Meeting Abstract
The Intergovernmental Panel on Climate Change predicts sea level rise up to 56 cm by 2100. Changing sea level may result in changes in competition among intertidal organisms, particularly sessile shellfish. Crassostrea virginica, an ecologically and commercially important oyster species in Apalachicola Bay, Florida, forms both intertidal and subtidal reefs. We deployed field experiments investigating potential responses of intertidal oysters to changes in inundation. Experiments occurred at two sites in Apalachicola Bay [East Cove of St. George Island (ASP) and Apalachicola National Estuary Research Reserve (ANERR)]. At each site, five units were deployed supporting stabilized oyster shell incrementally from mean low to high water levels, maximizing the range of inundation. Inundation was used as a proxy for sea level rise. Sites were adjacent to live intertidal oyster reefs growing at an elevation of approximately -0.44m NAVD88. Deployment lasted for one year starting in June 2012 and June 2013. Monitoring included: oyster abundance, orientation and length. After 12 months, mean oyster density peaked at 1018.8 ± 135.8 per m2 at intermediate elevation at ASP, and 976 ± 137.5 at intermediate elevation at ANERR. Oyster length at both sites peaked at low elevation. Oyster growth angle relative to the benthos varied significantly with elevation (p = 0.0005); higher growth angles occurred at lower elevations. These data suggest that changes in mean sea level may result in changes to oyster density and growth patterns, including size and reef structure. Specifically, with increasing vertical shell growth at lower elevation, intertidal oyster reefs may remain intertidal under some sea level rise scenarios.
