BIVALVE AQUACULTURE

Production and Maintenance of Dermo-Free Oysters for Physiological and Disease Studies

Research Team:
John Scarpa (HBOI) - Principle Investigator
Susan Laramore (HBOI)

The Everglades Restoration Project will affect many ecological systems throughout Florida. The oyster is a major component of many of the estuarine systems that may be impacted. Therefore, studies on basic physiology and responses of the oyster to possible environmental changes from the Everglades Restoration Project are necessary. However, the use of native wild oysters may affect experimental outcomes as the oysters may or may not be under stress from environmental perturbations or disease. Therefore, the South Florida Water Management District (SFWMD) has contracted Harbor Branch to maintain populations of healthy, disease-free oysters that will be available for use in studies to evaluate the impacts of environmental changes on native wild oyster populations.

SFWMD scientists are interested in documenting how environmental changes brought about by the Everglades Restoration Project may affect the susceptibility of the Everglades oyster populations to a parasitic disease commonly known as "Dermo". Dermo is caused by the parasitic protozoan, Perkinsus marinus. Moderately to heavily infected oysters usually exhibit a reduction in growth rate, poor condition, and reduced reproductive capacity. Oyster death results as a consequence of hundreds of thousands of parasites "taking over" the oyster, lysing tissues, and occluding hemolymph vessels. Temperature and salinity are the two most important environmental factors influencing Dermo disease. Prevalence and infection intensities of P. marinus increase with increasing salinity.

To meet the needs of the SFWMD, Harbor Branch researchers collect broodstock oysters, Crassostrea virginica, from the St. Lucie River during the natural spawning season. Oysters are spawned using standard hatchery production technology of thermal induction. All water used in culturing the oysters is filtered and UV-sterilized to maintain Dermo-free status. Oysters are cultured using standard procedures in a land-based nursery until they reach approximately 15 mm shell length. The oyster populations are sampled quarterly to monitor for Dermo using the whole-body burden method. Cohorts of oysters are maintained Dermo-free until needed by SFWMD scientists for their experiments.