Georgia Journal of Science

Article Title



Climate change is altering oceans in many ways such as modifications in salinity, temperature and pH. However, rarely are these factors experienced in isolation by organisms, rather they may be impacted by changes in all of them concurrently. This is especially challenging for marine larvae with calcium carbonate structures because survivorship and growth are susceptible to damage by changes in salinity and pH. We are specifically studying the Gulf and Caribbean sea urchin species Lytechinus variegatus; their aquatic habitat averages 27 ppt salinity and pH of 8.4. We predict that when they encounter salinities and pHs outside their normal range, there will be a decrease in survivorship and increase in skeletal abnormalities. To manipulate water conditions, we distributed larvae among 6 treatments with varying salinity and pH. Twenty - four hours after fertilization, larvae were placed in seawater of 25ppt, 27ppt or 32ppt in combination with pH of 7.6 or 8.4 for 6 possible treatments. Over the next 10 - 14 days, larval survivorship and skeletal abnormalities were measured. Results of this experiment show that survivorship was lower in treatments with a pH of 7.6 than pH of 8.4 regardless of salinity (p<0.001) and skeletal abnormalities increased. However, salinity also impacted larvae because deviations from a salinity of 27ppt resulted in decreased survivorship (p<0.001) and increased skeletal abnormalities. These results are consistent with our hypothesis and previous work, but replication is needed for statistical analysis of skeletal abnormalities. Lastly, there is a significant interaction between the effects of salinity and pH on mortality (p<0.001) that may also be present in skeletal abnormalities, suggesting that the combinatorial effects of these factors should be studied. We can use these data to understand how the complexity of climate change is impacting our oceans.

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