The influence of selected environmental parameters on the distribution of the dominant demersal fishes in the Kariega Estuary channel, South Africa

Richardson, Naomi; Whitfield, Alan K.; Paterson, Angus W.

doi:10.3377/1562-7020(2006)41[89:tiosep]2.0.co;2

Cited by 8 publications

(1 citation statement)

References 26 publications

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“…The width of the Kariega Estuary ranges from 40 to 90 m, with a water depth of 1–4 m (Whitfield, 1994). Sediment types differ, with the upper reaches comprising mainly coarse material deposited by the river, the middle reaches containing a high proportion of finer sediment particles and the lower reaches closer to the mouth containing large quantities of sand imported from the marine environment (Richardson et al, ).…”

Section: Methodsmentioning

confidence: 99%

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

Mbandzi

Wasserman

Deyzel

et al. 2018

Journal of Fish Biology

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

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Section: Methodsmentioning

confidence: 99%