A multitude of biologically active pharmaceuticals contaminate surface waters globally, yet their presence in aquatic food webs remain largely unknown. Here, we show that over 60 pharmaceutical compounds can be detected in aquatic invertebrates and riparian spiders in six streams near Melbourne, Australia. Similar concentrations in aquatic invertebrate larvae and riparian predators suggest direct trophic transfer via emerging adult insects to riparian predators that consume them. As representative vertebrate predators feeding on aquatic invertebrates, platypus and brown trout could consume some drug classes such as antidepressants at as much as one-half of a recommended therapeutic dose for humans based on their estimated prey consumption rates, yet the consequences for fish and wildlife of this chronic exposure are unknown. Overall, this work highlights the potential exposure of aquatic and riparian biota to a diverse array of pharmaceuticals, resulting in exposures to some drugs that are comparable to human dosages.

Standardized ecotoxicological tests still constitute the fundamental tools when doing riskassessment of aquatic contaminants. These protocols are managed towards minimal mortality in the controls, which is not representative for natural systems where mortality is often high. This methodological bias, generated from assays where mortality in the control group is systematically disregarded, makes it difficult to measure therapeutic effects of pharmaceutical contaminants leading to lower mortality. This is of concern considering that such effects on exposed organisms still may have substantial ecological consequences. In this paper, we illustrate this conceptual problem by presenting empirical data for how the therapeutic effect of Oxazepam-a common contaminant of surface waters-lower mortality rates among exposed Eurasian perch (Perca fluviatilis) from wild populations, at two different life stages. We found that fry hatched from roe that had been exposed to dilute concentrations (1.1 ± 0.3 μg l −1 ) of Oxazepam for 24 h 3-6 days prior to hatching showed lower mortality rates and increased activity 30 days after hatching. Similar effects, i.e. increased activity and lower mortality rates were also observed for 2-year old perch exposed to dilute Oxazepam concentrations (1.2 ± 0.4 μg l −1 ). We conclude that therapeutic effects from pharmaceutical contaminants need to be considered in risk assessment assays to avoid that important ecological effects from aquatic contaminants are systematically missed.

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Production and human consumption of pharmaceuticals result in contamination of surface waters worldwide. Little is known about the long-term (i.e., over decades) fate of pharmaceuticals in aquatic systems. Here, we show that the most prescribed anxiolytic in Sweden (oxazepam) persists in its therapeutic form for several decades after being deposited in a large freshwater lake. By comparing sediment cores collected in 1995 and 2013, we demonstrate that oxazepam inputs from the early 1970s remained in the sediments until sampling in 2013, despite in situ degradation processes and sediment diagenesis. In laboratory and pond experiments, we further reveal that therapeutic forms of oxazepam can persist over several months in cold (5 °C) lake water free from UV light. We conclude that oxazepam can persist in lakes over a time scale much longer than previously realized and that levels can build up in lakes due to both a legacy of past inputs and a growing urban population.

Differences between individuals in behavioral type (i.e. animal personality) are ecologically and evolutionarily important because they can have significant effects on fitness components such as growth and predation risk. In the present study we ere used the invasive round goby (Neogobius melanostomus) from an established population in controlled experiments to examine the relationships among personality, metabolic performance, and growth rate (inferred as size-at-age). Boldness was measured as the time to return to normal behavior after a simulated predator attack, where fish with shorter freezing times were categorized as "bold" and fish with longer times were categorized as "shy". We show that bold fish have significantly higher standard metabolic rate (SMR) than their shy conspecifics, whereas there was no difference between personality types in their maximum metabolic rate (MMR) or aerobic scope (AS). Bold fish furthermore had a smaller size-at-age as compared to shy fish. Together this provides evidence of a metabolic underpinning of personality where the high-SMR bold fish require more resources to sustain basic life functions than their low-SMR shy conspecifics, indicating that bold round goby from established populations with high densities (and high competition for food) pay a price of reduced growth rate.