1.06.P–ThFr04 - The Utility of Freshwater Molluscs as Biomonitoring Organisms to Assess Pollution Pressure on Wetland Ecosystems

Abstract

Wetlands (Ramsar Convention definition, which includes lakes and rivers) are amongst the most highly threatened and biodiverse ecosystems globally, contributing to a huge range of ecosystem services. However, wetland biomonitoring techniques for the assessment of water quality are not well established. Gastropod and bivalve molluscs have high potential as useful bioindicators due to their sedentary nature, high bioconcentration capacity, wide distribution, and known sensitivity to contaminants. Here, we reviewed the available data for field-based studies that examined changes to biochemical biomarkers in wild freshwater molluscs. We found a total of ten studies, and across these, the most common pollutants reported were metals, organochlorines, untreated municipal wastewater, and other persistent chemicals (e.g., polycyclic aromatic hydrocarbons and polychlorinated biphenyls). Tissues assessed across these studies comprised the digestive gland, gills, and soft tissue (whole body excluding shell). Lipid peroxidation (LPO), antioxidant enzymes- catalase (CAT) and superoxide dismutase (SOD) were frequently elevated across multiple species in response to either measured or hypothesised (due to land use) pollutant profiles, compared to reference sites. This elevation suggests oxidative stress is occurring in these organisms in response to polluted environments. In contrast, glutathione (GSH) and the biotransformation enzyme Ethoxyresorufin-O-deethylase (EROD) levels were reduced, indicating depletion of these enzymes as a result of the associated detoxification. Regarding species sensitivity, the zebra mussel (Dreissena polymorpha) frequently showed significant changes in biomarkers in response to polluted sites, whereas the swollen river mussel (Unio tumidus) showed consistently low or non-significant responses, which may reflect pollutant tolerance or poor biomarker sensitivity in this species. In conclusion, despite significant data gaps – most notably, the relative lack of studies using gastropod molluscs - a review of the available literature suggests that freshwater molluscs have potential as useful bioindicators for wetland ecosystems. Further studies should seek to incorporate a wider range of species across the Mollusca, as well as investigations into the potential impacts of emerging contaminants; such as pharmaceuticals.

Keywords: ecotoxicology, biomarkers, invertebrates.
 

Author(s)

Presenter: Doyinsola, Mustapha

Authors: 

Frances Orton Institute of Life and Earth Sciences, School of Energy, Geoscience, Infrastructure and Society (EGIS), Heriot-Watt University United Kingdom      Doyinsola Mustapha Heriot Watt University United Kingdom