Trophic relationships of polychaetes associated with different algal growth forms

Abstract

The trophic relations of the polychaete species associated with four different algal growth forms (filamentous, fan-shaped, bush-like and encrusting) were studied in the North Aegean Sea. Samples for the spatial analysis were collected in summer with a quadrate sampler (400 cm2) at a depth range of 15–40 m. Filamentous and encrusting forms were also seasonally sampled in order to detect the temporal changes. A total of 5,494 individuals belonging to 79 species were classified to 12 feeding guilds, considering the type of food, the feeding apparatus and the motility patterns involved. Carnivores dominated, followed by herbivores and filter-feeders, among all the algal forms studied, excepting the fan-shaped form where filter-feeders prevailed mainly due to a massive recruitment of spirorbids. With respect to the abundance of the various feeding guilds, filamentous and fan-shaped forms discriminated, whereas bush-like and encrusting forms showed high similarity. The occurrence of polychaete feeding guilds among both filamentous and encrusting forms showed seasonal changes, with summer and spring samples, respectively, discriminating. The results of the trophic group analysis conformed to previous information provided by a taxon composition analysis of the dominated by the same algae communities. However, a functional study can give additional information and is thus a useful tool for the study of hard bottom communities.