Oysters and eelgrass: potential partners in a high pCO 2 ocean

• Published in: Ecology
• Main Authors: Groner, Maya L., Burge, Colleen A., Cox, Ruth, Rivlin, Natalie D., Turner, Mo, Van Alstyne, Kathryn L., Wyllie‐Echeverria, Sandy, Bucci, John, Staudigel, Philip, Friedman, Carolyn S.
• Other Authors: University of Prince Edward Island, Washington Sea Grant, University of Washington, National Science Foundation, University of Maryland, Baltimore County, University of Maryland, School of Aquatic and Fishery Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: Pacific; Crassostrea gigas; Ocean acidification; Pacific oyster
• Online Access: http://dx.doi.org/10.1002/ecy.2393; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fecy.2393; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.2393; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ecy.2393; https://esajournals.onlinelibrary.wiley.com/doi/am-pdf/10.1002/ecy.2393; https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.2393

Abstract Climate change is affecting the health and physiology of marine organisms and altering species interactions. Ocean acidification ( OA ) threatens calcifying organisms such as the Pacific oyster, Crassostrea gigas . In contrast, seagrasses, such as the eelgrass Zostera marina , can benefit from the increase in available carbon for photosynthesis found at a lower seawater pH . Seagrasses can remove dissolved inorganic carbon from OA environments, creating local daytime pH refugia. Pacific oysters may improve the health of eelgrass by filtering out pathogens such as Labyrinthula zosterae ( LZ ), which causes eelgrass wasting disease ( EWD ). We examined how co‐culture of eelgrass ramets and juvenile oysters affected the health and growth of eelgrass and the mass of oysters under different pCO 2 exposures. In Phase I, each species was cultured alone or in co‐culture at 12 ° C across ambient, medium, and high pCO 2 conditions, (656, 1,158 and 1,606 μatm pCO 2 , respectively). Under high pCO 2 , eelgrass grew faster and had less severe EWD (contracted in the field prior to the experiment). Co‐culture with oysters also reduced the severity of EWD . While the presence of eelgrass decreased daytime pCO 2 , this reduction was not substantial enough to ameliorate the negative impact of high pCO 2 on oyster mass. In Phase II , eelgrass alone or oysters and eelgrass in co‐culture were held at 15 ° C under ambient and high pCO 2 conditions, (488 and 2,013 μatm pCO 2 , respectively). Half of the replicates were challenged with cultured LZ . Concentrations of defensive compounds in eelgrass (total phenolics and tannins), were altered by LZ exposure and pCO 2 treatments. Greater pathogen loads and increased EWD severity were detected in LZ exposed eelgrass ramets; EWD severity was reduced at high relative to low pCO 2 . Oyster presence did not influence pathogen load or EWD severity; high LZ concentrations in experimental treatments may have masked the effect of this treatment. Collectively, these results indicate that, ...