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Project Summary Sheet

U.S. Geological Survey, Greater Everglades Priority Ecosystems Science (PES) Initiative

Fiscal Year 2004 Study Summary Report

Study Title: Predicting Effects of Hydrologic Restoration on Manatees along the Southwest Coast of Florida
Study Start Date: 2000 Study End Date: 2005
Web Sites:
Location (Subregions, Counties, Park or Refuge): Total System
Funding Source: GE PES
Principal Investigator(s): James Reid
Study Personnel: James Reid, Brad Stith, and Susan Butler
Supporting Organizations: U.S. Fish and Wildlife Service - Ten Thousand Islands National Wildlife Refuge, the National Park Service - Everglades National Park, Big Cypress National Preserve, Florida Fish and Wildlife Conservation Commission - Florida Marine Research Institute, Rookery Bay National Estuarine Research Reserve, Mote Marine Laboratory, Marine Mammal Commission, and Cincinnati Zoo.

Associated / Linked Studies: Linkages to other projects/databases include TIME model, ATLSS model, and the associated PBS projects: “Impacts of Hydrological Restoration on Three Estuarine Communities of the Southwest Florida Coast and on Associated Fauna” (Carol McIvor) (; “Southwest Florida Coastal and Wetland Systems Monitoring Project” (E. Patino) ( Additional information on “Predicting Effects of Hydrologic Restoration on Manatees along the Southwest Coast of Florida” is available on the Sofia website:

Overview & Objective(s): Determine relative abundance, distribution, movements, and habitat use of manatees associated with coastal waters and rivers from Marco Island through Whitewater Bay. Identify resources critical to manatees in the region, including distribution and abundance of submerged aquatic vegetation and freshwater drinking sites. Develop an individual-based ATLSS model to predict manatee response to changes in hydrology achieved by the Southern Golden Gate Estates (SGGE) project specifically and more broadly by the Comprehensive Everglades Restoration Plan. Additional information on population trend, distribution, and habitat use, coupled with models of hydrology, bathymetry, aquatic vegetation, and salinity, will allow development of a population-level model capable of predicting their response to future changes. This SGGE modeling effort will provide invaluable information as a small-scale test case for understanding and predicting how restoration efforts in the Everglades will affect manatees.

Status: On track for completion in FY05

Recent Products:
Metadata reviewed, revised, and posted to SOFIA

Presentations at the 15th Biennial Conference on the Biology of Marine Mammalogy:

Brad Stith, Jim Reid, and Susan Butler, 2003, Modeling manatee response to restoration in the Ten Thousand Islands and Everglades National Park. Oral presentation at the 15th Biennial Conference on the Biology of Marine Mammals, 15-19 December 2003, Greensboro, North Carolina.

James P. Reid, Bradley M. Stith, and Susan M. Butler, 2003, Florida manatees in the western Everglades: Implications for restoration assessment. Oral presentation at the 15th Biennial Conference on the Biology of Marine Mammals, 15-19 December 2003, Greensboro, North Carolina.

Susan M. Butler, James P. Reid, and Bradley M. Stith, 2003, Detailed movements and habitat use patterns of radio tagged manatees in the western Everglades. Poster presentation at the 15th Biennial Conference on the Biology of Marine Mammals, 15-19 December 2003, Greensboro, North Carolina.

Planned Products:
Two presentations submitted to the First National Conference on Ecosystem Restoration, December 2004; Open File Report, November 2004; Telemetry database; Model output for ATLSS viewer; Scientific manuscripts for peer review

Specific Relevance to Information Needs Identified in DOI's Science Plan in Support of Ecosystem Restoration, Preservation, and Protection in South Florida (DOI's Everglades Science Plan) [See Plan on SOFIA's Web site:]:

This study supports two of the projects listed in the DOI science plan, including: Southern Golden Gate Estates Hydrologic Restoration, and Landscape-Scale Modeling.

The study supports the Southern Golden Gate Estates Hydrologic Restoration project (SGGE; p. 51) by 1) modeling predicted changes in hydrology and ecology in the Ten Thousand Islands NWR (p. 59), and 2) providing baseline data and monitoring of effects on a federally listed species, the West Indian manatee, within the Ten Thousand Islands NWR (p. 59-60).

The study supports the Landscape-Scale Modeling (LSM; p. 80-81) by 1) providing an individual-based demographic model of a threatened species, the West Indian manatee (p. 80), and 2) by providing Landscape-scale monitoring and assessment for MAP (p. 81, 90).

This study also supports the CERP Monitoring and Assessment Plan, Part 1, Southern Estuaries Module, Section Manatee Abundance and Distribution Relative to Freshwater Input (pp. 3-98 - 3-100).

This study also supports the Planning Aid Report, Multi-species Conservation under Comprehensive Everglades Restoration Plan (CERP), Project 30, Southern Golden Gate Estates Hydrologic Restoration Project (pp. 252-254, 262-264).

Each manatee project task addresses a number of USGS project tasks related to hydrology, habitats and species, ecological indicators, and threatened and endangered species. Because the manatee is a federally listed species, our work supports a variety of needs identified by the DOI for listed species.

Key Findings:

  1. Several lines of evidence based on the telemetry data indicate that reliable assess to freshwater for drinking is a critical habitat requirement for manatees. First, all tracked manatees made frequent, long-distance movements alternating between offshore seagrass beds and various inshore access points for freshwater (e.g. rivers, tidal creeks, and canals) at regular intervals ranging from 2-8 days throughout the year. Second, during the dry season most manatees visited only one or a few freshwater assess points that are known to be reliable sources of freshwater, compared to the wet season when many more inshore sites were assessed and are known to be seasonally reliable sources of freshwater. Third, manatees spend significantly more time within inshore areas during the dry season compared to the wet season. Because restoration activities are expected to change the timing and quantity of freshwater inflow to rivers and canals in the study area, we expect manatee movement patterns to change in response to the changing availability of freshwater.
  2. Due to the absence of warm springs and artificial sources of warm water, manatees within TTI/ENP are subject to cold stress and cold-related mortality during the winter at a higher rate than many areas further north. Telemetry data indicates that they exhibit complex behavioral responses to cold weather, including: 1) migrating south into Whitewater Bay, 2) bottom resting in warm water layers trapped in deeper sections of basins, canals, and rivers, and 3) sheltering in shallow bays that heat up rapidly following the passage of cold fronts and return of warmer temperatures. An on-going, complementary study by the USGS/Sirenia Project to characterize winter refugia for manatees in the northwestern Everglades region will help address how restoration activities might influence the thermal regimes of manatee over-wintering sites.

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