Common starfish can act as a bioindicator for heavy metal pollution

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Context of the study

Sørford, in the Southwest of Norway, is an extremely polluted area, cadmium, mercury, and lead in fish and mussels reach dangerously high levels. This was caused by a zinc plant and other smelters which discharged large quantities of cadmium, zinc, mercury and lead into the fjord for more than 65 years. Discharges were drastically reduced since 1986. Due to these and other measures, a gradient was established with high concentrations of heavy metals at the inner part of the fjord and low concentrations close to opening into the sea. However, non of the organisms in which the concentrations of heavy metals were measured (cod and mussels) displayed this gradient, and therefore can't serve as bioindicators. It's important to have an organism that can serve as a bioindicator to monitor the efficiency of the taken measures.

Content of the study

This study investigates whether the common starfish can serve as a bioindicator for the heavy metal contamination. It is assesed whether the body concentrations in the starfish follow changes in the environmental concentrations (in the sediment and or water).

Main results of the study

However, conditions are not (or only slowly) improving. The heavy metal contaminants are trapped in the sediments, this limits the efflux to the open sea, but also promotes internal cycling, which keeps them available for uptake by biota.