Patterns of agonistic behaviour, shelter occupation and habitat preferencein juvenile Lipophrys pholis, Coryphoblennius galerita and Gobius cobitis

The patterns of agonistic behaviour and substratum preferences were investi gated in captive groups of juveniles of Lipophrys pholis (Blenniidae), Cory phoblennius galerita (Blenniidae) and Gobius cobitis (Gobiidae). In monospe cific groups, size was an excellent predictor of the rank attained by each individual. In heterospecific groups, both C. galerita and L. pholis were d ominant over G. cobitis of similar size, and C. galerita dominated L. pholi s. Although G. cobitis showed higher rates of activity and of attacks per m inute, and a higher ratio of attacks over threats, all these measures were depressed in the presence of either blenniid. In both blennies, in monospec ific groups, the dominance rank of each fish was a good predictor of the ti me spent inside shelters. G. cobitis occupied preferentially the sandy subs tratum both in mono- and heterospecific groups. Both blennies, when in mono specific groups, occupied preferentially the rocky substratum, with C. gale rita showing the highest level of selectivity. In nature, C. galerita also showed a marked preference for rocky substrata, while G. cobitis was especi ally abundant in mixed bottoms. L. pholis occupied an intermediate position . In the blenniids studied, competition for access to shelter may be one ma jor functional consequence of agonistic behaviour in non-reproductive conte xts. (C) 1998 The Fisheries Society of the British Isles.