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In recent decades the Amazonian ecosystem has received large amounts of domestic and industrial effluents, as well as mining-related waste contributing significant quantities of metal to water bodies. Thus, the main objective of the study was to verify the sensitivity of a native Amazonian ostracod (Strandesia rondoniensis) species to isolated and mixed metal salts (CuSO4; ZnCl2; CdCl2 and HgCl2). The sensitivity will be compared to other species using species sensitivity distributions (SSDs) for an ecological risk assessment (ERA). The experiment consisted of simultaneously exposing each metal alone and in mixture, through a factorial design for toxicity with 25 different combinations for 48 h. For the ERA, metal concentrations measured in the water of various aquatic environments in the Amazon basin were considered based on the risk quotient values. The results showed that the metal toxicity gradient was Cd>Hg>Cu>Zn, respectively. The toxicity in the mixture showed that the combination of Cu-Cd and Cu-Zn better fit the model (CA), indicating mainly synergism when copper predominated in the mixture. Meanwhile, the Cu-Hg interaction fit the model better (IA), again indicating synergism when copper was at a higher concentration. The ERA showed a high risk (RQ > 1) for the Cd, Cu, and Hg metals. [ABSTRACT FROM AUTHOR]

Abstract Background The diversity and population genetic structure of many species have been shaped by historical and contemporary climatic changes. For the species of the South American Altiplano, the historical climatic changes are mainly related to the wet events of great magnitude and regional influence that occurred during the Pleistocene climatic oscillations (PCOs). In contrast, contemporary climate changes are associated with events of lesser magnitude and local influence related to intensifications of the South American Summer Monsoon (SASM). Although multiple studies have analyzed the effect of PCOs on the genetic patterns of highland aquatic species, little is known about the impact of contemporary climate changes in recent evolutionary history. Therefore, in this study, we investigated the change in population structure and connectivity using nuclear and mitochondrial markers throughout the distribution range of Heleobia ascotanensis, a freshwater Cochliopidae endemic to the Ascotán Saltpan. In addition, using geometric morphometric analyses, we evaluated the concomitance of genetic divergence and morphological differentiation. Results The mitochondrial sequence analysis results revealed the presence of highly divergent co-distributed and geographically nested haplotypes. This pattern reflects an extension in the distribution of groups that previously would have differentiated allopatrically. These changes in distribution would have covered the entire saltpan and would be associated with the large-scale wet events of the PCOs. On the other hand, the microsatellite results defined five spatially isolated populations, separated primarily by geographic barriers. Contemporary gene flow analyses suggest that post-PCO, climatic events that would have connected all populations did not occur. The morphometric analyses results indicate that there is significant morphological differentiation in the populations that are more isolated and that present the greatest genetic divergence. Conclusions The contemporary population structure and morphological variation of H. ascotanensis mainly reflect the post-PCO climatic influence. Although both markers exhibit high genetic structuring, the microsatellite and morphology results show the preponderant influence of fragmentation in recent evolutionary history. The contemporary genetic pattern shows that in species that have limited dispersal capabilities, genetic discontinuities can appear rapidly, erasing signs of historical connectivity.

Aquatic invertebrates are often used as indicator species for water quality. Aquatic invertebrates were collected and identified at a protected reserve for 30+ years and at a newly restored site, previously developed as a golf course. Dissolved oxygen and salinity measurements were also taken. Results show that salinity has a stronger influence on species communities than restored state.

This study was conducted to determine the substrate preferences of hydroid polyps sampled in eight different stations on the coastline of Antalya Bay. Sampling was performed by freedive to identify the hydroid polyp fauna and certain physicochemical (salinity, temperature, dissolved oxygen, electrical conductivity, chl-a) and biological characteristics were determined. A total of 35 hydroid species were identified as epiphytic, epilithic and epizoic in the region. The most commonly preferred substrates by the species were; rocks (20 species), Ellisolandia elongata (J.Ellis & Solander) K.R.Hind & G. W. Saunders, 2013 (18 species), Balanus sp. Costa, 1778 (9 species), macroalgae Posidonia oceanica (Linnaeus) Delile, 1813, and leaves (8 species). Among all species, one species prefers just epilithic substrates, four species prefer only epizoic substrates, and seven species prefer only epiphytic substrates. Acauloides ammisatum, Eudendrium sp., Turritopsis. nutricula, Pennaria. disticha, Clytia noliformis, Halecium tenellum, Halopteris diaphana, Dynamena disticha and Salacia desmoides are found in all substrate types (EP,EZ,EL). [ABSTRACT FROM AUTHOR]

The gut microbiome is one of the most important sites of host–microbe interactions, however, mechanisms governing the responses of host‐associated microbes to changing environmental conditions are poorly understood. To address this, we investigated individual and combined effects of dietary changes and increase in salinity (from freshwater to salinity 3) or antibiotic concentration on the gastrointestinal bacterial community of the aquatic snail Ampullaceana balthica. In parallel, the energy reserves of the host were quantified. A change of natural food source to biofilm forming green algae Scenedesmus obliquus as well as the combined treatment of salinity and S. obliquus decreased the richness and changed the composition of the A. balthica gastrointestinal bacterial community. In these treatments Pseudomonas became the dominant bacterium. However, energy reserves of the host were higher in these treatments compared to the reference aquaria specimens and the combined treatment of antibiotics with S. obliquus. The presence of antibiotics inhibited the dominance of Pseudomonas and resulted in lower energy reserves despite S. obliquus feeding. Therefore the host seems to be able to adapt and replace its bacterial community composition to respond to mild changes in salinity and food source. Antibiotics in the water can disturb this self‐regulating mechanism. Our study underlines the ability of aquatic macroinvertebrates to respond to sudden changes in food source and mild shifts in salinity. Moreover, it emphasizes the strong impact of the food source on the gastrointestinal microbiome and the importance of generalists during disturbance. [ABSTRACT FROM AUTHOR]

Graphene is a 2-dimensional nanomaterial with unique mechanical, thermal, electrical, and optical properties. With increasing applications of graphene-family nanomaterials (GFNs) in electronics, biomedicine, and surface coatings, concern for their impacts on aquatic ecosystems is rising. Current information on the toxicity of GFNs, including graphene oxide, is scarce. Filter-feeding bivalves, such as eastern oysters, are good models for nanomaterial exposure studies. We present results from a 72-h static renewal oyster study using 1 and 10 mg/L graphene oxide, which, to our knowledge, is the first report on in vivo effects of graphene oxide exposures in marine bivalves. Water samples were analyzed for graphene oxide concentration and size assessments. Gill and digestive gland tissues were evaluated for lipid peroxidation and glutathione-S-transferase (GST) activity. In addition, gill sections were fixed for histopathological analyses. Elevated lipid peroxidation was noted in oysters exposed to 10 mg/L graphene oxide. No significant changes in GST activity were observed, but reduced total protein levels were found in digestive gland tissues of exposed oysters at both concentrations. Loss of mucous cells, hemocytic infiltration, and vacuolation were observed in gills of exposed oysters. The results indicate that short-term graphene oxide exposures can induce oxidative stress and epithelial inflammation and adversely affect overall oyster health. Further investigations regarding the fate and sublethal effects of graphene oxide are critical to understanding the risks associated with a rapidly growing graphene consumer market. Environ Toxicol Chem 2019;38:820-830. Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

This study uses published and unpublished data to create a comprehensive and up-to-date synthesis of available information on a little-known group of invertebrates, namely, non-marine giant ostracods (cypridids ≥3 mm long). Approximately 8% of the ∼1000 living cypridid species are identified as 'giant'. They occur in a range of subfamilies, in all zoogeographic regions, except Antarctica, and mainly in small standing-water ecosystems. Only those in the subfamily Mytilocypridinae are reasonably well studied. This subfamily is endemic to Australia and comprises a diverse range of giant species (∼29 species in 6 genera), mainly in temporary habitats, mostly salt lakes, including in extreme conditions. We evaluate the current taxonomy of the Mytilocypridinae, analyse patterns in the field distributions and abiotic tolerances of species, and review the general biology of these ostracods. We also identify those species most in need of consideration in conservation planning, highlight critical gaps in knowledge and show how these ostracods could serve as useful models for testing ecological and evolutionary theories. The results of this study can be used to inform conservation planning for giant ostracods and direct further study of these unique invertebrates, which are an important component of the biodiversity of small standing-water ecosystems. It is important that conservation planning considers neglected taxa, supported by scientific studies. Accordingly, we critique the biology of giant ostracods, i.e. ostracods in the family Cyprididae that are ≥3 mm in length. These ostracods are common in small standing-water ecosystems, which are subject to a range of threats. We focus on the subfamily Mytilocypridinae, which consists of a diverse range of giant ostracods that are endemic to Australia and occur mainly in salt lakes, sometimes in extreme conditions. [ABSTRACT FROM AUTHOR]

Growing evidence has reported that diphenhydramine (DPH), an ionisable antihistamine, is widely present in surface waters across the world. Relative to vertebrates studied, its impact on invertebrates, particularly concerning cytochrome P450 (CYP) metabolism and oxidative stress, remains poorly understood. In this study, we aimed to investigate the effects of 2, 20, and 200 µg/L DPH on marbled crayfish (Procambarus virginalis) after 96-h exposure. Specifically, we assessed CYP activity, antioxidant enzyme responses, and acetylcholinesterase (AChE) activity in gills, muscle, and hepatopancreas. The crayfish CYP metabolised fluorogenic CYP-metabolic substrates of 7-benzyloxy-4-trifluoromethylcoumarin (BFC) and dibenzylfluorescein (DBF), which evidenced the activity of CYP2C and CYP3A isoforms, well known in mammalian detoxification metabolism. Both BFC and DBF dealkylations showed a positive correlation with each other but were negatively correlated to water and haemolymph DPH concentrations. Exposure to 200 µg/L DPH elicited an apparent inhibition trend, albeit not significant, in BFC- and DBF-transformation activities in crayfish. Other tested 7-benzyloxyresorufin and 7-pentoxyresorufin substrates were poorly metabolised, suggesting their relatively low activity or the lack of mammalian-like CYP1A and CYP2B isoforms in marbled crayfish. The significant modulation of antioxidant enzymes was demonstrated in gills and hepatopancreas. The exposure to DPH did not alter the activity of AChE. Integrated biomarker response version 2 showed the highest cumulative effect of DPH exposure on gills, implying that gill tissue is the most reliable matrix for evaluating DPH toxicity. Activities of glutathione peroxidase and glutathione-S-transferase were the most deviated determinants among the investigated biomarkers, providing insights into the DPH toxicity in crayfish. This study brought the first insight into utilising the fluorogenically active substrates BFC and DBF to demonstrate the CYP involvement in the detoxification metabolism in marbled crayfish. Further, our results provided information on valuable antioxidant defence mechanisms and biomarker responses for a future DPH toxicity assessment in aquatic organisms. [Display omitted] • Marbled crayfish may possess mammalian CYP2C- and CYP3A-like isoenzymes. • DPH altered CYP activity and oxidative stress-antioxidant status in crayfish. • Glutathione-like enzymes were identified as reliable indicators of DPH toxicity. • Crayfish gill tissue responded sensitively to the oxidative stress evoked by DPH. [ABSTRACT FROM AUTHOR]

Terrestrial resource pulses can significantly affect the community dynamics of freshwater ecosystems. Previously, its effect on the river community is considered to be stronger in summer, whereas weaker in winter when terrestrial invertebrates are less abundant. The movement of the terrestrial earthworms is triggered in winter, so they may be supplied to winter rivers as terrestrial resource pulse, but little is known about it. Here, we report that the massive numbers of the terrestrial earthworms were supplied intensively to an upstream of the small river in early winter. In particular, we found large numbers of megascolecid earthworms were supplied in an upstream of the small river in Northern Japan. Furthermore, we observed that supplied earthworms were consumed by salmonid fish species (masu salmon, white spotted char and rainbow trout) and aquatic invertebrates (gammarid amphipod, planarian flatworm, and stonefly larvae). These findings suggest that the terrestrial earthworms may play a key role in ecosystem functioning in winter when severe and other resources are scarce. [ABSTRACT FROM AUTHOR]

Abstract Free-living turbellarians mostly live in marine and freshwater environments, but they have been little considered in ecological studies. The coastal plain in southern Brazil harbors a diverse fauna and flora, but only a few studies have related environmental factors to the abundance, richness, and distribution of turbellarians. Hence, we analyzed the structure of turbellarian communities in floating vegetation in three differently sized limnic environments. We aimed to determine differences in abundance, density, and richness of turbellarians among these habitats in relation to environmental factors. We found 1,225 turbellarians (34 species) distributed among 6 taxa. The most abundant was Tricladida with 49.4% relative abundance; the remaining (Catenulida, Dalytyphloplanida, Macrostomorpha, Kalyptorhynchia, and Prorhynchida) were less abundant. We found no significant differences among population parameters and environments. Small shallow lakes are a potentially rich environment, while water channels are the richest environment. Larger shallow lakes are not very diverse for turbellarians. Similarities regarding turbellarian communities among close limnic systems could be explained by the connectivity of bodies of water that presents similar aquatic macrophytes and hydrological subsystems, while larger shallow lakes have a different community because they have their own contributing basin and could be influenced by other factors.

The utility of artificial and natural substrate samplers affects the distribution of macro invertebrates in freshwater ecosystems. This study evaluated the efficiency of litter substrates of Croton macrostachyus, Eucalyptus grandis, Ficus sure, and Salix subserrata and artificial substrates/ bricks in terms of macro invertebrates colonization, abundance, family richness, uniformity, and composition of the sampled macro invertebrates. Few researchers have evaluated the efficiency of artificial and natural substrates in the colonization and dispersal of macro invertebrates in freshwater ecosystems. The objectives of this assessment were to evaluate the efficiency of artificial and natural substrate samplers in collecting macro invertebrates for water quality assessments of the Gilgel Gibe Watershade and its tributaries. Five sampling areas were chosen to compare macro invertebrates colonization in relation to the effect of inorganic (bricks) and leaf litter as substrates. Four organic or bedding substrates were selected and collected from the upper and lower study sites based on native and exotic plant species and their diversity along the study sites. Therefore, the following litter species were collected: Croton macrostachyus, Eucalyptus grandis, Ficu ssure, and Salix subserrata. After 30 days, all samples from each site were collected. Past software was used for descriptive and diversity indices analysis. A total of 5491 macro invertebrates individuals were counted on both substrates (artificial/bricks and natural/litter species). The compositions of Ephemeroptera and Trichoptera differed by litter substrates and were consistently higher in litter bags containing artificial substrates. In general, the family richness, uniformity, and composition of the artificial substrate samplers for macro invertebrates were higher than those of the litter substrates, which may indicate that the artificial substrates was more efficient than the litter substrates in dispersing macro invertebrates due to its ability to allocate habitat support to macro invertebrates.

Pharmaceuticals are increasingly being detected in surface waters around the globe, giving rise to concerns that they may alter the physiology and behaviour of aquatic organisms exposed in the wild. Invertebrates represent important components of many ecosystems and bear a high potential for transmitting pharmaceutical contaminants to higher trophic levels. Here, we present a laboratory study in which we exposed a freshwater tropical snail, Melanoides tuberculata, to a serial dilution of the benzodiazepine oxazepam ranging from 50 ng/L to 5 mg/L. We tested for subsequent behavioural effects, including locomotor activity and foraging propensity, at two diurnal time points (day and night), and across three days. We found that the snails displayed a high level of behavioural tolerance to all treatments of oxazepam except at the highest exposure, where locomotor and foraging activity declined. We also detected a weak non-monotonic response curve suggestive of behavioural disinhibition at moderate exposure levels. Regardless of treatment, the snails were also less active after three days of exposure and more active during nighttime observations. We measured the uptake of oxazepam in tissues across treatments, showing that it bioconcentrated at up to 29 times the water exposure level (BCF range: 7 - 29). Finally, we characterized the uptake/depuration pharmacokinetics of oxazepam in snail tissues across time, which revealed that the snails reach a steady state equilibrium in < 8 hours of exposure and depurate at a similar rate. Overall, our study suggests that snails such as M. tuberculata, due to their behavioural resilience and high bioconcentration potential, could act as vectors for pharmaceutical transfer throughout the food web in pharmaceutical-polluted habitats (e.g., wastewater outfalls).

Agrochemicals including neonicotinoid insecticides and fungicides are frequently applied as seed treatments on corn, soybeans, and other common row crops. Crops grown from pesticide-treated seed are often directly planted in managed floodplain wetlands and used as a soil disturbance or food resource for wildlife. We quantified invertebrate communities within mid-latitude floodplain wetlands and assessed their response to use of pesticide-treated seeds within the floodplain. We collected and tested aqueous and sediment samples for pesticides in addition to sampling aquatic invertebrates from 22 paired wetlands. Samples were collected twice in 2016 (spring [pre-water level drawdown] and autumn [post-water level flood-up]) followed by a third sampling period (spring 2017). Meanwhile, during the summer of 2016, a portion of study wetlands were planted with either pesticide-treated or untreated corn seed. Neonicotinoid toxic equivalencies (NI-EQs) for sediment (X̅ = 0.58 μg/kg), water (X̅ = 0.02 μg/L), and sediment fungicide concentrations (X̅ = 0.10 μg/kg) were used to assess potential effects on wetland invertebrates. An overall decrease in aquatic insect richness and abundance was associated with greater NI-EQs in wetland water and sediments, as well as with sediment fungicide concentration. Post-treatment, treated wetlands displayed a decrease in insect taxa-richness and abundance before recovering by the spring of 2017. Information on timing and magnitude of aquatic insect declines will be useful when considering the use of seed treatments for wildlife management. More broadly, this study brings attention to how agriculture is used in wetland management and conservation planning. [ABSTRACT FROM AUTHOR]

The gastrointestinal (GI) microbiota is a group of complex and dynamic microorganisms present in the GI tract of an organism that live in symbiosis with the host and benefit the host with various biological functions. The communities of GI microbiota are formed by various aerobic, anaerobic, and facultatively anaerobic bacteria in aquatic species. In spiny lobsters, common GI microorganisms found in the GI tract are Vibrio, Pseudomonas, Bacillus, Micrococcus, and Flavobacterium, where the structure and abundance of these microbes are varied depending on the environment. GI microbiotas hold an important role and significantly affect the overall condition of spiny lobsters, such as secreting digestive enzymes (lipase, protease, and cellulase), helping in digesting food intake, providing nutrition and synthesising vitamins needed by the host system, and protecting the host against infection from pathogens and diseases by activating an immune mechanism in the GI tract. The microorganisms in the water column, sediment, and diet are primarily responsible for altering, manipulating, and shaping GI microbial structures and communities. This review also highlights the possibilities of isolating the indigenous GI microbiota as a potential probiotic strain and introducing it to spiny lobster juveniles and larvae for better health management. [ABSTRACT FROM AUTHOR]

Island biogeography is based on the idea that the larger an island, and the less it is isolated from other areas, the higher the biodiversity it contains. The premise of island size contributing to diversity is based on the fundamental ecological concept—the species area relationship (SAR). Wetlands and, in particular, arid zone spring wetlands can be considered islands as they are wetted habitat surrounded by a harsh and dry landscape—"girt by dirt"—forming an ideal setting to study island biogeography. While studies in spring wetlands have identified SARs that conform to the concept, others identified conflicting information. The aim of our study was to assess the relationship between spring wetland wetted area and its aquatic invertebrate taxonomic richness across three of Australia's Great Artesian Basin spring complexes. Wetted area and aquatic invertebrates were recorded for 32 individual spring wetlands. The constraint that wetted area has on invertebrate taxonomic richness was analysed using quantile regression. ANOSIM was used to compare differences in the invertebrate community between spring complexes. No significant relationship between wetted area and taxonomic richness was identified across all springs, but the aquatic invertebrate community and taxonomic richness was significantly different across the three spring complexes. Analyses were repeated for one spring complex. Increasing wetland size was found to constrain invertebrate taxonomic richness at Edgbaston Springs. These results contrast with the basic SAR concept but can potentially be the result of a "small island effect" where the relationship is overridden by anthropogenic disturbance. [ABSTRACT FROM AUTHOR]

Little is known about ocean viromes and the ecological drivers of the evolution of aquatic RNA viruses. This study employed a meta-transcriptomic approach to characterize the viromes of 58 marine invertebrate species across three seas. This revealed the presence of 315 newly identified RNA viruses in nine viral families or orders (Durnavirales, Totiviridae, Bunyavirales, Hantaviridae, Picornavirales, Flaviviridae, Hepelivirales, Solemoviridae, and Tombusviridae), with most of them being sufficiently divergent to the already documented viruses. Notably, this study revealed three marine invertebrate hantaviruses that are rooted to vertebrate hantaviruses, further supporting that hantaviruses may have a marine origin. We have also found evidence for possible host sharing and switch events during virus evolution. Overall, we have revealed the hidden diversity of marine invertebrate RNA viruses. [ABSTRACT FROM AUTHOR]

Ponds are increasingly being constructed to enhance amenity values in human-dominated lowland landscapes, but little is known of design features that influence macroinvertebrates which can provide important food resources for fish and waterbirds. We quantified pond characteristics, sampled benthic and water-column macroinvertebrates in winter, and related abundance, biomass and community composition to characteristics of 34 ponds on the lower Waikato River floodplain, northern New Zealand. Compositionally different macroinvertebrate communities occupied water-column and benthic habitats. Landscape setting had a significant effect on benthic composition in terms of biomass, while the independent effects of frequency of pond drying or flooding, respectively, influenced benthic (abundance, biomass) or water-column (abundance) communities. Distance-based linear models highlighted physicochemical conditions, water depth regimes and riparian vegetation composition as key variables accounting for dissimilarity in total macroinvertebrate biomass between ponds. Our results indicate that managing hydrological stability of ponds in terms of permanence and flooding influences the composition and biomass of invertebrate communities. Within this hydrological template, design of appropriate depth regimes and riparian conditions can enhance accrual of macroinvertebrate biomass, thereby increasing food resources for fish and waterbirds. [ABSTRACT FROM AUTHOR]

© 2015 McCauley et al. The common hippopotamus, Hippopotamus amphibius, transports millions of tons of organic matter annually from its terrestrial feeding grounds into aquatic habitats. We evaluated whether carbon stable isotopes (δ13C) can be used as tracers for determining whether H. amphibius-vectored allochthonous material is utilized by aquatic consumers. Two approaches were employed to make this determination: (1) lab-based feeding trials where omnivorous river fish were fed a H. amphibius dung diet and (2) field sampling of fish and aquatic insects in pools with and without H. amphibius. Lab trials revealed that fish fed exclusively H. amphibius dung exhibited significantly more positive δ13C values than fish not fed dung. Fish and aquatic insects sampled in a river pool used for decades by H. amphibius also exhibited more positive δ13C values at the end of the dry season than fish and insects sampled from an upstream H. amphibius-free reference pool. Fish sampled in these same pools at the end of the wet season (high flow) showed no significant differences in δ13C values, suggesting that higher flows reduced retention and use of H. amphibius subsidies. These data provide preliminary evidence that δ13C values may be useful, in certain contexts, for quantifying the importance H. amphibius organic matter.

Suction is widely used by animals for strong controllable underwater adhesion but is less well understood than adhesion of terrestrial climbing animals. Here we investigate the attachment of aquatic insect larvae (Blephariceridae), which cling to rocks in torrential streams using the only known muscle-actuated suction organs in insects. We measured their attachment forces on well-defined rough substrates and found that their adhesion was less reduced by micro-roughness than that of terrestrial climbing insects. In vivo visualisation of the suction organs in contact with microstructured substrates revealed that they can mould around large asperities to form a seal. We have shown that the ventral surface of the suction disc is covered by dense arrays of microtrichia, which are stiff spine-like cuticular structures that only make tip contact. Our results demonstrate the impressive performance and versatility of blepharicerid suction organs and highlight their potential as a study system to explore biological suction mechanisms.

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.

We report the presence of the North American Crangonyx floridanus co-occurring with C. pseudogracilis in two Irish rivers, following surveys in three rivers, eleven lake sites and an ornamental pond in 2020. This is the first record of C. floridanus in Ireland which was previously recorded in Britain in 2017. We predict that this species is likely to expand its range through the river and canal connections in Ireland as well as from inadvertent anthropogenic transmission. The taxonomic criteria are cryptic and for this reason, we used genetic methods to distinguish the two species in this study. The results highlight the need to investigate the distribution and impact of these two species in freshwater habitats in Ireland. [ABSTRACT FROM AUTHOR]

Contaminants alter the quantity and quality of insect prey available to terrestrial insectivores. In agricultural regions, the quantity of aquatic insects emerging from freshwaters can be impacted by insecticides originating from surrounding croplands. We hypothesized that, in such regions, adult aquatic insects could also act as vectors of pesticide transfer to terrestrial food webs. To estimate insect‐mediated pesticide flux from wetlands embedded in an important agricultural landscape, semipermanetly and temporarily ponded wetlands were surveyed in cropland and grassland landscapes across a natural salinity gradient in the Prairie Pothole Region of North Dakota (USA) during the bird breeding season in 2015 and 2016 (n = 14 and 15 wetlands, respectively). Current‐use pesticides, including the herbicide atrazine and the insecticides bifenthrin and imidacloprid, were detected in newly emerged insects. Pesticide detections were similar in insects emerging from agricultural and grassland wetlands. Biomass of emerging aquatic insects decreased 43%, and insect‐mediated pesticide flux increased 50% along the observed gradient in concentrations of insecticides in emerging aquatic insects (from 3 to 577 ng total insecticide g–1 insect). Overall, adult aquatic insects were estimated to transfer between 2 and 180 µg total pesticide wetland–1 d–1 to the terrestrial ecosystem. In one of the 2 study years, biomass of emerging adult aquatic insects was also 73% lower from agricultural than grassland wetlands and was dependent on salinity. Our results suggest that accumulated insecticides reduce the availability of adult aquatic insect prey for insectivores and potentially increase insectivore exposure to insect‐borne pesticides. Adult aquatic insects retain pesticides across metamorphosis and may expose insectivores living near both agricultural and grassland wetlands to dietary sources of toxic chemicals. Environ Toxicol Chem 2021;40:2282–2296. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Carbohydrate-binding modules (CBMs) are non-catalytic protein domains that bind to carbohydrates, and have been well studied in microorganisms. Endogenous CBMs in aquatic invertebrates, however, have not yet been identified, and little is known about their ecological significance to wetland environments. Using an approach of characterizing a recombinant CBM (CjCel9A) from a brackish bivalve, Corbicula japonica, this work identified CjCel9A-CBM􀁠s cellulose-binding activity. Scatchard plot analysis in the study of CjCel9A-CBM binding to α-cellulose showed a high corresponding partitioning coefficient (Kr) of 20.33, indicating CjCel9A-CBM􀁠s high affinity for cellulose. In addition, this affinity tolerated a high ion concentration buffer system, consistent with C. japonica􀁠s adaption to brackish wetland environments. Moreover, immuno-scanning electron microscopy (immuno-SEM) suggested that CjCel9A-CBM binds to α-cellulose unevenly, which was further determined to be caused by its higher affinity for crystalline cellulose (Cellulose I, mostly seen in plant leaves). Together, these findings suggest that CjCel9A-CBM is capable of immobilizing its associated catalytic domain on environmental crystalline cellulose (i.e., fallen leaves) in wetland sediments. Most importantly, they could provide a reasonable answer to a question recognized broadly in wetland ecologists, namely, why many wetland sediments have constant cellulase activities, although the sediments are being washed almost every day. [ABSTRACT FROM AUTHOR]

The gastrointestinal (GI) microbiota is a group of complex and dynamic microorganisms present in the GI tract of an organism that live in symbiosis with the host and benefit the host with various biological functions. The communities of GI microbiota are formed by various aerobic, anaerobic, and facultatively anaerobic bacteria in aquatic species. In spiny lobsters, common GI microorganisms found in the GI tract are Vibrio, Pseudomonas, Bacillus, Micrococcus, and Flavobacterium, where the structure and abundance of these microbes are varied depending on the environment. GI microbiotas hold an important role and significantly affect the overall condition of spiny lobsters, such as secreting digestive enzymes (lipase, protease, and cellulase), helping in digesting food intake, providing nutrition and synthesising vitamins needed by the host system, and protecting the host against infection from pathogens and diseases by activating an immune mechanism in the GI tract. The microorganisms in the water column, sediment, and diet are primarily responsible for altering, manipulating, and shaping GI microbial structures and communities. This review also highlights the possibilities of isolating the indigenous GI microbiota as a potential probiotic strain and introducing it to spiny lobster juveniles and larvae for better health management.

A bioconcentration factor (BCF) database and a toxicokinetic model considering only biota–water partitioning and biotransformation were constructed for neutral organic chemicals in midge. The database contained quality‐reviewed BCF and toxicokinetic data with variability constrained to within 0.5 to 1 log unit. Diverse conditions in exposure duration, flow set‐up, substrate presence, temperature, and taxonomic classification did not translate into substantial variability in BCF, uptake rate constant (k1), or depuration rate constant (kT), and no systematic bias was observed in BCFs derived in unlabeled versus radiolabeled studies. Substance‐specific biotransformation rate constants kM were derived by difference between the calculated biota–water partitioning coefficient (KBW) and experimental BCF for developing a midge biotransformation model. Experimental midge BCF was modeled as BCF = KBW/(1 + kM/k2) with log kM (kM in h–1) = –0.37 log KOW – 0.06T (in K) + 18.87 (root mean square error [RMSE] = 0.60), log k1 (k1 in L kgwet.wt–1 h–1) = –0.0747 W (body weight in mgwet.wt) + 2.35 (RMSE = 0.48). The KBW value was estimated using midge biochemical composition and established polyparameter linear free energy relationships, and the diffusive elimination rate constant (k2) was computed as k2 = k1/KBW. The BCF model predicted >85% of BCFs that associated with neutral organic compounds (log KOW = 1.46 – 7.75) to within 1 log‐unit error margin and had comparable accuracy similar to amphipod or fish models. A number of outliers and critical limitations of the kM model were identified and examined, and they largely reflected the inherent limitation of difference‐derived kM, the lack of chemical diversity, and inadequate temperature variation in existing data. Future modeling efforts can benefit from more BCF and toxicokinetic observations of BCF on structurally diverse chemicals for model training, validation, and diagnosis. Environ Toxicol Chem 2021;40:57–71. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Mercury (Hg) loading and methylation in aquatic systems causes a variety of deleterious effects for fish and wildlife populations. Relatively little research has focused on Hg movement into riparian food webs and how this is modulated by habitat characteristics. This study characterized differences in Hg exposure in aquatic invertebrates and riparian songbirds across a large portion of the Willamette River system in western Oregon, starting at a Hg-contaminated Superfund site in the headwaters (Black Butte Hg Mine) and including a reservoir known to methylate Hg (Cottage Grove Reservoir), all downstream reaches (Coast Fork and Willamette River) and off-channel wetland complexes (Willamette Valley National Wildlife Refuge Complex). After accounting for year, date, and site differences in a mixed effects model, MeHg concentrations in aquatic invertebrates varied spatially among habitat categories and invertebrate orders. Similarly, THg in songbird blood varied by among habitat categories and bird species. The highest Hg concentrations occurred near the Hg mine, but Hg did not decline linearly with distance from the source of contamination. Birds were consistently elevated in Hg in habitats commonly associated with enhanced MeHg production, such as backwater or wetlands. We found a positive but weak correlation between aquatic invertebrate MeHg concentrations and songbird THg concentrations on a site-specific basis. Our findings suggest that Hg risk to riparian songbirds can extend beyond point-source contaminated areas, highlighting the importance of assessing exposure in surrounding habitats where methylmercury production may be elevated, such as reservoirs and wetlands. [ABSTRACT FROM AUTHOR]

Several investigations have recently assessed the ability of some aquatic invertebrates to act as tools for avian influenza A virus (IAV) surveillance as well as their potential role(s) in IAV ecology. Because of this, as well as the high IAV seroprevalence rates noted in select mesocarnivores that commonly inhabit aquatic and semi‐aquatic habitats, we evaluated the effects that freshwater crayfish have on IAV in water at three dose levels and monitored for the presence of IAV in crayfish tissues (gill and green gland) and haemolymph at multiple time points. At relatively high, medium and low (approximately 104, 103 and 102 EID50/ml, respectively) doses, mesocosms containing crayfish (Orconectes sp.) had less detectable IAV RNA present when final water samples were assayed (9 days post‐contact [DPC]). In general, containers without crayfish present had nearly three‐fold greater quantities of viral RNA at 9 DPC. A varying number of RNA positive samples were detected for the three crayfish sample types collected. Gill tissue produced the largest number of positive non‐water samples (n = 26), with the highest quantities detected from crayfish sampled on 1 and 4 DPC (103.5 EID50 equivalent/ml). On a few occasions, gill (n = 8) and haemolymph samples (n = 1) produced higher quantities of viral RNA than their respective water samples or water samples collected 1–2 DPC earlier, but these differences were typically minor. Based upon water samples, statistical models indicated that the interaction of dose and crayfish exposure days explained most of the variation in these data. Future efforts should address if crayfish exposed to IAV‐laden water have the capacity to successfully transmit IAVs to mammals and birds which frequently prey upon them. [ABSTRACT FROM AUTHOR]

The free-floating American duckweed, Lemna minuta, is an invasive species now widespread in Europe. Yet, its impact on freshwater ecosystems has been poorly investigated. In this study, the effects of the presence of this invasive duckweed on water quality, and aquatic plant and invertebrate communities were evaluated in sites in Central Italy. Water chemical and physical factors and community descriptors were analyzed to identify these effects. Surveys were carried out across 17 paired aquatic sites. Site pairs were similar in microclimate, hydrogeology and water quality, but differed in relation to the presence/absence of L. minuta floating mats. In sites with mats, light and dissolved oxygen in water were negatively correlated with increasing mat coverage and thickness. The limited light and hypoxic conditions under mats inhibited plant growth and had a selective impact on the invertebrate community. Sites with L. minuta had aquatic communities with a lower plant taxa richness and a contrasting composition, compared with those in sites without. At sites with mats some plants were unaffected, but the majority of plant taxa documented at sites without Lemna were no present at sites with Lemna or were very rare (macroalgae, submerged rhizophytes). As for invertebrates, hypoxic-tolerant taxa dominated under mats (Ostracoda, Copepoda, Isopoda), whilst those more sensitive to oxygen depletion, or obligate herbivores, or those with a winged stage or swimming on water surface, were rare or absent (Ephemeroptera, Amphipoda, Chironomus, Notonecta). Lemna minuta mats presence was associated with alterations in the underlying aquatic ecosystem, severely threatening the conservation of these habitats. Active management strategies, including spread-prevention techniques, or mechanical removal combined with biological control, are required to conserve these habitats. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate and qualify field-based potential risks of seven neonicotinoid and phenylpyrazole (fipronil) insecticides on aquatic invertebrates, including estuary-resident marine crustaceans. One hundred and ninety-three estuarine water samples, with salinity ranging from 0.5 to 32.7, were collected from four estuarine sites in the Seto Inland Sea of Japan, in 2015–2018 and the insecticide levels were measured. Five neonicotinoid and fipronil insecticides were successfully identified, and their occurrence varied temporally. Marine crustaceans were simultaneously harvested every month from one of the estuarine water sampling sites in 2015–2017. Three predominant crustacean species, kuruma prawn (Penaeus japonicus), sand shrimp (Crangon uritai), and mysid (Neomysis awatschensis), were captured and their seasonal presence was species independent. A 96-h laboratory toxicity study with the insecticides using kuruma prawn, sand shrimp, and a surrogate mysid species (Americamysis bahia) indicated that fipronil exerted the highest toxicity to the three crustaceans. Using both toxicity data and insecticide occurrence in estuarine water (salinity ≥10, n = 169), the potential risks on the three marine crustaceans were quantified by calculating the proportion of mixture toxicity effects (P mix). The P mix of seven neonicotinoids on the crustaceans was less than 0.8%, which is likely to be too low to indicate adverse effects caused by the insecticides. However, short temporal detection of fipronil (exclusively in June and July) significantly affected the P mix , which presented the maximal P mix values of 21%, 3.4%, and 72% for kuruma prawn, sand shrimp, and mysid, respectively, indicating a significant effect on the organisms. As for estuarine water (salinity <10), some water samples contained imidacloprid and fipronil exceeding the freshwater benchmarks for aquatic invertebrates. The present study provides novel insights into the seasonally varying risks of insecticides to estuarine crustaceans and highlights the importance of considering whether ecological risk periods coincide with crustacean presence. Image 1 • Occurrence of neonicotinoids and fipronil in estuaries were investigated. • Seasonal presence of three marine crustaceans in estuaries were species independent. • Proportion of mixture toxicity effects (P mix) was used to quantify potential risk. • Short temporal detection of fipronil significantly affected P mix. • Necessity to consider seasonally varying ecological risks and crustacean presence. [ABSTRACT FROM AUTHOR]

This study presents a case study for rice farming change from a conventional to semi-organic process. Alterations of aquatic invertebrate composition and diversity between these two rice farming methods were compared. Aquatic invertebrates were collected in flooded rice fields between August and October 2015. Four phyla comprising 12 taxa were identified with average abundances in conventional and semi-organic samples of 5,717 and 10,676 individuals/m2, respectively, while the Shannon diversity index ranged between 0.45-0.62 and 0.35-0.59, respectively. Evenness index in conventional and semi-organic ranged between 0.26- 0.65 and 0.23-0.71 respectively, while the dominant index was highest in semi-organic farming. Water quality parameters as temperature, dissolved oxygen and pH were not significantly different between the two farming methods. Contamination occurred from chemical substances remaining in semi-organic rice fields. Abundant pollution indicator species such as Oligochaeta, Chironomidae and Viviparidae suggested pesticide or herbicide contamination from water sources as agrochemical residues persisted from previous conventional rice farming. [ABSTRACT FROM AUTHOR]

Consumer products such as perfluorooctanesulfonic acid (PFOS) and pharmaceuticals (PCPPs) enter aquatic ecosystems through inefficient removal during wastewater treatment. Often, the sterilization process of wastewater includes the addition of sodium hypochlorite that can react with PCPPs and other organic matter (i.e., dissolve organic matter) to generate disinfection by-products and can cause the final effluent to be more harmful to aquatic organisms. Here, we exposed Daphnia magna to two stages of wastewater, the pre-chlorinated wastewater (PreCl) and the final effluent. In addition, we exposed D. magna, to the final effluent with a concentration gradient of added PFOS, to investigate if this persistent contaminant altered the toxicity of the final effluent. After 48 h of contaminant exposure, we measured the daphnids metabolic responses to the different stages of wastewater treatment, and with the addition of PFOS, utilizing proton nuclear magnetic resonance spectroscopy and liquid chromatography tandem mass spectrometry. We found few significant changes to the metabolic profile of animals exposed to the PreCl wastewater; however, animals exposed to the final effluent displayed increases in many amino acids and decreases in some sugar metabolites. With the addition of PFOS to the final effluent, the metabolic profile shifted from increased amino acids and decreased sugar metabolites and energy molecules especially at the low and high concentrations of PFOS. Overall, our results demonstrate the metabolome is sensitive to changes in the final effluent that are caused by sterilization, and with the addition of a persistent contaminant, the metabolic profile is further altered. [ABSTRACT FROM AUTHOR]

Abstract Cytochrome P450s (CYPs) are a large gene superfamily that are found in all living organisms. CYPs have a key role in detoxification of xenobiotics and endogenous chemicals. Although aquatic invertebrate CYPs and their detoxification mechanisms have been reported, little is known about interspecific comparison of CYPs and their detoxification mechanism in the rotifer Brachionus spp. The aim of this study was to identify the entire CYP s in the rotifer Brachionus rotundiformis (B. rotundiformis) and compare B. rotundiformis -CYPs to the previously reported CYPs in other model Brachionus spp. (B. koreanus , B. plicatilis , and B. calyciflorus). To validate the model, the rotifer, specifically Brachionus rotundiformis was exposed to various concentrations of B[α]P, which is widely used PAH xenobiotic, and analyzed gene expression in response to B[α]P. Here, in silico analysis results showed the total of 26 CYP s from the rotifer B. rotundiformis. Based on the phylogenetic analysis, the 26 B. rotundiformis -CYPs were separated into five different clans: 2, 3, 4, mitochondrial, and 46 clans in comparison to three rotifers species, B. koreanus , B. plicatilis , and B. calyciflorus. To understand the detoxification mechanisms of 26 B. rotundiformis -CYPs, we investigated transcriptional expression of 26 CYP s and found that five CYP s (CYP3045A2 , CYP3045B4 , CYP3045C10 , CYP3049A5 , and CYP3049E8) were significantly increased (P < 0.05) in response to 10 and 100 μg B[α]P. In addition, we identified the aryl hydrocarbon receptor (AhR) and aryl hydrocarbon receptor nuclear translocator (ARNT) and observed slight up-regulation of B. rotundiformis - AhR and - ARNT , indicating that these CYPs are likely associated with detoxification mechanism and could be used as potential molecular biomarkers of B[α]P in B. rotundiformis. Overall, this study will be helpful for expanding our knowledge of invertebrate CYPs on detoxification mechanisms associated with AhR signaling pathway in rotifers. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Accurate bioenergetic carrying capacity estimates of wetlands on public and private lands, as well as those managed for crop production are important for managing waterfowl populations and habitats. Given the importance of wetlands in the Rainwater Basin region of Nebraska for spring migrating waterfowl, we quantified and compared seed and aquatic invertebrate biomass and true metabolizable energy (TME) at three wetland types; public wetlands, wetlands enrolled in the Wetlands Reserve Program (WRP), and cropped wetlands. Median seed biomass estimates at public, WRP, and cropped wetlands were 593 kg/ha, 561 kg/ha, and 419 kg/ha respectively. Cumulative TME varied among wetland type, with greater TME at cropped wetlands (2431 kcal/kg) than public (1740 kcal/kg) and WRP wetlands (1781 kcal/kg). Seed biomass estimates from this study were statistically greater than those currently used for management planning in the RWB, however, TME estimates were statistically lower than estimates currently assumed for WRP and public wetlands. Our estimates for aquatic invertebrate biomass were approximately 40-fold less than seed biomass estimates. Based on spring ponding frequency at wetlands in Nebraska's Rainwater Basin, and the caloric estimates derived for each wetland type, we concluded that the regions wetlands meet the energetic demand of spring migrating waterfowl during 10% of years. [ABSTRACT FROM AUTHOR]

Mycobacteriosis is a chronic bacterial disease reported in aquatic and terrestrial animals, including humans. The disease affects a wide range of cultured and wild organisms worldwide. Mycobacteriosis is well-known in aquatic vertebrates (e.g., finfish, marine mammals), while in the last few years, reports of its presence in aquatic invertebrates have been on the rise, for both freshwater and marine species. The number of cases is likely to increase as a result of increased awareness, surveillance and availability of diagnostic methods. Domestication of wild aquatic species and the intensification of modern aquaculture are also leading to an increase in the number of reported cases. Moreover, climate changes are affecting fresh and marine aquatic ecosystems. The increasing reports of mycobacteriosis in aquatic invertebrates may also be influenced by global climate warming, which could contribute to the microbes’ development and survival rates, pathogen transmission and host susceptibility. Several species of the genus Mycobacterium have been diagnosed in aquatic invertebrates; a few of them are significant due to their wide host spectrum, economic impact in aquaculture, and zoonotic potential. The impact of mycobacteriosis in aquatic invertebrates is probably underestimated, and there is currently no effective treatment other than facility disinfection. In this review, we provide an overview of the diversity of mycobacterial infections reported in molluscs, crustaceans, cnidarians, echinoderms and sponges. We highlight important issues relating to its pathological manifestation, diagnosis and zoonotic considerations.

The common hippopotamus, Hippopotamus amphibius, transports millions of tons of organic matter annually from its terrestrial feeding grounds into aquatic habitats. We evaluated whether carbon stable isotopes (δ13C) can be used as tracers for determining whether H. amphibius‐vectored allochthonous material is utilized by aquatic consumers. Two approaches were employed to make this determination: (1) lab‐based feeding trials where omnivorous river fish were fed a H. amphibius dung diet and (2) field sampling of fish and aquatic insects in pools with and without H. amphibius. Lab trials revealed that fish fed exclusively H. amphibius dung exhibited significantly more positive δ13C values than fish not fed dung. Fish and aquatic insects sampled in a river pool used for decades by H. amphibius also exhibited more positive δ13C values at the end of the dry season than fish and insects sampled from an upstream H. amphibius‐free reference pool. Fish sampled in these same pools at the end of the wet season (high flow) showed no significant differences in δ13C values, suggesting that higher flows reduced retention and use of H. amphibius subsidies. These data provide preliminary evidence that δ13C values may be useful, in certain contexts, for quantifying the importance H. amphibius organic matter.

Azole fungicides, designed to halt fungal growth by specific inhibition of fungal cytochrome P450 (CYP51), inhibit cytochrome P450s involved in the metabolism of xenobiotics in several non-target organisms thus raising environmental concern. The present study investigates the degree by which inhibition strengths of azoles toward cytochrome P450 in rat liver, the insect Chironomus riparius larvae and the snail Lymnaea stagnalis can be extrapolated from estimated in silico affinities. Azoles’ affinities toward human cytochrome P450 isoforms involved in xenobiotic metabolism (CYP3A4, CYP2C9 and CYP2D6) as well as fungal CYP51 were estimated with a ligand-protein docking model based on the ChemScore scoring function. Estimated affinities toward the selected enzymatic structures correlated strongly with measured inhibition strengths in rat liver (ChemScore vs . logIC 50 among cytochrome P450 isoforms: −0.662 < r < −0.891, n = 17 azoles), while weaker correlations were found for C. riparius larvae (−0.167 < r < −0.733, n = 9) and L. stagnalis (−0.084 < r < −0.648, n = 8). Inhibition strengths toward C. riparius and rat liver activities were found to be highly correlated to each other (r: 0.857) while no significant relationship was found between either of the species and L. stagnalis . The inhibition of cytochrome P450 due to azole fungicides could be estimated in vitro and to a lesser extent in silico for C. riparius but not for L. stagnalis , possibly due to different enzymatic susceptibility toward azole inhibition among the species. [ABSTRACT FROM AUTHOR]

Abstract: The present study presents a bioconcentration model for non‐ionic, polar, and ionizable organic compounds in amphipod based on first‐order kinetics. Uptake rate constant k1 is modeled as log k 1 = 1 0.81 log K OW   +   0.15 (root mean square error [RMSE] = 0.52). Biotransformation rate constant kM is estimated using an existing polyparameter linear free energy relationship model. Respiratory elimination k2 is calculated as modeled k1 over theoretical biota–water partition coefficient Kbiow considering the contributions of lipid, protein, carbohydrate, and water. With negligible contributions of growth and egestion over a typical amphipod bioconcentration experiment, the bioconcentration factor (BCF) is modeled as k1/(kM + k2) (RMSE = 0.68). The proposed model performs well for non‐ionic organic compounds (log KOW range = 3.3–7.62) within 1 log‐unit error margin. Approximately 12% of the BCFs are underpredicted for polar and ionizable compounds. However, >50% of the estimated k2 values are found to exceed the total depuration rate constants. Analyses suggest that these excessive k2 values and underpredicted BCFs reflect underestimation in Kbiow, which may be improved by incorporating exoskeleton as a relevant partitioning component and refining the membrane–water partitioning model. The immediate needs to build up high‐quality experimental kM values, explore the sorptive role of exoskeleton, and investigate the prevalence of k2 overestimation in other bioconcentration models are also identified. The resulting BCF model can support, within its limitations, the ecotoxicological and risk assessment of emerging polar and ionizable organic contaminants in aquatic environments and advance the science of invertebrate bioaccumulation. Environ Toxicol Chem 2018;37:1378–1386. © 2018 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Chemical impacts on the environment are routinely assessed in single‐species tests. They are employed to measure direct effects on nontarget organisms, but indirect effects on ecological interactions can only be detected in multispecies tests. Micro‐ and mesocosms are more complex and environmentally realistic, yet they are less frequently used for environmental risk assessment because resource demand is high, whereas repeatability and statistical power are often low. Test systems fulfilling regulatory needs (i.e., standardization, repeatability, and replication) and the assessment of impacts on species interactions and indirect effects are lacking. In the present study we describe the development of the TriCosm, a repeatable aquatic multispecies test with 3 trophic levels and increased statistical power. High repeatability of community dynamics of 3 interacting aquatic populations (algae, Ceriodaphnia, and Hydra) was found with an average coefficient of variation of 19.5% and the ability to determine small effect sizes. The TriCosm combines benefits of both single‐species tests (fulfillment of regulatory requirements) and complex multispecies tests (ecological relevance) and can be used, for instance, at an intermediate tier in environmental risk assessment. Furthermore, comparatively quickly generated population and community toxicity data can be useful for the development and testing of mechanistic effect models. Environ Toxicol Chem 2018;37:1051–1060. © 2017 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Potential toxic effects of thiamethoxam on nontarget organisms and the community structure of a generic Midwestern farm pond and emergent wetland were assessed using 2 versions of the comprehensive aquatic system model: CASMGFP, a generic farm pond model, and CASMGWL, a generic wetland model. The CASMGFP and CASMGWL are integrated bioenergetics‐based and habitat quality models that describe the daily biomass values of selected producer and consumer populations representative of generalized Midwestern farm ponds and emergent wetlands. The CASMGFP demonstrated the ability to reproduce values of population biomass reported for Midwestern (and other) pond ecosystems; the CASMGWL provided a similar modeling capability for Midwestern emergent wetlands. Lethal and sublethal effects of thiamethoxam were modeled as extrapolations of laboratory toxicity assays using the CASMGFP and the CASMGWL. Time series of daily environmental concentrations of thiamethoxam constructed for 6 regional pesticide applications across the United States failed to produce any calculated impacts on modeled population biomass or changes in community structure of modeled trophic guilds in the CASMGFP or the CASMGWL. However, evaluation of systematically increased daily concentrations demonstrated the ability of both models to simulate direct and indirect toxic effects of this pesticide. The present model study suggests that process‐based food web/ecosystem models can be used to characterize the potential ecological effects of thiamethoxam on generalized farm pond and emergent wetland ecosystems. Environ Toxicol Chem 2018;37:738–754. © 2017 SETAC [ABSTRACT FROM AUTHOR]