SCCF Marine Lab studying oyster growth in Caloosahatchee

Earlier this year, the SCCF Marine Laboratory deployed bags of oysters in the Caloosahatchee Estuary along the flow of the river to understand how changes throughout the estuary affect oyster growth and survival.

The study was a collaboration with Florida Gulf Coast University (FGCU), which is an ongoing partner of the SCCF Marine Lab for a bimonthly oyster spat survey.

Unfortunately, despite placing oysters at five sites, only one site could be studied over the study’s full 16 weeks due to rampant barnacle growth.

“Barnacles covered our living oysters, potentially competing for food and space for new oysters to settle and grow. This made it difficult to accurately measure and count oysters,” said SCCF Marine Lab Research Assistant Isabella McDonnell.

Advanced barnacle settlement, density, and growth could be partly due to Hurricane Ian, which stirred up nutrient-rich sediment, McDonnell said.

“Like oysters, barnacles are filter feeders, surviving and thriving from nutrients within the water. Barnacles may have also thrived due in part to decreased predation and feeding competition, as the hurricane likely altered the food web,” she said.

The team tracked the settlement of oyster larvae, growth, and mortality rates from the site at the base of the river, near Shell Point. FGCU students also collected larvae samples and counted the number of juvenile oysters settled. Overall, the number of oysters increased, and the average height decreased as new spat settled.