Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

Just Accepted

This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.

The response of demersal fish assemblages to an extreme flood event in a freshwater-deprived estuary, South Africa.

Phakama Nodo , Nicola James , Amber Childs , Motebang Nakin

Abstract

The Kariega Estuary, in South Africa, is an example of a freshwater-deprived estuary. Large scale water abstraction and droughts have resulted in this estuary either being uniformly marine, or hypersaline. A major episodic flood event, the largest ever recorded in this system, in October 2012, provided us with an opportunity to investigate the prolonged effect of an episodic flood on the demersal fish assemblage of a freshwater-deprived estuary. A beam trawl net was used for sampling the fish assemblages from December 2013 to November 2014. The flood event prior to the sampling period ‘reset’ the system, such that there was a longitudinal salinity gradient from the head to the mouth, which resulted in ‘normal’ estuarine conditions, typical of most estuaries. There was an increase in the abundance of bentho-pelagic marine migrant species, particularly early juveniles of important fishery species, in the middle and upper reaches during this study relative to previous studies conducted on this freshwater-deprived system. This suggests increased recruitment of these species into their estuarine nursery habitat. This study highlights the importance of understanding the effect of freshwater inflow on the demersal estuarine fish assemblage and the nursery role of this and other estuarine systems and their management.

MF17096  Accepted 23 August 2017

© CSIRO 2017