A study on the adaptation of marine organisms to changing salinities with special reference to the shore crab Carcinus maenas (L.)

Abstract

1. 1. A mathematical model is designed to describe the effect of (a) sudden and (b) sinusoidal changes in environmental salinity on the electrolyte concentrations in the blood of aquatic organisms. 2. 2. The model for sudden changes in salinity was checked experimentally for the shore crab Carcinus maenas. 3. 3. For this species it could be deduced that a decrease in permeability takes place within the range of salinity in which a strong regulation of the concentration of electrolytes in the blood is found. It appears that in C. maenas active transport is a linear function of environmental salinity. 4. 4. The decrease in permeability suggests a double function: (a) reduction of energy consumption needed in electrolyte regulation and (b) a damping effect on internal salinity fluctuations. Both are of value to the species in its migration to the estuary with its tidal fluctuations in salinity. 5. 5. The approach appears to offer simple methods for further comparative studies on the ionic adaptation of marine organisms to their environment.