The Distribution of Estuarine Macrophytes in Relation to Freshwater

Abstract

A continual flow of freshwater into estuaries was shown to create a salinity gradient along which different macrophyte communities were distributed. In systems with no freshwater inflow there was no spatial separation of macrophytes and salt marshes and the submerged macrophyte Zostera capensis, normally associated with the marine end of estuaries extended into the upper reaches. In small estuaries, salinities fluctuated because of the major influence of periodic small floods. During the study period the small estuaries studied were in a stable brackish condition (13-28 ppt.) and dominated by dense Ruppia cirrhosa communities which are normally associated with lower salinity regions (...)