Interplay between biology and sedimentology in a mudflat (Biezelingse Ham, Westerschelde, The Netherlands)

The aim of this research was to investigate the importance of biological processes on the sediment characteristics and the morphology of a mudflat in the Westerschelde (The Netherlands). For this purpose, a transect in the Biezelingse Ham mudflat was sampled on a monthly basis. In spring, the muddy part of the mudflat was dominated by a biofilm of microphytobenthos that altered the morphology of the mudflat and resulted in a two-fold increase in sediment stability. The biofilm also bound fine-grained sediment that was deposited. From June onwards, wind generated waves dominated the conditions at the mudflat which resulted in the disappearance of diatom biofilms, and caused a gradual erosion of the mudflat. During this period, meio- and macrofauna densities increased from which it was concluded that the hydrodynamic forces did not have a big impact on these communities. Spatial variations in sediment characteristics, morphology and biology were observed between stations 1 and 2 on the one hand and station 3 on the other. This resulted in different responses to the changing conditions on the mudflat. In general, the results from this field study indicate that sedimentology and biology, interact in a complex manner with the hydrodynamic regime both on a temporal as well as on a spatial scale. (C) 2000 Elsevier Science Ltd. All rights reserved.