Search

Since their introduction to North America in the 1980s, research to develop effective control tools for invasive mussels (Dreissena polymorpha and D. rostriformis bugensis) has been ongoing across various research institutions using a range of testing methods. Inconsistencies in experimental methods and reporting present challenges for comparing data, repeating experiments, and applying results. The Invasive Mussel Collaborative established the Toxicity Testing Work Group (TTWG) in 2019 to identify "best practices" and guide development of a standard framework for dreissenid mussel toxicity testing protocols. We reviewed the literature related to laboratory‐based dreissenid mussel toxicity tests and determined the degree to which standard guidelines have been used and their applicability to dreissenid mussel testing. We extracted detailed methodology from 99 studies from the peer‐reviewed and gray literature and conducted a separate analysis for studies using presettlement and postsettlement mussels. We identified specific components of methods and approaches that could be refined or standardized for dreissenid mussels. These components included species identification, collection methods, size/age class distinction, maintenance practices, testing criteria, sample size, response measures, reporting parameters, exposure methods, and mortality criteria. We consulted experts in the field of aquatic toxicology and dreissenid mussel biology on our proposed. The final recommendations contained in the present review are based on published standard guidelines, methods reported in the published and gray literature, and the expertise of TTWG members and an external panel. In addition, our review identifies research needs for dreissenid mussel testing including improved methods for early–life stage testing, comparative data on life stages and between dreissenid mussel species, inclusion of a reference toxicant, and additional testing of nontarget species (i.e., other aquatic organisms). Environ Toxicol Chem 2023;42:1649–1666. © 2023 His Majesty the King in Right of Canada. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Efforts to make research environments more inclusive and diverse are beneficial for the next generation of Great Lakes researchers. The global COVID-19 pandemic introduced circumstances that forced graduate programs and academic institutions to re-evaluate and promptly pivot research traditions, such as weekly seminar series, which are critical training grounds and networking opportunities for early career researchers (ECRs). While several studies have established that academics with funded grants and robust networks were better able to weather the abrupt changes in research and closures of institutions, ECRs did not. In response, both existing and novel partnerships provided a resilient network to support ECRs at an essential stage of their career development. Considering these challenges, we sought to re-frame the seminar series as a virtual collaboration for ECRs. Two interdisciplinary graduate programs, located in different countries (Windsor, Canada, and Detroit, USA) invested in a year-long partnership to deliver a virtual-only seminar series that intentionally promoted: the co-creation of protocols and co-led roles, the amplification of justice, equity, diversity and inclusion throughout all aspects of organization and representation, engagement and amplification through social media, the integration of social, scientific and cultural research disciplines, all of which collectively showcased the capacity of our ECRs to lead, organize and communicate. This approach has great potential for application across different communities to learn through collaboration and sharing, and to empower the next generation to find new ways of working together. [ABSTRACT FROM AUTHOR]

Urban settings, where >50% of the world's population resides, are increasingly faced with environmental challenges that threaten their sustainability. Aging infrastructure, water and air pollution, and increasing recognition of environmental injustices highlight the need for professionals to employ complex scientific reasoning across disciplines where they can effectively address the multifaceted issues of urban sustainability. Here we present an innovative model for preparing the next generation of public, private, and academic leaders to address complex problems in urban sustainability. Specifically, we outline the design and implementation of an integrated, adaptable graduate training program, with the goals of science leadership, curriculum relevancy, community impact, broader applicability, establishing a career development pathway in science, technology, engineering, and mathematics (STEM) programs, and program sustainability. This program addresses human‐ecosystem challenges using a transdisciplinary approach to produce scientific products in partnership with local communities, businesses, industries, scientists, and policy makers, while providing a mechanism to understand and overcome contemporary societal and ecological challenges. Students receive rigorous training in their home disciplines, coupled with training across disciplinary lines and developmental experiences, to prepare them to communicate, collaborate, and innovate in a variety of contexts. Training success is evaluated across measurable competency domains including problem definition, research methods, communication, collaboration, and problem‐solving. After 3 years the program expanded relationships across fields and professions, successfully established 18 internship opportunities with community partners, created a new dual‐title PhD program open to students in five academic departments, and facilitated the coproduction of knowledge with external partners. This model bridges the gaps between research, education, and application, providing an integrated, rigorous graduate training program that fosters collaborative problem‐solving between STEM graduate students and the broader community of professionals conducting sustainability work in a postindustrial urban setting. [ABSTRACT FROM AUTHOR]

Quagga mussels (Dreissena rostriformis burgensis) are a highly invasive aquatic species to North America, capable of filtering large volumes of water and causing severe ecological and economic impacts. Their range has been expanding since they first invaded the Great Lakes in the 1980s. To predict their spread, it is crucial to understand environmental parameters, which facilitate their range expansion. Two factors likely to influence their distribution include calcium and temperature, because the former is vital for shell development and the latter for metabolic activity. When these factors are optimal for mussels' fitness, the filtration rate has the potential to be maximized if other environmental conditions are also favorable, thus enabling mussels to exploit their growth potential. Deviations from optimal conditions likely result in filtration‐rate decline. We identify calcium concentrations and temperatures that maximize the mussel filtration rate for 2 phytoplankton species: Ankistrodesmus facaltus, a common food source for quagga mussels, and a less palatable Microcystis icthyoblabe. In laboratory experiments, filtration rates were measured through cell counts after 24 h of filtration when exposed to a range of temperatures between 2 and 30 °C, and calcium concentrations between 0 and 180 mg/L. Response surface methodology was used to identify a maximum filtration rate, which occurred at 22 mL/mg/h at 137 mg/L of calcium carbonate and 26 °C when fed Ankistrodesmus. To establish a quagga mussel population in a new water source, optimum conditions are required; thus, this information can be used to rank the relative susceptibility of water bodies to invasion by quagga mussels. Environ Toxicol Chem 2020;39:410–418. © 2019 SETAC [ABSTRACT FROM AUTHOR]

The temporal expansion of harmful algal blooms, primarily associated with cyanobacteria, may impact aquatic organisms at vulnerable life‐history stages. Broadcast spawning species release gametes into the water column for external fertilization, directly exposing sperm to potential aquatic stressors. To determine if cyanobacteria can disrupt reproduction in freshwater broadcast spawners, we evaluated sublethal effects of cyanobacteria exposure on quagga mussel (Dreissena rostriformis bugensis) sperm. In laboratory studies, sperm were collected after inducing mussels to spawn using serotonin and exposed to 11 cultures of cyanobacteria including Anabaena flos‐aquae, Aphanizomenon flos‐aquae, Dolichospermum lemmermannii, Gloeotrichia echinulata, 5 cultures of Microcystis aeruginosa, M. wesenbergii, and Planktothrix suspensa. Sperm motility, using endpoints of cumulative distance traveled and mean velocity, was calculated for a minimum of 10 individual sperm using a novel optical biotracking assay method. The distance and velocity at which sperm traveled decreased when exposed to Aphanizomenon flos‐aquae and 2 M. aeruginosa cultures. Our findings indicate that cyanobacteria impede the motility of quagga mussel sperm, which can potentially result in reproductive impairments to mussels and potentially other broadcast spawning species. Environ Toxicol Chem 2019;38:368–374. © 2018 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Dreissenid mussels Dreissena bugensis (quagga mussel) and Dreissena polymorpha (zebra mussel) are prolific invasive species to the freshwaters of the United States and Western Europe. In the Great Lakes, D. polymorpha has initially dominated the system since its invasion in the mid‐1980s; however, recently D. bugensis has displaced D. polymorpha as the dominant species. Dreissena bugensis has several competitive advantages over D. polymorpha, including greater tolerances to deeper and colder waters and lower respiration rates. Nevertheless, physiological differences between the species remain largely unknown. The oxidative stress response is a mechanism used by all organisms to mitigate environmental stress by reducing oxygen radicals in the body, and comparing this mechanism between similar species can be useful for understanding how different species compete in aquatic environments. We compared oxidative stress biomarkers (lipid peroxidation [LPO] and catalase [CAT] activity) in mussels after exposure to 4 stressors (i.e., high densities, temperature, hypoxia, and polychlorinated biphenyls [PCBs]) independently and in combinations of 2 stressors. Overall, D. bugensis had lower LPO and CAT activity than D. polymorpha when exposed to single stressors; however, in multiple stressor treatments D. bugensis had increased LPO, especially with high temperatures and PCBs. The lower lipid damage in D. bugensis compared with D. polymorpha under single stressor conditions may come at the cost of the ability to respond to multiple stressors. Environ Toxicol Chem 2018;37:1643–1654. © 2018 SETAC [ABSTRACT FROM AUTHOR]

A thorough assessment of aquatic nonindigenous species' risk facilitates successful monitoring and prevention activities. However, species- and vector-specific information is often limited and difficult to synthesize across a single risk framework. To address this need, we developed an assessment framework capable of estimating the potential for introduction, establishment, and impact by aquatic nonindigenous species from diverse spatial origins and taxonomic classification, in novel environments. Our model builds on previous approaches, while taking on a new perspective for evaluation across species, vectors and stages to overcome the limitations imposed by single species and single vector assessments. We applied this globally-relevant framework to the Laurentian Great Lakes to determine its ability to evaluate risk across multiple taxa and vectors. This case study included 67 aquatic species, identified as “watchlist species" in NOAA's Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS). Vectors included shipping, hitchhiking/fouling, unauthorized intentional release, escape from recreational or commercial culture, and natural dispersal. We identified potential invaders from every continent but Africa and Antarctica. Of the 67 species, more than a fifth (21%) had a high potential for introduction and greater than 60% had a moderate potential for introduction. Shipping (72%) was the most common potential vector of introduction, followed by unauthorized intentional release (25%), hitchhiking/fouling (21%), dispersal (19%), stocking/planting/escape from recreational culture (13%), and escape from commercial culture. The ability to assess a variety of aquatic nonindigenous species from an array of potential vectors using a consistent methodology is essential for comparing likelihoods of introduction, establishment, and impact. The straightforward design of this framework will allow its application and modification according to policy priorities by natural resource managers. The ability to use a variety of information sources facilitates completion of assessments despite the paucity of data that often plagues aquatic nonindigenous species management. [ABSTRACT FROM AUTHOR]

Natural variation in the structure and function of aquatic communities along environmental or spatiotemporal gradients can influence how systems respond to biotic and abiotic disturbances. Although these context-dependent responses are a well-established element of basic ecology, they have received little attention from an ecotoxicological perspective., As the scope of freshwater bioassessment expands from single catchments to broad-scale, regional surveys, it has become apparent that community responses to contaminants can vary significantly among locations. This variability is generally considered a nuisance and an impediment to recognising ecological patterns; however, natural spatiotemporal variation in communities also provides opportunities to test hypotheses about context-dependent responses to contaminants in aquatic ecosystems., This study presents three examples of context-dependent responses of benthic stream communities to contaminants. We show how longitudinal variation in community composition, the development of tolerance to contaminants and exposure to multiple stressors influence the historical context of a community and hence may determine community responses to contaminants., Aquatic ecotoxicologists have made significant progress identifying abiotic factors that influence contaminant bioavailability and toxicity. A similar effort could be undertaken to identify specific ecological factors (e.g. community composition, natural disturbance regimes and life-history characteristics) that contribute to variation in susceptibility of communities to contaminants. Understanding the nature of context-dependent responses and the mechanisms responsible for variation among communities should be a key element of ecological risk assessment and a research priority in ecotoxicology. [ABSTRACT FROM AUTHOR]

Management of nonindigenous species includes prevention, early detection and rapid response and control. Early detection and rapid response depend on prioritizing and monitoring sites at risk for arrival or secondary spread of nonindigenous species. Such monitoring efforts require sufficient biosecurity budgets to be effective and meet management or policy directives for reduced risk of introduction. Such consideration of risk reduction is rarely considered, however. Here, we review the concepts of acceptable level of risk (ALOR) and associated costs with respect to nonindigenous species and present a framework for aligning risk reduction priorities with available biosecurity resources. We conclude that available biosecurity resources may be insufficient to attain stated and desired risk reduction. This outcome highlights the need to consider policy and management directives when beginning a biosecurity program to determine the feasibility of risk reduction goals, given available resources. [ABSTRACT FROM AUTHOR]

Contaminant exposure in aqueous systems typically involves complex chemical mixtures. Given the large number of compounds present in the environment, it is critical to identify hazardous chemical interactions rapidly. The present study utilized a prototype for a novel high-throughput assay to quantify behavioral changes over time to identify chemical interactions that affect toxicity. The independent and combined effects of 2 chemicals, diazinon (an insecticide) and 4-nonylphenol (a detergent metabolite), on the swimming behavior of the freshwater crustacean Daphnia pulex were examined. Cumulative distance and change in direction were measured repeatedly via optical tracking over 90 min. Exposure to low concentrations of diazinon (0.125-2 µM) or 4-nonylphenol (0.25-4 µM) elicited significant concentration- and time-dependent effects on swimming behavior. Exposure to 0.5 µM 4-nonylphenol alone did not significantly alter mean cumulative distance but did elicit a small, significant increase in mean angle, the measure of change in direction. When 0.5 µM 4-nonylphenol was used in combination with diazinon (0.125-0.5 µM), it augmented the adverse impact of diazinon on the swimming behavior of Daphnia. Additionally, enhanced sensitivity to diazinon was observed in animals exposed to treated wastewater effluent for 24 h prior to a diazinon challenge. The present experiments demonstrate that exposure to 4-nonylphenol and complex chemical mixtures (e.g., treated wastewater) can enhance the toxicity of exposure to the insecticide diazinon. Environ Toxicol Chem 2015;34:1145-1153. © 2015 SETAC [ABSTRACT FROM AUTHOR]

ABSTRACT Trophic magnification factors (TMFs) provide a method of assessing chemical biomagnification in food webs and are increasingly being used by policy makers to screen emerging chemicals. Recent reviews have encouraged the use of bioaccumulation models as screening tools for assessing TMFs for emerging chemicals of concern. The present study used a food web bioaccumulation model to estimate TMFs for polychlorinated biphenyls (PCBs) in a riverine system. The uncertainty associated with model predicted TMFs was evaluated against realistic ranges for model inputs (water and sediment PCB contamination) and variation in environmental, physiological, and ecological parameters included within the model. Finally, the model was used to explore interactions between spatial heterogeneity in water and sediment contaminant concentrations and theoretical movement profiles of different fish species included in the model. The model predictions of magnitude of TMFs conformed to empirical studies. There were differences in the relationship between the TMF and the octanol-water partitioning coefficient ( KOW) depending on the modeling approach used; a parabolic relationship was predicted under deterministic scenarios, whereas a linear TMF- KOW relationship was predicted when the model was run stochastically. Incorporating spatial movements by fish had a major influence on the magnitude and variation of TMFs. Under conditions where organisms are collected exclusively from clean locations in highly heterogeneous systems, the results showed bias toward higher TMF estimates, for example the TMF for PCB 153 increased from 2.7 to 5.6 when fish movement was included. Small underestimations of TMFs were found where organisms were exclusively sampled in contaminated regions, although the model was found to be more robust to this sampling condition than the former for this system. Integr Environ Assess Manag 2014;X:000-000. ©2014 SETAC Integr Environ Assess Manag 2015;11:306-318. © 2014 SETAC [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are an environmental concern because of their adverse effects on humans and wildlife, and understanding the contribution of various matrices (i.e., sediment and water) to PCB exposure on aquatic communities is critical for successful remediation of impacted sites. The present study examined the toxicity of different routes of PCB exposure in aquatic invertebrates. In complementary laboratory and field experiments, the authors compared the effects of aqueous versus sedimentary exposure of PCBs on invertebrates. In laboratory bioassays, the planktonic Daphnia pulex and benthic Chironomus dilutus exhibited significant mortality when exposed to PCB-contaminated (1100 µg/g) sediment ( p = 0.03 and p < 0.01, respectively). In field experiments, adult Dreissena bugensis were placed in cages along a depth gradient at a reference site and a PCB-impacted site in St. Clair Shores, Michigan, USA. Mussels experienced significantly greater mortality ( p < 0.001) when placed in close proximity to impacted-site sediments compared with reference sediments. After 7 d, 94% of D. bugensis survived at the reference site compared with only 57% surviving at the impacted site. In addition, D. bugensis at the impacted site experienced significantly less mortality at the water surface ( p < 0.001) compared to those near the sediment. The present study demonstrates the importance of evaluating toxicity at the sediment-water interface. Environ Toxicol Chem 2014;33:641-647. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Many emerging contaminants tend to be biologically active at very low concentrations, occur in water as part of complex mixtures, and impact biota in ways that are not detected using traditional toxicity tests (e.g., median lethal concentration). To evaluate emerging contaminants, the authors developed a method for detecting sublethal behavioral effects by quantifying the swimming behavior of Daphnia pulex, a model organism for studying aquatic toxicity. This optical tracking technique is capable of measuring many swimming parameters, 2 of which-cumulative distance and angular change-are presented. To validate this technique, 2 prototypical compounds that exhibit different modes of action as well as corresponding insecticides that are commonly found in surface waters were investigated. The acetylcholinesterase (AChE) inhibitor physostigmine was used as the prototypical compound for the large number of AChE inhibitor insecticides (e.g., chlorpyrifos). Nicotine was used as the prototypical compound for neonicotinoid insecticides (e.g., imidacloprid). Results demonstrate that this assay is capable of detecting sublethal behavioral effects that are concentration-dependent and that insecticides with the same mode of action yield similar results. The method can easily be scaled up to serve as a high-throughput screening tool to detect sublethal toxic effects of a variety of chemicals. This method is likely to aid in enhancing the current understanding of emerging contaminants and to serve as a novel water-quality screening tool. Environ Toxicol Chem 2014;33:144-151. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are globally ubiquitous in sediments and surface waters. Interactions between biota and MPs are complex and influence their fate and effects in the environment. Once MPs enter aquatic systems, they are colonized by biofilms that may form from the excretion of extracellular polymeric substances (EPS) from microalgae. Biofilm accumulation may change the density of the MPs, contributing to their transport to the sediments. Furthermore, benthic plantivores may consume biofilm laden MPs allowing them to enter the food web. Thus, it is crucial to understand the role algae plays in the vertical transport of MPs in the aquatic environment. In this study, Chlamydomonas was cultured with MPs at different concentrations (0–0.4 mg/mL), and temperatures ranging from 2.5 to 32.5 °C to understand the deposition dynamics and impacts of MPs on EPS production and algal density. Temperatures ranging up to 25 °C increased algal density and MPs deposition. However, at 32.5 °C, algal density and MPs deposition declined. The quantity of MPs also affected algal cell density and EPS production. MPs concentration from 0 to 0.4 mg/mL increased EPS production at all temperatures. Similarly, an increase in algal cell density and MPs deposition occurred when MPs concentration was raised to 0.3 mg/mL. Algal cultures exposed to 0.3–0.4 mg/mL of MPs had a decrease in algal cell density, with no corresponding decline in EPS production. At certain conditions, MPs can facilitate biofilm formation by stimulating EPS production, which can increase cell density thereby expediting MPs transport to the sediment. • Microplastics (HDPE) stimulated extracellular polymeric substances production. • Microplastics (HDPE) exposure up to 0.3 mg/mL increased the growth of Chlamydomonas. • Microplastics (HDPE) exposure over 0.3 mg/mL decreased the growth of Chlamydomonas. • Temperatures up to 25 °C increased algal density and microplastics deposition. • Microplastics exposure over 0.3 mg/mL increased extracellular polymeric substances. [ABSTRACT FROM AUTHOR]

Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of consumers are important for determining the potential for microcystins to be transferred up the food web and for predicting potential human health impacts. The main objective of this work was to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. An oral route of exposure was employed in this study, in which juvenile yellow perch (Perca flavescens) were given a single oral dose of 5 or 20 µg of microcystin-LR (MC-LR) via food and accumulation in the muscle, liver, and tank water were measured over 24 h. Peak concentrations of the water soluble fraction of microcystin were generally observed 8-10 h after dosing in the liver and after 12-16 h in the muscle, with a rapid decline in both tissues by 24 h. Up to 99% of the total recoverable (i.e., unbound) microcystin was measured in the tank water by 16 h after exposure. The relatively rapid uptake and elimination of the unbound fraction of microcystin in the liver and muscle of juvenile yellow perch within 24 h of exposure indicates that fish consumption may not be a major route of human exposure to microcystin, particularly in the Great Lakes. [ABSTRACT FROM AUTHOR]

Changes in regional climate in the Rocky Mountains over the next 100 years are expected to have significant effects on biogeochemical cycles and hydrological processes. In particular, decreased discharge and lower stream depth during summer when ultraviolet radiation (UVR) is the highest combined with greater photo-oxidation of dissolved organic materials (DOM) will significantly increase exposure of benthic communities to UVR. Communities in many Rocky Mountain streams are simultaneously exposed to elevated metals from abandoned mines, the toxicity and bioavailability of which are also determined by DOM. We integrated field surveys of 19 streams (21 sites) along a gradient of metal contamination with microcosm and field experiments conducted in Colorado, USA, and New Zealand to investigate the influence of DOM on bioavailability of heavy metals and exposure of benthic communities to UVR. Spatial and seasonal variation in DOM were closely related to stream discharge and significantly influenced heavy metal uptake in benthic organisms. Qualitative and quantitative changes in DOM resulting from exposure to sunlight increased UV-B (290–320 nm) penetration and toxicity of heavy metals. Results of microcosm experiments showed that benthic communities from a metal-polluted stream were tolerant of metals, but were more sensitive to UV-B than communities from a reference stream. We speculate that the greater sensitivity of these communities to UV-B resulted from costs associated with metal tolerance. Exclusion of UVR from 12 separate Colorado streams and from outdoor stream microcosms in New Zealand increased the abundance of benthic organisms (mayflies, stoneflies, and caddisflies) by 18% and 54%, respectively. Our findings demonstrate the importance of considering changes in regional climate and UV-B exposure when assessing the effects of local anthropogenic stressors. [ABSTRACT FROM AUTHOR]

The effects of total organic carbon (TOC) and UV-B radiation on Zn toxicity and bioaccumulation in a Rocky Mountain stream community were assessed in a 10-d microcosm experiment We predicted that TOC would mitigate Zn toxicity and that the combined effects of Zn and UV-B would be greater than Zn alone. However, TOC did not mitigate Zn toxicity in this study. In fact, treatments with TOC plus Zn had significantly lower community respiration as compared with the controls and Zn concentrations associated with the periphyton increased in the presence of TOC. UV-B had no additive effect on periphyton Zn accumulation or community respiration. Heptageniid mayflies (Ephemeroptera) were particularly sensitive to Zn, and reduced abundances were observed in all Zn treatments. UV-B did not additionally impact Heptageniid abundances; however UV-B did have a greater effect on macroinvertebrate drift than Zn alone. Ephemeroptera, Plecoptera, and Trichoptera (groups typically classified as sensitive to disturbance) were found in highest numbers in the drift of UV-B + Zn treatments. Measures of Zn accumulation in the caddisfly Arctopsyche grandis, periphyton biomass, and total macroinvertebrate abundance were not sufficiently sensitive to differentiate effects of TOC, UV-B, and Zn. These results indicate that UV-B and TOC affect Zn bioavailability and toxicity by impacting species abundance, behavior, and ecosystem processes. [ABSTRACT FROM AUTHOR]

Daphnia (Crustacea) are extensively used as model organisms in ecotoxicology; however, little is known regarding their endocrine system. This study examines Daphnia vulnerability to vertebrate hormones. Twelve natural or synthetic vertebrate hormones were screened for activity on developmental and reproductive processes in Daphnia magna. Natural hormones tested included: β-estradiol, gonadotropin, hydrocortisone, insulin, melatonin, progesterone, somatostatin, testosterone, and thyroxine at concentrations ranging from 1 to 100 μg/L. Synthetic hormones tested included diethylstilbestrol (estrogenic), R-1881 (androgen), and ICI-182,780 (antiestrogen); all hormones were screened with a 6-d assay. Additionally, progesterone, insulin, testosterone, and thyroxine were screened for 25 d. Diethylstilbestrol decreased D. magna growth rate while thyroxine increased it. Short-term testosterone exposure reduced D. magna fecundity; however, long-term exposure did not, potentially indicating testosterone hydroxylation with long-term exposure. Hormones commonly considered sex-hormones (estrogens and androgens) in vertebrates do not appear to control sexual differentiation in D. magna; however, several vertebrate hormones do affect reproduction and development in D. magna making D. magna a potentially useful tool in monitoring for the presence of these hormones or compounds that mimic them. [ABSTRACT FROM AUTHOR]

Toxaphene is a persistent environmental contaminant that has been shown to alter male production in Daphnia magna and to induce P-450 activity in mammals. Cytochrome P-450-mediated metabolism may lead to xenobiotic detoxification resulting in acclimation. To determine if D. magna acclimate to toxaphene via P-450 pathways, chronic and acute toxicity tests were conducted with D. magna exposed to toxaphene in the presence and absence of piperonyl butoxide (PBO), an inhibitor of cytochrome P-450 enzymes. Toxaphene exposure increased male production in acute but not chronic assays, indicating that D. magna may acclimate to chronic toxaphene exposure. Upon co-administration of toxaphene and PBO in chronic tests, D. magna exhibited a decline in growth rate, fecundity and survival. The observed toxaphene acclimation in chronic tests, along with its increased toxicity in the presence of a P-450 suppressor, suggests that P-450 enzymes may contribute to detoxification and subsequent acclimation of D. magna to chronic toxaphene exposure. Additional chronic toxicity tests indicated that toxaphene acclimation occurs between 7 and 12 days following initial exposure, at which time sex determination is no longer affected. Thus, sublethal toxaphene toxicity effects such as reproductive impairments may be detectable with acute but not chronic tests, potentially due to the upregulation of P-450 isozymes. [Copyright &y& Elsevier]

Daphnia magna were evaluated for use as a screen for pesticides that have been demonstrated to have estrogenic (o' p'-DDT, di-n-butyl phthalate, toxaphene), anti-androgenic (p' p-DDE, linuron), thyroid (acetochlor, alachlor, metribuzin), insulin (amitraz) or lutenizing hormone (2,4-D) activity in vertebrates, and to establish daphnid sensitivity to these compounds. Pesticides with unknown effects on vertebrate endocrine systems (chlorosulfuran, cyanazine, diflubenzuron, metolachlor, and diquat) were also evaluated. Compounds were assayed for six days at environmentally relevant concentrations ranging from 0.001 to 100 μg/L, using female Daphnia and their offspring. Sublethal endpoints included offspring sex (sex determination), clutch size (fecundity), and adult size (growth rate). Toxaphene was the only compound that affected sexual differentiation, increasing male production. Daphnia fecundity declined with exposure to toxaphene, and daphnid growth rates were reduced by acetochlor exposure. Diflubenzuron, o' p'-DDT, and p' p-DDE significantly reduced Daphnia survival. No correlation existed between affected reproductive or developmental processes and specific endocrine systems or subsystems. Results from this study indicate that Daphnia make a good screen for assessing potential environmental impacts but are not a useful indicator of pesticide hormonal activity in vertebrates. This assay consistently detected sublethal but ecologically relevant effects of these pesticides on Daphnia at environmentally relevant concentrations typically below their listed EC[sub 50] value. [ABSTRACT FROM AUTHOR]

Exposure of Daphnia pulex to the insecticide and juvenile hormone-mimic methoprene resulted in a decrease in the incidence of all-male broods and an increase in the incidence of all-female broods compared with controls. These effects were observed at nominal concentrations of 10 and 100 µg/L, within the upper range of concentrations at which methoprene is applied in the environment. Because methoprene has been found to bind to the mammalian retinoid X receptor, we also tested the effects of retinoic acid on Daphnia reproduction. Neither 9-cis-retinoic acid nor all-trans-retinoic acid had any observable effect. Because juvenile hormone and ecdysteroids interact in many insect systems, we also exposed Daphnia to 20-OH-ecdysone. Exposure to the crustacean hormone 20-OH-ecdysone at levels of 1 and 10 µg/L resulted in an increase in all-male broods and a decrease in all-female broods, but 100 µg/L 20-OH-ecdysone resulted in a decrease in all-male broods and an increase in all-female broods. Our results suggest that juvenile hormone and ecdysteroids might play a role in the Daphnia sex determination system. [ABSTRACT FROM AUTHOR]

• Citizen science data are under-utilized by academic and management professionals. • Comparisons with quantitative surveys help legitimize findings by citizen science. • Differences in quantitative and citizen data were largely due to rare taxa. • Citizen stream surveys provided a conservative estimate of degradation. • Citizen science can provide a reliable complement to traditional survey methods. Conservation and management agencies may benefit from volunteer programs, or citizen science, to monitor a variety of ecosystem types. Citizen science can simultaneously engage individuals living in or near an ecosystem and provide environmental data that may otherwise be lacking. However, data produced by untrained volunteers is not always trusted among agency and academic researchers due to uncertainty surrounding accuracy and lingering stigma associated with 'amateur' assessments. Here we provide site-specific comparisons between quantitative ecological monitoring data and qualitative data produced by citizen scientists. Two citizen science organizations in the metro Detroit (Michigan, USA) area conduct regular monitoring of aquatic macroinvertebrates to assess urban stream quality. We conducted analogous sampling at seven locations over three years (12 total samples) using quantitative stream ecology methods to provide a site-specific comparison of stream assessments. Invertebrate assemblage composition varied between methods, overlapping by an average of 30% per site. Assemblage differences largely corresponded to under-sampling of small sessile taxa and large mobile taxa by volunteer and quantitative surveys, respectively. Most of the invertebrate taxa which differed between data types were naturally rare taxa. This resulted in predictable differences in quality assessment by quantitative and qualitative methods. Citizen volunteers regularly rated sites with low invertebrate richness as higher in quality than did quantitative assessments, resulting in a conservative indicator of stream degradation. Though qualitative citizen data and quantitative data varied, both methods had short-comings and strengths. Citizen science organizations can thus provide a useful complement to traditional monitoring practices, particularly given the long-term, spatially broad, and repeated nature of their sampling. [ABSTRACT FROM AUTHOR]

The impacts of microplastic particulates in benthic freshwater organisms have been largely unexplored despite abundant plastic accumulation in the sediments of these systems. We investigated the uptake of plastic particles by benthic filter feeding quagga mussels (Dreissena bugensis) and associated toxicity exhibited through impacts on mortality, filtration rate, reproduction and oxygen consumption. Matrix Assisted Laser Desorption/Ionization Imaging Mass Spectrometry (MALDI-IMS) technology was used to assess the microplastic inclusion. For this purpose, quagga mussels were exposed to four treatments ranging from 0.0 to 0.8 g/L of a high density fluorescent red polyethylene powder in the size range of 10–45 μm for 24-h, and the targeted endpoints were quantified. Identification of several micrograms of microplastics in the digestive tract suggests rapid clearance from the water column by filtering. At the higher concentrations, about 95% of the microplastics ingested remained in the mussels after 24-h. Microplastics were found in the gills which correlated with decreasing filtration rate at higher microplastic concentrations. Despite large-scale ingestion, plastic exposure did not affect survivorship, reproduction rates, or oxygen consumption in the period examined. MALDI-IMS identified unique mass spectra that correlated with microplastic inclusion. This research suggests that microplastics can impair feeding through decreased filtration rates of filter feeding organisms, potentially resulting in a reduction of overall fitness over time and that MALDI-IMS may have the potential to identify microplastics and changes in tissue at the borders of plastic inclusion. Image 1 • Plastics did not impact reproduction or mortality. • Acute exposure to microplastics can deter filter feeding. • Filter feeding organisms may be a sink for microplastics. • MALDI-IMS was used to assess the microplastic inclusions. • Potential unique mass spectra signals associated with microplastic inclusions. Microplastics can impair feeding through decreased filtration rates in quagga mussels and with about 95% of the microplastics ingested can remain in the mussels after 24 h. [ABSTRACT FROM AUTHOR]

Quagga (Dreissena rostriformis bugensis) and zebra (D. polymorpha) mussels are broadcast spawners that produce planktonic, free swimming veligers, a life history strategy dissimilar to native North American freshwater bivalves. Dreissenid veligers require highly nutritious food to grow and survive, and thus may be susceptible to increased mortality rates during harsh environmental conditions like cyanobacteria blooms. However, the impact of cyanobacteria and one of the toxins they can produce (microcystin) has not been evaluated in dreissenid veligers. Therefore, we exposed dreissenid veligers to eleven distinct cultures (isolates) of cyanobacteria representing Anabaena, Aphanizomenon, Dolichospermum, Microcystis, and Planktothrix species and the cyanotoxin microcystin to determine the lethality of cyanobacteria on dreissenid veligers. Six-day laboratory bioassays were performed in microplates using dreissenid veligers collected from the Detroit River, Michigan, USA. Veligers were exposed to increasing concentrations of cyanobacteria and microcystin using the green algae Chlorella minutissima as a control. Based on dose response curves formulated from a Probit model, the LC 50 values for cyanobacteria used in this study range between 15.06 and 135.06 μg/L chlorophyll- a , with the LC 50 for microcystin-LR at 13.03 μg/L. Because LC 50 values were within ranges observed in natural waterbodies, it is possible that dreissenid recruitment may be suppressed when veliger abundances overlap with seasonal cyanobacteria blooms. Thus, the toxicity of cyanobacteria to dreissenid veligers may be useful to include in models forecasting dreissenid mussel abundance and spread. • Dreissena spp. veligers are sensitive to environmental stressors including cyanobacteria and cyanotoxins. • The LC 50 for cyanobacteria and cyanotoxins to veligers reflect environmentally relevant concentrations globally. • High mortality of dreissenid veligers may occur during cyanobacteria blooms resulting in population level impacts. [ABSTRACT FROM AUTHOR]

Consumption guidelines are a common way of improving conscious consumption behaviors in areas where game fish are known to contain contaminants. However, guideline information can be difficult to distribute, and effectiveness difficult to measure. To increase the distribution and effectiveness of guideline information for the Detroit River, an educational campaign was launched in 2010, which included distribution of pamphlets with consumption information, posting of permanent signs at popular fishing locations, and hiring River Walkers to personally communicate with anglers. In 2013 and 2015, we conducted in-person surveys of active shoreline anglers to determine the effectiveness of education and outreach efforts. Results from the survey indicated that 55% of anglers were aware of the guidelines in 2013, and by 2015 36% had communicated the information to family or friends. However, anglers were often unwilling to reduce consumption of popular game species, despite high contaminant levels. Encouragingly, black anglers were most likely to supplement their diet with species lower in contaminants. Our results suggest that utilizing multiple educational strategies including reaching out directly to individual anglers may improve conscious consumption behavior among the targeted population, providing a template for educational campaigns to successfully target vulnerable populations. [ABSTRACT FROM AUTHOR]

Highlights • Interactions among stressors in ecosystems are common but hard to predict. • We identified interactions by pairing a systematic review with expert elicitation. • Many potential interactions (esp. synergies) were proposed but poorly studied. • Nutrient loading and invasive species were often the stressors in these interactions. • We used a conceptual model to integrate several potential interactions. Abstract Co-occurrence of environmental stressors is ubiquitous in ecosystems, but cumulative effects are difficult to predict for effective indicator development. Individual stressors can amplify (synergies) or lessen (antagonisms) each other's impacts or have fully independent effects (additive). Here we use the Laurentian Great Lakes, where a multitude of stressors have been studied for decades, as a case study for considering insights from both a systematic literature review and an expert elicitation (or structured expert judgment) to identify stressor interactions. In our literature search for pairs of stressors and interaction-related keywords, relatively few studies (9%, or 6/65) supported additive interactions with independent stressor effects. Instead, both antagonisms (42%, or 27/65) and synergies (49%, or 32/65) were common. We found substantial evidence for interactions of invasive dreissenid mussels with nutrient loading and between pairs of invasive species (predominantly dreissenids × round goby), yet both sets of records included mixtures of synergies and antagonisms. Complete quantification of individual and joint effects of stressors was rare, but effect sizes for dreissenid mussels × nutrient loading supported an antagonism. Our expert elicitation included discussion in focus groups and a follow-up survey. This process highlighted the potential for synergies of nutrient loading with dreissenid mussels and climate change as seen from the literature review. The elicitation also identified additional potential interactions less explored in the literature, particularly synergies of nutrient loading with hypoxia and wetland loss. To stimulate future research, we built a conceptual model describing interactions among dreissenid mussels, climate change, and nutrient loading. Our case study illustrates the value of considering results from both elicitations and systematic reviews to overcome data limitations. The simultaneous occurrence of synergies and antagonisms in a single ecosystem underscores the challenge of predicting the cumulative effects of stressors to guide indicator development and other management and restoration decisions. [ABSTRACT FROM AUTHOR]