Copepod response to ocean acidification in a low nutrient-low chlorophyll environment in the NW Mediterranean Sea

No abstracts are to be cited without prior reference to the author.

In order to identify how ocean acidification will influence biological interactions and fluxes among planktonic organisms and across trophic levels, a large-scale mesocosm experiment was performed in the oligotrophic Northwestern Mediterranean Sea. Nine mesocosms were deployed in the Bay of Calvi (Corsica, France) in summer 2012. Six mesocosms were subjected to different levels of CO2 partial pressures (550, 650, 750, 850, 1000 and 1250 μatm) covering the range of atmospheric pCO2 anticipated for the end of this century depending on future emission scenarios, and the last three mesocosms were unaltered (ambient pCO2 of ~ 450 μatm). During this 21-day experiment, we monitored copepod egg and nauplius stocks, estimated copepod (Acartia clausi and Centropages typicus) feeding rates and determined the abundance and taxonomic composition of the mesozooplankton community at the start and at the completion of the experiment. Zooplankton community revealed important differences among mesocosms most likely due to natural and experimental variability that cannot be related to CO2 conditions. Eggs and nauplii as well as feeding rates on microplankton showed no significant differences among CO2 levels. The above findings suggest that in low nutrient-low chlorophyll environments, ocean acidification will most likely not have significant effects on planktonic trophic interactions.