Biomarkers of exposure in fish inhabiting the Swan–Canning Estuary, Western Australia – a preliminary study

Abstract

The estuarine portion of the Swan–Canning riversystem runs through the centre of Perth,Western Australia's capital city, with apopulation of approximately 1.4 million people. Little is known about impact of chemicalsentering the estuary via road runoff andstormwater drains on biota inhabiting thesystem. Black bream (Acanthopagrusbutcheri) were collected from seven sites inthe Swan–Canning estuary during August andSeptember 2000, at the end of the winter (wet)season. Serum sorbitol dehydrogenase (s-SDH)was unaffected by the sex of the fish and nosignificant differences were observed betweenthe sites indicating that the measuredethoxyresorufin-O-deethylase (EROD)activity was not hindered by hepatic tissuedamage. The black bream were in an advancedstage of gonad maturation, which affected ERODhepatic activity with lower EROD activity infemale compared to male fish. EROD activityand bile metabolite levels were significantlyhigher at the site closest to the Perth CentralBusiness District, while most downstream sitewas the least impacted, which may be due totidal flushing of the lower estuary by marinewaters. The ratio of naphthalene-type tobenzo(a) pyrene (B(a)P)-typemetabolites suggests that the source ofpetroleum hydrocarbons within the river systemis a mixture polycyclic aromatic hydrocarbons(PAHs) from pyrolytic origin and from unburntfuels. Biomarker levels in the black breamindicate that major roads and drains aresignificant contributors of mixed functionoxygenase (MFO) inducing chemicals includingpolycyclic aromatic hydrocarbons (PAH) into theSwan–Canning estuary and that there is noupstream or downstream gradient in biomarkerresponse.