COMMUNITIES OF EPIBIOTA ON 2 ERECT SPECIES OF ANTARCTIC BRYOZOA

Two erect species of bryozoans, Alloeflustra tenuis (Kluge) and Nematoflustra flagellata (Waters), occur abundantly in similar localities at Signy Island, Antarctica. Both species are unilaminar and are colonized by a range of epibiotic taxa, principally other cheilostome bryozoans. A detailed study was undertaken of the bryozoan epibiota of these two species, collected by SCUBA over the depth range 36 to 40 m. The degree of colonization varied with host size and differed between the front and rear surfaces of each host species, and between host species. The species composition of the epibiota was also different between species and between surfaces within species. These variations are possibly related to differences between the host species in the abundance, structure and function of avicularia (putative protective structures). Specimens from deeper water (150 m) showed significantly reduced colonization by epibiota, but the same overall patterns of colonization between the two species and surfaces were still observed.