The warming trend at Helgoland Roads, North Sea: Phytoplankton response

We combine the temperature and phytoplankton data from one of the longest aquatic data sets in history, the Helgoland Roads (North Sea, 54degrees11.3'N, 7degrees54.0'E) timeseries to evaluate the effects of climate change on the base of marine food webs. The data shows that, despite an obvious warming of 1.1degreesC since 1962, the mean diatom day of the algal spring bloom is delayed and shifted to the end of the first quarter of the year. This is apparently related to a warming of the autumn (October-December) temperatures. It is the first indication of a warming related shift in phytoplankton succession, the consequences of which would range from lifecycle/food resource mismatches to regime shifts in the North Sea system.