Meeting Abstract
Climate change is affecting the health of marine organisms. Our ability to mitigate climate change effects is an important step in limiting future impacts to ecosystems. Ocean acidification (OA), or the decrease in seawater pH caused by the dissociation of atmospheric C02 in seawater, is a threat to calcifying organisms such as the Pacific oyster, Crassostrea gigas. In contrast, photosynthesizing plants, such as eelgrass, Zostera marina may benefit in future OA environments due to increased dissolved inorganic carbon (DIC) available in the water. By removing excess DIC, these plants can create local areas of pH refugia. C. gigas, may improve the health of Z. marina by removing potential pathogens, in particular the causative agent of eelgrass wasting disease, Labyrinthula zostera. One potential mitigation strategy to improve the health of both C. gigas and Z. marina is co-culture. In order to test the potential benefits of an oyster-eelgrass partnership, a full-factorial laboratory study with monoculture (juvenile C. gigas or Z. marina) and co-culture (C. gigas and Z. marina) under three C02 conditions, 400, 1000, and 1600 ppm was conducted. Half the tanks containing Z. marina or co-culture were exposed to L. zosterae. Increased mass of C. gigas was measured in low pH conditions in co-culture. In low pH conditions, the proportion of diseased Z. marina leaves decreased as compared to high pH conditions. An isotopically labeled C02 tracer indicated that the eelgrass incorporated the lighter isotope (δ12C), suggesting a draw down of the carbon due to photosynthesis. In OA conditions, the health of Z. marina can improve, and co-culture of Z. marina and C. gigas may be a beneficial mitigation strategy.
