Studies on bottom deposits of the Vaal River system

Lenhard, G.; Plooy, A. du

doi:10.1007/bf00142271

Cited by 9 publications

(3 citation statements)

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“…15,28 The Vaal River is known to be affected by a range of water quantity, quality and habitat altering impacts. [53][54][55][56][57] If these impacts persist, changes in the biology and ecology of the yellowfishes may result and ultimately affect the survivability of these species. The habitat requirements and the behavioural response information of the yellowfishes to changes in flows and weather events can be used to manage yellowfish and the Vaal River in which they occur.…”

Section: Discussionmentioning

confidence: 99%

Habitat preferences and movement of adult yellowfishes in the Vaal River, South Africa

et al. 2013

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The yellowfishes of the Vaal River (Labeobarbus kimberleyensis and L. aeneus) are charismatic, socially and economically important fishes, but very little is known about their interspecies habitat preferences and movement. This study is the first behavioural study of yellowfish in the Vaal River using radio transmitters to characterise habitat preferences and movement patterns. A total of 22 adult L. kimberleyensis and 13 adult L. aeneus individuals were tracked for between 1 month and 1 year from 23 September 2006 to 16 May 2010. Radio telemetry revealed that yellowfish established routine daily behavioural patterns through which the habitat preferences and movement of the species could be established. Home ranges of the yellowfish ranged from 1 km to more than 12 km in the Vaal River depending on the species and habitat availability. Habitat preferences varied between species and included deep slow-flowing habitats with associated cover features particularly in winter for L. kimberleyensis and shallow fast-flowing habitats particularly for L. aeneus in spring, summer and autumn. Changes in flows, habitat availability and atmospheric pressure affected the movement of yellowfish. The biology and ecology of the yellowfish in the Vaal River is noticeably more complicated and dynamic than previously documented. We recommend that the behavioural ecology of these and other yellowfish populations in the Vaal River should continue to be characterised, and the use of the movement of yellowfish be developed as an indicator of ecosystem change. Study areaThe study was carried out in a reach of the middle Vaal River, southwest of Johannesburg (Figure 1). The study area is located within the Orange-Vaal River Yellowfish Conservation and Management Association (OVRYCMA) area. Site selection was based on local OVRYCMA member information, historical catch records for yellowfish, historical data 5 and initial field surveys to ascertain the presence of sufficient adult yellowfish individuals for the study. The approximately 190-km reach of the Vaal River selected for the study extends from Parys to an area upstream of Bothaville (Figure 1). Within this reach, both L. kimberleyensis and L. aeneus are abundant, 4 despite disturbances such as water abstraction for agriculture, industry and mine use, wastewater releases and the use of natural products. Habitat diversity was considered to be representative of the middle reach of the Vaal River and included a high diversity of both deep (>3 m) and shallow areas (<1 m) with slow-(0 m/s) and fast-flowing (1 m/s) biotope types. Although some gauging weirs and other barriers that may affect the movement of yellowfish exist in the study area, all of the yellowfish monitored in the study had access to relatively large reaches of the Vaal River (>35 km).

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Section: Discussionmentioning

confidence: 99%

Habitat preferences and movement of adult yellowfishes in the Vaal River, South Africa

et al. 2013

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“…Compared to some lower catchment areas (e.g. Vaal River Barrage), water quality (in terms of pollution levels) in the Vaal Dam is considered to be good (Lenhard & du Plooy 1965;Braune & Rogers 1987;Crafford & Avenant-Oldewage 2009). The current paper reports on a winter survey of monogenean parasites conducted during June/July 2009.…”

Section: Study Sitementioning

confidence: 95%

“…This reservoir, with a surface area of 32 107 hectares (Braune & Rogers 1987), has a long history as the main source of water supply for municipalities and industries in Gauteng Province (Lenhard & du Plooy 1965) and is of great importance for the water supply of South Africa. Compared to some lower catchment areas (e.g.…”

Section: Study Sitementioning

confidence: 99%