Effect of water temperature on the biogeography of South African estuarine fishes associated with the subtropical/warm temperate subtraction zone.

Maree, R.C. and Booth, A and Whitfield, A.K. (2000) Effect of water temperature on the biogeography of South African estuarine fishes associated with the subtropical/warm temperate subtraction zone. South African Journal of Science, 96 (4). pp. 184-188. ISSN 0038-2353

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Abstract

Estuarine biogeographical regions along the southeastern coast of South Africa were investigated in terms of fish distribution and abundance patterns, with particular emphasis on the role of water temperature in influencing these patterns. Qualitative and quantitative analyses were conducted upon the ichthyofaunal assemblages to determine whether the location of the subtropical/warm temperate boundary corresponds to that proposed by Whitfield.(n1) Analyses included the distribution ranges of species associated with estuaries according to presence/absence data, cluster analysis of gill net catches in eight estuaries along the southeastern coast and the relative proportion of tropical to temperate marine species within these eight systems. Quantitative analysis indicated that the ichthyofaunal biogeographical regions are indeed a reflection of water temperature regimes and that the subtropical/warm temperate boundary is located between the Great Kei and Mbashe estuaries. A strong negative correlation was found between the number of temperate fish species and the mean of the minimum monthly temperatures recorded in the systems studied. Qualitative analysis revealed that a barrier appears to exist in the vicinity of the Swartkops estuary, which prevents the westward migration of tropical 'vagrants'. The influence of the Agulhas Current along the east coast and its divergence from the coastline in the Algoa Bay region, as well as upwelling phenomena on the southeast and south coasts are identified as major factors that influence marine and estuarine temperature regimes and therefore the ichythyofauna of this region.

Item Type:Article
Uncontrolled Keywords:estuaries, South Africa, estuarine fishes, water temperature, fish distribution
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Ichthyology & Fisheries Science
Research Institutes and Units > South African Institute for Aquatic Biodiversity (SAIAB)
ID Code:565
Deposited By: Ms Vivien Botha
Deposited On:12 Mar 2007
Last Modified:01 Aug 2012 07:31
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