PARENT SESSION
Oral Session # 23: Marine Ecology I: Crabs, Coral, and Lobsters.
Presiding: J Wilson
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 202.
Prevalence of parasitic Hematodinium sp. in Georgia blue crabs (Callinectes sapidus): a result of habitat degradation?
Wrona, Amanda*,1, Sheppard, Michael2, Lee, Richard3, Wiegert, Richard1, 1 University of Georgia, Athens, GA2 Savannah State University, Savannah, GA3 Skidaway Institute of Oceanography, Savannah, GA
ABSTRACT- Blue crab (Callinectes sapidus) populations in Georgia are in severe decline. Factors that may be responsible include overfishing, habitat degradation, and disease. For aquatic estuarine species like blue crabs, habitat degradation may include changes in water salinity to values that cause increased physiologic stress and decreased survival. As salinities in Georgia estuaries have been increasing over the past few years due to drought conditions, Hematodinium sp., a lethal parasitic dinoflagellate that infects blue crabs, has been found in a large percentage of Georgia crabs (as high as 50% of crabs sampled in some areas). High prevalence of this parasite is thought to coincide with high estuarine salinity. In January 2002, we began to monitor for Hematodinium within the Sapelo Island National Estuary Research Reserve, GA in order to investigate the relationship between Hematodinium infection in blue crabs, water conditions, and crab abundance. Monthly samples of crabs taken from commercial traps and by trawl were tested using a neutral red assay technique. The parasite was found in crabs from 78 to 165 mm CW in size and most often occurred in males (21%) vs. females (9%). Infection is positively correlated with both water salinity and temperature and negatively correlated with commercial catches. Peak infection (33% prevalence) occurred in August, when water temperatures and salinity were greatest and prevalence was lowest in January, (3%) following several weeks of cold temperatures and heavy rain that lowered salinity and water temperatures to 16 ppt. and 7.6 °C.
Key words: Callinectes sapidus, Hematodinium sp., blue crab, habitat degradation