SALINITY, FLOODS AND THE INFAUNAL MACROBENTHIC COMMUNITY OF THE ST LUCIA ESTUARY, KWAZULU-NATAL, SOUTH AFRICA

Abstract

Summary The St Lucia estuary and lake comprise some 80 % of the estuarine area of KwaZulu-Natal. The system is subject to floods and hypersaline conditions, the latter twice exceeding 100 since 1970. The lake is connected to the sea by a meandering tidal channel called the Narrows, which historically has been largely overlooked in terms of benthic research in favour of the lake. Changes in the macrobenthic infauna of the Narrows were investigated over an eleven year period during which the Narrows was exposed to unprecedented cyclonic flooding in February 1984, floods in October 1987, a net freshwater outflow following heavy seasonal rainfall in November 1989, and a period of hypersalinity following mouth closure between December 1992 and September 1993. Although the benthos was generally numerically and gravimetrically dominated by the crab Paratylodiplax blephariskios, significant changes in species composition and densities were recorded after the cyclonic flooding in 1984, during the net fresh water o...