Impacts of Sea Level Rise & Ecosystem Restoration on Wildlife

Science Center Objects

The interior marshes of the Ten Thousand Islands National Wildlife Refuge (TTINWR) are currently negatively impacted by sea level rise through saltwater intrusion from the south which furthers mangrove encroachment into the freshwater marsh.

Interior marshes of the Ten Thousand Islands National Wildlife Refuge
Interior marshes of the Ten Thousand Islands National Wildlife Refuge 

The Science Issue and Relevance: Changes in faunal assemblages may serve as indicators of change in water levels or hydroperiod. The interior marshes of the Ten Thousand Islands National Wildlife Refuge (TTINWR) are currently negatively impacted by sea level rise through saltwater intrusion from the south which furthers mangrove encroachment into the freshwater marsh. In the future, these marshes will have freshwater flow from the Picayune Strand Restoration Project (PSRP) to the north which could serve to slow the rate of marsh loss and help to retain the freshwater Eleocharis cellulosa-dominated marsh which is an important habitat for wading birds, shorebirds, and their prey in TTINWR. Foraging success for migratory shorebirds and wading birds is tightly coupled to spring water levels, when prey is concentrated in shallow waters during the annual drydown. Changes in freshwater flows from restoration might also alter bird usage of these interior marshes if changes in timing or duration of water levels are outside of the range needed by foraging shorebirds and wading birds. Studies have shown that diets high in saltwater prey can be detrimental to growth of nestling and adult wading birds such as white ibis as well as other freshwater dependent bird species.

Fish sampling in TTINWR
Fish sampling in TTINWR

Methodology for Addressing the Issue: This project will examine fish community composition in the interior marsh of TTINWR in relation to parameters such as water depth, salinity and dissolved oxygen. The data collected at the northerly tier of sampling sites are near 0 ppt salinity, the lower tier is 25 – 35 ppt, and the mid tier of sites falls in the teens of salinity values. Fish sampling will be done every third week as water levels begin to drop (for ideal bird foraging, Jan – May). Two Breder and two minnow traps will be set at each of the 9 sites for 24 hours. All fish captured will be brought back to the lab for identification.

Future Steps: Without restoration, rising sea level will continue to shrink the foraging habitat available to the birds of TTINWR; however, designing flow schedules (from a restored Picayune) to yield the right balance of water flow at the right time of year, TTINWR could continue to support and expand healthy populations of shorebirds and wading birds. This project will examine fish communities as prey for wading birds and shorebirds. These data will help quantify environmental conditions preferred by fish communities and help us understand how the pressure of sea level rise and the benefits of freshwater flow from restoration might impact fish and bird communities in the future.

Wading birds and shorebirds in TTINWR
Wading birds and shorebirds in TTINWR