Abstract
Populations of six sympatric species, Galathea intermedia, Pisidia longicornis, Pagurus bernhardus, P. cuanensis, P. prideauxi, and Anapagurus chiroacanthus from two shallow sounds, were investigated during 18 months. Four types of bottom were distinguished. G. intermedia and P. longicornis were positively correlated with the amount of coarse substrate mainly consisting of empty shells; A. chiroancanthus showed a negative correlation. The pattern of distribution was studied by using the coefficient of dispersion. G. intermedia and P. longicornis were contagiously distributed; the other species occurred in too low numbers for the result~ to be valid. G. intermedia lived c. 1 year, and the larvae settled from Aug. to Nov. 0.002% were infected by Lernaeodiscus galatheae. P. longicornis reached an age of c. 2 years (some probably 3) and reproduced the first. The larvae settled mostly in Aug. and Sept. P. bernhardus, older than c. 1 year, probably migrated to deeper water. 2.1% were infected by Peltogaster paguri. P. cuanensis lived at least 2 years; few reproduced the first. One brood a year is probable. 1.3% were infected by Athelges paguri, 2.0% by P. paguri, 5.5% by Peltogaster curuatus, and 1.7% by Gemmosaccus sulcatus. Young P. prideauxi occurred in shallow water when the temperature exceeded 8–10°C. A commensal polychaete, Iphitime paguri, new to the Norwegian fauna, was found. A. chiroacanthus lived c. 2 years and reproduced the first. One brood a year occurred. 0.7% were infected by P. paguri and 0.5% by G. sulcatus. Selection of shells by the pagurids has been discussed. Labrus berggylta was the main predator.
