Cellular responses of the starfish Parvalustra exigua to metal pollution in False Bay, South Africa

Abstract

The cushion sea star Parvalustra exigua from five sites along the shore of False Bay on the
southern coast of South Africa was studied using two cellular biomarkers, the neutral red
retention assay (NRR) and the lysosomal destabilization assay (DI) to assess damage in the
coelomocytes in response to metals. This was compared to pollution levels using a pollution
load index (PLI) calculated for metals present. Laboratory exposures to cadmium were done to
verify biomarker responses. The PLIs for the sites correlated with the levels of anthropogenic
activities and effluent inflow. The highest pollution was at Muizenberg, with human habitation
on the shore level, a fishing harbour and informal settlements. These specimens had shorter
NRR times, indicating more damage than those from sites with lower pollution. The DI results
also correlated with pollution levels. This study provided evidence that P. exigua has potential
for monitoring environmental pollution, using biomarkers, especially in southern coastal
areas due to its distribution.

Key words: Parvalustra exigua, heavy metals, pollution load index, neutral red retention
assay, lysosomal destabilization assay, biomarkers.