The Influence of Concrete Formulation on Short Term Marine Biofouling in Savin Hill Cove, Massachusetts

As sea levels rise, sea walls are used to prevent water intrusion. Anything put in the ocean will biofoul, as marine organisms settle onto it. Our research seeks to understand how two different concrete substrate types compare in influencing marine settlement. We determined how settlement on commercial concrete blocks compared to that on GROW Concrete Oyster Reef Restoration Tiles (CORRT) containing additional calcium carbonate. We installed a total of twelve concrete blocks in the intertidal zone within Savin Hill Cove, three of each type at two separate sand bars, one at the cove mouth and the other in the inner cove. The blocks were monitored and photographed over a six-week period to record any settlement and use of the substrate by marine organisms, and supplemental data about the habitats was collected. We expected to find more abundant and rapid growth on the blocks located at the cove mouth due to it having more waterflow, direct exposure to Dorchester Bay, and richer biological diversity in the immediate environment. No discernible differences were found between the two sites’ marine growth, however the inner cove site had more variable abiotic conditions, with salinity and temperature averages of 22.7ppt and 23.7°C respectively, compared to the outer cove’s 26.3ppt and 24.0°C. Several confounding factors were discovered during the experimental period, including possible impacts of both invertebrate herbivory and predation by periwinkles (Littorina littorea) and European green crabs (Carcinus maenas), on which supplemental population data was collected. Caging experimentation would be ideal to understand the effects of this herbivory and predation observed. We also feel that continuing this research for a longer experimental period would have provided a stronger response signal, as would timing it to correspond with the local shellfish spawning period for a more comprehensive understanding of recruitment by these substrates.