Intraguild predatory interactions between the jellyfish Cyanea capillata and Aurelia aurita
- 344 Downloads
While qualitative observations of jellyfish intraguild predation abound in the literature, there are only few rate measurements of these interactions. We quantified predation rates among two common jellyfish in northern boreal waters, Cyanea capillata and its prey Aurelia aurita, both of which also feed on crustacean zooplankton and fish larvae. A series of incubation experiments using a wide range of prey concentrations (0.38–3.8 m−3) in large containers (2.6 m3) was carried out. By replenishing the prey continuously as they were captured we maintained a nearly constant prey concentrations. Ingestion rates increased linearly up to prey concentrations of 1.92 m−3, yielding maximum clearance rates of ∼2.37 ± 0.39 m3 predator−1 h−1 for C. capillata predators 16 ± 2.3 cm in diameter. Mean ingestion rate at saturated prey concentrations (1.92–3.85 m−3) was 4.01 ± 0.78 prey predator−1 h−1. Behavioral observations suggested that predators did not alter their swimming behavior during meals, and thus that feeding rates were generally handling limited rather than encounter limited. Predators captured more prey than needed, and semi-digested prey was often discarded when fresh prey was encountered.
KeywordsIntraguild Predation Digestion Rate Maximum Ingestion Rate Prey Concentration Predator Size
This work formed part of the EUROGEL project (EVK3-CT-2002–00074; U Båmstedt). JT received additional support from a grant from the Norwegian Research Council to U Båmstedt (146994/120), and LG and AG were supported by fellowships from ENSAT-Ecole Nationale Supérieure Agronomique de Toulouse. We thank T Sørlie and H Hjertsen for assistance with setting up the flow in the tanks. Aino Hosia and Jon Egil Skjæraasen kindly commented on earlier drafts. The experiments comply with the current laws of Norway, where the experiments were performed.
- Båmstedt U, Martinussen MB, Fyhn HJ, Grahl-Nielssen O (2007) Biometrics and biochemical composition of the scyphomedusae Aurelia aurita, Cyanea capillata, and Periphylla periphylla, and the lobate ctenophore Bolinopsis infundibulum (in preparation)Google Scholar
- Martinussen MB, Båmstedt U (1995) Diet, estimated daily food ration and predator impact by the schyphozoan jellyfishes Aurelia aurita and Cyanea capillata. In: Skjoldal HR, Hopkins C, Erikstud KE, Leinaas HP (eds) Ecology of fjords and coastal waters. Elsevier, Amsterdam, pp 127–145Google Scholar
- Ohman MD (1988) Behavioral responses of zooplankton to predation. Bull Mar Sci 43:530–550Google Scholar
- Pinheiro J, Bates D, DebRoy S, Sarkar D (2005) nlme: Linear and nonlinear mixed effects models, R package version 3.1–65Google Scholar
- R Development Core Team (2005) R: a language and environment for statistical computing, Vienna, Austria. ISBN 3–900051–07-0. URL http://www.R-project.org
- Stibor H, Vadstein O, Diehl S, Gelzleichter A, Hansen T, Hantzsche F, Katechakis A, Lippert B, Loseth K, Peters C, Roederer W, Sandow M, Sundt-Hansen L, Olsen Y (2004) Copepods act as a switch between alternative trophic cascades in marine pelagic food webs. Ecol Lett 7:321–328CrossRefGoogle Scholar