1. Predators affect prey by killing them directly (lethal effects) and by inducing costly antipredator behaviours in living prey (risk effects). Risk effects can strongly influence prey populations ...and cascade through trophic systems. A prerequisite for assessing risk effects is characterizing the spatiotemporal variation in predation risk. 2. Risk effects research has experienced rapid growth in the last several decades. However, preliminary assessments of the resultant literature suggest that researchers characterize prédation risk using a variety of techniques. The implications of this methodological variation for inference and comparability among studies have not been well recognized or formally synthesized. 3. We couple a literature survey with a hierarchical framework, developed from established theory, to quantify the methodological variation in characterizing risk using carnivore-ungulate systems as a case study. Via this process, we documented 244 metrics of risk from 141 studies falling into at least 13 distinct subcategories within three broader categories. 4. Both empirical and theoretical work suggest risk and its effects on prey constitute a complex, multi-dimensional process with expressions varying by spatiotemporal scale. Our survey suggests this multi-scale complexity is reflected in the literature as a whole but often underappreciated in any given study, which complicates comparability among studies and leads to an overemphasis on documenting the presence of risk effects rather than their mechanisms or scale of influence. 5. We suggest risk metrics be placed in a more concrete conceptual framework to clarify inference surrounding risk effects and their cascading effects throughout ecosystems. We recommend studies (i) take a multi-scale approach to characterizing risk; (ii) explicitly consider 'true' predation risk (probability of prédation per unit time); and (iii) use risk metrics that facilitate comparison among studies and the evaluation of multiple competing hypotheses. Addressing the pressing questions in risk effects research, including how, to what extent and on what scale they occur, requires leveraging the advantages of the many methods available to characterize risk while minimizing the confusion caused by variability in their application.
There is a large and growing interest in non‐consumptive effects (NCEs) of predators. Diverse and extensive evidence shows that predation risk directly influences prey traits, such as behaviour, ...morphology and physiology, which in turn, may cause a reduction in prey fitness components (i.e. growth rate, survival and reproduction). An intuitive expectation is that NCEs that reduce prey fitness will extend to alter population growth rate and therefore population size.
However, our intensive literature search yielded only 10 studies that examined how predator‐induced changes in prey traits translate to changes in prey population size. Further, the scant evidence for risk‐induced changes on prey population size have been generated from studies that were performed in very controlled systems (mesocosm and laboratory), which do not have the complexity and feedbacks of natural settings. Thus, although likely that predation risk alone can alter prey population size, there is little direct empirical evidence that demonstrates that it does. There are also clear reasons that risk effects on population size may be much smaller than the responses on phenotype and fitness components that are typically measured, magnifying the need to show, rather than infer, effects on population size.
Herein we break down the process of how predation risk influences prey population size into a chain of events (predation risk affects prey traits, which affect prey fitness components and population growth rate, which affect prey population size), and highlight the complexity of each transition. We illustrate how the outcomes of these transitions are not straightforward, and how environmental context strongly dictates the direction and magnitude of effects. Indeed, the high variance in prey responses is reflected in the variance of results reported in the few studies that have empirically quantified risk effects on population size. It is therefore a major challenge to predict population effects given the complexity of how environmental context interacts with predation risk and prey responses.
We highlight the critical need to appreciate risk effects at each level in the chain of events, and that changes at one level cannot be assumed to translate into changes in the next because of the interplay between risk, prey responses, and the environment. The gaps in knowledge we illuminate underscore the need for more evidence to substantiate the claim that predation risk effects extend to prey population size. The lacunae we identify should inspire future studies on the impact of predation risk on population‐level responses in free‐living animals.
A widespread assumption is that predation risk can reduce prey population size via non‐consumptive effects. However, the authors intensive literature search yielded only 10 studies that examined a risk–population size relationship. These studies found that risk may positively, negatively or neutrally alter prey population size.
Paroxetine (PAR) is a selective serotonin reuptake inhibitor (SSRI) antidepressant increasingly detected in surface waters worldwide. Its environmental presence raises concerns about the potential ...detrimental effects on non-target organisms. Thus, this study aimed to increase knowledge on PAR's potential environmental impacts, assessing the effects of commercial formulation (PAR-c) and active ingredient (PAR-a) on fish. Therefore, the short-term exposure effects of PAR-c and PAR-a were assessed on zebrafish (Danio rerio) embryos/larvae to determine the most toxic formulation through median lethal (LC50) and effective concentrations (EC50). PAR-c and PAR-a induced morphological abnormalities (scoliosis) in a dose-dependent manner from 96 hours post-fertilization onwards, suggesting the involvement of a fully functional biotransformation system. As PAR-c exhibited higher toxicity, it was selected to be tested in the subsequent stage (juvenile stage), which was more sensitive (lower LC50). PAR-c significantly decreased fish swimming activity and disrupted fish stress response. Overall, the results highlight the ability of PAR-c to adversely affect fish swimming performance, an effect that persisted even after exposure ceases (21-day depuration), suggesting that PAR-c may impair individual fitness.
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•Paroxetine active ingredient (PAR-a) and commercial formulation (PAR-c) toxicities were studied.•PAR-c was more toxic to Danio rerio's early and young life stages than PAR-a.•D. rerio juvenile stage was the most sensitive.•Acute exposure to PAR-c has long-lasting effects on fish behaviour.
Summary
With climate change, heat waves are becoming increasingly frequent, intense and broader in spatial extent. However, while the lethal effects of heat waves on humans are well documented, the ...impacts on flora are less well understood, perhaps except for crops. We summarize recent findings related to heat wave impacts including: sublethal and lethal effects at leaf and plant scales, secondary ecosystem effects, and more complex impacts such as increased heat wave frequency across all seasons, and interactions with other disturbances. We propose generalizable practical trials to quantify the critical bounding conditions of vulnerability to heat waves. Collectively, plant vulnerabilities to heat waves appear to be underappreciated and understudied, particularly with respect to understanding heat wave driven plant die‐off and ecosystem tipping points.
Novel insecticides are continuously being developed for application in response to increased legal restriction of previously developed insecticides and resistance in target insects. These novel ...insecticides, such as flupyradifurone (FPF), remain relatively untested on non‐target organisms, including bumblebees. Further, existing tests on honeybees tend to focus on adult mortality and thus sub‐lethal effects, such as impacts on reproductive output, are neglected, despite their importance for population‐level impacts.
To address if the novel insecticide FPF has sub‐lethal effects on bumblebee reproduction and behaviour, we established microcolonies and chronically exposed them to field‐realistic concentrations over a 14‐day period.
We found that exposure to FPF reduced the bumblebees' reproductive output in terms of the number of larvae produced and the mean mass of each larval instar. FPF‐treated bees also stored less sucrose and constructed fewer honeypots. However, adult bumblebee mortality was similar between control and FPF‐exposed microcolonies.
Our results show that field‐realistic FPF exposure leads to increased larval mortality and/or delayed larval development, as well as reduced nectar storage, without affecting adult mortality.
Policy implications. Insecticides that impair bumblebee reproduction can have long‐term population‐level consequences, even if adult bees do not experience increased mortality. Despite this fact, sub‐lethal effects, such as impacts on reproduction, are not mandatorily assessed within the regulatory process. Our findings highlight the importance of determining sub‐lethal effects of pesticides across developmental stages, as well as using pollinator species other than honeybees within the regulatory process.
Insecticides that impair bumblebee reproduction can have long‐term population‐level consequences, even if adult bees do not experience increased mortality. Despite this fact, sub‐lethal effects, such as impacts on reproduction, are not mandatorily assessed within the regulatory process. Our findings highlight the importance of determining sub‐lethal effects of pesticides across developmental stages, as well as using pollinator species other than honeybees within the regulatory process.
The presence of microplastics (MPs) in the environment has raised many concerns, and therefore approaches and technologies to remove them in situ are of high interest. In this context, we ...investigated the interactions between polyethylene MPs (fragments with a mean size of 149 ± 75 μm) and an aquatic floating macrophyte Lemna minor in order to assess its potential use for in situ phytoremediation. We first investigated the long-term effects of a high (100 mg/L = 9600 MPs/L), but still environmentally relevant concentration of MPs on L. minor. Subsequently bioadhesion of MPs was studied and the number and strength of MPs adhering to plant biomass were assessed. MPs did not adversely affect various parameters of plants (e.g., specific growth rate, chlorophyll contents, total antioxidant capacity, electron transport system activity, and contents of energy-rich molecules) throughout the duration of the experiment (12 weeks), except for the first week of the experiment, when protein content and total antioxidant capacity were affected. On the other hand, MPs affected the root length of L. minor during the first eight weeks of the experiment, while further exposure resulted in a decrease in the effects, indicating the ability of L. minor to tolerate the presence of MPs for a long period of time. MPs adhered rapidly to the plant biomass and the average percentages of strongly and weakly adhered particles were 6.5% and 20.0%, respectively, of the total MPs applied. In summary, results of this study suggest that L. minor can tolerate hotspot concentrations of MPs and can collect MPs from the water surface. Therefore, phytoremediation using floating plants could be considered as a potential method for in situ removal of MPs from the aquatic environment.
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•Microplastics (MPs) adhere to the biomass of Lemna minor.•MPs have no significant effect on Lemna minor growth over a 12-week period.•6.5% and 20.0% of all MPs are strongly and weekly adhered, respectively.•Phytoremediation could be used to remove MPs from the aquatic environment.
Diclofenac sodium, a non‐steroidal anti‐inflammatory drug widely used in both human and veterinary medicine, has been detected in aquatic environments; therefore, its ecotoxicological effects on ...aquatic organisms need to be clarified. Recently, toxicity testing using zebrafish (Danio rerio) embryos has been recommended from the point of view of animal welfare; therefore, we investigated the suitability of using sub‐lethal endpoints observed during embryogenesis for predicting lethal effects in early life stage zebrafish exposed to diclofenac sodium. After exposure to diclofenac sodium (0.4‐7.0 mg/L) from 2 hours post‐fertilization to 30 days post‐hatching, abnormal embryogenesis, characterized by the presence of edema and body curvature, was observed in the 7.0 mg/L exposure group but not in any other groups including controls. The body curvature was found to be the result of abnormal development of the spine. All abnormal embryos hatched without delay, but died within 1 week after hatching, suggesting that the combination of the sub‐lethal endpoints of edema and abnormal development of the spine during embryogenesis may predict lethal effects in early life stage zebrafish exposed to diclofenac sodium. Further investigations to verify these findings are needed. The value of the no observed effect concentrations for the embryogenesis, survival and growth endpoints were 3.5, 1.8 and >3.5 mg/L, respectively.
We investigated the suitability of using sub‐lethal endpoints observed during embryogenesis for predicting lethal effects in early life stage zebrafish exposed to diclofenac sodium (0.4‐7.0 mg/L). In the 7.0 mg/L exposure group, edema and abnormal development of the spine were observed. All abnormal embryos hatched without delay but died within 1 week after hatching, suggesting that the sub‐lethal combination of edema and abnormal development of the spine during embryogenesis may predict lethal effects in early life stage zebrafish exposed to diclofenac sodium.
Pharmaceuticals such as non-steroidal anti-inflammatory drugs (NSAIDs) have been found in the marine environment. Although there is a large body of evidence that pharmaceutical drugs exert negative ...impacts on aquatic organisms, especially in the freshwater compartment, only limited studies are available on bioconcentration and the effects of NSAIDs on marine organisms. Bivalves have a high ecological and socio-economic value and are considered good bioindicator species in ecotoxicology and risk assessment programs. Therefore, this review summarizes current knowledge on the bioconcentration and the effects of three widely used NSAIDs, diclofenac, ibuprofen and paracetamol, in marine bivalves exposed under laboratory conditions. These pharmaceutical drugs were chosen based on their environmental occurrence both in frequency and concentration that may warrant their inclusion in the European Union Watch List. It has been highlighted that ambient concentrations may result in negative effects on wild bivalves after long-term exposures. Also, higher trophic level organisms may be more impacted due to food-chain transfer (e.g., humans are shellfish consumers). Overall, the three selected NSAIDs were reported to bioconcentrate in marine bivalves, with recognized effects at different life-stages. Immune responses were the main target of a long-term exposure to the drugs. The studies selected support the inclusion of diclofenac on the European Union Watch List and highlight the importance of extending research for ibuprofen and paracetamol due to their demonstrated negative effects on marine bivalves exposed to environmental realistic concentrations, under laboratory conditions.
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•NSAIDs, some included in the Watch List, are of concern in the marine environment.•Studies on bioconcentration and effects of NSAIDs on marine organisms are limited.•NSAIDs accumulated by marine bivalves, showed mainly sub-lethal effects.•Immune responses are the main target of long-term exposure to NSAIDs.
Abstract Although pesticide-free techniques have been developed in agriculture, pesticides are still routinely used against weeds, pests, and pathogens worldwide. These agrochemicals pollute the ...environment and can negatively impact human health, biodiversity and ecosystem services. Acetamiprid, an approved neonicotinoid pesticide in the EU, may exert sub-lethal effects on pollinators and other organisms. However, our knowledge on the scope and severity of such effects is still incomplete. Our experiments focused on the effects of the insecticide formulation Mospilan (active ingredient: 20% acetamiprid) on the peripheral olfactory detection of a synthetic floral blend and foraging behaviour of buff-tailed bumblebee ( Bombus terrestris ) workers. We found that the applied treatment did not affect the antennal detection of the floral blend; however, it induced alterations in their foraging behaviour. Pesticide-treated individuals started foraging later, and the probability of finding the floral blend was lower than that of the control bumblebees. However, exposed bumblebees found the scent source faster than the controls. These results suggest that acetamiprid-containing Mospilan may disrupt the activity and orientation of foraging bumblebees. We hypothesize that the observed effects of pesticide exposure on foraging behaviour could be mediated through neurophysiological and endocrine mechanisms. We propose that future investigations should clarify whether such sub-lethal effects can affect pollinators’ population dynamics and their ecosystem services.
Two million tonnes of pesticides are currently used globally to improve crop production, yet these pesticides induce adverse effects on soil quality and biodiversity. Moreover, less than 1% of ...pesticides reach the target pests, while the rest contaminate the surrounding environment. In particular, earthworms are exposed to pesticides and are thus an ideal biological model for ecotoxicological research. Here, we review acute and sub-lethal effects of pesticides on earthworms. We found that pesticides alter growth, reproduction, behaviour, essential enzymes, and DNA of earthworms, even at low pesticide concentrations. These sub-lethal biomarkers allow to evaluate the overall response of an earthworm to pesticides, and to identify the risk for other non-target organisms.
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