ASSESSING THE EFFECTIVENESS OF DESICCATION IN CONTROLLING BIOFOULING IN WATER COLUMN CULTURED OYSTERS Crassostrea virginica IN THREE CHESAPEAKE BAY LOCATIONS

Oysters and the equipment associated with water column oyster aquaculture serve as habitat for a host of other organisms. These marine plants and animals, collectively referred to as biofouling, can detract from the growing conditions available to the oysters. Effects of these organisms range from reducing flow and food available to the oysters, to unsightly blemishes on the shell, to oyster mortality in extreme cases. Desiccation, or periodic air drying, of oysters and cages has been used to control colonization by biofouling organisms. However, the specific duration of desiccation time periods has yet to be thoroughly assessed. In this project, we research the effectiveness of different temporal desiccation regimes in controlling biofouling, and examine relevant oyster parameters associated with desiccation.  

Three sites were selected for inclusion. Sites were selected with differing salinity and exposure conditions. One control and two desiccation regimes were followed at each site; control (no desiccation), 8 hours of desiccation per week, and 24 hours of desiccation per week. Oysters were deployed between July - December 2018.

In two sites, biofouling was found to be significantly higher on non-desiccated oysters but minimal differences were observed among oysters desiccated for 8 or 24 hours (Figure 1). At one site, percent coverage by a species of macroalgae increased in the desiccated oysters. Species composition varied with each site. Total percent coverage varied both geographically and temporally.