Abstract
The study aimed to determine the distribution and relative abundance of freshwater fishes in and adjacent to Agulhas National Park. Fourteen fish species were collected during surveys carried out in the Heuningnes and Ratel river systems and a variety of endorheic pans from 2003 to 2005. Seven of the species are marine fishes tolerant of low salinity (Mugil cephalus, Liza richardsonii, Monodactylus falciformis, Caffrogobius gilchristi, Rhabdosargus holubi, Solea bleekeri, Gilchristella aestuaria) with the remaining seven species being primary freshwater fishes. Three are indigenous, including Pseudobarbus burchelli, Sandelia capensis, and Galaxias zebratus of which two morphological forms were recorded within Agulhas National Park. The remaining four species are invasive aliens (Cyprinus carpio, Lepomis macrochirus, Micropterus salmoides, Micropterus punctulatus). Classification using physico-chemical variables indicated four major wetland groups, with fishes occurring predominantly in the group comprising palustrine, lacustrine and riverine wetlands, and in one instance in a brackish endorheic pan. Management actions which should facilitate conservation of indigenous fishes in the Agulhas region are suggested.
Highlights
The Agulhas plain at the southern tip of Africa has been recognised as an area of high conservation importance for both terrestrial plants (Rebello & Siegfried 1992; Cowling & Mustart 1994; Cowling et al 1999) and wetland biota (De Villiers 1988; Ryan et al 1988; Rebelo 1992)
The Heuningnes River system is recognised as a priority system for freshwater fish conservation in the Cape Floristic Region (Impson et al 1999)
Formal conservation of the area commenced in September 1999 with the proclamation of the Agulhas National Park (ANP)
Summary
The Agulhas plain at the southern tip of Africa has been recognised as an area of high conservation importance for both terrestrial plants (Rebello & Siegfried 1992; Cowling & Mustart 1994; Cowling et al 1999) and wetland biota (De Villiers 1988; Ryan et al 1988; Rebelo 1992). Where the terrestrial vegetation of the region has been the subject of intensive research (e.g., Cowling et al 1988; Cowling & Holmes 1992a; Willis et al 1996; Cole et al 2000), studies of aquatic systems have mostly been once-off assessments (Silberhauer & King 1991; Jones et al 2000) and concentrated predominantly on water chemistry. The objective of this study was to improve understanding of the aquatic biota of the region, by describing the diversity and distribution of fishes in and adjacent to the park.
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