central Florida. This report serves as an archive of unprocessed digital boomer seismic reflection data, trackline maps, navigation files, GIS information, Field Activity Collection System (FACS) logs, observer's logbook, and FGDC metadata. Filtered and gained digital images of the seismic profiles are also provided. Refer to the Acronyms page for expansion of all acronyms and abbreviations used in this report. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are also provided.

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USGS2006

Archive of digital boomer seismic reflection data collected during USGS field activities 95LCA03 and 96LCA02 in the Peace River of West-Central Florida, 1995 and 1996

In October and November of 1995 and February of 1996, the U.S. Geological Survey, in cooperation with the Southwest Florida Water Management District, conducted geophysical surveys of the Peace River in west-central Florida from east of Bartow to west of Arcadia. This report serves as an archive of unprocessed digital boomer seismic reflection data, trackline maps, navigation files, GIS files, Field Activity Collection System (FACS) logs, observers' logbooks, and formal FGDC metadata. Filtered and gained digital images of the seismic profiles are also provided. Refer to the Acronyms page for expansion of acronyms and abbreviations used in this report. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are also provided.

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USGS2006

Potentiometric surface of the Upper Floridan aquifer, west-central Florida, May 2005

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is a highly productive aquifer and supplies more than 10 times the amount of water pumped from either the surficial aquifer system or the intermediate aquifer system in most of the study area (Duerr and others, 1988). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2005. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in a tightly cased well that taps a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 67.27 inches for west-central Florida (from June 2004 through May 2005) was 14.20 inches above the historical cumulative average of 53.07 inches (Southwest Florida Water Management District (SWFWMD), 2005). The above average precipitation is attributed to the active hurrican season for Florida in 2004. Historical cumulative averages are calculated from regional rainfall summary reports (1915 to the most recent completed calendar year) and are updated monthly by the SWFWMD. This report, prepared by the U.S. Geological Survey (USGS) in cooperation with the SWFWMD, is part of a semiannual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the USGS during May 23-27, 2005. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the SWFWMD boundary by the USGS office in Altamonte Springs, Florida (Kinnaman, 2006). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition. Water levels in about 19 percent of the wells measured in May 2005 were lower than the May 2004 water levels (Blanchard and others, 2004). Data from 409 wells indicate that the May 2005 water levels ranged from about 5 feet below to about 18 feet above the May 2004 water levels (fig. 1). The largest water-level declines occurred in southwestern Hernando County, northeastern Hillsborough County, and parts of Hillsborough, Sumter, and Sarasota Counties. The largest water-level rises occurred in southeastern Hillsborough County, eastern Manatee County, and western Hardee County (fig. 1). Water levels in about 95 percent of the wells measured in May 2005 were lower than the September 2004 water levels (Blanchard and Seidenfeld, 2005). Data from 405 wells indicate that the May 2005 water levels ranged from about 22 feet below to 14 feet above the September 2004 water levels. The largest water-level decline was in east-central Manatee County and the largest water-level rise was in central Sarasota County.

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USGS2006

EAARL submarine topography: Biscayne National Park

This lidar-derived submarine topography map was produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs for the purposes of habitat mapping, ecological monitoring, change detection, and event assessment (for example: bleaching, hurricanes, disease outbreaks). As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring water depth and conducting cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to managers of coastal tropical habitats.

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USGS2006

Potentiometric surface of the Upper Floridan aquifer, west-central Florida, September 2005

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public-supply, domestic use, irrigation, and brackish-water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2005. The potentiometric surface is an imaginary surface, connecting points of equal altitude to which water will rise in tightly cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 55.19 inches for west-central Florida (from October 2004 through September 2005) was 2.00 inches above the historical cumulative average of 53.19 inches (Southwest Florida Water Management District, 2005). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period September 19-23, 2005. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Altamonte Springs, Florida (Kinnaman, 2006). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a "snapshot" of conditions at a specific time, nor do they necessarily coincide with the seasonal high water-level condition.

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USGS2006

EAARL topography: Dry Tortugas National Park

This lidar-derived submarine topography map was produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs for the purposes of habitat mapping, ecological monitoring, change detection, ad event assessment (for example: bleaching, hurricanes, disease outbreaks). As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring water depth and conducting cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to managers of coastal tropical habitats.

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USGS2006

Flow and salt transport in the Suwannee River estuary, Florida, 1999–2000: Analysis of data and three-dimensional simulations

A three-dimensional numerical model was developed to assist in the evaluation of the effects of changes in freshwater flow on the salinity regime of the lower Suwannee River, its estuary, and Suwannee Sound. Hydrodynamic and salt-transport modeling were supported by data from a comprehensive data-collection network operated in the lower Suwannee River during 1998-2000. The study area included all of the downstream-most 12 kilometers of the Suwannee River, Suwannee Sound, and part of the Gulf of Mexico. Development, calibration, and application of the hydrodynamic and salt-transport model were completed by using data primarily collected during October 1999-September 2000.

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USGS2006

A cyclostratigraphic and borehole-geophysical approach to development of a three-dimensional conceptual hydrogeologic model of the karstic Biscayne aquifer, southeastern Florida

A fundamental problem in the simulation of karst ground-water flow and solute transport is how best to represent aquifer heterogeneity as defined by the spatial distribution of porosity, permeability, and storage. Combined analyses of cyclostratigraphy, including lithofacies and depositional environments, and borehole-geophysical logs, has improved the conceptualization of porosity, permeability, and storage within the triple-porosity karstic Biscayne aquifer in an approximately 95-square-mile study area of Miami-Dade County in southeastern Florida. The triple porosity of the Biscayne aquifer is principally: (1) matrix of interparticle and separate-vug porosity, providing much of the storage, and under dynamic conditions, diffuse-carbonate flow; (2) touching-vug porosity creating stratiform ground-water flow passageways; and (3) less common conduit porosity composed mainly of bedding-plane vugs, thin solution pipes, and cavernous vugs. These three conduit porosity types are all pathways for conduit ground-water flow. To develop an accurate three-dimensional conceptual hydrogeologic model of the Biscayne aquifer in the study area, a detailed analysis of data was conducted that include continuously drilled cores, digital borehole images, borehole-fluid conductivity and temperature logs, and borehole-flowmeter measurements from 25 wells that fully penetrate the Biscayne aquifer. Six depositional environments for major lithologic components of the Biscayne aquifer--the Tamiami Formation, Fort Thompson Formation, and Miami Limestone--include: (1) middle ramp, (2) platform margin-to-outer platform, (3) open-marine platform interior, (4) restricted platform interior, (5) brackish platform interior, and (6) freshwater terrestrial environments. High-frequency cycles form the fundamental building blocks of the rocks composing the Biscayne aquifer. Vertical lithofacies successions, which have stacking patterns that reoccur, fit within the high-frequency cycles. Upward-shallowing subtidal cycles, upward-shallowing paralic cycles, and aggradational subtidal cycles define three types of ideal high-frequency cycles that occur within the Fort Thompson Formation and Miami Limestone. Based on vertical cycle patterns, high-frequency cycles group into two cycle sets: an older progradational cycle set and an overlying younger aggradational cycle. A primary observation is that a predictable vertical pattern of porosity and permeability commonly exists within the three ideal cycles because the porosity and permeability relate directly to lithofacies. Sixteen major lithofacies of the Fort Thompson Formation and Miami Limestone have been assigned to one of three pore classes (I, II, and III). Touching-vug porosity and conduit porosity characterize pore class I, which commonly comprises the lower part of upward-shallowing cycles within the Fort Thompson Formation and an upper aggradational cycle of the Miami Limestone. Matrix porosity distinguishes pore class II, which commonly occurs in the upper part of the upward-shallowing subtidal cycles and middle part of the upward-shallowing paralic cycles. Micrite-dominated, leaky, low-permeability lithologies are characteristic of pore class III, which commonly caps upward-shallowing paralic cycles and occurs throughout much of a lower aggradational cycle of the Miami Limestone. These relations among lithofacies, cyclicity, and aquifer attributes (porosity, permeability, and storage) are crucial features of the architecture of a three-dimensional conceptual hydrogeologic model of the karstic Biscayne aquifer. This study shows that development of these relations is critical to producing a realistic cycle-based karstic aquifer framework for the Biscayne aquifer and for karst aquifers within other platform carbonates.

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USGS2006

Evaluation of emerging contaminants of concern at the South District Wastewater Treatment Plant based on seasonal sampling events, Miami-Dade County, Florida, 2004

The Comprehensive Everglades Restoration Plan has identified highly treated wastewater as a possible water source for the restoration of natural water flows and hydroperiods in selected coastal areas, including the Biscayne Bay coastal wetlands. One potential source of reclaimed wastewater for the Biscayne Bay coastal wetlands is the effluent from the South District Wastewater Treatment Plant in southern Miami-Dade County. The U.S. Geological Survey, in cooperation with the Comprehensive Everglades Restoration Plan Wastewater Reuse Technology Pilot Project Delivery Team, initiated a study to assess the presence of emerging contaminants of concern in the South District Wastewater Treatment Plant influent and effluent using current wastewater-treatment methods. As part of the study, 24-hour composite and discrete samples were collected at six locations (influent at plants 1 and 2, effluent pump, reuse train, chlorine dioxide unit, and ultraviolet pilot unit) at the plant during: (1) a dry-season, low-flow event on March 2-3, 2004, with an average inflow rate of 83.7 million gallons per day; (2) a wet-season, average-flow event on July 20-21, 2004, with an average inflow rate of 89.7 million gallons per day; and (3) high-rate disinfection tests on October 5 and 20, 2004, with average flow rates of 84.1 and 119.6 million gallons per day, respectively. During these four sampling events, 26, 27, 29, and 35 constituents were detected, respectively. The following transformations in concentration were determined in the waste stream: -100 to 180 percent at the effluent pump and -100 to 85 percent at the reuse train on March 2-3, 2004, and -100 to 1,609 percent at the effluent pump and -100 to 832 percent at the reuse train on July 20-21, 2004; -100 to -37 percent at the effluent pump, -100 to -62 percent at the reuse train, -100 to -56 percent at the chlorine dioxide unit, and -100 to -40 percent at the ultraviolet pilot unit on October 5, 2004; and -100 to -4 percent at the effluent pump, -100 to 17 percent at the reuse train, -100 to -40 percent at the chlorine dioxide unit, and -100 to -14 percent at the ultraviolet pilot unit on October 20, 2004. Samples were tested for detection of household and industrial (organic) wastewater compounds, pharmaceutical compounds, antibiotic compounds, and hormones in influent. Two 'known' endocrine disrupting compounds?17 beta-estradiol (E2) and diethoxynonylphenol? and four 'suspected' endocrine-disrupting compounds?1,4-dichlorobenzene, benzophenone, tris(2-chloroethyl) phosphate, and tris(dichloroisopropyl) phosphate?were detected during these sampling events. Phenanthrene and indole showed the greatest concentration ranges and highest concentrations for the organic wastewater compounds. Acetaminophen showed the greatest concentration range and highest concentration, and warfarin showed the smallest concentration range for the pharmaceutical compounds. Sulfamethoxazole (a sulfonamide) showed the greatest concentration range and highest concentration, and sulfathiozole (also a sulfonamide) showed the smallest concentration range for the antibiotic compounds. Two hormones, 17 beta-estradiol (E2) and estrone (E1), were detected in influent. Samples were also tested for detection of organic wastewater compounds, pharmaceutical compounds, antibiotic compounds, and hormones in effluent. Indole showed the greatest concentration range and highest concentration, and triphenyl phosphate showed the smallest concentration range for the organic wastewater compounds. Dehydronifedipine showed the greatest concentration range and highest concentration, and warfarin had the smallest concentration range for the pharmaceutical compounds. Anhydro-erythromycin (a macrolide degradation product) showed the greatest concentration range, and sulfadiazine (a sulfonamide) and tetracycline showed the lowest concentration ranges for the antibiotic compounds. One hormone, 17 beta-estradiol (E2), was det

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USGS2006

Northern Florida reef tract benthic metabolism scaled by remote sensing

Holistic rates of excess organic carbon production (E) and calcification for a 0.5 km 2 segment of the backreef platform of the northern Florida reef tract (NFRT) were estimated by combining biotope mapping using remote sensing with community metabolic rates determined with a benthic incubation system. The use of ASTER multispectral satellite imaging for the spatial scaling of benthic metabolic processes resulted in errors in E and net calcification (G) of 48 and 431% respectively, relative to estimates obtained using AISA hyperspectral airborne scanning. At 19 and 125%, the E and G errors relative to the AISA-based estimates were less pronounced for an analysis that used IKONOS multispectral satellite imagery to spatially extrapolate the chamber process measurements. Our scaling analysis indicates that the holistic calcification rate of the backreef platform of the northern Florida reef tract is negligible at 0.07 g CaCO 3 m -2 d -1 . All of the mapped biotopes in this reef zone are net heterotrophic, resulting in an estimated holistic excess production rate of -0.56 g C m -2 d -1 , and an overall gross primary production to respiration ratio of 0.85. Based on our finding of ubiquitous heterotrophy, we infer that the backreef platform of the NFRT is a sink for external inputs of suspended particulate organic matter. Further, our results suggest that the inward advection of inorganic nutrients is not a dominant forcing mechanism for benthic biogeochemical function in the NFRT. We suggest that the degradation of the northern Florida reef tract may parallel the community phase shifts documented within other reef systems polluted by organic detritus.

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USGS2006

Multimodeling: new approaches for linking ecological models

The Everglades region of South Florida presents one of the major natural system management challenges facing the United States. With its assortment of alligators, crocodiles, manatees, panthers, large mixed flocks of wading birds, highly diverse subtropical flora, and sea of sawgrass, the ecosystem is unique in this country (Davis and Ogden 1994). The region is also perhaps the largest human-controlled system on the planet in that the major environmental factor influencing the region is water, and water flows are managed on a daily basis--subject to the vagaries of rainfall--by a massive system of locks, pumps, canals, and levees constructed over the past century. The changes brought about by such control have led to extensive modifications of historical patterns and magnitudes of flow, causing large declines in many native species, extensive changes in nutrient cycling and vegetation across south Florida, and great increases in pollutants such as mercury. Constrained by the conflicting demands of agriculture, urban human populations, and wildlife for control of water resources, and the varying agendas of hosts of government agencies and nongovernmental organizations, there is now an ongoing effort to plan for major changes to the system with expenditure estimates of eight billion dollars or more over the next several decades (USACOE 1999). Carrying out such planning, particularly as it impacts the natural systems of the region, provides one of the major challenges to the new field of computational ecology.

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USGS2006

Variability in supply and cross-shelf transport of pink shrimp ( Farfantepenaeus duorarum ) postlarvae into western Florida Bay

The variability in the supply of pink shrimp ( Farfantepenaeus duorarum ) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp.

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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

Woody debris in the mangrove forests of South Florida

Woody debris is abundant in hurricane‐impacted forests. With a major hurricane affecting South Florida mangroves approximately every 20 yr, carbon storage and nutrient retention may be influenced greatly by woody debris dynamics. In addition, woody debris can influence seedling regeneration in mangrove swamps by trapping propagules and enhancing seedling growth potential. Here, we report on line‐intercept woody debris surveys conducted in mangrove wetlands of South Florida 9–10 yr after the passage of Hurricane Andrew. The total volume of woody debris for all sites combined was estimated at 67 m 3 /ha and varied from 13 to 181 m 3 /ha depending upon differences in forest height, proximity to the storm, and maximum estimated wind velocities. Large volumes of woody debris were found in the eyewall region of the hurricane, with a volume of 132 m 3 /ha and a projected woody debris biomass of approximately 36 t/ha. Approximately half of the woody debris biomass averaged across all sites was associated as small twigs and branches (fine woody debris), since coarse woody debris >7.5 cm felled during Hurricane Andrew was fairly well decomposed. Much of the small debris is likely to be associated with post‐hurricane forest dynamics. Hurricanes are responsible for large amounts of damage to mangrove ecosystems, and components of associated downed wood may provide a relative index of disturbance for mangrove forests. Here, we suggest that a fine:coarse woody debris ratio ≤0.5 is suggestive of a recent disturbance in mangrove wetlands, although additional research is needed to corroborate such findings.

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USGS2005

Manatee occurrence in the northern Gulf of Mexico, west of Florida

Reports of West Indian manatees ( Trichechus manatus ) in the US Gulf of Mexico west of Florida have increased during the last decade. We reviewed all available manatee sighting, capture, and carcass records (n = 377) from Alabama, Louisiana, Mississippi, and Texas since the early 1900s; only 40 of these were previously published. Manatees were reported most often in estuarine habitats, usually either near a freshwater source or natural or industrial warm-water springs/runoffs during winter months. The recent increase in manatee records may be due to a combination of increased public awareness and dispersal of manatees, most likely seasonal migrants from Florida. We caution that the presence of artificial warm-water sources outside of the manatee’s traditional range may attract an increasing number of manatees and could increase the incidence of cold-related mortality in this region.

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