The Swan-Canning Estuary, in southwestern Australia, undergoes distinct seasonal changes, with freshwater discharge predominant in the winter (wet) season and low flow with high salinity predominant in the dry summer season. To investigate seasonal variability in biomarkers of exposure in fish, black bream (Acanthopagrus butcheri) were collected from seven sites in the Swan-Canning Estuary in winter 2000 and in summer 2001. No interseasonal or intersite differences in serum sorbitol dehydrogenase concentration were found, indicating the measured mixed-function oxygenase (MFO) enzymes were not influenced by liver damage. The ethoxyresorufin-O-deethlyase (EROD) activity of the postspawning females was higher in summer than in winter but was significantly lower than that in males in both seasons, suggesting estradiol suppression in females. Sexual differences in ethoxycoumarin-O-deethylase (ECOD) activity were not evident in either season. Both EROD and ECOD activities and polycyclic aromatic hydrocarbons (PAH) biliary metabolites had significantly different patterns of induction between seasons. The ratio of naphthalene-type to benzo(a)pyrene-type biliary metabolites was significantly higher in summer, indicating the sources of petroleum hydrocarbons were petrogenic compared to in winter, when the source was a mixture of pyrogenic and petrogenic PAHs. There was no upstream or downstream gradient of response in any biomarker in either season, demonstrating that there were multiple sources of contaminant input into the estuary. Although winter biomarker levels were triggered by the discharge runoff from major roads and drains, summer biomarker levels appear to have been related to recreational boating use on the estuary.

The yellowtail trumpeter (Amniataba caudavittata) is an estuarine-dependent omnivorous fish found in the Swan-Canning Estuary, Western Australia. Thirty five fish were injected with either the polycyclic aromatic hydrocarbon, benzo[a]pyrene (B[a]P), the synthetic flavenoid b-naphthoflavone (BNF), or used as controls. The fish were then sampled at 3 and 7 days postinjection. Induction of the enzyme ethoxyresorufin O-deethylase (EROD) activity was nonsignificant while ethoxycoumarin O-deethylase (ECOD) activity induction differed amongst treatments. A high interindividual variability in the EROD activity was observed. The measurement of sorbitol dehydrogenase in the serum (s-SDH) was elevated (BNF 2.2 times and B[a]P 3.2 times the control fish) demonstrating that liver cell damage had occurred. Increases in biliary metabolites of both B[a]P-type and pyrene-type (19 times and 3.4 times the controls respectively) indicated that detoxification of pyrene-type compounds had taken place. Fish of the Terapontidae family, such as the yellowtail trumpeter, were found to be suitable for biomonitoring the health of the Swan-Canning Estuary. A combination of ECOD activity, s-SDH, and the measurement of biliary metabolites represents a suitable suite of biomarkers for environmental monitoring of the sublethal effects of PAH pollution in these fish. # 2008 Wiley Periodicals, Inc. Environ Toxicol 23: 68-76, 2008

No abstract

No abstract

-During the 1970's the Peel-Harvey Estuary experienced severe symptoms of nutrient enrichment. There were large inputs of nutrients to the system, and only limited oceanic flushing occurred, via the long, narrow Mandurah Entrance Channel. In 1994 the Dawesville Channel was constructed to increase oceanic flushing within the Peel-Harvey Estuary; reduce the occurrence of toxic phytoplankton blooms (eg. blue-green Nodularia spumzgena) and decrease macroalgal growth. The present paper compares the benthic invertebrate fauna in the Peel-Harvey Estuary before and after the Dawesville Channel was constructed.One hundred sediment cores were collected during early autumn and late winter 2000, yielding a total of 17,443 benthic invertebrates, comprising 52 species. Polychaetes, molluscs and crustaceans dominated species richness and density in both seasons. There was a clear difference in benthic invertebrat~species richness and density between seasons. During early autumn, benthic invertebrate communities in the Peel-Harvey Estuary had a low species richness (27 species), but this increased substantially (46 species) in late winter. Total mean density guadrupled from 6397m· 2 in early autumn to 26,180m· 2 in late winter. The increased species richness was due to increases in small crustaceans with a short lifespan and, to a lesser extent, chironomid insect larvae. With the exception of one site, the increased density was general throughout both Peel Inlet and the Harvey Estuary. There was no apparent correlation between increased densities and proximity to the entrance channels.Pre-Dawesville Channel data on benthic invertebrates are few. Molluscs provided the best comparisons between pre and post Dawesville Channel benthic invertebrates. In the late 1970's mollusc diversity was low and was dominated by two small estuarine species: the bivalve Arthritica semen and the gastropod Hydrococells brazieri. A two-year study at one site in Peel Inlet recorded a maximum density of 45,491 m 2 for A. semen and 19,959m 2 for H. brazieri. By the 1980's the de~sity of both species had declined; H. brazieri had nearly disappeared from the Peel-Harvey Estuary. In 2000, the mean densities of A. senzen and H. brazieri remained low. Several marine species that were recorded in the post Dawesville Channel samples were not recorded in the 1970's. Data suggests that the Peel-Harvey Estuary has become more marine, and that increased recruitment of planktonic larvae through the short, narrow Dawesville Channel and improved water guality has probably enabled these species to establish themselves. All of these species were recorded in very low densities, and they have not established the dense populations previously attained by H. brazierz and A. semen.