Behavioural effects of temperature, predation-risk and anxiolytic exposure on the European perch (Perca fluviatilis)

• 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.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

Behavioural ecotoxicology

Benzodiazepines

Freshwater fish

Multiple stressors

Scototaxis

ekotoxikologi

Ecotoxicology

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