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projects > impacts of hydrological restoration on three estuarine communities of the southwest florida coast and on associated animal inhabitants > work plan

Project Work Plan

U.S. Geological Survey Greater Everglades Science Initiative (Place-Based Studies)

Fiscal Year 2004 Project Work Plan


Project Title: Coupling SAV Dynamics and Hydrology / Dynamics of Fishes and Crustaceans in Marsh Habitat (Enhanced BioResources)
Project Start Date: 2000 Project End Date: 2005
Project Funding: USGS Place-Based Studies Initiative
Principal Investigator: Carole C. McIvor
Email address:
Phone: 727 803-8747 ext 3022 Fax: 727 803-2032
Mail address: USGS Center for Coastal & Watershed Studies, 600 Fourth Street South, St Petersburg, FL 33701

Project Summary: This project seeks to characterize habitat relationships between selected faunal groups and their mangrove environment on the Southwest Florida coast. We are describing how mangrove-associated fish species are distributed in fringing forest habitat along a salinity gradient in the tidal portions of the Shark River; the ecology and population dynamics of diamondback terrapins in the Big Sable Creek complex; experimentally determining the preferred habitat of the specialist fish Rivulus marmoratus via field and laboratory experiments; and how the conversion of mangrove forests to intertidal mudflats in the Big Sable Creek complex has affected fish composition and use of those habitats.

Project Objectives: The objectives are 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; and (4) determine the fisheries impact of the hurricane-induced conversion of mangrove forests to intertidal mudflats in the Big Sable Creek complex.

Project Strategy: The overall strategy for Task 1 is 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 (Loftus and Trexler), 10 yr from the mangrove ecotone of Taylor Slough and adjacent tidal creeks (Lorenz), and 10-12 yr from Florida Bay (Robblee); and contribute to the basic ecological understanding of mangrove-associated fishes. The strategy for the planned experiments on mangrove rivulus is to conduct field and laboratory experiments that will elucidate mechanisms underlying the patterns we see in the observational field data, and to make the combined observational and experimental data available to scientists and policymakers in client agencies who must decide whether to list the fish species under the Endangered Species Act. The strategy in the terrapin work is to combine mark/recapture data and genetic data to describe a population of diamondback terrapins largely unimpacted by commercial fishing, a rarity along both Atlantic and Gulf of Mexico coasts. The strategy in adding the fish sampling within the Big Sable Creek complex within the last year is twofold: to add a 4th totally marine-influenced site to the existing 3-site salinity transect in Shark River thereby increasing our inference space, and secondly to try to tease apart the dual impacts facing Shark River - increased freshwater inflow and rising sea level. Big Sable Creek will experience only the latter.

Potential Impacts and Major Products: Potential Impacts: (1) Data are baseline, prior to restoration changes upstream and can be used in part as performance measures for hydrological restoration; (2) Beginning of a long-term dataset on mangrove-associated fishes in Shark River. These data can be linked to those from the fresh marshes of the Everglades and to those from subtidal seagrasses in Florida Bay, therein forming a powerful dataset for inferences about controls of fish productivity along this entire gradient; (3) Data on two species of special concern, mangrove rivulus and diamondback terrapins, can be used to promote their management and possibly prevent their listing.

Major Products: factsheets, talks and presentations to both lay and scientific audiences, peer-reviewed manuscripts, basis of a master's thesis and a portion of a PhD dissertation

Collaborators: Duke University, University of South Florida

Clients: Everglades National Park, ultimately US Fish & Wildlife Service, National Marine Fisheries Service

B. WORK PLAN (include all tasks)

Title of Task 1: Describe fish community structure in fringing mangrove forests along a salinity gradient in Shark River
Task Funding: USGS Place-Based Studies Initiative

Task Leaders: Carole McIvor
Phone: 727 803-8747, ext 3022
FAX: 727 803-2032
Task Status (proposed or active): Active
Task priority: (High, medium, low)
Task Personnel: Carole McIvor, Noah Silverman (ETI contractor, biotechnician), Gary L. Hill (USGS logistics coordinator, captain, biotechnician, 0.5 FTE), Katie Kuss (ETI contractor, database manager, 0.5 FTE), part-time contract field technician

Task Summary and Objectives: The task seeks to describe the fish species composition, density and biomass of mangrove-associated fishes along a salinity gradient in Shark River. By coupling species data with environmental data (salinity, salinity variability, depth of forest inundation, temperature, dissolved oxygen), we will be able to develop empirical relationships between species distributions and specific habitat parameters.

Work to be undertaken during the proposal year and a description of the methods and procedures: Bi-monthly field sampling at 3 sites along Shark River using 9 total 2x3 m2 bottomless lift nets, and 9 total 1x1.5 m2 intertidal rivulet nets. Most importantly, we must develop a rating curve for each rivulet so that from the height of any given tide, we can infer the volume of water drained through our nets. For this latter procedure, we require 2 state-of-the-art velocity meters designed for use in shallow channels. These meters automatically record to data loggers, measure changing depth with change in tidal stage, and allow for the input of changing cross-sectional area. These meters are presently not budgeted for. Note: This task demands the use of a research houseboat as a base of operations.

Planned Outreach: Updated factsheet, manuscript on specialist mangrove fish Rivulus marmoratus in preparation, manuscript on fish community structure in planning stages

Title of Task 2: Define population structure and genetics of diamondback terrapins at Big Sable Creek complex immediately south of Shark River.
Task Funding: USGS Place-Based Studies Initiative
Task Leaders: Carole McIvor, Kristen Hart (USGS SCEP, PhD candidate at Duke University)
Phone: McIvor information above. Kristen Hart: 252 504-7571
FAX: Hart: 252 504-7648
Task Status (proposed or active): Active
Task priority: (High, medium, low) High
Task Personnel: Carole McIvor, Kristen Hart, Gary L. Hill, also a volunteer from Duke University

Task Summary and Objectives: Terrapins have been captured with dip nets on 4 weeklong trips between 11/01 and 5/03. Approximately 260 unique individuals with a sex ratio of 1:1 have been captured, measured, weighed, PIT tagged and had blood drawn for genetic samples. Initial population size estimate is about 692 individuals. The objectives are to refine this population estimate, better characterize habitat use, and finish analysis of blood samples previously collected for DNA characterization.

Work to be undertaken during the proposal year and a description of the methods and procedures: In FY2004, we will conduct 1 final trip of 10 days duration during which we: (1) obtain additional mark/recapture data; and (2) characterize habitat use in the headwater reaches of creeks. Additionally we will refine the current population estimate, and analyze the stored genetic samples.

Planned Outreach: talks at scientific meetings, new factsheet, write 2 manuscripts for peer review

Title of Task 3: Determine optimal habitat and salinity conditions for mangrove rivulus.
Task Funding: USGS Place-Based Studies Initiative (seeking NOAA/NMFS funding)
Task Leaders: Carole McIvor (field experiments), Pam Schofield (USGS Center for Aquatic Research Studies, Gainesville: laboratory experiments)
Phone: McIvor information above. Pam Schofield: 352 378-8181 ext 370
FAX: Schofield: 352 378-4956
Task Status (proposed or active): Proposed
Task priority: (High, medium, low)
Task Personnel: McIvor, Schofield, Silverman, part-time laboratory tech (Gainesville)

Task Summary and Objectives: Data from Task 1 on the distribution of 256 mangrove rivulus indicates that they are common all along the salinity gradient being sampled at Shark River (Tarpon Bay to 3 km upstream of Ponce de Leon Bay). They reach their greatest abundance at the mid-salinity site, but have their highest condition factor at the most downstream site. These data raise two questions: "What is their optimal habitat?" "How might optimal habitat (as measured by salinity) be changed with hydrological restoration and increased freshwater flow?"

Work to be undertaken during the proposal year and a description of the methods and procedures: Beginning October 2003, McIvor and colleagues will set up a pilot field experiment to test the design and effectiveness of 1/4 m2 growth cages for Rivulus. By December 2003, full-scale field experiment will be underway (15 total cages along the salinity gradient in Shark River). By March 2004, Dr. Schofield will have an analogous set of independent aquaria with replicates at 3 representative salinities set up and running in the Gainesville facility. Both field and lab experiments will be finished by the end of project funding. In both instances we will be using growth rate as an index of habitat preference or quality.

Planned Outreach: talks at scientific meetings, a manuscript on preferred habitat and salinity conditions for the mangrove rivulus. Note: This proposed manuscript plus the distributional manuscript in progress might be adequate to prevent listing of this little-known species being considered for listing under the Endangered Species Act.

Title of Task 4: Continue analysis of effects of hurricane-induced habitat conversion of mangroves to mudflats at Big Sable Creek complex (1 yr of data collection)
Task Funding: Requesting USGS Place-Based Studies Initiative (currently in last yr of funding under GCC: 1 yr of data only)
Task Leaders: Carole McIvor (a joint GCC proposal with T.J. Smith)
Phone: McIvor information above
Task Status (proposed or active): Active but funding ends Sept 30 2003, hydrological data needs critical
Task priority: (High, medium, low)
Task Personnel: Carole McIvor, Noah Silverman (ETI contractor, deserving of a SCEP position. Data collected to date will be used for a master's degree in Marine Science at USF, St Petersburg)

Task Summary and Objectives: 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 asks, "What is 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. Fish collection is proceeding smoothly, but quantifying the area or volume of water drained by 6 targeted intertidal rivulets requires purchase and installation of discharge meters presently not budgeted for. (See description of needs under Task 1.)

Work to be undertaken during the proposal year and a description of the methods and procedures: We currently have 4 sets of samples and will have 2 more by end of the fiscal year. We will continue with our present fish collection methods (intertidal rivulet nets). However, an additional year of data would greatly strengthen our analysis, conclusions, and inference space. Note: This task demands the use of a research houseboat as a base of operations.

Planned Outreach: talks at scientific meetings; a manuscript on fish community stricture at comparable mangrove and mudflat sites at Big Sable Creek complex, ENP; master's thesis on same topic 


  • Task 1 specifically supports restoration goal SO1, how hydropatterns and flow affect Everglades ecosystems, and SG3 establishing ecosystem baselines.
  • Task 2 (diamondback terrapins) and
  • Task 3 (experimental studies on habitat preferences of the specialist fish Rivulus marmoratus) specifically support SG1 understanding habitat requirements for the recovery of threatened or endangered species. Note that both these 2 species we are working on are species of special concern, i.e., being considered for listing.
  • Task 4 directly addresses the impacts of global climate change on natural ecosystems. Although the task is presently funded by the GCC program and has been worded to address hurricane-induced change, should this task be absorbed by PBS, the task can easily relate to restoration goal SO1, the effects of sea level changes on mangrove ecosystems as follows: when mangroves lose elevation in a hurricane and fail to regenerate, rising sea level in the absence of a new source of sediment makes it increasingly difficult to ever recover those mangrove forests.

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