The impact of ocean acidification on the growth and survival of the larvae of the Pacific oyster

Principal Investigator: Ruth Cox
Co-Investigator: Maya Groner

Climate change is having a detrimental impact on wild and farmed fisheries. For shellfish, one particular threat is ocean acidification, which has had both ecological and economic impacts in many areas of the world, and has led to decline of wild shellfish and shellfish aquaculture.

Seagrasses can remove carbon dioxide (CO2) and bicarbonate (HCO) from the water column and, potentially, reduce the impact of acidification on shellfish. Studies have shown that co-culturing of shellfish with eelgrass may reduce the impact of ocean acidification on shellfish growth and survival. However, little is known about the impact of acidification on the health of eelgrass. Slime mold is known to cause low to moderate disease in healthy plants, but can cause severe infection in stressed plants. One potential source of stress is ocean acidification. Our objective was to establish a pilot project to determine whether eelgrass grown at increased levels of acidification is more susceptible to wasting disease.

Our laboratory work assessed the impact of acidification on larval oysters to determine whether the presence of eelgrass would mitigate impacts on growth or survival. We also assessed whether acidification would impact the health of the eelgrass itself, by assessing whether it makes eelgrass more susceptible to wasting disease.

We found that the prevalence (number of diseased leaves) increased during the study in all treatments, and that eelgrass plants that were and were not exposed to slime mold both had a much higher prevalence of disease at more acidic pH levels.