Bioassays on Sediment Toxicity

Abstract

In order to evaluate the impacts of environmental pollutants on biota, it is essential to consider assessment strategies which include bioassay sensors for both sediments and water ecosystems. The different approaches currently applied in such environmental impact assessment programs appear to vary. The presently practised approaches to conserve aquatic sediment quality need to be re-evaluated in order to establish a uniform and meaningful criteria applicable to sediments/water which fulfil the requirements for the setting of uniform standards. We need at present more information to improve our knowledge in this direction. Even the small physico-chemical ecosystem alteration could effect the next level of ecosystem compartment (biota) through adsorption, desorption and eventual diffusion of many metabolic by-products. These effects are normally monitored via the responses in the organisms such as MFO (MFO = mixed function oxygenases activity — detoxification), genotoxicity and immunosuppression responses. Such bioassay approaches provide us with information in the area of toxicity and sublethal toxicity. Sublethal toxicity assessment includes such bioassays as DNA unwinding, umu-assay and phagocytosis which improves information on the genotoxic potential. These measurements, when applied to sediment/water components of an ecosystem, could provide information on the potential adverse effects in sediments to biota.