River flow, zooplankton and dominant zooplanktivorous fish dynamics in a warm‐temperate South African estuary

• DOI: 10.1111/jfb.13617
• Publication Date: 2018-04-26T08:37:13Z
• Authors: N. Mbandzi; R. J. Wasserman; S. H. P. Deyzel; N. G. Vine; A. K. Whitfield
• Keywords: 0106 biological sciences; Salinity; Fishes; 01 natural sciences; Gastrointestinal Contents; Zooplankton; Diet; Copepoda; South Africa; Rivers; Water Movements; Animals; 14. Life underwater; Seasons; Estuaries; Animal Distribution; Ecosystem

The possible links between river flow, zooplankton abundance and the responses of zooplanktivorous fishes to physico‐chemical food resource changes are assessed. To this end, seasonal abundance, distribution diet estuarine round‐herring Gilchristella aestuaria Cape silverside Atherina breviceps were studied in Kariega Estuary. Spatio‐temporal differences determined for selected variables, fish distribution. Results indicated that, following a flood event winter (>30 m 3 s −1 ), altered conditions occurred throughout estuary depressed stocks. Abundance G. was highest spring, with species dominant upper middle zones estuary, while A. summer preferred lower zones. catch per unit effort both zooplanktivores also declined significantly flooding, thus suggesting that these reliant on as primary source healthy populations. Copepods dominated stomach contents species, indicating potential strong interspecific competition food, particularly reaches. Temporal evident dietary overlap two correlated availability findings study emphasize close trophic linkages under changing environmental conditions, flow provide important baseline information similar studies elsewhere South Africa rest world.