oa African Zoology - Recruitment, diversity and the influence of constrictions on the distribution of fishes in the Wilderness lakes system, South Africa

Volume 22, Issue 2
  • ISSN : 1562-7020
  • E-ISSN: 2224-073X



The Wilderness lakes system comprises three interconnected lakes; Rondevlei, Langvlei and Eilandvlei. The latter is further connected by the Serpentine channel to a lagoon at Wilderness. The fish fauna is dominated by euryhaline marine species which migrate into the system as 0 + juveniles. During February 1984 it was calculated that 52,000 juvenile marine fishes migrated up the Serpentine towards Eilandvlei which serves as the system's major nursery area. Migration occurred mainly during the day and mostly towards high water. Fish communities throughout the system were sampled using seine and gill nets, and the Shannon-Weaver function used to descriptionbe them in terms of diversity. The system can be divided into three areas on the basis of this function. The lowest diversity in numbers and biomass occurs in Rondevlei and Langvlei which are furthest from the estuary mouth. Eilandvlei has an intermediate diversity with the Wilderness lagoon supporting the most diverse community. Although Eilandvlei and Langvlei have similar environments, there is a lower diversity in Langvlei. This is attributed to macrophyte encroachment and the shallow depth of the channel connecting these two lakes. In comparison with other South African coastal lake systems the fish fauna of the Wilderness lakes system is species poor. This is partly a result of the shallowness of interconnecting channels, intermittent open mouth phase and low diversity of marine/estuarine fishes in adjacent coastal waters.

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