Holes in the tundra: Invasive earthworms alter soil structure and moisture in tundra soils.

Human introductions have resulted in earthworms establishing in the Arctic, species known to cause cascading ecosystem change. However, few quantitative outdoor experiments have been performed that describe how these soil modifying earthworms are reshaping structures in tundra soils. In this study, we used three-dimensional (3-D) X-ray images of soil cores (approximately 10 cm diameter, 20 cm height, N = 48) to assess how earthworms (Aporrectodea sp. and Lumbricus sp.) affect soil structure and macropore networks in an outdoor mesocosm experiment that lasted four summers. Effects were assessed in both shrub-dominated (heath) and herb-dominated (meadow) tundra. Earthworms almost doubled the macroporosity in meadow soils and tripled macroporosity in heath. Interestingly, the fractal dimension of macropores decreased in response to earthworm burrowing in both systems, indicating that the presence of earthworms reduced the geometric complexity in comparison to other pore-generating processes active in the tundra. Observed effects on soil structure occurred along with a dramatically reduced soil moisture content, which was observed the first winter after earthworm introduction in the meadow. Our findings suggest that predictions of future changes in vegetation and soil carbon pools in the Arctic should include major impacts on soil properties that earthworms induce.

Water temperature affects the biotransformation and accumulation of a psychoactive pharmaceutical and its metabolite in aquatic organisms.

Pharmaceutically active compounds (PhACs) have been shown to accumulate in aquatic and riparian food-webs. Yet, our understanding of how temperature, a key environmental factor in nature, affects uptake, biotransformation, and the subsequent accumulation of PhACs in aquatic organisms is limited. In this study, we tested to what extent bioconcentration of an anxiolytic drugs (temazepam and oxazepam) is affected by two temperature regimes (10 and 20 °C) and how the temperature affects the temazepam biotransformation and subsequent accumulation of its metabolite (oxazepam) in aquatic organisms. We used European perch (Perca fluviatilis) and dragonfly larvae (Sympetrum sp.), which represent predator and prey species of high ecological relevance in food chains of boreal and temperate aquatic ecosystems. Experimental organisms were exposed to target pharmaceuticals at a range of concentrations (0.2-6 µg L-1) to study concentration dependent differences in bioconcentration and biotransformation. We found that the bioconcentration of temazepam in perch was significantly reduced at higher temperatures. Also, temperature had a strong effect on temazepam biotransformation in the fish, with the production and subsequent accumulation of its metabolite (oxazepam) being two-fold higher at 20 °C compared to 10 °C. In contrast, we found no temperature dependency for temazepam bioconcentration in dragonfly larvae and no detectable biotransformation of the parent compound that would result in measurable concentrations of oxazepam in this organism. Our results highlight that while organisms may share the same aquatic ecosystem, their exposure to PhACs may change differently across temperature gradients in the environment.

Six common behavioral trials and their relevance for perch performance in natural lakes.

Behavioral traits measured in laboratory settings are commonly used when predicting ecological effects and evolutionary outcomes in natural systems. However, uncertainties regarding the relevance of simplified lab-based behavioral tests for complex natural environments have created doubts about the use of these tests within aquatic ecology and ecotoxicology. In this study, we scrutinize the assumption that fish performance in six commonly applied behavioral assays has relevance for in situ behavior, by comparing individual behavior tracked in both artificial laboratory settings as well as in two natural lakes. We show that: i) commonly measured behavioral traits of individual fish (Perca fluviatilis) have low predictive power for within-lake behaviors if interpreted alone, but that; ii) composite variables synthesized from several (six) behavioral assays explain important in situ measures such as swimming activity, dispersion, home-range size, and habitat preference. While our findings support recent criticisms against the use of single behavioral tests for predicting environmental effects, we provide empirical evidences suggesting that fish performances in multiple laboratory assays are highly relevant for fish behavior in nature.

Fish on steroids: Temperature-dependent effects of 17ß-trenbolone on predator escape, boldness, and exploratory behaviors.

Hormonal growth promoters (HGPs), widely used in beef cattle production globally, make their way into the environment as agricultural effluent-with potential impacts on aquatic ecosystems. One HPG of particular concern is 17ß-trenbolone, which is persistent in freshwater habitats and can affect the development, morphology and reproductive behaviors of aquatic organisms. Despite this, few studies have investigated impacts of 17ß-trenbolone on non-reproductive behaviors linked to growth and survival, like boldness and predator avoidance. None consider the interaction between 17ß-trenbolone and other environmental stressors, such as temperature, although environmental challenges confronting animals in the wild seldom, if ever, occur in isolation. Accordingly, this study aimed to test the interactive effects of trenbolone and temperature on organismal behavior. To do this, eastern mosquitofish (Gambusia holbrooki) were subjected to an environmentally-relevant concentration of 17ß-trenbolone (average measured concentration 3.0 ±â€¯0.2 ng/L) or freshwater (i.e. control) for 21 days under one of two temperatures (20 and 30 °C), after which the predator escape, boldness and exploration behavior of fish were tested. Predator escape behavior was assayed by subjecting fish to a simulated predator strike, while boldness and exploration were assessed in a separate maze experiment. We found that trenbolone exposure increased boldness behavior. Interestingly, some behavioral effects of trenbolone depended on temperature, sex, or both. Specifically, significant effects of trenbolone on male predator escape behavior were only noted at 30 °C, with males becoming less reactive to the simulated threat. Further, in the maze experiment, trenbolone-exposed fish explored the maze faster than control fish, but only at 20 °C. We conclude that field detected concentrations of 17ß-trenbolone can impact ecologically important behaviors of fish, and such effects can be temperature dependent. Such findings underscore the importance of considering the potentially interactive effects of other environmental stressors when investigating behavioral effects of environmental contaminants.

No evidence of increased growth or mortality in fish exposed to oxazepam in semi-natural ecosystems.

An increasing number of short-term laboratory studies on fish reports behavioral effects from exposure to aquatic contaminants or raised carbon dioxide levels affecting the GABAA receptor. However, how such GABAergic behavioral modifications (GBMs) impact populations in more complex natural systems is not known. In this study, we induced GBMs in European perch (Perca fluviatilis) via exposure to a GABA agonist (oxazepam) and followed the effects on growth and survival over one summer (70days) in replicated pond ecosystems. We hypothesized that anticipated GBMs, expressed as anti-anxiety like behaviors (higher activity and boldness levels), that increase feeding rates in laboratory assays, would; i) increase growth and ii) increase mortality from predation. To test our hypotheses, 480 PIT tagged perch of known individual weights, and 12 predators (northern pike, Esox lucius) were evenly distributed in 12 ponds; six control (no oxazepam) and six spiked (15.5±4µgl-1 oxazepam [mean±1S.E.]) ponds. Contrary to our hypotheses, even though perch grew on average 16% more when exposed to oxazepam, we found no significant difference between exposed and control fish in growth (exposed: 3.9±1.2g, control: 2.9±1g [mean±1S.E.], respectively) or mortality (exposed: 26.5±1.8individuals pond-1, control: 24.5±2.6individuals pond-1, respectively). In addition, we show that reduced prey capture efficiency in exposed pike may explain the lack of significant differences in predation. Hence, our results suggest that GBMs, which in laboratory studies impact fish behavior, and subsequently also feeding rates, do not seem to generate strong effects on growth and predation-risk in more complex and resource limited natural environments.

Bioaccumulation of five pharmaceuticals at multiple trophic levels in an aquatic food web - Insights from a field experiment.

Pharmaceuticals derived from manufacturing and human consumption contaminate surface waters worldwide. To what extent such pharmaceutical contamination accumulates and disperses over time in different compartments of aquatic food webs is not well known. In this study we assess to what extent five pharmaceuticals (diphenhydramine, oxazepam, trimethoprim, diclofenac, and hydroxyzine) are taken up by fish (European perch) and four aquatic invertebrate taxa (damselfly larvae, mayfly larvae, waterlouse, and ramshorn snail), by tracing their bioconcentrations over several months in a semi-natural large-scale (pond) system. The results suggest both significant differences among drugs in their capacity to bioaccumulate and differences among species in uptake. While no support for in situ uptake of diclofenac and trimethoprim was found, oxazepam, diphenhydramine, and hydroxyzine were detected in all analyzed species. Here, the highest bioaccumulation factor (tissue:water ratio) was found for hydroxyzine. In the food web, the highest concentrations were found in the benthic species ramshorn snail and waterlouse, indicating that bottom-living organism at lower trophic positions are the prime receivers of the pharmaceuticals. In general, concentrations in the biota decreased over time in response to decreasing water concentrations. However, two interesting exceptions to this trend were noted. First, mayfly larvae (primarily grazers) showed peak concentrations (a fourfold increase) of oxazepam, diphenhydramine, and hydroxyzine about 30days after initial addition of pharmaceuticals. Second, perch (top-predator) showed an increase in concentrations of oxazepam throughout the study period. Our results show that drugs can remain bioavailable for aquatic organism for long time periods (weeks to months) and even re-enter the food web at a later time. As such, for an understanding of accumulation and dispersion of pharmaceuticals in aquatic food webs, detailed ecological knowledge is required.

Large difference in carbon emission ­ burial balances between boreal and arctic lakes.

Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths and control of these fundamentally different pathways are therefore of interest when assessing the continental C balance and its response to environmental change. In this study, based on new high-resolution estimates in combination with literature data, we show that annual emission:burial ratios are generally ten times higher in boreal compared to subarctic - arctic lakes. These results suggest major differences in lake C cycling between biomes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Such effects are of major importance for understanding climatic feedbacks on the continental C sink - source function at high latitudes. If predictions of global warming and northward expansion of the boreal biome are correct, it is likely that increasing C emissions from high latitude lakes will partly counteract the presumed increasing terrestrial C sink capacity at high latitudes.

Long-Term Persistence of an Anxiolytic Drug (Oxazepam) in a Large Freshwater Lake.

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.

Antihistamines and aquatic insects: bioconcentration and impacts on behavior in damselfly larvae (Zygoptera).

Because aquatic insects use histamines as neurotransmitters, adverse impacts on aquatic insects living in aquatic environments that receive antihistamines with wastewater effluent are plausible. In this study, we exposed damselfly larvae to low concentrations of two commonly used antihistamines (Hydroxyzine and Fexofenadine, 360 ± 42 and 2,200 ± 43 ng l(-1), respectively), and recorded damselfly larvae behavior before and after exposure. Further, after the second set of behavioral assays was performed, we quantified bioconcentration of the antihistamines in the damselfly bodies. Our results showed significant changes in damselfly behavior following antihistamine exposure. After Hydroxyzine exposure, the damselfly larvae became less active, and they showed reduced fleeing response (i.e. increased boldness) after being exposed to Fexofenadine, the latter also being significantly different from the non-exposed (control) individuals. Further, we found high levels of bioconcentration in the damselflies; Hydroxyzine showed an average bioconcentration factor (BCF) of 2000. As such, our results indicate that low concentrations of antihistamines can have sub-lethal effects on aquatic insects manifested as behavioral changes, and that bioconcentration of these substances can be high. Therefore, the need to investigate the impact of emergent aquatic contaminants also on aquatic insects, and on behaviors that are of ecological importance, is further highlighted.

Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations.

Environmental pollution by pharmaceuticals is increasingly recognized as a major threat to aquatic ecosystems worldwide. A variety of pharmaceuticals enter waterways by way of treated wastewater effluents and remain biochemically active in aquatic systems. Several ecotoxicological studies have been done, but generally, little is known about the ecological effects of pharmaceuticals. Here we show that a benzodiazepine anxiolytic drug (oxazepam) alters behavior and feeding rate of wild European perch (Perca fluviatilis) at concentrations encountered in effluent-influenced surface waters. Individuals exposed to water with dilute drug concentrations (1.8 micrograms liter(-1)) exhibited increased activity, reduced sociality, and higher feeding rate. As such, our results show that anxiolytic drugs in surface waters alter animal behaviors that are known to have ecological and evolutionary consequences.