Continuous plankton records: relationships between species of phytoplankton and zooplankton in the seasonal cycle

Seasonal fluctuations in abundance and their geographical variations in the north-east Atlantic Ocean and the North Sea for 49 taxa of both phytoplankton and zooplankton have been studied by multivariate techniques. Most of the observed variability in both seasonal and geographical fluctuations in abundance can be attributed to differences between the taxa with respect to population growth rates modulated by temperature coupled with the distribution of overwintering stocks, with the overall pattern also influenced by the timing of the establishment and breakdown of vertical stability in the water column. The observations indicate that for any species, the similarity between its seasonal cycles in the various areas, which represent a wide range of hydrographic regimes, is appreciably greater than any differences induced by interaction between the species in any particular area.