Bioenergetic characterization in Aurelia aurita (Cnidaria: Scyphozoa) polyps and application to natural polyp populations

Bioenergetic modeling is useful in understanding the benthic polyp population dynamics of metagenetic scyphozoan jellyfishes. We investigated the effects of environmental factors on the respiration and feeding rates of polyps of Aurelia aurita s.l. under controlled laboratory conditions in order to construct an empirical energy budget model for application to natural polyp populations. The carbon weight-specific respiration rate of polyps increased exponentially with increasing temperature from 8 to 28°C and was constant at salinities ranging from 15 to 33. The general functional response of polyps feeding on various zooplankton taxa was expressed by a linear increase in ingestion rate as a function of prey density, although it was affected by the size and/or swimming ability of prey organisms. Accordingly, the clearance rate was constant irrespective of prey density at a given temperature. The rate increased linearly with temperature from 8 to 26°C. Integrating these results, we constructed a carbon budget model of A. aurita polyps as a function of temperature and mesozooplankton prey density. An application of this model to polyps in Fukuyama Harbor, the Inland Sea of Japan, suggested that they consistently attain a positive growth (somata and offspring) rate, ranging from 0.0039 to 0.34 μg C μg C−1 d−1. Our model allows estimation of the potential growth rates of polyps in temperate coastal waters where temperature and mesozooplankton biomass data are available, contributing to comprehensive understanding of polyp population dynamics in nature.