Oysters

FL.O.O.R. monitors the development and health of natural and constructed oyster reefs in the Indian River Lagoon and St. Lucie Estuary. Recruitment, growth, and survival of oysters is measured to evaluate the success of oyster restoration projects and to better understand oyster health within the estuary.

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An ongoing effort at FOS is monthly monitoring of spat recruitment at sites throughout the Indian River Lagoon and St. Lucie Estuary. Cleaned, disarticulated oyster shells, collected from local restaurants, are strung in pairs onto a PVC T-bar (pictured to the left). The array allows the shells to hang, suspended in the water column at the same elevation of live oysters in adjacent reefs. If conditions are favorable, spat will settle onto the hanging oyster shells. The shells are swapped out monthly, taken back to the lab and the spat is counted. Additionally, a small subset of shells is harvested bi-annually to assess oyster condition index. Collectively, these data can be used to better understand oyster health within the lagoon and estuary.

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Newly settled spat on an oyster shell.

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Oyster biomass

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Oyster gametes under the microscope

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July 2020 to the present, monthly oyster spat per shell counts and salinity in the Indian River Lagoon (left) and St. Lucie Estuary (right). The data on spat counts have been standardized to a 28-day month ± standard error and is reported for the month collected. Each month, shells are deployed at seven locations (3 in the IRL; 4 in the SLE) and collected one month later. Salinity data was retrieved from the Jensen Beach (IRL) and Mid-Estuary (SLE) sensors of the Indian River Lagoon Observatory Network (irlon.org). A 7-day moving average low-pass filter was applied to salinity data to reduce high-frequency noise. The background colors correspond to salinity conditions for oysters: red indicates lethal (0-5 psu), yellow indicates stress (5-10 and 25-40 psu), and green indicates optimal (10-25 psu).