Seasonality of echinoderm plankton in Lough Hyne Marine Nature Reserve

Zooplankton was sampled almost monthly over a two-year period in and immediately outside Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. In the laboratory, echinoderm larvae were isolated and counted at class level. Mean numbers of all echinoderm larvae and of the separate classes thereof were calculated for the three sites sampled. Echinoderm larvae showed peaks of abundance in spring and summer and were virtually absent in winter. Peaks of abundance at sites in Lough Hyne occurred in July and consisted mainly of asteroid larvae. Peaks of abundance in a coastal site immediately outside Lough Hyne consisted mainly of ophiuroid larvae. Holothuroid larvae were rare, and crinoid larvae were not found. The results of three-factor ANOVA with date, class and site as fixed factors revealed differences between the separate classes and between sites. The environmental parameters of each site - substrata, water exchange, current - and associated echinoderm benthos appeared to influence the echinoderm plankton.