Characterisation of microcontaminants in Darwin Harbour, a tropical estuary of northern Australia undergoing rapid development.

The detection of microcontaminants in aquatic environments raises concerns about their potential to exert ecotoxicological effects and impact human health. In contrast to freshwater habitats, little information is available on environmental concentrations in urban estuarine and marine environments. This study investigated an extensive range of organic and inorganic microcontaminants in the Darwin Harbour catchment, a tropical estuary in northern Australia undergoing rapid urbanisation and industrial development. We sampled wastewater effluent and surface water from seven sites in Darwin Harbour for pharmaceuticals and personal care products, alkylphenols, hormones, pesticides, herbicides and metals. In vitro bioassays were used to estimate the (anti)estrogenic and (anti)androgenic activities of samples. Seventy-nine of 229 organic microcontaminants analysed were detected at concentrations ranging from 0.01 to 20 µg/L, with acesulfame, paracetamol, cholesterol, caffeine, DEET and iopromide detected at the highest concentrations in wastewater effluent (20 µg/L, 17 µg/L, 11 µg/L, 11 µg/L, 10 µg/L and 7.6 µg/L, respectively). Levels of estrogenic activity ranged from estradiol equivalency quotients (EEQs) of <0.10 to 6.29±0.16 ng/L while levels of androgenic activity ranged from dihydrotestosterone equivalency quotients (DHTEQs) of <3.50 to 138.23±3.71 ng/L. Environmental concentrations of organic microcontaminants were comparable to ranges reported from aquatic environments worldwide with sewage effluent discharges representing the dominant source of entry into Darwin Harbour. The measured concentration range of DEET was higher than ranges reported in previous studies.

Investigation of the mud crab (Scylla serrata) as a potential bio-monitoring species for tropical coastal marine environments of Australia.

Mud crabs, Scylla serrata, were sampled from four estuaries (the Normanby, Herbert, Burdekin and Fitzroy Rivers) along the coast of northern Queensland, Australia, representing a pollution gradient from low to high contamination based upon previous chemical monitoring. Four biomarkers; glutathione-S-transferase (GST) activity, cholinesterase (ChE) inhibition and the urinary metabolite concentrations of naphthalene (NPH) and benzo-a-pyrene (BaP) were evaluated in S. serrata hepatopancreas, haemolymph and urine. Site-specific evidence of elevated GST activity and BaP metabolite concentrations and significant ChE inhibition was detected. Biomarker responses from this field study provide evidence of contaminant exposure of S. serrata from river estuaries along the coast of northern Queensland and indicate that further investigation is warranted. Based on the current results, and with further work on characterising the dose-response and seasonal variation in this species, mud crabs have great potential as indicator species for water quality and ecosystem monitoring programs across tropical coastal regions of Australia.

The assessment of vitellogenin as a biomarker of exposure to estrogenic compounds in two Australian perciformes.

Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17beta-estradiol exposed (E2) male barramundi (20 mg kg(-1)) and male black bream (2.5-5.0 mg kg(-1)) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg(-1)), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P<0.001). E2 male black bream were significantly different than control males (Student t, P<0.001) and control and E2 females displayed highly significant differences (Student t, P<0.001). These results indicate that exposure to 17beta-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds.