Caridina nilotica Biomarker Sensitivity Distribution for Roundup ® : Towards Derivation of Water Quality Guideline Values

Abstract

Currently, the species sensitivity distribution (SSD) approach is considered a useful tool in aquatic ecotoxicology for predictive effect assessments of toxicants. This approach is based on the variation in species sensitivities expressed by a statistical distribution, and the data comes from many ecotoxicological studies. In recent times, biomarkers have been suggested to be included in ecotoxicological risk assessment. This study, therefore, sought to answer the question: Could biomarker sensitivity distribution (BSD) of a single species be used to derive water quality guideline values? To answer this question, different biological system scales of Caridina nilotica were exposed to environmentally relevant concentrations of Roundup® herbicide in a series of short-term (< 4 d) and long-term (> 4 d) experiments. Short-term biomarkers assessment included different life stages, lipid peroxidation (LPx) and acetylcholinesterase (AChE), while adult life stage, AChE, LPx, growth and reproductive measures were assessed for long-term biomarkers. Biomarker sensitivity distributions (BSDs) were constructed and used short-term and long-term water quality guideline (WQG) values were estimated. These were compared to SSD-derived water quality guideline values for Roundup®. Observations from the comparison suggested that the different biological system scales of C. nilotica are more sensitive to long-term Roundup® exposure than SSD results. This study has shown that an in-depth study with one species using the BSD approach can provide reasonable ecotoxicological data that can be used to derive site-specific guidelines to protect sensitive species or taxonomic groups. As a novelty, this study has demonstrated the possibility of using the BSD approach in deriving WQG values.