Susan Kinnear

Cylindrospermopsin: A Decade of Progress on Bioaccumulation Research

Cylindrospermopsin (CYN) is rapidly being recognised as one of the most globally important of the freshwater algal toxins. The ever-expanding distribution of CYN producers into temperate zones is heightening concern that this toxin will represent serious human, as well as environmental, health risks across many countries. Since 1999, a number of studies have demonstrated the ability for CYN to bioaccumulate in freshwater organisms. This paper synthesizes the most current information on CYN accumulation, including notes on the global distribution of CYN producers, and a précis of CYN’s ecological and human effects. Studies on the bioaccumulation of CYN are systematically reviewed, together with an analysis of patterns of accumulation. A discussion on the factors influencing bioaccumulation rates and potential is also provided, along with notes on detection, monitoring and risk assessments. Finally, key gaps in the existing research are identified for future study.

Interpreting the possible ecological role(s) of cyanotoxins: compounds for competitive advantage and/or physiological aide?

To date, most research on freshwater cyanotoxin(s) has focused on understanding the dynamics of toxin production and decomposition, as well as evaluating the environmental conditions that trigger toxin production, all with the objective of informing management strategies and options for risk reduction. Comparatively few research studies have considered how this information can be used to understand the broader ecological role of cyanotoxin(s), and the possible applications of this knowledge to the management of toxic blooms. This paper explores the ecological, toxicological, and genetic evidence for cyanotoxin production in natural environments. The possible evolutionary advantages of toxin production are grouped into two main themes: That of “competitive advantage” or “physiological aide”. The first grouping illustrates how compounds produced by cyanobacteria may have originated from the need for a cellular defence mechanism, in response to grazing pressure and/or resource competition. The second grouping considers the contribution that secondary metabolites make to improved cellular physiology, through benefits to homeostasis, photosynthetic efficiencies, and accelerated growth rates. The discussion also includes other factors in the debate about possible evolutionary roles for toxins, such as different modes of exposures and effects on non-target (i.e., non-competitive) species. The paper demonstrates that complex and multiple factors are at play in driving evolutionary processes in aquatic environments. This information may provide a fresh perspective on managing toxic blooms, including the need to use a “systems approach” to understand how physico-chemical conditions, as well biological stressors, interact to trigger toxin production.

Populating regional Australia: What are the impacts of non-resident labour force practices on demographic growth in resource regions?

Abstract Resource-based activity provides a strong stimulus to local economies, largely through the high incomes paid to employees in the resources sector, plus the large levels of expenditure through supporting business chains. However, the role that resource development plays in driving regional population dynamics remains poorly understood, particularly with respect to the rising use of non-resident labour force practices. Supply of labour via fly-in, fly-out (FIFO) and drive-in, drive-out (DIDO) options creates a range of direct and indirect pressures on host communities. These are predominantly linked with difficulties in counting the non-resident population, and hence planning for, and investing in, the social infrastructure required to meet the new demand. Non-residency also represents a distinct ‘opportunity cost’ for regions, because local population growth is a powerful business case for public and private investment in infrastructure and services. The dual effect of FIFO/DIDO is thus not only to introduce new demand for infrastructure and services, but also to deny regions the chance for baseline population growth, and with it, the likelihood of improving living standards. This paper presents a case study illustrating the value of resource activity in stimulating local population growth in Central Queensland, and how the strength of this stimulus varies with patterns of resident and non-resident workforce mixes. Demographic modelling prepared using the economic multiplier approach suggest that in excess of up to 180,000 additional people could move into the region by 2018 in direct response to resource sector growth, if the workforce was fully resident. However, the extent of population in-migration – and consequent economic growth – reduces as the proportion of non-resident workforce increases. Under predominantly DIDO or predominantly FIFO scenario, the regional population boost is decreased by up to 23% or 44%, respectively. Populating regional Australia will be an essential part of the national growth strategy going forward. However, without a change in policy to re-emphasise the importance of supplying labour locally, the role that resource regions will play in this growth, and the positive impacts associated with local population increases, will not be maximised.

Distribution of the cyanobacterial toxins cylindrospermopsin and deoxycylindrospermopsin in a stratified lake in north-eastern New South Wales, Australia

This paper describes the vertical water column distribution of the cyanobacterial toxins cylindrospermopsin and deoxycylindrospermopsin in a water body containing the cyanobacteria Aphanizomenon ovalisporum and Cylindrospermopsis raciborskii. The study site was Cobaki Village Lake, a small stratified anthropogenic lake in north-eastern New South Wales, Australia. Water quality analysis indicated that stratification and oxygenation of the water column were significant in both the distribution of the cyanobacterial populations and their associated toxin concentrations. Toxin was distributed throughout the entire water column, but the highest concentrations were recorded in the hypolimnion. Maximum toxin concentrations were detected in February 2007 (38.2 μg L–1 cylindrospermopsin (CYN) and 42.2 μg L–1 deoxy-CYN). The relative distribution of CYN and deoxy-CYN paralleled the distribution of NH3H and NOX within the water column, with oxygenated chemical species dominating above 15 m and de-oxygenated chemical species dominating below 15 m. Cyanobacterial cell concentrations were highest in the oxic, warm and low conductivity waters of the epilimnion and cyanobacterial species succession was associated with nutrient and trace-metal depletion in this surface layer. These research findings are directly relevant to the management of water supplies affected by toxic blue-green algal blooms, particularly with respect to the considered placement of off-take devices to avoid layers of cyanobacterial cell and toxin concentrations.

Humic Substances Increase Survival of Freshwater Shrimp Caridina sp. D to Acid Mine Drainage

Humic substances (HS) are known to decrease the toxicity of heavy metals to aquatic organisms, and it has been suggested that they can provide buffering protection in low pH conditions. Despite this, little is known about the ability for HS to increase survival to acid mine drainage (AMD). In this study, the ability of HS to increase survival of the freshwater shrimp (Caridina sp. D sensu Page et al. in Biol Lett 1:139–142, 2005) to acid mine drainage was investigated using test waters collected from the Mount Morgan open pit in Central Queensland with the addition of Aldrich humic acid (AHA). The AMD water from the Mount Morgan open pit is highly acidic (pH 2.67) as well as contaminated with heavy metals (1780 mg/L aluminum, 101 mg/L copper [Cu], 173 mg/L manganese, 51.8 mg/L zinc [Zn], and 51.8 mg/L iron). Freshwater shrimp were exposed to dilutions in the range of 0.5 % to 5 % AMD water with and without the addition of 10 or 20 mg/L AHA. In the absence of HS, all shrimp died in the 2.5 % AMD treatment. In contrast, addition of HS increased survival in the 2.5 % AMD treatment by ≤66 % as well as significantly decreased the concentration of dissolved Cu, cobalt, cadmium, and Zn. The decreased toxicity of AMD in the presence of HS is likely to be due to complexation and precipitation of heavy metals with the HS; it is also possible that HS caused changes to the physiological condition of the shrimp, thus increasing their survival. These results are valuable in contributing to an improved understanding of potential role of HS in ameliorating the toxicity of AMD environments.

The Need to Measure and Manage the Cumulative Impacts of Resource Development on Public Health: An Australian Perspective

Australia is home to several resource-intensive regions that feature vast mineral, ore and/or coal deposits pooled in one physical location (Figure 1). These areas are usually character‐ ised by multiple mediumto large-scale extraction and processing facilities, and typically in‐ clude extensive road, rail and port infrastructure. The Australian resources sector has been defined by the Commonwealth of Australia [1] as:

Effect of key water quality variables on macroinvertebrate and fish communities within naturally acidic wallum streams

Adverse impacts of acidification on aquatic biota have been observed worldwide; however, most reports are based on fresh waters acidified by anthropogenic means. By contrast, naturally low pH values may not affect biota within naturally acidic fresh waters. This field study provides information on the water quality, macroinvertebrate and fish communities in little-studied, naturally acidic wallum streams in Central Queensland, Australia. Mid-range pH sites (pH 5–6) were compared with low pH sites (pH 5–3.8) to investigate the effect of pH and other key water quality variables on these communities. Field data indicated that pH had less of an effect in these systems in terms of biotic changes compared with other water quality variables, with dissolved oxygen (% saturation) identified as the key driver for changes in macroinvertebrate composition. Fish were present at all sites, including those with pH <4. Several possible explanations for this lack of pH effect are discussed. These results provide support for the reduced importance of acidity, relative to other water quality parameters, in naturally acidic waters. The work also provides baseline data on the biota of little-studied wallum streams.

Emissions Reporting in the Australian Road Freight Transport Sector: Is There a Better Method than the Default Option?

As emissions from the global road freight transport sector continue to rise, an understanding of how emissions are produced, estimated and measured is increasingly important. This article identifies the key influences on greenhouse emissions from heavy-duty diesel trucking, and evaluates the reporting options currently available under the Australian National Greenhouse Emissions Reporting Scheme. The latter is done through a case study of emissions modelling, used to illustrate the trade-offs in different reporting options. The article concludes that routine reporting based on method 2 should deliver more accurate reportable emissions, as well opportunities to better understand emissions profiles and strategies for reducing emissions.

Influence of Aldrich humic acid and metal precipitates on survivorship of mayflies (Atalophlebia spp.) to acid mine drainage.

Humic substances (HS) have been shown to decrease the toxicity of environmental stressors, but knowledge of their ability to influence the toxicity of multiple stressors such as metal mixtures and low pH associated with acid mine drainage (AMD) is still limited. The present study investigated the ability of HS to decrease toxicity of AMD to mayflies (Atalophlebia spp.). The AMD was collected from the Mount Morgan (Mount Morgan, Queensland, Australia) open pit. Mayflies were exposed to concentrations of AMD at 0%, 1%, 2%, 3%, and 4% in the presence of 0 mg/L, 10 mg/L, and 20 mg/L Aldrich humic acid (AHA). A U-shaped response was noted in all AHA treatments, with higher rates of mortality recorded in the 2% and 3% dilutions compared with 4%. This result was linked with increased precipitates in the lower concentrations. A follow-up trial showed significantly higher concentrations of precipitates in the 2% and 3% AMD dilutions in the 0 mg/L AHA treatment and higher precipitates in the 2% AMD, 10 mg/L and 20 mg/L AHA, treatments. Humic substances were shown to significantly increase survival of mayflies exposed to AMD by up to 50% in the 20 mg/L AHA treatment. Humic substances may have led to increased survival after AMD exposure through its ability to influence animal physiology and complex heavy metals. These results are valuable in understanding the ability of HS to influence the toxicity of multiple stressors.

Humic acid decreases acute toxicity and ventilation frequency in eastern rainbowfish (Melanotaenia splendida splendida) exposed to acid mine drainage.

Acid mine drainage (AMD) is a global problem leading to the acidification of freshwaters, as well as contamination by heavy metals. The ability of humic substances (HS) such as humic acid (HA) to decrease toxicity of heavy metals is widely known, whereas limited studies have examined the ability of HS to decrease toxicity linked with multiple stressors such as those associated with AMD. This study investigated the ability of HA to decrease acute toxicity defined as morbidity and ventilation frequency (measured via the time elapsed for ten operculum movements) in eastern rainbowfish (Melanotaenia splendida splendida) exposed to the multiple stressors of AMD-driven heavy metal concentrations, together with low pH. Water from the Mount Morgan open pit (a now closed gold and copper mine site), located at Mount Morgan, Central Queensland, Australia, was used as the AMD source. Fish were exposed to zero per cent (pH 7.3), two per cent (pH 6.7), three per cent (pH 5.7) and four per cent (pH 4.6) AMD in the presence of 0, 10 and 20mg/L Aldrich Humic Acid (AHA) over 96h. HA was shown to significantly decrease the acute toxicity of AMD and its adverse effects on ventilation frequency. These results are important in showing that HA can influence toxicity of metal mixtures and low pH, thus indicating a potential role for HA in decreasing toxicity of multiple environmental stressors more widely, and possible value as a rehabilitation aid.