Abstract
M.Sc.
The general conservation status of freshwater ecosystems worldwide is poor and
continues to decline at a rapid rate. This decline is a result of severe alteration of
freshwater ecosystems caused by human activities. With an ever increasing human
population as well as economic development, an increase in the demand for water is
inevitable, as well as an increase in pollution to freshwater ecosystems. The sectors
which are responsible for this are the domestic, agricultural, recreational and
industrial sectors as they all depend on fresh flowing water. Aquatic ecosystems are
heavily degraded on a global level by these human activities and impacts. South
Africa is no different to the rest of the world. The quality of water in South African
river systems has deteriorated due to increasing industrial, mining and agricultural
activities in the catchments. Fish are often used as an indicator for ecological
integrity as they are long-lived and therefore a good indicator of long-term exposure.
Relatively little is known about Labeobarbus polylepis (Small-scale yellowfish) with
reference as an indicator species as well as its feeding habits. This study consists of
two components, namely the bioaccumulation of heavy metals by L. polylepis and the
feeding biology of L. polylepis. Each of these components will be completed separate
from one another.
The first component of this study was the assessment of the water quality from five
river systems in South Africa, namely the Phongola, Assegaai, Elands and Komati
rivers, as well as the Ngodwana Dam. The aims for this component of the study were
to evaluate the overall health of the five different populations of L. polylepis and to
obtain site specific metal bioaccumulation data for each locality. Suggestions and
proposals for future monitoring and management of these waterbodies were also
made.