Interactions between polyps of Aurelia aurita and planktonic larvae of scyphozoans: an experimental study

Abstract

Predation by polyps of the scyphozoan Aurelia aurita (L.) on planula larvae of their own species and on planulae of the scyphozoan Cjfanea capillata (L.) was studied in laboratory experiments. Transplant experiments in the field tested whether high densities of established A. aurita polyps could affect the recruitment of planktonic larvae and if Interactions between the polyps occur. More planula larvae of C. caplllata than of A. aurita were eaten by the polyps. The transplant experiments showed that dense covers of A. aurita polyps can affect recruitment of planulae and other planktonic larvae to hard-bottom communities. The most likely explanation is predation on the larvae. Interactions indicat- ing competition for space or food between already established polyps and settling planulae were observed. Mortality among established polyps was greater at high than at low densities. Planula larvae of both A. aurita and C. capillata showed an increased rate of metamorphosis in the presence of A. aurita polyps in the laboratory experiments.