The University of Newcastle, Australia

Case studies

Aquatic toxicology

Aquatic toxicology at the university of Newcastle

Dr Geoff MacFarlane and Dr Richard Yu

Research themes

The aquatic toxicology group at the University of Newcastle undertakes research in the field of aquatic ecotoxicology: examining the fate and effects of environmental contaminants on predominantly estuarine and marine biota. Research themes include:

1. Metals in estuarine and marine systems

Much of our past research has involved the effects of metal pollutants on estuarine and marine organisms, namely assessing strategies of metal bioaccumulation and sub-lethal impacts due to metal uptake at the molecular through to population level for informed impact assessment. We have elucidated the accumulation pathways and selected mechanisms of tolerance to metals by mangroves. Further, we have developed reliable biomarkers of metal stress in mangroves including photosynthetic performance, gene expression markers and the oxidative stress markers. We have developed successful biological indicators/biomarkers of metal stress in estuarine invertebrate models (including molluscs and crustaceans) at the molecular, physiological, population and community level. Further, we have developed bioremediation strategies employing aquatic organisms (zooremediation) to remediate metal contaminant loads in estuaries. Most recently, research has turned to endangered estuarine saltmarsh habitats, characterising metal accumulation patterns by dominant saltmarsh taxa and risk assessment of metals on saltmarsh productivity and maintenance.

2. Marine molluscan models for impact assessment of estrogenic EDCs

Wastewater treatment plant effluent is often released into estuarine and marine receiving bodies and can contain a complex cocktail of chemicals which mimic estrogen. Research in this field has involved elucidating the effects and mechanisms of action of these environmental estrogens on the reproductive performance of molluscs. We have demonstrated that exposure of estrogens to causes significant vitellogenin induction and sex reversal in bivalves. We have further developed vitellogenin and reproductive endpoints as potential estrogen-specific biomarkers for impact assessment in both the lab and field. Further, we have elucidated mechanisms of how estrogens may facilitate vitellogenin induction at the molecular level.

3. Deciphering the molecular mechanisms of endocrine disruption caused by aquatic hypoxia

Aquatic hypoxia caused by eutrophication is a pressing worldwide environmental problem. Through international collaboration, we research the molecular mechanisms of how hypoxia impacts fish reproduction through interfering with their endocrine function. In particular, we are interested in understanding the role of the hypoxia-inducible factor-1 (HIF-1), a transcription factor induced under hypoxic conditions, in regulating key processes of fish reproduction, such as sex differentiation and determination. We have demonstrated novel mechanistic links explaining how HIF-1 regulates gene expression involved in hormone biosynthesis and signalling at both the transcriptional (gene promoter activation/suppression) and post-transcriptional levels (miRNAs).

4. Developing eDNA survey techniques to monitor aquatic wildlife populations

Environmental DNA (eDNA) is nuclear or mitochondrial DNA shed from an organism into the environment. In recent years, eDNA has emerged as a promising tool for sensitive, specific and rapid detection and monitoring of aquatic species, including both threatened and invasive species, with the potential to complement costly and time-consuming traditional survey methods. Recently, we have successfully developed methods for eDNA sampling and quantification (using real-time PCR technology) for specific detection of target species in freshwaters.

Research support

Research in this area has been supported by ARC Discovery and Linkage Programs, FRDC, Hunter Water and NSW DPI Fisheries.