Toxicity assessment of pollutants in the marine environment of Kuwait using Microbial bioassay

Abstract

The Arabian Gulf offers a suitable location for investigating the potential impact of toxic chemicals on marine life, because it is a semienclosed, relatively shallow, small body of water. This study was carried out to evaluate the relative sensitivity, precision, and accuracy of three published microbial bioassay procedures to ascertain their ability to detect toxicity in the marine environment of Kuwait. The bioassay procedures used were dissolved oxygen depletion (DOD), viable plate count (VPC), and optical density (OD). Mixed marine bacteria isolated from the local seawater of Kuwait was used, and test samples (pollutants) investigated include mercuric chloride (HgCl2), lindane, and a wastewater samples. The DOD technique was evaluated as best for sensitivity of testing toxicity. In both brief and extended exposures, activity quotient values given by this technique were much lower than the LC50 and IC50 values given by the VPC and OD techniques. However, both VPC and OD techniques showed better reproducibility than the DOD technique, as indicated by lower coefficient of variation (CV) values. When evaluating complexity, the OD assay would be considered the least complex, then the DOD, and last would be the VPC. Although both VPC and OD assays showed better reproducibility than the DOD technique, as indicated by lower CV values, the DOD demonstrated a higher sensitivity in detecting toxicity, and showed several other advantages such as rapidity and lower expenditure of routine assay requirements. However, the initiation of short-term bioassay in Kuwait for predicting effect of pollutants in the marine environment is of necessity and importance.