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Behavioural effects of temperature, predation-risk and anxiolytic exposure on the European perch (Perca fluviatilis)
School of Biological Sciences, Monash University, Victoria, Australia. Department of Biosciences, Åbo Akademi University, Turku, Finland..
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
School of Biological Sciences, Monash University, Victoria, Australia..
Umeå University, Faculty of Science and Technology, Department of Chemistry.
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2018 (English)Manuscript (preprint) (Other academic)
Abstract [en]

With the ability to resist biodegradation and exert therapeutic effects at low concentrations, emerging contaminants have become environmental stressors for wildlife. One such contaminant is the anxiolytic oxazepam, a psychoactive pharmaceutical which is frequently detected in surface waters globally. Despite the growing interest in understanding how wildlife responds to such contaminants, the synergistic fitness effects of pharmaceuticals and increased variability in temperature remain unclear. Here, by using a multi-stressor approach, we investigated the effects of 7-d oxazepam exposure (6.5 μg/L) on anxiety-related behaviours in juvenile European perch (Perca fluviatilis). The multi-stressor approach was achieved by exposing perch to oxazepam at either low (10°C) or high (18°C) temperature, with or without a predation cue, generating 8 treatments. Our exposures resulted in a successful uptake of the drug from the water, i.e. oxazepam was measured at muscle tissue concentrations around 50 ± 17 ng/g (mean ± SD). We found significant effects on boldness induced by the studied drug: 92.8% of the fish in the 'oxazepam and predation and high temperature' treatment entered the white background (representing a novel area where exposure to presumed risks are higher) within the first 5 min, compared to 79.3% of the 'control and predation and high temperature' fish. We also found a significant effect on temperature on the total time freezing (i.e. staying motionless). Specifically, fish in the low temperature treatments (oxazepam, predation and control) froze for longer than fish in the high temperatures, respectively. Our study is the first to show altered anxiety-related behaviours in a native juvenile fish resulting from oxazepam, predation and high temperature. As adaptation to a range of biotic and abiotic pressures is essential to living organisms, our study highlights the need to focus on multiple stressors to improve understanding of how organisms not only survive, but adapt to human-induced environmental change.

Place, publisher, year, edition, pages
2018.
Keywords [en]
Behavioural ecotoxicology, Benzodiazepines, Freshwater fish, Multiple stressors, Scototaxis
National Category
Environmental Sciences
Research subject
Ecotoxicology
Identifiers
URN: urn:nbn:se:umu:diva-151126OAI: oai:DiVA.org:umu-151126DiVA, id: diva2:1242428
Available from: 2018-08-28 Created: 2018-08-28 Last updated: 2018-08-28
In thesis
1. Fish on drugs: behaviour modifying contaminants in aquatic ecosystems
Open this publication in new window or tab >>Fish on drugs: behaviour modifying contaminants in aquatic ecosystems
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Contamination of surface waters is a worldwide problem. One group of emerging contaminants that reach aquatic ecosystems via sewage treatment plant effluents and agricultural run-offs is pharmaceuticals. Impacts of pharmaceuticals on the behaviour of aquatic organisms can have important ecological and evolutionary consequences because behaviour is directly linked to fitness. The aim of my doctoral thesis was to increase our understanding of the fate and effects of behaviour modifying drugs in aquatic ecosystems.

While studying an aquatic ecosystem spiked with pharmaceuticals, I found that the benthic species at the bottom of the food chain were the main receivers (highest bioaccumulation factor; BAF) while fish at the top of the food web had the lowest uptake of the studied drugs. Interestingly, the BAF of the anxiolytic pharmaceutical oxazepam, increased in fish (perch; Perca fluviatilis) over the study period, suggesting that this drug can be transferred between trophic levels in food webs. To assess whether oxazepam could affect growth and survival in perch, I exposed perch populations to oxazepam for 2-months in a replicated pond experiment. In this study, I tested the hypothesis that oxazepam exposed perch would grow faster but also suffer from increased predation. Oxazepam has been shown previously to induce ‘anti-anxiety’ behaviours that improve foraging but may also make individuals more exposed to predators. In contrast, I found no statistically significant increase in growth and mortality in the exposed perch. However, the study revealed that the natural predator of perch (pike; Esox lucius) became less effective at catching prey when exposed to oxazepam. This exposure effect on predation efficiency likely contributed to the absence of predation effects in the exposed ponds. In two following laboratory studies I investigated effects of behaviour modifying drugs (oxazepam and a growth hormone, 17β-trenbolone) in combination with additional stressors (temperature and predator cues). Drug and temperature interactions were found for 17β-trenbolone, where water temperature interacted with treatment to induce changes in predator escape behaviour, boldness, and exploration in mosquitofish (Gambusia holbrooki). However, in the other study, we found that oxazepam, temperature, and predator cue all affected perch ‘anti-anxiety’ behaviours, but independently.

I conclude that pharmaceuticals can alter ecologically important behaviours in fish, and that at least some, can accumulate in aquatic food webs. It seems that in situ effects of behaviour modifying drugs in aquatic ecosystems depend on both species-specific responses and abiotic interactions. As such, it is far from straightforward to predict net ecosystem effects based on experiments conducted using single species and static conditions. Future studies should assess the effects of pharmaceuticals in aquatic ecosystems under more complex conditions for us to gain a better understanding of what consequences behaviour modifying drugs have in the environment.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2018. p. 33
Keywords
Aquatic ecosystems, Behavioural effects, Ecotoxicology, Endocrine disruptors, Pharmaceuticals, Interaction effects
National Category
Environmental Sciences
Research subject
Ecotoxicology
Identifiers
urn:nbn:se:umu:diva-151138 (URN)978-91-7601-912-2 (ISBN)
Public defence
2018-09-21, Lilla Hörsalen, KB.E3.01, KBC-huset, Umeå, 12:00 (English)
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Available from: 2018-08-31 Created: 2018-08-28 Last updated: 2018-08-30Bibliographically approved

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Lagesson, AnnelieKlaminder, JonatanBrodin, Tomas

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