Science Serving Maryland's Coasts

Brittany Rosener, Clemson University

Class Year: 

Project Title: 

Assessment of fitness between cryptic species of Acartia tonsa in the Chesapeake Bay area in relation to hypoxia exposure

Acartia tonsa are copepods prevalent in the Chesapeake Bay and serve as a major prey component in estuarine food webs as well as aquaculture. Two genetically distinct cryptic species of A. tonsa have been identified in the Chesapeake Bay. These morphologically similar lineages, F and S lineage, appear to show preference to salinity levels with the F lineage preferring low salinities and the S lineage preferring a more saline environment. Research was conducted to determine a difference in lineage preference and tolerance to stressors of hypoxic conditions at different temperatures. Results showed A. tonsa of both lineages had a high tolerance to hypoxia at a temperature of 25°C and an increased mortality rate in a 30°C environment. Further tests and are needed to determine a significant difference in F and S lineage survivorship in the 30°C hypoxic conditions. Additionally, during the study population lineage proportions were determined from collection sites at varying salinities along the Choptank River. These F and S lineage proportions reiterated the salinity preferences of the lineages but also indicated a decrease in the prevalence of F lineage A. tonsa in the Choptank River since previous records in 2003.