Seasonal responses of macroinvertebrate assemblages to magnesium in a seasonally flowing stream.

Macroinvertebrates can be highly sensitive to elevated salinity in freshwater environments, and are known to respond to saline discharges. Magnesium (Mg) is a mine-related contaminant and is a potential environmental risk to a seasonally-flowing, receiving water stream in Kakadu National Park, located in the wet-dry tropics of Australia. The macroinvertebrate assemblage in the stream in the was characterised at four hydrographic phases, from early wet season flow to early dry season pools at flow cessation.

Elevated Magnesium Concentrations Altered Freshwater Assemblage Structures in a Mesocosm Experiment.

Magnesium (Mg) is a mining-related contaminant in the Alligators Rivers Region of tropical northern Australia. A mesocosm experiment was used to assess Mg toxicity to aquatic freshwater assemblages. Twenty-five 2700-L tubs were arranged, stratified randomly, on the bed of Magela Creek, a seasonally flowing, sandy stream channel in the Alligator Rivers Region of northern Australia.

Acute and chronic toxicity of magnesium to the early life stages of two tropical freshwater mussel species.

Magnesium (Mg) is a common contaminant in mine water discharges. Although Mg is an essential element in biological processes, increased concentrations from anthropogenic sources can stress aquatic ecosystems. Additionally, studies evaluating the effects of Mg on north Australian freshwater species have indicated that in very soft waters there is a high risk to some species.

Response of the Native Springtail Parisotoma insularis to Diesel Fuel-Contaminated Soils Under Field-Realistic Exposure Conditions at Subantarctic Macquarie Island.

A number of sites contaminated by petroleum hydrocarbons from past fuel spills are currently undergoing remediation on subantarctic Macquarie Island (under the jurisdiction of Tasmania, Australia). To assess the environmental risks these spills pose, and to establish remediation targets and guideline values, toxicity data for a range of native biota are required. The availability of data for local biota is limited, especially for soil invertebrates, which are critical to soil health.

Chronic ammonia toxicity to juveniles of 2 tropical Australian freshwater mussels (Velesunio spp.): Toxicity test optimization and implications for water quality guideline values.

Freshwater mussels play key roles in aquatic ecosystems, but are experiencing a global decline. Although studies have reported high acute sensitivity of mussels to some contaminants, chronic toxicity data are lacking for deriving high-reliability water quality guideline values. Ammonia is a contaminant of potential concern in some catchments of tropical northern Australia, where freshwater mussels are important ecological and cultural components.

Freshwater chronic ammonia toxicity: A tropical-to-temperate comparison.

The chronic toxicity of ammonia to tropical freshwater species is understudied, and thus data on temperate species have been used to derive water quality guideline values for tropical regions. Such practices may lead to underprotective guideline values due to differences in toxicities observed between tropical and temperate species. In addition, the presence of ammonia in low-ionic-strength waters may also result in higher toxicity, and studies on this factor are limited.

Acute ammonia toxicity to the larvae (glochidia) of the tropical Australian freshwater mussel Velesunio spp. Using a modified toxicity test protocol.

Ammonia is recognized as a major pollutant worldwide, originating from natural and anthropogenic sources. Studies have reported that freshwater mussels are among the most sensitive taxa to ammonia, but few data are available on ammonia toxicity for the early life stages of freshwater mussels from tropical regions. We report on the modification of a 24-h acute toxicity test protocol for tropical freshwater mussels and application of the test using ammonia.

Modeling the pH-ammonia toxicity relationship for Hydra viridissima in soft waters with low ionic concentrations.

There are limited data concerning the toxicity of ammonia in fresh soft waters. Ammonia toxicity is largely dependent on pH and temperature. The US Environmental Protection Agency (USEPA) has derived equations to adjust species toxicity estimates based on changes in pH and temperature.

Increasing uranium exposure durations to the aquatic snail Amerianna cumingi does not result in lower toxicity estimates.

Reproductive inhibition (egg production) of the aquatic snail Amerianna cumingi over 4 d has been used to derive toxicity estimates for toxicants of concern in tropical Australia. Toxicity estimates from this test have been used as chronic data points in species sensitivity distributions (SSDs) for deriving site-specific guideline values. However, revised guidance for the Australian and New Zealand Water Quality Guidelines advises that test durations for adult macroinvertebrates should be ≥14 d to be considered chronic.

Soil invertebrate community change over fuel-contaminated sites on a subantarctic island: An ecological field-based line of evidence for site risk assessment.

A number of fuel spills, of both recent and historic origins, have occurred on World Heritage-listed subantarctic Macquarie Island. Sites contaminated by mainly diesel fuels are undergoing remediation by the Australian Antarctic Division. The risks posed by these sites are being managed using a "weight of evidence" approach, for which this study provides a preliminary line of evidence for the ecological assessment component of this site management decision framework.

Manganese toxicity to tropical freshwater species in low hardness water.

Elevated manganese (Mn) is a common contaminant issue for mine water discharges, and previous studies have reported that its toxicity is ameliorated by H(+), Ca(2+), and Mg(2+) ions. In the present study, the toxicity of Mn was assessed in a high risk scenario, that is, the slightly acidic, soft waters of Magela Creek, Kakadu National Park, Northern Territory, Australia. Toxicity estimates were derived for 6 tropical freshwater species (Chlorella sp.

Toxicity of diesel contaminated soils to the subantarctic earthworm Microscolex macquariensis.

Several fuel spills have occurred on subantarctic Macquarie Island (54°30' S 158°57' E) associated with storing fuel and generating power for the island's research station. The Australian Antarctic Division began full-scale, on-site remediation of these sites in 2009. To develop appropriate target concentrations for remediation, acute and chronic tests were developed with the endemic earthworm, Microscolex macquariensis, using avoidance, survival, and reproduction as endpoints.