Helgoland Roads: 45 years of change in the North Sea
Friday seminar by Karen Wiltshire
The Helgoland Roads time series is one of the richest temporal marine data sets available. They include daily surface water sampling from 1962 until the present day, resulting in a pelagic data set comprising of phytoplankton, salinity, Secchi and nutrient analyses. Concurrently the time series are augmented by the biological parameters zooplankton, rocky shore macroalgae and macro-zoobenthos and bacteria data series which were sampled discontinuously until the 1990ties and which now have been restarted. Until recently it was relatively difficult to interpret the long term data acquired at Helgoland. This was mainly due to a lack of meta-information and quality control of the data which has now been rectified. We present these data sets and give examples of the major changes in evidence for phytoplankton, through to macro-benthos at Helgoland. We discuss the changes in currents, salinity, temperature and nutrients. The changes in the hydrography, temperature and salinity and relate this to changes in species are presented. The evidence we have for neobiota and their placement in the system as well as species shifts are evaluated and related to climatic and hydrographic shifts in the North Sea.
Karen H. Wiltshire, Biologische Anstalt Helgoland, Alfred Wegener Institute for Polar and Marine Research, Helgoland, Germany