To find out how some of the more common Antarctic marine invertebrate and algal species react to different levels of contaminants, toxicological experiments are ongoing in our purpose-built aquarium systems at Casey and Davis stations, and in the marine research facilities at Kingston. Results from these experiments indicate the levels of specific contaminants likely cause an impact on the local Antarctic biota.
These common Antarctic invertebrate species have been used in toxicity assessments to determine how local species react to levels of contaminants found at impacted sites, such as adjacent to rubbish tips and sewage outfalls. From left to right are the amphipod Paramoera walkeri, the microgastropod Skenella paludinoides, and the ostracod Bradleya antarctica (Photos: Catherine King).
Standard toxicity tests have been developed with a number of common Antarctic invertebrates including the sea urchin Sterechinus neumayeri, the amphipod Paramoera walkeri, the microgastropod Skenella paludinoides, and the ostracod Bradleya Antarctica, at a range of sub-lethal and lethal endpoints. Tests investigating growth and photosynthetic capacity of common microalgae species including Phaeocystis sp. and Geminigera sp. are currently being developed.
In other parts of the world, programs such as Musselwatch monitor for exposure to specific contaminants by measuring the levels accumulating in the body tissues of filter-feeding invertebrates, such as common blue mussels (Mytilus edulis). Species such as these mussels are called ‘sentinel species’ because they are placed at specific locations in the marine environment and used as a ‘look out’ for excessive pollution, thereby providing an early warning that thresholds may be exceeded. Histological alterations in the major tissues (liver, gill, gonad, muscle) of invertebrates and fish collected from impacted sites are also used as an indicator of biological impact and a direct response to contaminant exposure.
Some of the more common and widespread Antarctic invertebrate species that are being used as biomarkers or sentinels of Antarctic pollution include two filter-feeding bivalves, the clam Laternula elliptica and the scallop Adamussium colbecki, and the fish Trematomus bernacchii. The rates of accumulation and depuration (cleansing) of contaminants, and physiological and histo-pathological changes in major tissues are being investigated as potential indicators of stress caused by exposure to contaminants.
Results of ecotoxicological tests and bioindicator assessments form part of a weight of evidence approach, alongside ecological monitoring, chemical analysis and dispersal modelling. Together these measures are currently being used to inform and direct clean-up and remediation activities at contaminated sites, and operational upgrades to existing infrastructure and practises dealing with waste discharge from stations.