Enzymatic digestive activity in Mytilus chilensis (Hupe 1854) in response to food regimes and past feeding history

Digestive enzyme activities (amylase, cellulase, laminarinase and protease) were analysed in mussels (Mytilus chilensis) from intertidal and subtidal habitats in Yaldad Bay, Chiloe, Chile, In order to analyse the effects of t he past-feeding history (origin) and new nutritional conditions (habitat) o n these enzymatic activities, a cross-over transplant was carried out and t he analysis performed after a 7-day acclimation period. Crystalline styles showed higher carbohydrase and lower protease activities than digestive gla nds, with the highest differences recorded for subtidal mussels. Cellulase is the enzyme with the highest activity in both the digestive gland and cry stalline style in all the experimental conditions. Intertidal mussels trans planted to a subtidal habitat showed enzyme resources significantly higher than in their original habitat. In the inverse case, mussels transferred fr om an original subtidal habitat to an intertidal one, a significant decreas e in carbohydrase and protease activities was observed. The "past feeding h istory" is involved in the specific and total carbohydrase and protease act ivities, with a highly significant effect on amylase and cellulase activiti es in both the crystalline style and the digestive gland. Laminarinase acti vity can be interpreted considering the habitat (trophic regime), either in dividually or interacting with mussels' origin, in relation with the feedin g periods. The results establish that in M. chilensis, an investment in enz yme resources is one of the mechanisms employed to optimise the acclimated response in terms of energy gains when variations in the food regime occur.