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Monitoring Sea Level Rise Using Floral and Faunal Assemblages and Observed Associations in the Shark and Harney River Basins of Southwest Florida James B. Murray, G. Lynn Wingard

A habitat association between Polymesoda caroliniana and sev-eral plant species including; Cladium jamaicense, Acrostichum sp., Rhizophora mangle, Laguncularia racemosa, and Avicennia germinans is being observed in the Shark River and Harney River basins along the Southwest Coast of the South Florida estuaries. Site surveys conducted in the spring of 2008 within the Shark River system of southwest Florida found “nests” of Polymesoda caroliniana closely associated with the prop root structures of Rhizophora mangle and Laguncularia racemosa. The mangrove forests are under storied by C. jamaicense and Acrostichum sp., with the Acrostichum sp. specimens showing degradation at some sites. These areas appear to be the obligate margin of the mesohaline/oligohaline tidal exchange zone. Some of the plants in these regions have a low tolerance to saltwater intrusions and have low survival rates with even short duration exposures to el-evated salinities.

Cores taken at the mouth of the Harney River and the north leg of the Shark River in the summer of 2005 were found to have P. caroliniana debris in abundance at a depth of 114-165cm, and 10-64cm respectively, which is an indicator of freshwater to upper estuarine environment based on modern ob-servations. Debris was also found in core samples in the Lostman’s River Second Bay area at a depth of 72-76cm. The depositional rates are cur-rently being determined for these cores (Wingard,et.al., “Descriptions and Preliminary Report on Sediment Cores from the Southwest Coastal Area, Part II: Collected July 2005, Ever-glades National Park, Florida”, OFR 2006-1271). Evidence of a substantial change in the outflow regime was seen in the mid-system cores from the Harney and Shark Rivers. The lower portions of both cores were deposited in freshwater environ-ments, with no indicators of estuarine influence; however, with a loss of the larger freshwater fauna in the upper portions of the cores, a shift toward more estuarine conditions is evident.

The observed associations between P. caroliniana and plant species such as C. jamaicense, Acrostichum sp., and Myrica cerifera, may provide both short term indications, and longer term indications of changes in the salinity re-gimes within these wetland environments. The plant assemblages will re-spond quickly to environmental changes where P. caroliniana populations will be able to withstand slightly broader ranges of salinity regimes. These as-semblages and the apparent associations are an indicator of the overall sa-linity changes due to sea level changes as tidal exchanges move higher into the estuaries and freshwater wetlands.

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Mix of freshwater, mesohaline, and euryhaline

Mix of freshwater, mesohaline, euryhaline, and polyhaline

Mix of freshwater (including planorbellids) and euryhaline

Freshwater

Shark River Core north of main channel

GLW705-SR2A

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No visible mollusk material

Freshwater dominant

Euryhaline(based on few fragments)

Harney River Corenear water monitoring station

GLW705-HR2A

For additional information on south FL research refer to: http://sofia.usgs.gov

RESEARCH ACTIVITIES:map the distribution of the plant and animal speciesdocument the local associations between animal and plant species and begin to quantify population size at individual sitesconduct experiments to determine the salinity tolerances of P. caroliniana

Polymesoda caroliniana nested among young mangrove trees near the shoreline

Dr. Lynn Wingard conducting live counts of P. caroliniana among mangroves at low tide

Paleoecological Record of the Shark and Harney River Basins

Basic lithology of the 2005 cores taken from the Harney and Shark Rivers

P. caroliniana individuals in one of our salinity tolerance test tanks.

We are currently conducting salin-ity tolerance experiments on Polymesoda caroliniana in our ex-perimental marine systems in Reston VA. P. caroliniana is a resil-ient lab rat species as they are op-portunistic feeders, as well as being saprophytic and tolerant of a broad range of water conditions.To date a definitive salinity tolerance range has not been determined. The environment in which we are conducting tests closely mimics the native environment including most of the plant species found in the native locations.

GOAL OF RESEARCH: Began study in 2008 to map distribution of Polymesoda caroliniana within Harney and Shark River Basins of Everglades National Park.Develop modern floral and faunal association map for individual sites and the greater Basins to monitor sea level change within the park.

Cladium jamaicense

Rhizophora mangle

Acrostichum sp. Avicennia germinans

P. caroliniana nested in peat-mud among mangrove trees near the shoreline. Picture taken during low tide.

Common environment association of P. caro-liniana and various plant assemblages

Harney River

Harney River

Shark River

Shark River

Locations where live P. caroliniana have been documented. Size of label is proportionate to populations observed. Locations of observed Cladium jamaicense, Acrostichum sp., Rhizophora mangle, Laguncularia racemosa, and Avicennia germinans.

Core site locations of July 2005 containing debris of P. caroliniana in the lower sections

Legend

James Murray surveying P. caroliniana populations within a C. jamaicense stand along the shoreline.

Acrostichum sp. along shoreline Mangroves understoried by Cladium jamaicense

Gulf of Mexico

Shark River and Harney River Basins