Feeding strategies and diet composition of four Antarctic cnidarian species

Abstract

The diet of four species of Antarctic cnidarians, two hydroids and two anthozoans, was investigated. One hydroid, Tubularia ralphii, and one anthozoan, Anthomastus bathyproctus, seem to basically consume zooplankton whereas the other hydroid species, Oswaldella antarctica, has a diet mainly based on the ®ne fraction of seston. The last cnidarian investigated, the stoloniferan alcyonacean, Clavularia cf. frankliniana, feeds mainly on resuspended material. The wide range of diets of these Antarctic cnidarians indicates opportunistic behaviour by feeding on dierent sources and taking advantage of the available food sources. Data related to low C/N ratios in the sediment and high NO 2 concentrations in areas with dense communities of benthic suspension feeders, along with data on capture rates, lead us to hypothesize that these organisms play an important role in the recycling processes of organic matter in Antarctic benthic ecosystems.

Trophic ecology of the zoanthidPalythoa caribaeorum(Cnidaria: Anthozoa) on tropical reefs

“…Most previous studies have identified zooplankton as the principal food item of suspensivorous cnidarians such as corals (Porter, 1974;Lasker, 1976), hydroids (Barangé, 1988;Coma et al, 1999;Orejas et al, 2001) and octocorals (Sebens & Koehl, 1984;Coma et al, 1994Coma et al, , 1995Ribes et al, 1998;Orejas et al, 2001;Rossi et al, 2004;Tsounis et al, 2006). Most of the studies, however, were undertaken in temperate regions, while tropical coral reef ecosystems have distinct dynamics and high productivity even in oligotrophic waters (Lewis, 1977;Rougerie et al, 1992), with the reef fauna rapidly removing planktonic biomass (Erez, 1990).…”