DYNAMICS AND DISTRIBUTION OF MICROPHYTOBENTHIC CHLOROPHYLL-A IN THE WESTERN SCHELDT ESTUARY (SW NETHERLANDS)

The temporal dynamics and spatial distribution of microphytobenthic ch lorophyll-a in the layer 0-1 cm were determined in the Western Scheldt estuary over the period 1991-1992. Connections between the annually a veraged benthic chlorophyll-a and station elevation and sediment compo sition (as a measure of the hydrodynamic energy caused by currents and waves) were also examined. Microphytobenthic chlorophyll-a showed one main peak in early summer and a smaller peak in autumn. The mean chlo rophyll-a concentration of 113 mg Chi-a m(-2) in the upper centimeter is of the same order of magnitude as in other estuarine areas. The ave rage annual primary production of the microphytobenthos has been estim ated at 136 g C m(-2) y(-1). The primary production of sediment inhabi ting microalgae is at least 17% of the total primary production in the estuary. Considerable differences in annually averaged chlorophyll-a emerges between the stations. These differences are related mainly to the interaction between station elevation and clay content of the sedi ment.