Energy metabolism and metabolic depression during exercise in Callinectes sapidus, the Atlantic blue crab: effects of the bacterial pathogen Vibrio campbellii.
Callinectes sapidus (Rathbun), the Atlantic blue crab, commonly harbors low to moderate amounts of bacteria in hemolymph and other tissues. These bacteria are typically dominated by Vibrio spp., which are known to cause mortality in the blue crab. The dose-dependent lethality of an isolate of Vibrio campbellii was determined in crabs; the mean 48 h LD(50) (half-maximal lethal dose) was 6.2 x 10(5) colony forming units g(-1) crab. Injection of a sublethal dose of V. campbellii into the hemolymph of the crab resulted in a rapid and large depression (30-42%) of metabolic rate, which persisted for 24 h. Because gills are an organ of immune function as well as respiration, we were interested in how bacteria injected into the crab would affect the energetic costs associated with walking. Overall metabolism (aerobic and anaerobic) more than doubled in crabs walking for 30 min at 8 m min(-1). The metabolic depression resulting from bacterial injection persisted throughout the exercise period and patterns of phosphagen and adenylate consumption within walking leg muscle were not affected by treatment. The ability of crabs to supply required energy for walking is largely unaffected by exposure to Vibrio; however, Vibrio-injected crabs are less aerobic while doing so. This depressed metabolic condition in response to bacteria, present during moderate activity, could be a passive result of mounting an immune response or may indicate an actively regulated metabolic depression. A compromised metabolism can affect the performance of daily activities, such as feeding and predator avoidance or affect the ability to cope with environmental stressors, such as hypoxia.
Thibodeaux
Lindy K
LK
Hollings Marine Laboratory, 331 Fort Johnson, and Grice Marine Laboratory, College of Charleston, 205 Fort Johnson, Charleston, SC 29412, USA.
Burnett
Karen G
KG
Burnett
Louis E
LE
D000818:Animals; D001120:Arginine / Q000378:metabolism; D003386:Brachyura / Q000378:metabolism / Q000382:microbiology; D004734:Energy Metabolism; D006458:Hemolymph / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009132:Muscles / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D013312:Stress, Physiological; D019802:Succinic Acid / Q000378:metabolism; D014733:Vibrio / Q000378:metabolism / Q000472:pathogenicity; D014735:Vibrio Infections / Q000401:mortality; D016138:Walking
D019344:Lactic Acid; D001120:Arginine; D019802:Succinic Acid; D010100:Oxygen