Reproduction and longevity of Aurelia labiata in Roscoe Bay, a small bay on the Pacific coast of Canada

Abstract

Reproduction by the moon jelly, Aurelia labiata, was observed in a small bay on the west coast of Canada. The bay is located in an area isolated from human contact except in the summer, is sheltered from wind and wave action by mountain ridges, and has limited tidal flushing due to a gravel bar at the entrance that dries at lower low water. Planulae appeared in brood sacs beginning in October and November. The planulae were shed by the end of March and ephyrae emerged in June. Juvenile medusae were estimated to constitute about 30—40% of medusae in the bay in each of the two years of this study. Medusae remained in the bay throughout the year. There was no major visible mortality in the adult population during the two year observation period. Medusae appear to be lost from the bay as a result of tidal flushing. It is argued that in Roscoe Bay Aurelia labiata medusae live for more than one year and that up to 40% of the adult medusae may be two years of age or older.