Meeting Abstract

P3.88  Tuesday, Jan. 6  Digestive enzyme activity following feeding in low salinity in the blue crab, Callinectes sapidus, and the Dungeness crab, Cancer magister CURTIS, Daniel L*; MCGAW, Iain J; Univ. Nevada, Las Vegas and Bamfield Marine Sciences Centre; Univ. Nevada, Las Vegas and Bamfield Marine Sciences Centre curtisd4@unlv.nevada.edu

Digestive processes were examined in two crab species of differing osmoregulatory ability during hyposaline exposure. The blue crab, Callinectes sapidus, an efficient osmoregulator, displayed a summation of the metabolic responses to low salinity and digestion which enabled gastric processing (mechanical digestion) to continue unabated in low salinity. In contrast, the Dungeness crab, Cancer magister, which is classed as a weak osmoregulator displayed a decreased foregut contraction rate and an increased time for clearance of digesta from the gut. This was associated with a reduction in oxygen uptake when exposed to low salinity following feeding. Since the costs associated with mechanical digestion are minimal, it was hypothesized that the observed reduction in oxygen uptake may be the result of modulation of more costly downstream processes such as extracellular digestion and/or protein synthesis. The current study examined changes in digestive enzyme activity (protease, chymotrypsin, and amylase) in the hepatopancreas and gut fluid following feeding in low salinity in both a weak (Cancer magister) and an efficient (Callinectes sapidus) osmoregulator.