AbstractWastewater effluent is a major source of known and potential endocrine disrupting chemicals (EDCs) in aquatic environments due to the large number of anthropogenic chemicals present in these effluents and their incomplete removal by conventional sewage treatment methods. Consequently, aquatic species exposed to wastewater effluent experience chronic exposure to a complex mixture of contaminants. Although many studies have documented the presence of EDCs in freshwater environments, and the adverse effects on aquatic organisms exposed to EDCs, few studies have been carried out in marine environments or in Australia, where the consequences of exposure still remain largely unknown.
This thesis investigated known and potential EDCs in the Darwin Harbour region (i.e., Darwin Harbour plus catchments in the Beagle Gulf immediately outside Darwin Harbour), located in northern Australia, and looked for evidence of effects on the native tropical marine snail Telescopium telescopium. Water, sediment and T. telescopium were collected from estuarine sites exposed to secondary treated municipal wastewater and corresponding reference sites (those without wastewater outfalls present). Telescopium telescopium was used in this thesis as it is widely distributed throughout tropical northern Australia, has been demonstrated to accumulate organic contaminants from its surroundings, and is a traditional food source for local indigenous people.
Water and sediment were screened for a wide range of contaminants comprising known and potential EDCs from the following groups: hormones, pharmaceuticals and personal care products (PPCPs), herbicides, pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and metals. In addition, the standard bioassays YES and YAS (yeast estrogenic screen and yeast androgenic screen, respectively) were used to assess (anti)estrogenic and (anti)androgenic activity. Tissues of T. telescopium were analysed for a selection of EDCs and metal contaminants, along with nitrogen (δ15N) and carbon (δ13C) stable isotope analysis to obtain information on the biological uptake of nutrients from wastewater effluent. Histopathology was carried out to provide corresponding information on the health status of the animals with a view to providing ecologically-relevant biological end points of chronic contaminant exposure.
Known and potential EDCs were detected in water, sediments and biota across the Darwin Harbour region with the highest concentrations present at wastewater outfall sites. Both (anti)estrogenic and (anti)androgenic activity were present in water and sediments. Stable isotope analysis confirmed the assimilation of nutrients by T. telescopium from wastewater effluent via sediments. Despite evidence of exposure to EDCs there was little indication of compromised health or endocrine disruption in T. telescopium according to the histological condition observed. The results demonstrate that wastewater effluent is indeed a major source of known and potential EDCs to the tropical marine environment of the Darwin Harbour region, aquatic organisms are exposed to complex mixtures of chemicals of unknown toxicity and T. telescopium is a suitable natural bioindicator for sewage-derived compounds such as organic contaminants.
|Date of Award||Sep 2013|
|Supervisor||Keith Mcguinness (Supervisor)|