Towards Sustainable Environmental Quality : Priority Research Questions for the Australasian Region of Oceania

Environmental challenges persist across the world, including the Australasian region of Oceania, where biodiversity hotspots and unique ecosystems such as the Great Barrier Reef are common. These systems are routinely affected by multiple stressors from anthropogenic activities, and increasingly influenced by global megatrends (e.g., the food-energy-water nexus, demographic transitions to cities) and climate change. Here we report priority research questions from the Global Horizon Scanning Project, which aimed to identify, prioritize, and advance environmental quality research needs from an Australasian perspective, within a global context. We employed a transparent and inclusive process of soliciting key questions from Australasian members of the Society of Environmental Toxicology and Chemistry. Following submission of 78 questions, 20 priority research questions were identified during an expert workshop in Nelson, New Zealand. These research questions covered a range of issues of global relevance, including research needed to more closely integrate ecotoxicology and ecology for the protection of ecosystems, increase flexibility for prioritizing chemical substances currently in commerce, understand the impacts of complex mixtures and multiple stressors, and define environmental quality and ecosystem integrity of temporary waters. Some questions have specific relevance to Australasia, particularly the uncertainties associated with using toxicity data from exotic species to protect unique indigenous species. Several related priority questions deal with the theme of how widely international ecotoxicological data and databases can be applied to regional ecosystems. Other timely questions, which focus on improving predictive chemistry and toxicology tools and techniques, will be important to answer several of the priority questions identified here. Another important question raised was how to protect local cultural and social values and maintain indigenous engagement during problem formulation and identification of ecosystem protection goals. Addressing these questions will be challenging, but doing so promises to advance environmental sustainability in Oceania and globally

The effects of water quality on the toxicity of pesticides to the Australian non-biting midge Chironomus tepperi

© 2019 Molly Nicola HoakEnvironmental toxicology, or ecotoxicology, is the study of the effects of anthropogenic contamination on the environment, from singular organisms to whole ecosystems. Until recently laboratory aquatic environmental toxicology has largely been focused on investigating the effects of one or two contaminants on standard test organisms. But in recent years there has been a push to make ecotoxicology laboratory tests more indicative of the multiple stressors (e.g. salinity, nutrients, pH, temperature, metals, pesticides, pharmaceuticals) than can affect an aquatic ecosystem. There has also been more emphasis on developing ecotoxicity testing models with local species, particularly in countries outside of North America and Europe. This focus on local species with multiple stressors has been useful for regulators in Australia as they can now derive water quality guidelines based on more accurate information. The aims of this thesis were to contribute to the increasing amount of information of Australian standard ecotoxicology organisms and their response to multiple stressors. Firstly, I investigated the effects of a single stressor (phosphorus) on the Australia standard ecotoxicology species Chironomus tepperi. This was in order to characterise the response of C. tepperi to elevated concentrations of phosphorus. I conducted laboratory bioassays investigating how both lower and higher concentrations of phosphorus affected the growth, emergence, and energy reserves of C. tepperi larvae. I conducted these bioassays in sediment and water to determine the whether there was any moderating effect of the sediment on the response of C. tepperi to phosphorus manipulation. In the water-only bioassay, the addition of P decreased emergence time and increased wing length in C. tepperi adults. In the sediment tests, the addition of P had a less clear effect on development but resulted in lower lipid concentrations in C. tepperi larvae compared to treatments with low P concentrations, suggesting utilisation of energy reserves. The next chapter was an extension of the previous where I added both varying concentrations of the pesticide permethrin and P in sediment bioassays. I again examined the growth, emergence, and energy reserves response of C. tepperi to these exposures. In this chapter, I found that at very high permethrin concentrations, an increased concentration of P did not alter the toxicity and there was still a reduction in survival after 96 hours and the proportion emerged. However, P did alter the effects of permethrin on emergence day and on the energy reserves in C. tepperi larvae after 96 hours. In the last data chapter, I investigated the effects of salinity on the toxicity of a different pesticide, imidacloprid. Salinity was chosen as salinisation is an increasing problem in fresh waters, and imidacloprid is a pesticide still in heavy use in many places around the world. In this chapter I used water-only bioassays to investigate the effects of salinity on imidacloprid toxicity to C. tepperi. Overall, increasing salinity and increasing imidacloprid concentrations had a negative effect on the survival and emergence of C. tepperi. This effect was shown in both acute (96 hour) and chronic (15 day) bioassays. In energy reserves there was an overall increase in glycogen, lipid, and protein concentrations in response to the combination of stressors. This thesis overall shows that there is a need to investigate how water quality can affect the toxicity of commonly used pesticides. This is not only important in ecotoxicology to better understand the model organisms and their response, but it is also useful in for regulators as there is a need to understand how local aquatic conditions will increase or decrease the toxicity of a pollution event

conduc_emerg_analysis

Emergence rates of Chironomus tepperi across different conductivity treatment

conspecific_analysis

Oviposition of Chironomus tepperi in relation to visual and chemical cues from conspecific

egg_hatching_NSW_popn

Egg hatching of Chironomus tepperi across a gradient of conductivitie

larval_growth_analysis

Growth of larval Chironomus tepperi in different conductivitie

Data from: The influence of potential stressors on oviposition site selection and subsequent growth, survival and emergence of the non-biting midge (Chironomus tepperi)

Theory predicts that animals should prefer habitats where their fitness is maximized but some mistakenly select habitats where their fitness is compromised, that is, ecological traps. Understanding why this happens requires knowledge of the habitat selection cues animals use, the habitats they prefer and why, and the fitness costs of habitat selection decisions. We conducted experiments with a freshwater insect, the non‐biting midge Chironomus tepperi to ask: (a) whether females respond to potential oviposition cues, (b) to explore whether oviposition is adaptive in relation to metal pollution and conductivity, and (c) whether individuals raised in poor quality sites are more likely to breed in similarly poor locations. We found the following: (a) females responded to some cues, especially conductivity and conspecifics, (b) females preferred sites with higher concentrations of bioavailable metals but suffered no consequences to egg/larval survival, (c) females showed some avoidance of high conductivities, but they still laid eggs resulting in reduced egg hatching, larval survival, and adult emergence, and (d) preferences were independent of natal environment. Our results show that C. tepperi is susceptible to ecological traps, depending on life stage and the relative differences in conductivities among potential oviposition sites. Our results highlight that (a) the fitness outcomes of habitat selection need to be assessed across the life cycle and (b) the relative differences in preference/suitability of habitats need to be considered in ecological trap research. This information can help determine why habitat preferences and their fitness consequences differ among species, which is critical for determining which species are susceptible to ecological traps

humic acid analysis

Oviposition of Chironomus tepperi in response to humic aci

larval_survival_analysis

Survival of larval Chironomus tepperi across different conductivitie