On the biology ofAurelia aurita(L.) 1. Release and growth ofAurelia aurita(L.) ephyrae in the Gullmar Fjord, Western Sweden, 1982–83

Publisher Website
Google Scholar
Abstract
The occurrence and growth of Aurelia aurita were studied by means of field sampling with Bongonets from October 1982 until June 1983. By means of a rig with settling plates, placed at 10 m depth close to the sampling area, the settling of planulae, strobilation of scyphistomae and the release of ephyrae were followed. The abundance of ephyrae during late autumn was very high compared to previous reports from e.g. the Baltic Sea and it exceeded the winter-spring abundance by two orders of magnitude. The scyphistomae were highly polydisc (>5 segments) during the autumn, monodisc during the winter and moderately polydisc (2–4 segments) during the spring. Parts of the autumn generation of ephyrae survived the winter. The possibility that this overwintering period was spent in diapause on or close to the bottom is discussed, as are environmental parameters such as temperature, light and availability of food.