No abstract

Coastal wetlands are important ecosystems that support biological communities and human populations. Anthropogenic activities have over the years affected these coastal wetlands globally leading to a loss of about 50% of these areas. There have therefore been calls to conserve these wetlands in order to sustain future generations. However, data to support conservation efforts on most of these ecosystems is lacking. The ecological health status of an aquatic system is one indicator that can form the basis of conservation or restoration actions. In Ghana, the Brenu Lagoon in the Central Region has been neglected in terms of ecological health research over the years. This study therefore aimed at assessing the ecological health of the Brenu lagoon using benthic macroinvertebrates. The study showed that the lagoon is hypersaline and moderately polluted with a dominance of two stress-tolerant species – Capitella Capitata and Ampithoe sp. The current state of pollution of the lagoon may be associated with waste disposal and agricultural activities within the catchment of the lagoon. Further studies are required to establish the linkage between these activities and the state of the lagoon on the basis of which remedial actions can be taken.

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.