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Mann R.M.,University of Technology, Sydney | Hyne R.V.,Ecotoxicology and Environmental Contaminants Section | Simandjuntak D.L.,University of New South Wales | Simpson S.L.,CSIRO
Environmental Toxicology and Chemistry | Year: 2010

An underlying assumption of laboratory-based toxicity tests is that the sensitivity and exposure of organisms in the laboratory is comparable to that in the field. We sought to make a comparison between field-based and laboratory-based sediment toxicity tests using a recently developed rapid amphipod reproduction test that encompasses gametogenesis, fertilization, and embryo development before hatching. The test species, Melita plumulosa, is an epibenthic, detritivorous amphipod native to Eastern Australia. Test sediments were sourced from Lake Macquarie, a large saltwater lagoon located 100 km north of Sydney (New South Wales, Australia) that has received heavy-metal pollution over many decades, primarily from a Pb/Zn smelter but also from collieries, coal-fired power stations, and urban areas. This has led to a north-south trace-metal concentration gradient, including Pb, Zn, Cd and Cu, in the sediments of Lake Macquarie. Sediments from these northern bays were demonstrated to reduce amphipod fecundity in laboratory-based tests. For the current study, the amphipod reproduction test has been modified for use in situ. In situ test chambers were deployed at the mouth of Cockle Creek, Lake Macquarie. Sediments that were demonstrated to reduce fecundity of M. plumulosa in the laboratory reproduction test were not similarly toxic when amphipods were exposed to the same sediments in situ. Factors related to the regular tidal renewal of overlying water likely altered exposure profiles in situ, including the provision of additional or alternative nutrition that obviated the need for amphipods to interact with the contaminated sediments, and a washout effect that prevented the accretion of dissolved zinc in the overlying water. Environ. Environ. Toxicol. Chem. 2010;29:2566-2574. © 2010 SETAC Copyright © 2010 SETAC. Source

Choung C.B.,Macquarie University | Hyne R.V.,Ecotoxicology and Environmental Contaminants Section | Stevens M.M.,Yanco Agricultural Institute | Hose G.C.,Macquarie University
Environmental Pollution | Year: 2013

The effects of a co-occurring insecticide-herbicide mixture were evaluated using model ecosystems (microcosms) in the laboratory. Microcosms dosed with a high concentration (10 μg/L) of the insecticide terbufos, alone and as a mixture with the herbicide atrazine (25 μg/L), exhibited community level effects attributed to the elimination and decline of invertebrate populations, and also indirect effects. There were no community level effects at a lower concentration of terbufos (0.1 μg/L) alone or in a mixture with atrazine, although delayed population effects were observed. Female chironomids also emerged later and those from terbufos-only microcosms were smaller. Exposure to atrazine alone was also associated with lower abundances of cladocerans and reduced emergence of chironomids. The risk posed by atrazine is low and is unlikely to exacerbate the effects of terbufos. Nevertheless, the population-level effects highlight that terbufos poses a potential risk to aquatic ecosystems, regardless of whether atrazine is also present. © 2012 Published by Elsevier Ltd. Source

Choung C.B.,Macquarie University | Hyne R.V.,Ecotoxicology and Environmental Contaminants Section | Mann R.M.,University of Technology, Sydney | Stevens M.M.,Charles Sturt University | Hose G.C.,Macquarie University
Environmental Pollution | Year: 2011

To examine the link between corn agriculture and the observed decline of the endangered southern bell frog (SBF), the effects of two corn crop pesticides on larval growth and development were investigated. Tadpoles were exposed to terbufos sulfone (10 μg/L), a major breakdown product of the insecticide terbufos, and the herbicide atrazine (25 μg/L) individually and as a mixture until the completion of metamorphosis. Atrazine did not interact synergistically with terbufos sulfone or result in significant effects on growth and development alone, although there was some indication of accelerated metamorphosis in the pilot study. Terbufos sulfone alone and as a mixture (terbufos/atrazine) significantly slowed larval development and ultimately delayed metamorphosis. The observed developmental effects from an environmentally relevant concentration of terbufos sulfone indicates a risk posed by this persistent degradation product to the endangered SBF, which breeds and develops in the rice bays adjacent to corn fields treated with pesticides. © 2010 Published by Elsevier Ltd. Source

Phyu Y.L.,University of Technology, Sydney | Palmer C.G.,Rhodes University | Palmer C.G.,University of Technology, Sydney | Warne M.S.J.,Information Technology | And 6 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2013

The majority of ecotoxicological data are generated from standard laboratory-based experiments with organisms exposed in nonflowing systems using highly purified water, which contains very low amounts of dissolved organic matter and suspended particulates. However, such experimental conditions are not ecologically relevant. Thus, there is a need to develop more realistic approaches to determining toxicity, including both lethal and sublethal effects. This research provides information on the effect of natural water constituents, such as suspended particulates and dissolved organic matter, in river water (RW) on the chronic toxicity (7-day reproductive impairment) of the pesticides atrazine, chlorothalonil, and permethrin to the freshwater cladoceran Ceriodaphnia cf. dubia. Standard bioassays were conducted under standard laboratory and more environmentally realistic conditions (using RW). The 7-day IC25 (reproduction impairment) values of atrazine, chlorothalonil, and permethrin to C. cf. dubia ranged from 862.4 to >1000, 51.3 to 66.4, and 0.19 to 0.23 μg/L, respectively. Using the Globally Harmonized System of Classification and Labelling of Chemicals, atrazine is classified as moderately to highly toxic, whereas permethrin and chlorothalonil were both highly toxic. The presence of dissolved organic matter and suspended particles in natural RW did not significantly (p > 0.05) change the toxicity of any of the pesticides to C. cf. dubia compared with that tested in laboratory water (LW). For the tested pesticides, toxicity testing in LW provided an adequate estimate of the hazard posed. © 2012 Springer Science+Business Media New York. Source

Phyu Y.L.,University of Technology, Sydney | Palmer C.G.,University of Technology, Sydney | Warne M.S.J.,Catchment Water Science | Hose G.C.,Macquarie University | And 2 more authors.
Chemosphere | Year: 2011

Pesticides predominantly occur in aquatic ecosystems as mixtures of varying complexity, yet relatively few studies have examined the toxicity of pesticide mixtures. Atrazine, chlorothalonil and permethrin are widely used pesticides that have different modes of action. This study examined the chronic toxicities (7-d reproductive impairment) of these pesticides in binary and ternary mixtures to the freshwater cladoceran Ceriodaphnia cf. dubia. The toxicity of the mixtures was compared to that predicted by the independent action (IA) model for mixtures, as this is the most appropriate model for chemicals with different modes of action. Following this they were compared to the toxicity predicted by the concentration addition (CA) model for mixtures. According to the IA model, the toxicity of the chlorothalonil plus atrazine mixture conformed to antagonism, while that of chlorothalonil and permethrin conformed to synergism. The toxicity of the atrazine and permethrin mixture as well as the ternary mixture conformed to IA implying there was either no interaction between the components of these mixtures and/or in the case of the ternary mixture the interactions cancelled each other out to result in IA. The synergistic and antagonistic mixtures deviated from IA by factors greater than 3 and less than 2.5, respectively. When the toxicity of the mixtures was compared to the predictions of the CA model, the binary mixture of chlorothalonil plus atrazine, permethrin plus atrazine and the ternary mixture all conformed to antagonism, while the binary mixture of chlorothalonil plus permethrin conformed to CA. Using the CA model provided estimates of mixture toxicity that did not markedly underestimate the measured toxicity, unlike the IA model, and therefore the CA model is the most suitable to use in ecological risk assessments of these pesticides. © 2011 Elsevier Ltd. Source

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