Relationship between sediment structure and infaunal amphipod communities along the Durban outfalls region on the east coast of South Africa.

Abstract

Increased human habitation brings associated pressures with it, such as the introduction of contaminants to coastal waters. The major sources of these occur along the KwaZulu-Natal coast via Sappi Saiccor discharge points, Tioxide, AECI, the Mlaas canal, Central Works Outfall and Southern Works Outfall. This study investigated the effects of sediment structure on benthic amphipod communities exposed to sewage and industrial waste from the Central Works and Southern Works Outfalls along the Durban coastline, and used a 4-year dataset of sediment grain size analysis, metal concentrations, Total Kjeldahl Nitrogen (TKN) and Chemical Oxygen Demand (COD) at impacted and reference sites. Results exhibited that the levels of effluent being discharged onto the Durban coast from the Southern Works and Central Works Outfalls do not accumulate in the fine grained sediments in sites where it would be expected. The Mdloti reference site which was dominated by coarse sediment showed the highest concentrations of metals. In addition, the outfalls do not have significant effects on the amphipod communities in the vicinity. Community structure between sites with similar grain sizes tends to be very similar thereby highlighting the possible influence of grain sizes on determining community patterns. Overall, there seemed to be no effect of pollutants on the biology or accumulation in the receiving environment.