THE EASTERN OYSTER CRASSOSTREA VIRGINICA GROWS A THICKER CALCIUM CARBONATE SHELL IN STRONG-WAVE-ENERGY AQUACULTURE ENVIRONMENTS

The eastern oyster Crassostrea virginica is a reef-building foundation species that plays a key role in aquaculture and coastal restoration. Oysters adjust the growth of their calcium carbonate shells in response to environmental conditions, including tidal position, predator cues, parasitism, sedimentation, and wave energy. While morphological responses to environmental cues in oysters are well-studied, the precise effects of wave energy on shell thickness are unknown. We compared oysters from two aquafarms, one sheltered by land on three sides and the other exposed to waves on three sides, to investigate differences in morphology. Here we show that oysters at an aquafarm exposed to waves on three sides grew thicker shells relative to their size. Additionally, oysters at the more-exposed aquafarm were longer, wider, and had less tissue mass relative to their size. We attribute these morphological differences to stronger wave energy at the aquafarm exposed on three sides, although further experimentation is required to quantify wave energy at the two sites and test our hypothesis. While increased shell roundness and shell thickness makes oysters more marketable for aquaculture, the accompanying loss of tissue mass depletes the health and market value of these oysters. Furthermore, restoration of oyster reefs may be hindered by strong and frequent waves in unsheltered locations. Understanding how environmental conditions influence physical characteristics of oysters is essential to selecting effective sites for aquaculture and restoration.