Enzymatic digestive activity in epifaunal (Mytilus chilensis) and infaunal (Mulinia edulis) bivalves in response to changes in food regimes in a natural environment

Abstract.

The response of digestive enzymes to variable nutritional conditions over a 7-day acclimatisation period in epifaunal (Mytilus chilensis) and infaunal (Mulinia edulis) bivalves were determined. This study has established that the cellulase complex was the most important enzyme in the digestive gland and the crystalline style of Mytilus. In Mulinia, protease and laminarinase were prominent in the digestive gland, and laminarinase, in the style. The enzyme activity in M. chilensis was markedly different between its original habitat (tidal flat) and following a period of acclimatisation in a subtidal habitat, and showed increases in all specific and total digestive enzyme activities. However, transplant to a subtidal habitat affected the enzyme system in Mulinia in different ways. The differences observed in enzyme behaviour in response to variable feeding conditions reflected a more rapid adaptation of the epifaunal species (Mytilus), whereby over a 7-day period enzyme production increased in response to an improvement in feeding conditions. Enzyme response was less noticeable in the infaunal species (Mulinia).