Gambusia holbrooki: pest or potential bioindicator for endocrine disruption in Victorian freshwaters, Australia?

Freshwater aquatic systems are often challenged by harmful anthropogenic contaminants such as sewage effluents, agricultural pesticides, and industrial and urban run-off. Water quality monitoring is necessary to understand effects on aquatic organisms. Biological monitoring tools such as biomarkers are useful to detect effects in fish and aquatic organisms through cellular, molecular, biochemical, physiological or/and behavioural biomarkers. However, the identification of a suitable fish bioindicator is a challenge because most fish species do not have a wide distribution to enable comparisons between sites or may require a big effort to capture. Gambusia holbrooki (mosquitofish) are wide-spread around Australia and are easy to capture with dip nets. G.holbrooki responses to endocrine active compounds (EACs) have been studied in the laboratory, providing data for comparisons. In this study, the focus is on the evaluation of data gathered from the suite of biomarkers (EROD, Vitellogenin protein induction and gonopodial measurements) together with chemical analyses of the water (estrogenic and AhR activity) to understand the condition of peri-urban creeks and rivers in Victoria. The suitability of using G.holbrooki as a sentinel species for the monitoring of EACs in Australian creeks and rivers based on the biomarkers chosen for this study is also discussed. Adult male G.holbrooki were collected from February to May between 2007 to 2009 from various land use types such as urban, rural, wastewater treatment plant impacted (WWTP) and reference sites (Ref) around Victoria, using a dip net. Gonopodial indices assessed were fish body length, gonopodial length:body length ratio, R4: 6 ratio, fish body mass and absence of hooks and serrae. Vitellogenin protein induction and hepatic EROD activity were analysed in fish. Fish from a number of sites showed various effects in the gonopodial indices suggesting endocrine disruption. However, G.holbrooki are also highly plastic and adaptable to a variety of water conditions making interpretations of morphological characteristics complicated. Confounding factors such as temperature, individual site history, predator absence/presence, extreme weather conditions and other factors may have influenced fish gonopodial indices. Significant effects in vitellogenin protein and hepatic EROD activity induction were observed in fish from some of the sites. Estrogenic and AhR activity was detected at all sites including the reference sites. There was no consistent pattern observed in the water activity measurements and biomarker results. Despite the number of challenges that were encountered with the use of G.holbrooki for the biomarkers chosen for this study, results obtained were useful for G.holbrooki from the wild. Therefore it is concluded that G.holbrooki is a suitable bioindicator for estrogenic EACs for Victorian and Australian creeks and rivers. Although environmental factors may confound the results of some of the biomarkers that were chosen for this study, it should not deter the future use of G.holbrooki as a bioindicator. Instead, fish populations from affected study sites should be monitored over time with more frequent sampling to better understand natural variation. Results of this study will contribute to a long-term risk assessment study of the release and potency of estrogenic contaminants entering Victorian creeks and rivers

Screening for potential effects of endocrine-disrupting chemicals in peri-urban creeks and rivers in Melbourne, Australia using mosquitofish and recombinant receptor-reporter gene assays

Sexually mature male mosquitofish (Gambusia holbrooki) were collected from various sites around Melbourne in 2009 to evaluate the performance of gonopodial indices as a biomarker for endocrine disruption in Melbourne's waterways. The mosquitofish indices assessed were body length (BL), gonopodial length (GL)/BL ratio, ray 4:6 ratio and the absence or presence of hooks and serrae, and these varied between sites. The study was complemented by measurements of estrogenic, retinoid, thyroid and aryl hydrocarbon (AhR) receptor activities of the water. Male mosquitofish were 16.3-21.5 mm in length, and although there was a statistically significant positive relationship showing that bigger fish had longer gonopodia than small fish (r2 = 0.52, p < 0.001), there were few significant differences in GL/BL ratio of fish between sites. Measured estrogenic activity was mostly in the range 0.1-1.7 ng/L EEQ, with one site having much higher levels (similar to 12 ng/L EEQ). Aryl hydrocarbon (AhR) receptor activity was observed in all water samples (7-180 ng/L beta NF EQ), although there was no consistent pattern in the level of AhR activity observed, i.e., 'clean' sites were as likely to return a high AhR activity response as urban or wastewater treatment plant (WWTP)-impacted sites. There was no correlation between measurements of receptor actvity and gonopodial length (GL):BL ratio and BL. We conclude that the mosquitofish gonopodia only fulfills part of the criteria for biomarker selection for screening. The mosquitofish indices assessed were cheap and easy-to-perform procedures; however, there is no baseline data from the selected sites to evaluate whether differences in the morpholical indices observed at a site were a result of natural selection in the population or due to estrogenic exposure

Toxicity of wine effluents and assessment of a depuration system for their control: assay with tadpoles of Rhinella arenarum (BUFONIDAE)

We evaluated the toxicity of the winery effluent and the efficiency of a symbiotic depuration system by means an experiment with Rhinella arenarum tadpoles. The studied effluent was taken from warehouses during the cleaning season. These effluents subsequently subjected to the purification treatment under evaluation. The effluent samples differentiated into two treatment levels: “raw” where the effluent was evaluated with field conditions and “treated” where the effluent was previously filtered with the symbiotic depuration system. The results of the bioassays compared with the physicochemical parameters determined in the effluent samples. The lethal response had a clear-cut correspondence with the effluent quality assessed utilizing physicochemical parameters. In all cases, dilution of the samples resulted in a significant reduction of their toxicity. It concluded that (a) winery effluents could be harmful to tadpoles of R. arenarum, (b) the symbiotic purification system used to treat wine effluents it would produce a significant reduction in the contaminant levels of the effluent. However, this reduction in contaminant levels does not provide sufficient safety for the release of the effluents into the environment.Fil: Navas Romero, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Herrera Moratta, Mario Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Rodríguez, María Rosa. Universidad Nacional de San Juan. Facultad de Ingeniería; ArgentinaFil: Quiroga, Lorena Beatriz. Universidad Nacional de San Juan. Facultad de Filosofía, Humanidades y Artes. Instituto de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Echegaray, Marcelo Eduardo. Universidad Nacional de San Juan. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Sanabria, Eduardo Alfredo. Universidad Nacional de San Juan. Facultad de Filosofía, Humanidades y Artes. Instituto de Ciencias Básicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentin