Two aspects of the physiology of the burrowing shrimp Caliianassa tyrrhena (Decapoda: Thalassinidea) were studied in order to investigate the effects of the general pollution load: total (TRR) and weight-specific respiration rate (SRR) as well as the digestive enzyme activity of the digestive gland.
Caliianassa tyrrhena exhibited a very low respiration rate (mean TRR=64-29 μl 02 animal−1h−1, N=60; mean SRR=0·18 μl 02mg DW−1h−1, N=61).
The slope of the TRR-DW logarithmic regression (b=0·64) showed that respiration in C. tyrrhena is proportional to body surface. Size is the dominant factor (among size, sex, season and locality) determining the variation in respiration rate. Comparison between the two sites with the different pollution load showed that there were no significant differences in the respiration rates of the same size class and season, except for the youngest animals in summer which showed a significant decrease in their respiration rate at the polluted site.
A similar ‘inhibitory’ effect of pollution has been observed in the activity of the majority of the 19 digestive enzymes tested. Only three e.g., trypsin, β-galactosidase and α-glucosidase showed an increase in polluted waters.
One could suggest, therefore, that C. tyrrhena can be considered to be preadapted to the low oxygen conditions encountered in the sediments, because of its burrowing mode of living.