Ecotoxicologists must facilitate the setting of standards for safeguarding aquatic life

Intensified agriculture and accelerated development have resulted in large amounts of toxic chemicals entering our natural water bodies, imposing health risks to aquatic fauna. Considering the toxin levels at which ill effects are induced, the existing national guidelines for the release of effluents are seen to be inadequate for ensuring the safety of biota inhabiting these aquatic systems. The volume of research work on various aspects of ecotoxicology in Sri Lanka has increased in the recent past. A large majority of studies have focused on assessing the toxic effects of heavy metals – from among the wide range of toxicants – on selected aquatic and soil biota. Locally, many of the studies have used fish and amphibians for bioassays, while a few have investigated toxicity to earthworms and freshwater prawns. The frequently used endpoints of toxicity are the Lethal Concentrations (LC50 values). Other studies have evaluated the Effective Concentration (EC 50), Low effect concentration (LOEC) and No effect concentration (NOEC) considering sub-lethal impacts such as retardation in growth and development, occurrence of physical abnormalities, and histological, haematological and genetic aberrations. While many of the investigations so far have focused on selected species, ramifications at the community and ecosystem levels have not been assessed and still remain mere predictions. This article presents an overview of recent ecotoxicological research carried out in Sri Lanka on the effects of aquatic and soil toxicants on fauna. The scope of the published work has been outlined and the gaps in research identified. The article also touches upon directions for future ecotoxicological research in Sri Lanka.