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Asymmetry

Student: Ms AJ Holland
Supervisor: Dr WJ Muller
Degree: PhD (Water Resource Science)


DDT (Dichloro-Diphenyl-Trichloroethan) is an organic pesticide, which was banned for agricultural use internationally after toxic environmental effects to bird life were discovered in the 1970s and 1980s. In South Africa it is still used but restricted to malaria vector control. DDT can accumulate in body fat and increased in concentrations can be found in animals higher in the food chain, such as birds and humans. Its metabolic products (DDE and DDD) are highly persistent in soil and sediment and have similar chemical and physical properties as DDT. DDT is also an endocrine disrupting chemical (EDC), effecting the endocrine systems of exposed animals and is especially toxic to aquatic invertebrates.

The effects of DDT, and its breakdown products, on animals which are lower in the food chain could be monitored through measuring the stress response of these animals and thus provide an early-warning system of
consequences of increased DDT concentrations in the environment. One possible indicator of environmental stress through pollutants (bioindicator) is the measurement of fluctuating asymmetry (FA) - the measurement of random deviations from the near-perfect symmetry of naturally bilateral-symmetrical characteristics of an individual. The use of FA as a bioindicator for pollutants has not yet been established.

This project examines the relationship between fluctuating asymmetry and water quality stress caused by DDT in aquatic invertebrates such as mayflies, and its potential use as a bioindicator in aquatic biomonitoring.


Last Modified: Fri, 14 Aug 2015 11:42:44 SAST