National 11.8.2016 03:59 pm

Richards Bay mass fish deaths linked to algae

Excessive algae in KZN's Lake Mzingazi have been detrimental to many fish. Photo: Zululand Observer

Excessive algae in KZN's Lake Mzingazi have been detrimental to many fish. Photo: Zululand Observer

The fish deaths were almost certainly the result of excessive nutrients in the water which causes algae to bloom, which depletes oxygen.

Following a report in which the death of masses of fish in Lake Mzingazi in Richards Bay was attributed to a rapid rise in water levels during July’s heavy rainfall, a marine ecologist has now found that excessive nutrients in the water are to blame.

The Zululand Observer reports that the fish deaths were almost certainly the result of eutrophication – excessive nutrients in the water.

That’s the viewpoint of Ezemvelo senior marine ecologist Santosh Bachoo, after samples of water and dead fish were sent for toxicity testing.

The extra nutrients cause increased algae bloom, which in turn deplete oxygen. Although a natural occurrence, high nutrient concentrations have also been linked to spiralling population growth and human settlement patterns, as well as to an influx of fertilizers and detergents.

Stagnation and raised temperatures are also determining factors. Taste and odour problems are also associated with algae blooms.

Caxton News Service

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