Identifying the sources and bioaccumulation mechanisms of mercury in aquatic coastal food webs of Australia

mercury in aquatic coastal food webs of Australia ©MMF

Identifying the sources and bioaccumulation mechanisms of mercury in aquatic coastal food webs of Australia

This collaborative research project, led by the Institute of Applied Ecology (University of Canberra), will assess the pathways for mercury (Hg) that enter and can be transmitted through food chains in coastal marine settings in south-eastern Australia. Mercury is one of the greatest threats to coastal and marine populations in Australia and worldwide as it has potential to both bioaccumulate and biomagnify at the top of food chains. Iconic marine mammals, Burrunan dolphin (Tursiops australis), endemic to Port Phillip Bay (PPB), Victoria, are especially at high risk of mercury (Hg) poisoning due to their longevity and high trophic position (Monk et al. 2013).

Coastal zones are usually characterized by catchments that are heavily industrialized, have high population density and receive high inputs of toxins such as Hg through agricultural and urban drainages in addition to atmospheric deposition. In addition, highly productive coastal zones create favourable conditions for Hg methylation by anaerobic bacteria and bioaccumulation in food webs. Therefore, there is a strong need to determine Hg bioaccumulation and biomagnification rates in coastal food webs in order to minimize risks to iconic marine mammals and human-health from Hg contamination of coastal ecosystems.

The project will involve the collection sediment and biota samples (seagrass, benthic algae, phytoplankton, zooplankton, zoobenthos, and fish) from vegetated and unvegetated habitats in shallow waters of Port Phillip Bay that overlap with dolphins feeding habitats and historical hot spots of elevated Hg concentrations. Both sediment and biota samples will be analysed for total Hg and selenium, methyl Hg, carbon and nitrogen isotopes and other trace elements by cutting-edge spectroscopy-based techniques (Perkin Elmer SCIEX Elan DRC-e ICP-MS, High Pressure Liquid Chromatography coupled to ICP-MS and isotope ratio mass spectrometer).

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