Trophic ecology of a benthic marine hydroid, Campanularia everta

Abstract

The diet and prey capture rate were studied in Campanularia everta (Hydrozoa) in the western Mediterranean Sea during both a 1 yr period and a diel period. A sample of 20 colonies was collected from the thall~ of the alga Halirneda tuna every 2 wk, and the stomach content of 100 polyps was examined. The d~e t of C. everta consisted primarily (88%) of particulate organic matter between 30 and 80 pm in size (probably detritus). Zooplankton accounted for only 12% of the diet; the predominant prey items were crustacean eggs, larvae, and fragments, and as well as other benthic invertebrate larvae. In terms of biomass, zooplankton contributed 54% of the diet. The percentage of prey-containing polyps was rather constant at around 70'X over both the annual and diel cycles. Prey capture rates were quite high overall (between 0.6 and 2.7 prey items per polyp) and likewise the number of polyps with prey is remained high throughout the year, with maximum values in autumn and minimum values in summer. Digestion t~m c was less than 2 h Prey capture estimates were slightly fewer than 4000 prey m-2 d-l in summer and 800 000 prey m-' d-l in winter. Accordingly, C. everta may ingest a mean of 1925 pg C m-2 d.' in particulate organic matter and 2260 pg C m-' d -' in zooplankton each year, representing a total of 1528 mg (: m-2 yrrl Each pg C of polyps (somatic biomass) ingests a mean value of 69.6 1-19 C of prey per year. These figures suggest that the contribution of hydroids to the transfer of energy from the plankton to the benthos in littoral systems may be much hlgher than that suggested by hydroid biomass values themselves

Morpho‐functional adaptation to suspension feeding inEudendrium(Cnidaria, Hydrozoa)

“…Coma et al (1995) observed that the diet of Campanularia everta mainly consists of particulate organic matter and similar results were reported by Simkina (1980) for Garveia franciscana, and by Torrey (1904) for Corymorpha palma, although the collection method is unknown.…”

“…There is evidence that some species of hydroids may use particulate matter suspended in the water column S. PUCE, G. BAVESTRELIO, A. ARILLO, F. AZZINI, C. CERRANO (Torrey, 1904;Simkina, 1980;Coma et al, 1995), but the collection strategy remains unclear. The observation that the coelenteron of some Eudendrium species, collected during a period of strong rough sea, was filled with sediment, induced us to test in these hydroids, by means of laboratory experiments, the existence of a filter-feeding strategy related to particle concentration and water movement intensity.…”

On the occurrence of Obelia medusa blooms and empirical evidence of unusual massive accumulations of Obelia and Amphisbetia hydroids on the Argentina shoreline

“…In general terms, under favorable conditions, hydroid colonies grow rapidly; exploit food items that may be highly diluted within the water mass with high assimilation efficiencies (Coma et al, 1995(Coma et al, , 1999Gili et al, 1998;Genzano, 2005); form substantial biomasses; and reproduce. Larval production in metagenetic life cycles depends on the colony size and, hence, the number of gonothecae in which the medu-sae stages are formed.…”

Feeding strategies and diet composition of four Antarctic cnidarian species

“…Several studies reported that dino¯agel-lates, diatoms, tintinnids and bacteria are sparse in hydroid gut contents (Gili et al 1996a). However, nanoplankton, mainly of plant origin, is the most abundant food source in the Southern Ocean, and Coma et al (1995) demonstrated that detritus from plant matter or particles of unspeci®ed origin represent more than 90% of prey captured in a Mediterranean hydroid. Diatoms have been also reported to be an important food source for the Antarctic hydroid Silicularia rosea (Gili et al 1996b).…”