Large scale spatial variations in the seasonal abundance of Calanus finmarchicus

Data collected by the Continuous Plankton Recorder (CPR) survey between 1962 and 1974 in the North Atlantic and adjacent seas were used to examine large scale spatial variations in the seasonal cycle of near-surface abundance of the copepod Calanus finmarchicus. Through most of this region, the dominant seasonal pattern was minimum abundance between November and February followed by an increase to maximum abundance in May. Two large ( > 600 000 km2) areas had seasonal cycles that differed markedly from this dominant pattern. South of Newfoundland, maximum abundance occurred between February and May, while south of Greenland, maximum abundance occurred between April and October. This delayed seasonal cycle south of Greenland has not been identified previously, and it is speculated that regional changes in seasonal patterns may result from regional temperature and/or timing of food availability differences.