Effects of hydrological restoration on manatees: integrating data and models for the Ten Thousand Islands and Everglades

This project will extend previous studies into ENP, where manatees have not been intensively studied. To ascertain how restoration may affect the distribution and abundance of manatees in the region, an individual-based model has been under development, but completion of that model requires a hydrologic model for the rivers and estuaries affected by the accelerated Picayune Strand restoration. This study will provide integrated regional hydrologic models covering nearly the entire southwest coast below Naples, including portions of Picayune Strand and Big Cypress, providing much needed hydrologic modeling capabilities for evaluating restoration effects on coastal, estuarine, and freshwater ecosystems. This effort will enable us to model manatee response to restoration, and more adequately address science and management needs. Three tasks will be undertaken to develop the necessary components for this regional model: (1) Link the TIME hydrology model and the ATLSS manatee model to assess restoration effects in the Everglades and Picayune Strand, (2) Model changes to manatee thermal refugia due to hydrological restoration, and (3) Design and implement a regional manatee monitoring program using aerial surveys and use robust statistical analysis techniques to estimate manatee distribution and abundance before restoration.

A significant population of the endangered West Indian manatee occurs in southwest Florida, throughout extensive estuarine and coastal areas within the Ten Thousand Islands (TTI; managed primarily by FWS) and Everglades National Park (ENP; managed by NPS). Planned restoration activities for the Everglades and Picayune Strand (an Acceler-8 project which discharges into TTI) may impact manatees by changing availability of freshwater for drinking, the quality and availability of seagrass forage, and the quality and availability of passive thermal basins used for refuge from lethal winter cold fronts. Changes in freshwater availability and forage are expected to result in a shift in manatee distribution, which could necessitate new management actions to reduce human-manatee interactions. Restoration also could negatively impact important passive thermal refugia by increasing cold sheet flow during winter or disrupting haloclines that maintain warm bottom layers of salty water. Recent telemetry and aerial survey studies of manatees in TTI have revealed much about their use of this area: this project will extend the study into ENP.