Predatory impact of an epiphytic hydrozoan in an upwelling area in the Bay of Coliumo (Dichato, Chile) |
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| Authors: | C Orejas J -M Gili V Alv W Arntz |
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| Institution: | C. Orejas, J. -M. Gili, V. Alvà,W. Arntz |
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| Abstract: | The natural diet of the epiphytic hydrozoan Obelia geniculata has been studied in an upwelling area in the Bay of Coliumo (Dichato, Chile) during two 24-h cycles. Number of prey per predator and predatory density have been measured. In both cycles more than 78% of the diet consisted of eggs of invertebrates and faecal pellets. Compared with other species of hydrozoans studied in a similar way, O. geniculata had a heterogeneous diet and a capture rate which was scarcely related to the peaks of abundance of its prey. This catch rate was between 632×103 and 10 393×103 prey m−2 day−1, which corresponds to a mean ingestion rate of 113% of the hydranth biomass per day. These results indicate the importance of small-sized benthic suspension feeders in upwelling systems. |
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| Keywords: | trophic ecology hydroids upwelling bentho-pelagic coupling |
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