Variability in the population structure of Calanus finmarchicus in Icelandic waters in spring

Abstract

Since 1961, long-term monitoring of zooplankton has been carried out during spring (May-June) on standard sections around Iceland. An analysis of the onshore-offshore variability in the population structure of Calanus finmarchicus during this time of the year indicates that off the east, south, and west coasts of Iceland reproduction is highest over the banks, while off the Vestfirdir Peninsula breeding activities appear to be largely confined to the frontal area between the Atlantic Water close to the land and the cold Polar Water farther out. In the deep waters north-east of Iceland, where the Arctic influence is generally greatest, the percentage of juvenile stages is very low, suggesting little reproduction in these cold water masses.