Ecophysiological performance and life cycle strategies of North Sea shrimps

The high level of digestive enzyme polymorphism in C. crangon specimens seems to be an important feature for their biological success in the North Sea. This pronounced polymorphism has different impacts on the metabolism of North Sea shrimps. On the one hand, it affects the sequence of proteins necessary for the accumulation of lipids. This change in the sequence of specific proteins is a challenge to the metabolism of C. crangon, because it results in a limited lipid storage capacity. Lipid storage is important to overcome periods of food paucity and to fuel reproduction. However, in C. crangon the midgut gland does not function as principal energy depot. Instead, the midgut gland serves as a dynamic metabolic center that directly provides dietary energy necessary for diverse biological processes including reproduction. This metabolic center seems to be supported by the expression of digestive enzyme isoforms.