Abstract
M.Sc. (Zoology)
Viticulture is an important agricultural practice in many countries. The long term use
of pesticides in vineyards has resulted in increased concentrations of such pollutants
in sediments, water and other environmental compartments. Mitigation measures in
agriculture, especially vineyard agriculture, are a prerequisite to the sustained integrity of the natural environment, and specifically the aquatic environment. Mitigation presents itself in the form of water bodies, riparian buffer strips, ground vegetation cover, grassed field paths, natural or artificial wetlands and modification of pesticide application rate. However, to our knowledge no studies exist which highlight the state of dams related to viticulture or the use of mitigation measures, in South Africa. The study aimed to quantify the cumulative risk posed to dams on wine farms and the effect of pesticides (fungicides, herbicides and insecticides) on aquatic ecosystems while evaluating the use of mitigation measures in South African viticulture. Epilithic diatom community structure assessment and frustule abnormalities; zooplankton and macroinvertebrate community structure assessment, and characterization of mitigation measures were carried out at nine representative study sites on wine farms in the Western Cape, South Africa. Pesticide risk
assessment models PRIMET and PERPEST were employed to assess the risk that
pesticides pose at each site from available data. The Relative Risk Model was used
to assess the risk posed to identified Risk Regions. Different risk categories were
observed across the sites from PRIMET and PERPEST, ranging from no risk to high
risk for specific pesticides and relative risk among the risk regions was assessed.
Diatom community structure displayed spatial and temporal variability between sites
as well as observable diatom frustule abnormalities due to pesticide input. Zooplankton and macroinvertebrate communities displayed variability spatially as well as temporally and this was linked to the presence of pesticides confirming the predictions from PRIMET, PERPEST and the RRM.