Meeting Abstract
P3.101 Tuesday, Jan. 6 HYPOXIA IMPAIRS ANTIBACTERIAL DEFENSE IN THE DUNGENESS CRAB, CANCER MAGISTER SCHOLNICK, D. A.; HAYNES, V. N.*; SCHWEITZER, K. I.; Pacific University, Oregon; Pacific University, Oregon; Pacific University, Oregon david.scholnick@pacificu.edu
We examined the possibility that long-term decreases in environmental oxygen (hypoxia), similar to those experienced by many coastal marine crustaceans, can limit the ability of crabs to respond to indigenous bacteria in the hemolymph and increase the rate of bacterial infection. Male Dungeness crabs, Cancer magister, were collected off of the central Oregon coast and maintained in UV sterilized seawater at 9oC. Crabs were exposed to either 50 or 100% air-saturated water for 72 h. Hemolymph was sampled every 24 h and levels of bacteria were measured as the total numbers of colony forming units (CFU) present per mL of hemolymph. Immune response was assessed as a change in the total number of circulating hemocytes and granulocytes. Hemolymph lactic acid levels were measured to determine if changes in bacterial infection alter levels of anaerobic metabolism in hypoxic waters over time. Bacteremia increased after 24 h of exposure to hypoxia and persisted for 72 h (P < 0.05; ANOVA). Colony forming units increased from about 10 to over 4,000 per mL hemolymph during 72 of hypoxia. Crabs exposed to air-saturation had no measurable change in CFUs over the course of the experiment. The total number of circulating hemocytes were unaltered by hypoxia for 48 h and showed only a small decrease after 72 h (P < 0.05; ANOVA), consistent with a reduced capability to respond to bacteria under low oxygen conditions. Exposure to hypoxia increased hemolymph lactate levels only after 48 h suggesting that over time, elevated bacterial concentrations may limit normal respiratory function. These results suggest that low oxygen can suppress immune response and limit the crabs ability to manage intrinsic bacterial levels.
