CHANGES AND CAUSES OF VARIABILITY IN SALINITY AND DISSOLVED INORGANIC-PHOSPHATE IN THE IRISH SEA, ENGLISH-CHANNEL, AND DUTCH COASTAL ZONE

In an attempt to investigate the sources of variability in salinity an d dissolved inorganic phosphate (DIP) in the English Channel, Irish Se a, and southern North Sea, time series (20-40 yr) of observations at f our different stations were studied. Highest salinities and lowest DIP , both associated with the lowest residuals, were found at station El in the English Channel near Plymouth, which is assumed to be represent ative of the natural signal of Atlantic Water entering the shelf seas. The influence of freshwater run-off, reflected in lower salinities an d, more recently, in increased DIP concentration, is clearly shown at the station near the Isle of Man in the Irish Sea and at two stations in the Dutch coastal zone. However, comparison of the time series at t he four different stations revealed that, while the two stations in th e Dutch coastal zone were correlated to some extent, there was no sign ificant cross-correlation between the other stations. The conclusion i s that physical, chemical, and biological processes in the different a reas affect the natural variability of the Atlantic signal to such an extent that the different properties studied at the stations are not r elated. (C) 1996 International Council for the Exploration of the Sea