ENZYMATIC-ACTIVITY AS AN INDEX OF TROPHIC RESOURCE UTILIZATION BY THE SNOW CRAB CHIONOECETES-OPILIO (O FABRICIUS)

In order to assess the food utilization of Chionoecetes opilio, we measured the activity of 5 enzymes in the digestive gland: 2 metabolize animal products (chitinase and phosphorylase-a), and 3 digest vegetal products (cellulose, alpha-amylase, and laminarinase). The analysis was made on 18 morphometrically mature males and 2 mature females. Chitinase had a high activity level (mean = 6.728 +/- 1.689 units/mg of protein). Phosphorylase-a had a much lower activity level (mean = 0.114 +/- 0.039 unit/mg). Alpha-amylase, while present in every cmb, had a low activity level (mean = 0.102 +/- 0.031 unit/mg). Cellulase was present in 85% of the crabs (mean = 0.115 +/- 0.089 unit/mg). Laminarinase was hardly detected (maximum 0.002 unit/mg). The presence of active enzymes digesting vegetal products indicates that the snow cmb is not a strict carnivore but is able to metabolize energy from various trophic sources, including vegetal detritus.