The Effects of Hurricane Harvey on Oyster Restoration

The eastern oyster (Crassostrea virginica) provides many ecological and economical services in the Galveston Bay and other estuarine ecosystems along the Gulf of Mexico and the Atlantic coast. They build reefs that many species utilize as habitats, filter water, and are an important fishery. However, overfishing, pollution and storms, such as Hurricane Harvey, have contributed to the loss of many functional oyster reefs. With this decline, substantial efforts, like the construction of bagged reefs in intertidal environments, have been made to restore oyster populations. The objective of this project was to determine how oyster abundance and size changed on restored intertidal reefs in Sweetwater Lake, Galveston Bay over four years (2016-2019) and coincidentally, determining how these oyster population characteristics changed before and after Hurricane Harvey. Across all years, oyster size and abundance were measured from five reefs, each with replicate bags (n=5). Larval recruitment for oyster size and abundance were collected using caged trays and were monitored during peak recruitment periods. Oyster abundance varied interannually by reef likely due to local hydrodynamics. Mean oyster size decreased, post-Harvey, likely due to the constraining of oyster growth and adult oyster mortality. Hurricane Harvey caused an estimated freshwater discharge that was three times the Bay’s normal volume. Spat abundance and size were impacted by this freshwater influx as larval oysters faced decreased transport success and slow growth in a low salinity environment. For intertidal oyster reef restoration in hurricane prone areas, tidal dynamics should be considered for oyster size and abundance characteristics.