Freshwater Organisms Research Articles

Reconciling biodiversity conservation and flood risk reduction: The new strategy for freshwater protected areas

AbstractAimNatural disaster risk reduction (DRR) is becoming a more important function of protected area (PAs) for current and future global warming. However, biodiversity conservation and DRR have been handled separately and their interrelationship has not been explicitly addressed. This is mainly because, due of prevailing strategies and criteria for PA placement, a large proportion of PAs are currently located far from human‐occupied areas, and habitats in human‐occupied areas have been largely ignored as potential sites for conservation despite their high biodiversity. If intensely developed lowland areas with high flooding risk overlap with important sites for biodiversity conservation, it would be reasonable to try to harmonize biodiversity conservation and human development in human‐inhabited lowland areas. Here, we examined whether extant PAs can conserve macroinvertebrate and freshwater fish biodiversity and whether human‐inhabited lowland flood risk management sites might be suitable to designate as freshwater protected areas (FPAs).LocationAcross Japan.MethodsWe examined whether extant PAs can conserve macroinvertebrate and freshwater fish biodiversity and analysed the relationship between candidate sites for new FPAs and flood disaster risk and land use intensity at a national scale across Japan based on distribution data for 131 freshwater fish species and 1395 macroinvertebrate species.ResultsWe found that extant PAs overlapped with approximately 30% of conservation‐priority grid cells (1 km2) for both taxa. Particularly for red‐listed species, only one species of freshwater fish and three species of macroinvertebrate achieved the representation target within extant PAs. Moreover, more than 40% of candidate conservation‐priority grid cells were located in flood risk and human‐occupied areas for both taxa.Main conclusionsFloodplain conservation provides suitable habitat for many freshwater organisms and helps control floodwaters, so establishing new FPAs in areas with high flood risk could be a win‐win strategy for conserving freshwater biodiversity and enhancing ecosystem‐based DRR (eco‐DRR).

Plants and palynomorphs from the Lower Devonian (upper Emsian) of the Holy Cross Mountains, Poland

We present a preliminary assessment of a new Lower Devonian biota from an exposure of the Zagórze Formation at Bukowa Góra quarry in the Łysogóry Region of the Holy Cross Mountains, Poland. Abundant plant macrofossils preserved as carbonaceous compressions, adpressions, and permineralizations occur alongside a diverse assemblage of microfossils. Palynostratigraphic analysis places the fossiliferous sequences in the narrow Pro. Zone within the AP Zone of the douglastownense-eurypterota Miospore Zone, which corresponds to the upper part of the Emsian. Palynofacies analysis confirms that these sediments formed in a shallow-water, alluvial environment. The biota contains a rich assemblage of freshwater and brackish water organisms and fully terrestrial ones. Common elements include filamentous green algae, arthropods, terrestrial fungi-like filaments, nematophytes and abundant land plants. Scolecodonts and acritarchs are much rarer, suggesting limited marine influence. The new flora contains stem-group vascular plants, lycophytes and euphyllophytes. Among the permineralized remains is some of the earliest evidence of complex vascular systems, including cruciform and plate-like stelar organizations and secondary wood. We record the earliest fossil evidence of a dissected stele of the cladoxylopsid type. Innovations such as these were fundamental to the later evolution of arborescent growth in plants and the development of forest ecosystems. The biota complements and extends our knowledge of Emsian biotas in Euramerica just prior to the rapid changes that marked the Middle Devonian. It provides insights into a diverse early terrestrial community and raises further questions about the affinities and roles of arthropods and nematophytales in these ecosystems.

Anaerobic biodegradation of dipyrone: Determination of transformation products by LC-HRMS and ecotoxicity assessment using target organisms and QSAR model

The degradation of dipyrone (metamizole) was studied for the first time under mesophilic anaerobic conditions using a synthetic wastewater similar to that found in anaerobic digestion (AD) treatment plants. Dipyrone concentration effect (250–25,000 µg L−1) was evaluated in short term batch and long-term semi-continuous operation. After 48 days, biogas production and biodegradability were reduced in the batch AD by 17.7% and 18.8%, respectively, regardless of the dipyrone concentration. However, additions of 1000 µg L−1 to the long-term AD system stimulated biogas production and increased organic matter removal by 68% and 30%, respectively. Although removals of the main metabolite 4-MAA (N-methyl-4-aminoantipyrine) and other transformation products were observed in the batch tests after 48 days, a continuous accumulation of dipyrone by-products in the long-term AD reflected its recalcitrant nature. The occurrence of these metabolites coincided with an increased toxicity of the AD effluent to Aliivibrio fischeri of 79% bioluminescent bacteria-inhibition observed immediately after the addition of the dipyrone, while the germination of Lactuca sativa seeds and growth of Raphidocelis subcaptata were stimulated by the same conditions. The toxicity of by-products was mainly attributed to hydrazinic group according to predictions elaborated by ECOSAR software. The results showed that long term exposure to dipyrone main by-product 4-MAA, as a consequence of build up into environment over continuous discharges of effluents, can significantly affect freshwater organisms.

What is the mechanism of submerged macrophyte biodiversity affecting biomass productivity along water depth: Niche complementarity or selection effect?

The impact of biodiversity on ecosystem functions and services remains a hot topic in ecology, especially under increasing biodiversity loss. Studies on the relationship between biodiversity and ecosystem functioning have identified two regulatory mechanisms: i.e., “niche complementarity” and “selection effect”. However, the relative importance of these mechanisms within communities and how they change along ecological gradients remain unclear. Moreover, most studies have focused on relatively stable ecosystems (e.g., forest, grassland), with limited attention paid to ecosystems with obvious seasonal changes, e.g., freshwater ecosystems. In this study we conducted a seasonal survey of submerged macrophyte communities to clarify the mechanisms of biodiversity on biomass productivity accounting for seasons and water depth. Our results showed that (1) seasonal variations of community indicators exhibited different trends along the water depth gradient. Biomass productivity showed high seasonal variation at intermediate depth while temporal beta diversity showed the opposite pattern. (2) Water depth not only inhibited biomass productivity directly but also indirectly by reducing species richness and enhancing temporal beta diversity. (3) The positive effect of species richness on biomass productivity was lower than the negative effect of evenness (path coefficients: 0.13 vs. 0.27), indicating that “selection effect” played a more important role in the relationship. (4) In shallow areas, the mechanism underlying the effects of biodiversity on biomass productivity was more from “selection effect”, whereas, in deep areas, the effects were related to both “niche complementarity” and “selection effect”. Our findings suggest that “niche complementarity” and “selection effect” are two complementary mechanisms underpinning the relationship between biodiversity and biomass productivity, and their relative importance varies with specific ecological gradients. Our results also provide a reference for studies on other freshwater organisms with analogous distribution patterns as submerged macrophytes with water depth. Scale dependence of the above relationship should be considered in future studies.

First Isolation and Characterization of Streptococcus agalactiae From a Stranded Wild Common Dolphin (Delphinus delphis)

Streptococcosis is an infectious bacterial disease of both homeotherms and poikilotherms. Among the Streptococcus species that infect marine animals, Streptococcus agalactiae has the broadest host spectrum, including different aquatic organisms in freshwater and marine environments. The common dolphin (Delphinus delphis) is categorized as Endangered in the Mediterranean Sea. There are few reports of a streptococcal infection of D. delphis, caused by Streptococcus phocae and Streptococcus iniae. Here we report the isolation and identification of S. agalactiae in a stranded, wild male common dolphin that was found dead in September 2020 on the seashore next to the city of Bat-Yam, Israel. The carcass was fresh with a moderate nutritional status and with no apparent fishing gear or other anthropogenic-related signs. A post-mortem examination did not reveal an apparent cause of death, but further laboratory analysis demonstrated a S. agalactiae bacterial presence in urine, lungs and pericardial fluid that was characterized as type Ia-ST7 by whole genome sequencing. Interestingly, this isolate was found to be almost identical to another isolate recently recovered from a wild sandbar shark (Carcharhinus plumbeus) in the same area in Israel, the eastern Mediterranean Sea.

Climate change and mercury in the Arctic: Biotic interactions

Global climate change has led to profound alterations of the Arctic environment and ecosystems, with potential secondary effects on mercury (Hg) within Arctic biota. This review presents the current scientific evidence for impacts of direct physical climate change and indirect ecosystem change on Hg exposure and accumulation in Arctic terrestrial, freshwater, and marine organisms. As the marine environment is elevated in Hg compared to the terrestrial environment, terrestrial herbivores that now exploit coastal/marine foods when terrestrial plants are iced over may be exposed to higher Hg concentrations. Conversely, certain populations of predators, including Arctic foxes and polar bears, have shown lower Hg concentrations related to reduced sea ice-based foraging and increased land-based foraging. How climate change influences Hg in Arctic freshwater fishes is not clear, but for lacustrine populations it may depend on lake-specific conditions, including interrelated alterations in lake ice duration, turbidity, food web length and energy sources (benthic to pelagic), and growth dilution. In several marine mammal and seabird species, tissue Hg concentrations have shown correlations with climate and weather variables, including climate oscillation indices and sea ice trends; these findings suggest that wind, precipitation, and cryosphere changes that alter Hg transport and deposition are impacting Hg concentrations in Arctic marine organisms. Ecological changes, including northward range shifts of sub-Arctic species and altered body condition, have also been shown to affect Hg levels in some populations of Arctic marine species. Given the limited number of populations and species studied to date, especially within Arctic terrestrial and freshwater systems, further research is needed on climate-driven processes influencing Hg concentrations in Arctic ecosystems and their net effects. Long-term pan-Arctic monitoring programs should consider ancillary datasets on climate, weather, organism ecology and physiology to improve interpretation of spatial variation and time trends of Hg in Arctic biota.

Seasonal variation and ecological risk assessment of microplastics ingested by economic fishes in Lake Chaohu, China

Microplastic (MP) contaminations in freshwater organisms have attracted substantial attention worldwide. However, seasonal field studies of MPs concentrations in aquatic life are scarce. In this study, we analyzed the seasonal variation and ecological risk of MPs concentrations in economic fish species from Lake Chaohu in China between wet and dry seasons. Within both seasons, MPs in fish were systematically analyzed using methods of KOH digestion, NaCl density floatation and raman spectroscopy. MPs abundance in economic fishes were significantly higher in dry season than that in wet season, which can be ascribed to the MPs' amplification effects in lacustrine ecosystems during dry season. Whereas, our results recorded similar and homogenized characteristic composition of MPs in economic fishes between wet and dry seasons. In both seasons, fiber was the main morphological type, black and blue were the most common MPs color, and MPs ranging from <0.5 mm accounting for the most abundant size. In addition, polypropylene (PP) and polyethylene terephthalate (PET) accounted for the most abundant polymer type detected by economic fishes in both seasons. In terms of feeding groups and habitat preferences, planktivorous and pelagic fish species exhibited sensitive variations of MPs concentrations between wet and dry seasons, thus being highlighted as good bioindicators of MPs contaminants in freshwater ecosystems. Our results revealed higher ecological risks of MPs in wet season than that in dry season when indicating from polymer risk index (H). By providing detailed and direct toxicity information, our study highlights the usage of polymer risk index for ecological risk assessment in aquatic organisms.

The surfactant Dioctyl Sodium Sulfosuccinate (DOSS) exposure causes adverse effects in embryos and adults of zebrafish (Danio rerio)

Dioctyl Sodium Sulfosuccinate (DOSS, CAS 577-11-7) is a chemical emulsifying surfactant that is widely used in the food and the cosmetic industry, and it is also the major component of the crude oil chemical dispersant Corexit™. Despite of its wide use, the studies related to its negative effect have been evaluated mainly in marine environments showing that DOSS is highly bioactive, extremely low volatile, and potential to persist in the environment longer than other dispersant components. Up to date, there is no available information of DOSS concentration in freshwater environments, little is known about its downstream fate after excretion and its effect on freshwater organisms. The objective of this study was to evaluate the effect of DOSS at different concentrations in embryos and adults of zebrafish Danio rerio in an acute-static bioassays of 96 h. The median lethal concentration in embryos was 33.3 mg/L. Malformations started to be observed at 10 mg/L. In adults, the gene expression analysis in gill tissues showed a deregulation in genes associated with the antioxidant system and the nucleotide excision repair mechanism. Additionally, Micronuclei (DNA damage) in erythrocytes, and fat degeneration in liver, hypertrophy and hyperplasia in gills, and hyaline drops in kidney tissues were also observed. In conclusion, the concentrations of DOSS evaluated here would be of health relevance to fish based on morphological alterations in embryos and changes in the gene expression profile, DNA damage and tissue impairment in adults.

Can microplastics from personal care products affect stream microbial decomposers in the presence of silver nanoparticles?

Microplastics (MPs) are emerging contaminants of great concern due to their abundance and persistence over time in aquatic environments. However, studies on their impacts on freshwater organisms are scarce. In resemblance, silver nanoparticles (Ag-NPs) are incorporated into textiles and personal care products and are also classified as emerging contaminants. We used the leaf litter decomposition model system to investigate the effects of MPs from a commercially used personal care product, alone or in mixture with Ag-NPs, on the diversity and activities of freshwater microbial decomposers. We exposed stream microbial communities associated with leaf litter to increasing concentrations of MPs (polyethylene extracted from a personal care product; 100 μg L−1 up to 1 g L−1 5 concentrations plus 1 control) for 27 days in the absence or presence of Ag-NPs (0.1 mg L−1 and 1 mg L−1). The exposure to MPs, alone or in mixture with Ag-NPs, negatively affected fungal diversity and sporulation, with a reduction in leaf litter decomposition (Cohen's d > 1.5; r> 0.8; Bonferroni, P < 0.01). Shifts in community structure of sporulating fungi were observed, and effects were more pronounced in mixtures with Ag-NPs at the highest concentration. Mixtures of MPs with Ag-NPs (at the higher concentration) had the strongest impacts on extracellular enzymatic (β-glucosidase, Cohen's d > 1; r > 0.5; phenol oxidase, Cohen's d > 1; r > 0.4) activities (ANOVAs, P < 0.05). Apart from sporulation rates, observed toxicity in mixtures was lower than that expected based on individual toxicity effects, mainly for higher concentrations (Bonferroni, P < 0.05). Our study provided evidence of the potential harmful effects of MPs, alone or in mixtures with Ag-NPs, on the activities of aquatic fungi and on a key ecosystem process, determinant to organic matter turnover in streams.

Структурно-функциональные характеристики фитопланктона озера Вендюрского, испытывающего влияние форелевого хозяйства

The paper presents the results of a study of the phytoplankton of small Lake Vendyurskoe (south of Karelia) in the spring ice period, in summer and autumn seasons of 2020. The dynamics of quantitative and structural indices of lake algae during the trout farm operation is considered in comparison with the indices of previous years. For the studied seasons of 2020 there were identified 122 taxa of algal flora belonging to 8 divisions. The structure of algocenoses can be characterized by rich species diversity and quantitative development as diatom green structure with golden algae insertions. In autumn the representatives of cyanobacteria were encountered en masse in some areas. Phytoplankton abundance in the spring ice period varied within 612 thousand cells/l - 2188 thousand cells/l, the biomass reached 2.9 mg/l with a minimum value of 0.1 mg/l. Phytoplankton abundance for the studied summer period of 2020 averaged 2216±796 thousand cells/l with a maximum value of 3986 thousand cells/l, the average biomass in the lake did not ex-ceed 1.325±0.504 mg/l. Phytoplankton abundance in autumn averaged 4934±1665 thousand cells/l with a maximum value of 7832 thousand cells/l; biomass averaged 5.8±1.5 mg/l with a maximum value of 7.9 mg/l. According to the eco-logical and geographical characteristics, most representatives of the algal flora found in the lake are widespread freshwater organisms belonging to the planktonic flora and preferring a neutral reaction of the environment. The Shannon index increased from 2.8 in the center of the lake to 3.3 in the trout farming area, which indicates good species diversity. The Sorensen index of 0.8 revealed the homogeneity between phytoplankton communities in different areas of the lake. Most of the identified types of saprobity indices belong to the representatives of the &#x0D; β-mesosaprobic and oligo-beta-mesosaprobic zones (up to 78% of the total number of identified indicator species). The saprobity index corresponded to the 2nd class of water purity (pure, α-oligosaprobic), which is due to the species composition of the dominant phytoplankton complex, however, the biomass indicates that the lake belongs to the 3rd class of water purity (satisfactorily clean, β-mesosaprobic).

Environmental Consequences of Rubber Crumb Application: Soil and Water Pollution.

End-of-life tires are utilized for various purposes, including sports pitches and playground surfaces. However, several substances used at the manufacture of tires can be a source of concerns related to human health or environment’s adverse effects. In this context, it is necessary to map whether this approach has the desired effect in a broader relation. While the negative effects on human health were investigated thoroughly and legislation is currently being revisited, the impact on aquatic or soil organisms has not been sufficiently studied. The present study deals with the exposure of freshwater and soil organisms to rubber crumb using the analysis of heavy metal and polycyclic aromatic hydrocarbon concentrations. The obtained results refer to substantial concerns related to freshwater contamination specifically, since the increased concentrations of zinc (7 mg·L−1) and polycyclic aromatic hydrocarbons (58 mg·kg−1) inhibit the growth of freshwater organisms, Desmodesmus subspicatus, and Lemna minor in particular. The performed test with soil organisms points to substantial concerns associated with the mortality of earthworms as well. The acquired knowledge can be perceived as a roadmap to a consistent approach in the implementation of the circular economy, which brings with it a number of so far insufficiently described problems.

Differential effects of microplastic exposure on anuran tadpoles: A still underrated threat to amphibian conservation?

Microplastics (MPs) have been reported to threaten a wide variety of terrestrial, marine, and freshwater organisms. However, knowledge about the effects of MPs on anuran amphibians, one of the most threatened taxa worldwide, is still limited. To assess the effects of MPs on the growth and survival of the Italian agile frog (Rana latastei) and green toad (Bufotes balearicus), we exposed tadpoles to three different concentrations (1, 7, and 50 mg L−1) of an environmental relevant mixture of microplastics (HPDE, PVC, PS and PES), recording data on their activity level, weight and mortality rates. While the effects of MPs on green toad tadpoles were negligible, Italian agile frog tadpoles were severely affected both in terms of growth and activity level, with high mortality rates even at the lowest MP density (1 mg L−1). Our results suggest that MP contamination of freshwater habitats may contribute to the ongoing decline of anuran amphibians.

The joint effects of salt and 6PPD contamination on a freshwater herbivore

Using sodium chloride (NaCl) for de-icing roads is known to have severe consequences on freshwater organisms when washed into water bodies. N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, also known as 6PPD, is an antiozonant mainly found in automobile tire rubber to prevent ozone mediated cracking or wear-out. Especially the ozonated derivate, 6PPD-quinone, which is washed into streams after storm events, has been found to be toxic for coho salmon. Studies on other freshwater organisms could not confirm those findings, pointing towards distinct species-specific differences. Storm events result in greater run-offs from all water-soluble contaminants into freshwater bodies, potentially enhancing the concentrations of both chloride and 6PPD during winter. Here we show that these two contaminants have synergistic negative effects on the population growth of the rotifer Brachionus calyciflorus, a common freshwater herbivore. Hence, while only high concentrations of 6PPD and even higher concentrations of 6PPD-quinone, beyond environmentally relevant concentrations, had lethal effects on rotifers, the addition of NaCl enhanced the sensitivity of the rotifers towards the application of 6PPD so that their negative effects were more pronounced at lower concentrations. Similarly, 6PPD increased the lethal effect of NaCl. Our results support the species-specific toxicity of 6PPD and demonstrate a synergistic effect of the antiozonant on the toxicity of other environmentally relevant stressors, such as road salt contamination.

Toxic impact of polystyrene microplastic particles in freshwater organisms

The ongoing COVID-19 pandemic is leading to an increase of the global production of plastics since the use of personal protective equipment (PPEs, i.e. gloves, gowns, masks, packaging items), has become mandatory to prevent the spread of the virus. Plastic breaks down into micro/nano particles due to physical or chemical or biological actions into environment. Due to small dimensions, ubiquitous and persistent nature, the plastic particles represent a significant threat to ecosystems and can entry into food chains. Among the plastic polymers used for PPEs, polystyrene is less studied regarding its eco-geno-toxicity. This study aims to investigate acute, chronic and subchronic effects of the microplastic polystyrene beads (PS-MP, size 1.0 μm) on three freshwater species, the alga Raphidocelis subcapitata, the rotifer Brachionus calyciflorus, the crustacean Ceriodaphnia dubia and the benthic ostracod Heterocypris incongruens. Furthermore, the potential genotoxicity and the ROS production due to the PS-MP were also determined in C. dubia.Results revealed that the acute effects occurred at concentrations of PS-MP in the order of dozens of mg/L in B. calyciflorus and C. dubia and hundreds of mg/L in H. incongruens.Regarding long-term toxicity, increasing chronic effects with EC50s in the order of units (C. dubia), hundreds (B. calyciflorus) and thousands (R. subcapitata) of μg/L were observed. Both for acute and chronic/sub chronic toxicity, daphnids were more sensitive to polystyrene than ostracods. Moreover, when C. dubia neonates were exposed to the PS-MP, alterations in genetic material as well as the production of ROS occurred, starting from concentrations in the order of units of μg/L, probably due to inflammatory responses. At last, the risk quotient (RQ) as a measure of risk posed by PS-MPs in freshwater environment, was calculated obtaining a value of 7.2, higher than the threshold value of 1.

Exposure to polystyrene microplastics reduces regeneration and growth in planarians

The potential adverse effects of microplastics (MPs) on ecosystems and human health have received much attention in recent years. However, only limited data are available on the mechanisms for the uptake, distribution, and effects of MPs in freshwater organisms, especially with respect to tissue repair, regeneration and impairment of stem cell functions. To address this knowledge gap, we conducted exposure experiments in which planarians (Dugesia japonica) were exposed to polystyrene (PS)-MPs mixed in liver homogenate and examined the tissue growth and regeneration, stem cell functions, and oxidative stress. The body and blastema areas decreased upon exposure to PS-MPs, indicating that the growth and regeneration of planarians were delayed. The proliferation and differentiation processes of stem cells were inhibited, and the proportion of mitotic stem cells decreased, which may be related to the activation of the TGFβ/SMAD4 and Notch signaling pathways. The enhancement of antioxidant enzyme activities and malondialdehyde on the first day of exposure to PS-MPs confirmed the oxidative stress response of planarians to PS-MPs. The present study demonstrated the likelihood of biotoxicity induced by PS-MPs. These results will provide clues for further investigations into the potential risks of PS-MPs to human stem cells.

Micro(nano)plastics Prevalence, Food Web Interactions, and Toxicity Assessment in Aquatic Organisms: A Review

Plastic pollution is a fast-rising environmental catastrophe. Microplastics and nanoplastics (MNPs) are ubiquitous components of most aquatic environments, and their burgeoning prevalence is endangering aquatic organisms. Recent studies have documented the entanglement of marine and freshwater biota by plastic litters, particularly ghost fishing gear, resulting in suffocation, drowning, or starving to death. Numerous reports have shown that aquatic organisms readily ingest and accumulate these emerging contaminants in their digestive systems. Given experimental evidence that contaminants-laden MNPs can persist in the gastrointestinal tract for considerable durations, investigations have documented a high probability of lethal and sublethal toxicological effects associated with direct and indirect MNPs ingestions. These include chronic protein modulation, DNA damage, embryotoxicity, gastrointestinal toxicity, genotoxicity, growth inhibition toxicity, histopathotoxicity, liver toxicity, neurotoxicity, oxidative stress, reproductive toxicity, and tissue damage. Today, reports have proven the transfer of MNPs across the aquatic food web to humans. However, the mechanisms of multiple contaminants-laden MNPs-induced toxicities, size-dependent toxicity, and the comprehensive mode-of-action and alterations of digestive, reproductive, and neurological systems’ functionality in marine organisms are still unclear. Thus, this review mainly addresses the prevalence, food web interactions, and toxicity assessment of micro(nano) plastics in marine and freshwater organisms. It summarizes documented studies based on the following broad objectives: (1) the occurrence and prevalence of micro(nano) plastic particles in marine and freshwater environments; (2) the ingestion of MNPs by aquatic biota and the food web exposure routes and bioaccumulation of contaminated MNPs by higher trophic entities; (3) the adsorption and desorption of persistent organic pollutants, metals, and chemical additives on/from micro(nano)plastics; and (4) the probable ecotoxicological effects of micro(nano)plastics ingestion on aquatic biota.

Trophic transfer of microplastics in a model freshwater microcosm; lack of a consumer avoidance response

Microplastics are considered freshwater pollutants of emerging concern. Although microplastics have been identified in a range of taxa, only a limited number of studies have focussed on the trophic transfer of microplastics. The duckweed Lemna minor can act as a microplastic vector in a model freshwater food chain. Here we show for the first time scanning electron microscopy images of 1 μm polystyrene (PS) and 10–45 μm polyethylene (PE) microplastics adsorbed on L. minor surfaces. A feeding test and a novel feeding-choice test were designed to investigate microplastic transfer from freshwater plants to invertebrates. Both tests show that the freshwater amphipod Gammarus duebeni feeds on plant biomass irrespective of the presence of microplastics, indicating lack of avoidance of microplastics. A number of G. duebeni that were fed L. minor with adsorbed PE microplastics had accumulated microplastics in their digestive tracts at the end of the tests. Fragmentation of microplastics transferred via plant feed and using low concentrations was noted for the first time. PE fragments, including particles in the nanosized range, were observed in G. duebeni digestive tracts. Yet, there was no apparent acute negative effect on G. duebeni weight or survival. These findings demonstrate microplastic trophic transfer and fragmentation in a freshwater organism. The finding that novel nanoplastics are found in the gut does show that biological processes are co-determinants of the fate of plastics in the environment and emphasise the importance of nanoplastic impact studies.

Safety and efficacy of a feed additive consisting of ethoxyquin (6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline) for all animal species (FEFANA asbl).

Ethoxyquin is synthetised from p‐phenetidine, a possible mutagen, which remains in the additive as an impurity at concentrations of < 2.5 mg/kg additive. Ethoxyquin is considered safe for all animal species at the proposed inclusion level of 50 mg/kg complete feed. However, owing the presence of p‐phenetidine, no safe level of the additive in feed for long‐living and reproductive animals could be identified. The FEEDAP Panel derived a health‐based guidance value of 0.006 mg ethoxyquin dimer (EQDM)/kg bw per day and applied it to the sum of ethoxyquin and its transformation products. A maximum total concentration of 50 mg ethoxyquin/kg complete feed for all animal species, except dairy ruminants, would not pose a risk for the consumer. However, in the absence of data on p‐phenetidine residues in tissues and products of animal origin, no conclusion on the safety for the consumer could be drawn. The conclusions on consumer safety assume that the maximum total concentration of 50 mg EQ/kg feed is expressed as the sum of EQ, EQDM, EQI and DHEQ. Exposure of the unprotected user to p‐phenetidine via inhalation should be minimised. No safety concerns for groundwater are expected. It is not possible to conclude on the safety of EQ for the terrestrial compartment. A risk for the aquatic compartment cannot be excluded when ethoxyquin is used in terrestrial animals. Unacceptable risk is not expected for freshwater sediment‐dwelling organisms. A risk of secondary poisoning via the terrestrial food chain is not expected, whereas a risk via the aquatic food chain cannot be excluded. No concerns for aquatic organisms are expected for ethoxyquin used in fish farmed in land‐based system, a risk cannot be excluded for marine sediment dwelling organisms when ethoxyquin is used in sea‐cages. Ethoxyquin is considered efficacious in the range 25–50 mg/kg complete feed.

Nanoplastics enhance the toxic effects of titanium dioxide nanoparticle in freshwater algae Scenedesmus obliquus

The increased usage of titanium dioxide nanoparticles (nTiO2) in consumer products has led to their prevalence in freshwater systems. Nanoplastics, a secondary pollutant, can significantly influence the toxic effects of nTiO2 in freshwater organisms. The present study investigates the role of fluorescent nanoplastics (FNPs) in modifying the harmful effects of P25 nTiO2 in freshwater algae Scenedesmus obliquus. Three different concentrations of nTiO2, 0.025, 0.25, and 2.5 mg/L, were mixed with 1 mg/L of the FNPs to perform the mixture toxicity experiments. The presence of the FNPs in the mixture increased the toxicity of nTiO2 significantly. A significant increment in the oxidative stress parameters like total ROS, superoxide (O2∎−), and hydroxyl radical generation was observed for the mixture of nTiO2 with the FNPs in comparison with their individual counterparts. The lipid peroxidation, and the antioxidant enzyme activities in the algal cells correlated well with the reactive species generation results. The treatments with the binary mixture resulted in notable decrease in the esterase activity in the algal cells. The mixture toxicity results were further validated with Abbott's independent action model. Additionally, optical microscopic analysis and FTIR analysis were performed to study the morphological and surface chemical changes in the algae. This study demonstrated that the FNPs played a key role in enhancing the toxicity of nTiO2 in freshwater algae.

Intelligent high-throughput intervention testing platform in Daphnia.

We present a novel platform for testing the effects of interventions on the life‐ and healthspan of a short‐lived freshwater organism with complex behavior and physiology—the planktonic crustacean Daphnia magna. Within this platform, dozens of complex behavioral features of both routine motion and response to stimuli are continuously quantified over large synchronized cohorts via an automated phenotyping pipeline. We build predictive machine‐learning models calibrated using chronological age and extrapolate onto phenotypic age. We further apply the model to estimate the phenotypic age under pharmacological perturbation. Our platform provides a scalable framework for drug screening and characterization in both life‐long and instant assays as illustrated using a long‐term dose‐response profile of metformin and a short‐term assay of well‐studied substances such as caffeine and alcohol.