The overall strategy was to collect robust empirical field data on forage fish distribution and abundance that can serve multiple purposes: as performance measures in restoration assessment; as the beginning of a long-term dataset analogous to three very powerful datasets from other locales in the Greater Everglades Ecosystem: 15-20 yr from freshwater marshes, 10 yr from the mangrove ecotone of Taylor Slough and adjacent tidal creeks, and 10-12 yr from Florida Bay; and contribute to the basic ecological understanding of mangrove-associated fishes.
McIvor, Carole C. , 2007, Impacts of Hydrological Restoration on Three Estuarine Communities of the Southwest Florida Coast and on Associated Animal Inhabitants.Online Links:
U.S. Department of Agriculture - Natural Resources Conservation Service (NRCS) Department of the Interior - U.S. Geological Survey Department of Commerce - National Oceanic and Atmospheric Administration (NOAA) Environmental Protection Agency (EPA) Smithsonian Institution - National Museum of Natural History (NMNH)
Additional project personnel include Gary L. Hill, Noah Silverman, Kristen Hart, and Katie Kuss.
727 803-8747 ext. 3022 (voice)
727 803-2032 (FAX)
carole_mcivor@usgs.gov
A primary goal of Everglades restoration is the recreation of water flows and water quality more closely approximating pre-drainage conditions in both freshwater and estuarine ecosystems within Everglades National Park. These estuarine systems include submerged aquatic vegetation (SAV), mangroves (tidal forests), and brackish marshes. Four primary groups of animals are closely associated with, and often dependent upon, one or more of these ecosystems: fish and decapod crustaceans (shrimp, crabs), diamondback terrapins, manatees, and wading birds. This research focuses on fish and decapod crustaceans and diamondback terrapins in mangrove tidal forests and associated creeks.Concern about the fate of mangrove ecosystems derives from their known use as habitat for a wide range of aquatic animal species, especially fishes and decapod crustaceans of forage as well as of commercial and recreational importance. Additionally, in South Florida, mangroves on Cape Sable support a seemingly healthy population of diamondback terrapins, a species at risk in many salt marsh environments on the Gulf and Atlantic coasts.
This project was undertaken to:
(1) determine what fish species make routine use of flooded fringing mangrove forests along the tidal portion of the major drainage of the historical Everglades, i.e., Shark River, and to develop empirical relationships that link species composition, density and biomass to environmental variables at those sites; (2) describe the population structure of a species of special concern, the diamondback terrapin, in mangrove tidal creek habitat within the complex of creeks that make up Big Sable Creek on Cape Sable, and secondarily to determine how this population is related to other populations on the Atlantic and Gulf coasts via DNA analysis; (3) experimentally determine via field and lab experiments the preferred habitat of a species of special concern but a common fish along the Shark River salinity gradient, mangrove rivulus; (4) determine the fisheries impact of the hurricane-induced conversion of mangrove forests to intertidal mudflats in the Big Sable Creek complex.
Mark-recapture techniques were used for Diamondback terrapins. Three weeklong sampling trips were made to the Big Sable Creek system to capture, mark, and recapture terrapins. Captures were concentrated in the upper reaches of creeks in the system. On each sampling trip, named creeks and their navigable branches were surveyed systematically for terrapins at AM and PM low tides. Dip nets were used to capture turtles, with the new moon tides providing the best conditions for capture success.
In the mangrove forests of Shark River, pilot studies were performed to determine the best design for capturing fishes and decapod crustaceans using flooded forests. We used 2x3 m2 pull-up nets buried in the forest floor to quantify the density, biomass, and population dynamics of a unique mangrove fish, mangrove rivulus, that remains in the forest even during low tide events. The remainder of the fish and decapod assemblage was targeted with 1.5x1.0 m block nets placed over the mouths of intertidal rivulets at slack flood tide. These nets capture fish and crustaceans leaving the forest on the ebb tide. Nine nets of each type were arrayed along the estuarine salinity gradient as follows: three of each type near the freshwater/oligohaline interface in Tarpon Bay, three each midway along the salinity gradient on the Harney River, and three each about 3 km up from the mouth of the Shark River near Ponce de Leon Bay, the site of highest salinity. Nets were sampled bimonthly to capture patterns of juvenile recruitment and changes in relative abundance of species influenced by wet and dry season changes.
We worked throughout navigable, mangrove-lined tidal creeks within the Big Sable Creek (BSC) complex and conducted all sampling trips around new moons to take advantage of spring tides (i.e., highest high and lowest low tides). Dip netting was most successful during a 2-hour window around both day and evening low tides.
In addition to taking standard morphometric measurements on each turtle and recording a GPS location for each capture and recapture location, we marked each newly captured terrapin in four ways: (1) by notching the marginal scutes in a systematic pattern, (2) by inserting an individually numbered 9-or 10-digit alpha-numeric passively induced transponder (PIT) tag, (3) by taking head-on, dorsal, ventral, and side view photographs for photo-id (with particular emphasis on capturing the unique pattern of each turtle’s plastron), and (4) by taking blood samples to be screened for microsatellite DNA markers which resulted in locus-specific scores for each individual. For consistency, K. Hart performed all the notching, PIT tagging, photographing, and blood sampling throughout the study. We used the redundant marking system to ensure no tag loss or errors in identification. We also used strict, consistent protocols to catalog animals so that the possibility of misidentification would be essentially zero. We re-weighed and re-measured recaptured turtles, and released all new turtles after workup at their original capture site and all recaptured turtles at their recapture location. Additionally, we attached radiotransmitters to a subset of females to conduct short-term tracking in the study site. For analyses, we constructed a unique 5-capture history for each of the 300 terrapins from the capture and recapture data collected on each trip. Each capture history consisted of the seen (1) or not seen (0) record of the individual during each of the five sampling periods. We used Program MARK and AIC model selection procedures to derive estimates of survival and capture probability. We used Program JOLLY to estimate abundance.
We marked a total of 300 terrapins. We captured 24 animals in crab pots on the first sampling trip (November 2001), but thereafter captured terrapins only with dip nets.
Initial samples have been taken in mangroves in Shark River, and marsh sites are set up: sampling will begin there in the rainy season. Mangrove sites have been chosen on Lostmans River.
1. We continued to describe fish community structure in fringing mangrove forests along a salinity gradient in Shark River based on periodic field sampling at 3 sites along a longitudinal salinity gradient. We used 9 total 2x3 m2 bottomless lift nets, and 9 total 1x1.5 m2 intertidal rivulet nets. Quantitative estimates of recovery of marked fishes of 2 common species were completed for the lift nets. By the end of FY2004 we will have estimates of discharge from all 9 intertidal rivulet sites. From these data we can thus standardize all capture data to fish per cubic meter at these latter nets.
2. We continued to define population structure and genetics of diamondback terrapins at Big Sable Creek complex immediately south of Shark River. Terrapins have been captured with dip nets on 6 weeklong trips between 11/01 and 10/03. A total of 300 unique individuals with a male: female sex ratio of 1.16:1.0 have been captured, measured, weighed, PIT tagged and had blood drawn for genetic samples. Initial population size estimate is about 1,415 individuals based on the Schnabel method. We estimated downed log cover in 6 headwater creeks to correlate with terrapin capture locations. Final objectives are to refine this population estimate, better characterize habitat use, and finish analysis of blood samples previously collected for DNA characterization.
3. We continued analysis of effects on fisheries of hurricane-induced habitat conversion of mangroves to mudflats at Big Sable Creek complex. Due to destruction from passage of two category 4/5 hurricanes (1935, 1960), some mangroves at Big Sable Creek complex did not recover. Rather, they were converted to intertidal mudflats. This task addresses the fisheries consequence of this storm-induced habitat conversion. The objective is to compare on a quantitative basis the fish species composition, density and biomass in replicate habitats of the two types. We currently have 9 complete sets of samples. We must still make discharge measurements to standardize our catch data to fish per cubic meter of water.
4. Status of the data: Shark River fishes 4.5 years, Big Sable Creek fishes 1.5 years, terrapins 2.5 years, Submerged Aquatic Vegetation (SAV) in Shark River 1 year. Data collection and data entry has been completed for the project. Data analysis and interpretation is ongoing.
Person who carried out this activity:
727 803-8747 ext. 3022 (voice)
727 803-2032 (FAX)
carole_mcivor@usgs.gov
Hart, Kristen M. McIvor, Carole C.; King, Ti, Unknown, Integrating Ecology and Genetics to Define Population Extent for a Continuously-distributed Species, Diamondback terrapins (Malaclemys terrapin): U.S. Geological Survey, St. Petersburg, FL.Online Links:
Hart, Kristen M. Naro-Maciel, Eugenia; Good,, Unknown, Green Sea Turtles (Chelonia mydas) of Everglades National Park: Habitat Associations and Genetic Analyses: U.S. Geological Survey, St. Petersburg, FL.Online Links:
Hart, Kristen M. McIvor, Carole C., Unknown, Using sea turtles to find seagrass: Tracking juvenile Chelonia mydas with satellite telemetry in the southwest coastal Everglades, Florida, USA: U.S. Geological Survey, St. Petersburg, FL.Online Links:
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727 803-8747 ext 3028 (voice)
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hhenkel@usgs.gov
Terrapin Mark-Recapture Study
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727 803-2030 (FAX)
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U.S. Department of the Interior, U.S. Geological Survey
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