Water quality in South African temporarily open/closed estuaries: a conceptual model

Abstract

Of the five types of estuaries found in South Africa, temporarily open/closed estuaries comprise approximately 70% of the total. This paper provides an overview and a simple conceptual model of the water quality features and characteristics of temporarily open/closed estuaries in South Africa. Available literature on estuaries in the warm- and cool-temperate biogeographic regions of South Africa was reviewed and assessed against this model. The structure and water quality characteristics of the estuaries considered supported the conceptual model under the three dominant mouth states: open, semi-open and closed. However, the scale and extent to which biogeochemical processes within estuaries influence water quality is still poorly understood and further research is required to improve understanding of these processes in temporarily open/closed estuaries.