SEASONAL SHIFTS OF SEDIMENT WITHIN AN ESTUARY MEDIATED BY ALGAL GROWTH

Measurements of the level of mud flats in the Deben estuary (Suffolk, England) show seasonal change with accretion of ~ 5 cm between April and September during algal growth, and erosion of that amount during autumn and winter when algae are dead or absent. Although some seasonal change might occur in the absence of algae, the rates of deposition involved require that erosion be inhibited and sedimentation be maximised from the available suspensions. In this the binding and baffling activity of algae is apparent. The total amount of deposition on the flats (105 tonnes) is far more than can be supplied from the river or the sea, and transfer between the channel banks and the tidal flats on a seasonal basis is postulated. © 1979.