Meeting Abstract
The abundance and distribution of many benthic invertebrates depends on success in their larval life-history stage. In the coming century, the world’s oceans will drop in pH due to the increased uptake of atmospheric carbon dioxide. Past studies have documented morphological changes in larvae reared under elevated pCO2 conditions. Larvae might minimize exposure to low pH by modifying swimming behaviors. However, larval swimming responses to boundaries between acidified and normal seawater remains unknown. We quantified vertical distributions of larvae of the sand dollar Dendraster excentricus released from the bottom of a stratified column with a layer of ambient seawater over- or underlying a layer of acidified seawater. As larvae approached a transition from normal to acidified water, they exhibited twirling swimming behavior followed by downward swimming. Larvae transitioning from low pH to normal seawater maintained upward swimming. In both cases, larvae used swimming responses to substantially avoid acidified seawater. The results of this study imply behavioral avoidance of low pH water masses by larvae that may have important ramifications for the distribution of both larval and adult marine invertebrates in the coming century.
