Meeting Abstract

P2.68  Thursday, Jan. 5  Effects of Elevated Oceanic CO₂ on Sperm Motility and Swimming Speed in Sea Urchins: Implications of Ocean Acidification for Fertilization Success CASTRO, D.A.*; PODOLSKY, R.D.; College of Charleston; College of Charleston dacastro1@g.cofc.edu

Increases in atmospheric CO₂ are dramatically increasing CO₂ levels in the ocean, driving a decrease in oceanic pH. Because several key biological processes are sensitive to small changes in pH, there is increasing concern about continued introduction of CO₂ into the atmosphere. Research on ocean acidification is rapidly expanding, though most efforts to date have focused on risks to calcifying organisms. In contrast, relatively little attention has been paid to other biological processes that are pH sensitive, especially involving developmental stages that may be especially vulnerable to environmental change. We focused on the consequences of ocean acidification for external fertilization by analyzing the effect of CO₂-induced acidification on sperm activity in the sea urchin Arbacia punctulata. CO₂-driven declines in pH equivalent to increases predicted 100, 200, and 300 years in the future led to significant decreases in both sperm motility and swimming speed, with the most dramatic declines in the near-term. These changes in motility and speed relate directly to parameters used in standard models of fertilization kinetics. We are coupling predictions of these models with measures of fertilization rate under the same gas concentrations to estimate the impact of changes in sperm activity on fertilization success in sea urchins.