Helgoland Roads meso- and macrozooplankton time-series 1974 to 2004: lessons from 30 years of single spot, high frequency sampling at the only off-shore island of the North Sea

The Helgoland Roads meso- and macrozooplankton time-series 1974 to 2004 is a high frequency ( every Monday, Wednesday and Friday), fixed position monitoring and research programme. The distance to the coastline reduces terrestrial and anthropological disturbances and permits the use of Helgoland Roads data as indicators of the surrounding German Bight plankton populations. The sampling, determination and IT methodologies are given, as well as examples of annual succession, and inter-annual population dynamics of resident and immigrant populations. Special attention is given to the phenology and seasonality of zooplankton populations. The influence of winter sea surface temperature on the seasonality of spawning of the common sole Solea solea is given as an example for merozooplankton populations.