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Trophic role of ambush‐foraging hydromedusae in the W hite S ea
Author(s) -
Prudkovsky Andrey A.
Publication year - 2013
Publication title -
marine ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 58
eISSN - 1439-0485
pISSN - 0173-9565
DOI - 10.1111/maec.12033
Subject(s) - predation , biology , foraging , trophic level , zooplankton , zoology , copepod , predator , cnidaria , ecology , fishery , crustacean , coral
The purpose of this study was to determine the trophic role of three ambush‐feeding hydromedusae inhabiting the W hite S ea, both in the natural environment (in the sea) and in an experimental system in the laboratory. A glantha digitale (up to 35 ind.·m −3 ), B ougainvillia superciliaris (up to 4 ind.·m −3 ), and S arsia tubulosa (up to 50 ind.·m −3 ) were the most abundant hydromedusae species apart from O belia spp. There was a variety of zooplankton prey in the stomachs of ambush‐foraging medusae in the sea. A prey selection index C (Pearre [Pearre S.J., 1982]) was positive and significant for copepod prey and cirriped nauplii ( B . superciliaris and S . tubulosa ), copepods, cladocerans and chaetognath eggs ( A . digitale ). In laboratory experiments, A . digitale was poor at capturing cirriped larvae. It may be that a deficiency in desmoneme nematocysts prevents A . digitale from retaining this prey . Diet, ingestion and digestion rates of these three ambush‐foraging medusae did not agree completely. It appears that A . digitale has a shorter digestion time compared with the anthomedusae. Individual predation rates in the sea were low for A . digitale in comparison with anthomedusae. B ougainvillia superciliaris cleared 0.018–0.06 l ind. −1 h −1 with O ithona similis nauplii as a food source in an experimental setting. The average predation rate of medusae in the sea was in the range of experimental values. The prey with the latest onset of reproduction, such as eurythermic copepods, were the most affected by medusae predation. Also, anthomedusae feeding substantially increased mortality rates for cirriped larvae due to high selectivity for this prey.