PHYTOPLANKTON PRIMARY PRODUCTION, CHLOROPHYLL AND COMPOSITION IN AN INLET OF THE WESTERN WADDEN SEA (MARSDIEP)

From February 1974 to April 1976, estimates for in situ phytoplankton primary production in the Marsdiep tidal inlet area of the western Dutch Wadden Sea were made from incubator primary production data using a constant light source. Low values were estimated in winter with a minimum in January (average 0.016 g C·m-2·d-1. Values increased rapidly from the middle of March during the spring phytoplankton bloom to a maximum in May (average 1.1 g C·m-2 ·d-1, maxima of 3 g C·m-2·d-1 or more). During summer these estimates showed large short-term variations in in situ primary production from incubator data as well as in in situ measurements during 1 to 3 days in June and August in the years 1971 to 1979. This variability forms a problem in estimating annual phytoplankton primary production in the area. It also prevents a reliable comparison of the present estimate with earlier estimates of annual primary production based on fewer data (one per month or less). It is likely that also in other areas, in particular in coastal regions, similar difficulties in estimating primary production will be encountered. © 1979.