Some physiological consequences of keepingMytilus edulis in the laboratory
© Biologischen Anstalt Helgoland 1970
1. Nutritive and temperature stresses in experiments cause a decline in general body condition and dry weight ofMytilus edulis L. Carbohydrate and protein are lost from the body; these losses are greater from the germinal (mantle) than from the somatic (non-mantle) tissues. There is a more rapid loss of carbohydrate than of protein.M. edulis is able to maintain and continue maturation of the gametes in spite of this considerable utilisation of general body reserves.
2. The greater the degree of stress imposed on the test animals the greater is the utilisation of carbohydrate and protein. However, the mussels maintain a balance between these two components so that, at any one time, the carbohydrate to protein ratio does not differ between individuals subjected to different degrees of stress.
3. During the cultures there was a decline in oxygen consumption. Nitrogen excretion either increases or slightly decreases. The ratio oxygen consumed to nitrogen excreted declines in all experiments, indicating an increased use of protein as an energy substrate. The greater the degree of stress imposed upon the test animal, the greater the rate of decline of the O:N ratio. The values for this ratio suggest thatM. edulis normally utilises carbohydrate or fat substrates, though proteins may also be utilised in response to stress.
4. Indices of physiological condition should prove useful in determining the degrees of stress that are experienced by lamellibranchs under cultivation. In order to measure the effects of stress, knowledge of the normal seasonal variations in physiological indices is needed, to serve as a “base-line” with which induced changes in condition may be compared.