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Co-Restoration of Seagrass and Clams

A hand is holding eight clams, with dozens more in a pink basket in the background.

The Gulf Shellfish Institute (GSI) is a non-profit, scientific research organization dedicated to advancing shellfish aquaculture across Florida’s Gulf Coast for both economic and environmental benefit. A large focus of GSI is linking aquaculture production with restoration of historically abundant shellfish populations. GSI’s applied research efforts also document the ecological functions shellfish provide to our estuaries and coastal communities. 

Shellfish support many marine ecosystems and are natural filterers of the sea! Oysters form complex reefs that are a home for various life stages of crustaceans, mollusks, fish, and a plethora of seabirds! Scallops, mussels, and clams have been suggested to support seagrass growth! They can remove unwanted particles from the water above and transfers various nutrients to the sediments below. In addition, the southern hard clam (Mercenaria campechiensis) is frequently found near seagrass meadows and perhaps has contributed to seagrass recovery after die-off events. Particularly in the southwest region of Florida, some seagrasses have declined from diminished water conditions due to poor water quality and harmful algal blooms. GSI, the Florida Fish and Wildlife Conservation Commission (FWC), the Fish and Wildlife Research Institute (FWRI) and others aim to test a three-year MEHRMA funded project to determine if southern hard clams help recovery of natural seagrasses in Sarasota Bay, Florida. In addition, GSI and scientists at the University of Florida’s Soil, Water & Ecosystem Sciences Department seek to understand the water quality of Sarasota Bay with the newly introduced clams. They will collect samples every four months from the study site to measure C:N ratios and benthic chlorophyll a in the sediments, and ammonium, nitrate and sulfide concentrations in the surrounding porewater.   

3 images showing bags of clams underwater, a diver underwater writing on a clipboard, and seagrass blades surrounded by a square shape made out of a PVC tube and white tubes.

FWRI's contribution to this project has involved has involved helping with the initial set-up of 48 experimental “plots” or squares, roughly 26' × 26', to be used as “boundaries” for the establishment of over 46,000 clams! Clams were hand placed by GSI, FWC, and FWRI into selected plots in pre-determined areas with visually low, medium, and high seagrass abundances. FWRI will then monitor these experimental plots using a 1-m2 PVC quadrat to determine percent coverage of seagrass. This project is still in its infancy, and it is unknown whether hard clams in Sarasota Bay will promote new and sustained growth of seagrass, but FWRI will continue to monitor its progress in the many years to come! 


Clams deployed in plots with different abundances of seagrass in Sarasota Bay.