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Environmental DNA (eDNA) is an increasingly useful method for detecting pelagic animals in the ocean but typically requires large water volumes to sample diverse assemblages. Ship-based pelagic sampling programs that could implement eDNA methods generally have restrictive water budgets. Studies that quantify how eDNA methods perform on low water volumes in the ocean are limited, especially in deep-sea habitats with low animal biomass and poorly described species assemblages. Using 12S rRNA and COI gene primers, we quantified assemblages comprised of micronekton, coastal forage fishes, and zooplankton from low volume eDNA seawater samples (n = 436, 380-1800 mL) collected at depths of 0-2200 m in the southern California Current. We compared diversity in eDNA samples to concurrently collected pelagic trawl samples (n = 27), detecting a higher diversity of vertebrate and invertebrate groups in the eDNA samples. Differences in assemblage composition could be explained by variability in size-selectivity among methods and DNA primer suitability across taxonomic groups. The number of reads and amplicon sequences variants (ASVs) did not vary substantially among shallow (600 m), but the proportion of invertebrate ASVs that could be assigned a species-level identification decreased with sampling depth. Using hierarchical clustering, we resolved horizontal and vertical variability in marine animal assemblages from samples characterized by a relatively low diversity of ecologically important species. Low volume eDNA samples will quantify greater taxonomic diversity as reference libraries, especially for deep-dwelling invertebrate species, continue to expand.

Pesticides are chemicals used to enhance crop production. However, their residues can persist and accumulate in various environmental settings. This study assessed the occurrence of pesticide residues and ecological risks in surface water and sediment from the Libga and Builpela dams in northern Ghana. A total of 42 pesticides were analysed. Toxic units were used to assess the acute risk to sediment-dwelling organisms and aquatic biota. Risk quotients were employed to assess the chronic risk to aquatic organisms. Chlorpyrifos, atrazine, profenofos, and chlorfenvinphos were the main chemicals found in surface water. The concentrations were highest near the Builpela dam (0.413μg/L, 2.927μg/L, 0.304μg/L, 0.692μg/L, 0.073μg/L, 0.290μg/L, 0.06μg/L, and absent in the Libga dam). In the sediment, the organophosphates pyrimiphos-methyl and chlorpyrifos were found at high concentrations. They were found in higher quantities in the Libga dam (0.554mg/kg and 0.052mg/kg, respectively) and Builpela dam (0.051mg/kg and 0.043mg/kg, respectively). For organochlorines, p,p'-DDE and p,p'-DDD were the main residues detected at high concentrations. However, concentrations were higher for p,p'-DDD at Builpela than for p,p'-DDE. Additionally, high concentrations of atrazine were detected in this study. The toxic units showed a high acute risk for organisms that live in sediment as a result of chlorpyrifosfos and chlorfenvinphos residues. Similarly, pirimiphos-methyl and chlorfenvinphos, followed by chlorpyrifos, contributed to high acute risk in aquatic invertebrates. Risk quotients showed that both dams had a high long-term risk for aquatic life; however, the risk was higher at the Builpela dam due to Pirimiphos-methyl and Chlorfenvinphos. Ghana's pesticide regulations are less comprehensive and enforcement is often weaker in protecting aquatic organisms. It is recommended to enforce strict limits on pesticide residues. Additionally, there is a need to regularly review and update these regulations based on new scientific data to protect aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The world's oceans are largely free from intensive farming, but momentum to intensify and expand mariculture--the cultivation of aquatic organisms in the ocean--is growing. Despite optimism that mariculture will create economic and nutritional benefits for humans, it can also generate a host of risks, including environmental degradation, harms to wildlife integrity and welfare, captivity effects, and shifts in how humans view the nonhuman world. Collectively, we refer to these four types of risks as "dewilding." In this systematic review, we searched Scopus and Web of Science for recent literature documenting mariculture's dewilding impacts to organize and collate this evidence under one unified framework. We find that mariculture's dewilding impacts are consistently documented, though often in isolation, and that captivity and conceptual dewilding impacts are recognized as potential harms far less than impacts on the environment and wildlife. Future work examining mariculture's dewilding impacts will be paramount to guiding human decision-making and activity going forward. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is an environmental estrogen which perturbs hormone signaling pathways adversely affecting aquatic organisms. To evaluate the impact of developmental exposure to long term yet environmentally relevant low doses of BPA, wild-type juvenile zebrafish of 35 days post fertilization were treated with BPA (1 and 10 µg/L), treatment control (0.5% v/v methanol) and control for 60 days. Both BPA treatments led to significantly increased morality overtime. Length increment and specific growth rates became significantly high in BPA exposed zebrafish overtime. Obesogenic property of BPA was not evident with longexposure to low BPA doses. A significantly high and BPA dose-dependent female-biased sex ratios were observed following the juvenile exposure. Significantly low swimming speed was recorded in the fish of both BPA-treated tanks than that of control. Condition factor was significantly low in BPA exposed fish indicating the poor-wellness. There were numerous histopathological alterations of gonads, liver and kidney indicating impacts of juvenile exposure in zebrafish. Altered growth, swimming, mortality, feminization and histopathological changes in zebrafish induced by BPA indicate the risks associated with developmental exposures. The findings call for more comprehensive studies to comprehend the ecological risks imposed by low concentrations of environmental estrogens in urban aquatic ecosystems. [ABSTRACT FROM AUTHOR]

AbstractThe fast-increasing use of chemicals led to large numbers of chemical compounds entering the aquatic environment, raising concerns about their potential effects on ecosystems. Therefore, assessment of the ecotoxicological features of organic compounds on aquatic organisms is very important. Daphnia magna and Fathead minnow are two aquatic species that are commonly tested as standard test organisms for aquatic risk assessment and are typically chosen as the biological model for the ecotoxicology investigations of chemical pollutants. Herein, global quantitative structure–toxicity relationship (QSTR) models have been developed to predict the toxicity (pEC(LC)50) of a large dataset comprising 2106 chemicals toward Daphnia magna and Fathead minnow. The optimal descriptor of correlation weights (DCWs) is calculated using the notation of simplified molecular input line entry system (SMILES) and is used to construct QSTR models. Three target functions, TF1, TF2, and TF3 are utilized to generate 12 QSTR models from four splits, and their statistical characteristics are also compared. The designed QSTR models are validated using both internal and external validation criteria and are found to be reliable, robust, and excellently predictive. Among the models, those generated using the TF3 demonstrate the best statistical quality with R2 values ranging from 0.9467 to 0.9607, Q2 values ranging from 0.9462 to 0.9603 and RMSE values ranging from 0.3764 to 0.4413 for the validation set. The applicability domain and the mechanistic interpretations of generated models were also discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Riverine habitat fragmentation by barriers, including impoundments, is common and their effects on obligate aquatic organisms are manifold. Organisms, such as Atlantic salmon (Salmo salar), that make extensive river migrations are particularly vulnerable to the effects of impoundments. In this study, we use acoustic telemetry to examine the migratory behaviour of Atlantic salmon, as they migrate to sea for the first time as juvenile ‘smolts’, in a river with a series of dams that form a complex hydropower scheme. We demonstrate that overall migration success in the River Dee catchment and particularly through standing waters was remarkably high. We speculate that high migration success in standing waters could be due to relative current speeds providing good quality directional cues to migrants. Migration success past the two dams in this study, was relatively high, although the number of unsuccessful passage attempts before a successful passage was also very high. The vast majority of smolts passed the dams when the turbines were operational. At one dam, smolts did not use an available fish pass but migrated through the generating turbines. These findings provide several routes through which generation could be managed to enhance the success of downstream smolt migration in rivers where there are similar patterns of hydrogeneration in place. [ABSTRACT FROM AUTHOR]

As an important drinking water source in Beijing, it is of great significance to carry out watershed aquatic ecological health assess- ment and analyze the key influencing factors affecting aquatic ecological health for aquatic ecological protection in the watershed upstream of Miyun Reservoir. Based on the habitat, water quality and aquatic organisms data of 20 small watersheds upstream of Miyun Reservoir, and combining with the ecological status of the mountainous watersheds upstream of Miyun Reservoir, we built an evaluation index system cover- ing 10 indexes in 3 categories, namely, habitat structure, water quality and aquatic organisms, and utilized the comprehensive health index method based on the entropy method to comprehensively evaluate the health of the aquatic ecosystems of the watersheds. The results show that the health status of the water ecosystem in the upper basin of Miyun Reservoir is generally sub-healthy, with 10% of the sub-watersheds in the healthy grade; 65% of the sub-watersheds in the sub-healthy grade; and 25% of the sub-watersheds in the general grade. The health status of aquatic ecosystems in the watershed upstream of Miyun Reservoir has strong spatial heterogeneity, the areas with higher health. grades mainly distributed in the upper reaches of the Baimaguan River, the Liuli River, the middle reaches of the Tanghe River and the up- per reach of the Tianhe River, and those with relatively lower health grades are mainly distributed in the Chaohe River, the middle and lower reaches of the Baihe River, the lower reaches of the Tanghe River, the Qingshui River, and the upper reaches of the Andamu River. Anthro- pogenic disturbance and surface source pollution, low vegetation cover and soil erosion are the key factors affecting the water ecological health of the upper Miyun Reservoir watershed. [ABSTRACT FROM AUTHOR]

The rapid growth of aquaculture over the last century has led to the widespread introduction of aquatic species to freshwater environments. Bighead carp (Cyprinidae: Hypophthalmichthys nobilis) and silver carp (Cyprinidae: Hypophthalmichthys molitrix), collectively referred to as bigheaded carp, are among the top finfishes produced in aquaculture. These filter feeders possess feeding structures that allow them to efficiently remove plankton and other particles from the water. Unfortunately, when introduced into the wild and outside their historical range, their feeding traits generally result in the exploitation and suppression of phytoplankton and zooplankton, reducing food resources for native invertebrates and vertebrates.We conducted a meta‐analysis of published experiments to examine how bigheaded carp directly and indirectly affect organisms in aquatic food webs to better understand their ecological role within ecosystems. Specifically, we addressed the following questions: (1) What is the overall magnitude and direction of bigheaded carp effects on different aquatic organisms? (2) Do bigheaded carp affect organisms in planktonic and benthic habitats? (3) Are effects similar between bighead carp and silver carp? (4) Are effects consistent among experimental arenas (i.e., mesocosm, ponds)?We detected direct and indirect effects of bigheaded carp across multiple trophic levels. Large zooplankton often exhibited the strongest negative effects, with taxa‐specific differences between carp species. The suppression of zooplankton cascaded down to primary producers, resulting in an increase in phytoplankton (i.e., indirect effect). However, we observed no compensatory increases in rotifers when large zooplankton were reduced. Growth rates of planktivorous native fishes were the slowest when stocked with bigheaded carp. Our results further indicated that egested waste from bigheaded carp appeared to subsidise (i.e., direct effect) some benthic invertebrates such as Chironomidae midges. Effects of carp on zooplankton were generally similar between mesocosms and ponds.Invasive bigheaded carp greatly restructure their surrounding food web, both positively and negatively, through a complex suite of direct and indirect effects. These changes manifested across multiple trophic levels and differing habitats. Our analysis provides a more complete understanding of how these invasive carps change their surroundings by exploiting food resources and transferring materials from planktonic to benthic habitats. Taken together, the suite of direct and indirect effects shows how an invasive species can create imbalances within aquatic ecosystems, often to the detriment of native taxa.Bigheaded carp are invasive in many countries across the globe because of their popularity in aquaculture. Our findings reaffirm the threat these planktivores pose to native freshwater organisms. [ABSTRACT FROM AUTHOR]

Passive acoustic monitoring (PAM) technology enables the acquisition of acoustic information from aquatic organisms without causing disturbance or harm, facilitating various ecological studies and aiding in the management of aquaculture activities. As shrimp aquaculture technology advances, the industry's scale and density are increasing. However, challenges such as low feed utilization and water quality deterioration have severely constrained the rapid development of the industry. PAM technology can be used to study sound in the environment by using it to understand shrimp feeding behaviour, guide feeding decisions, and implement intelligent automated feeding systems, thereby improving feed utilization and mitigating water quality deterioration problems. This article primarily discusses how shrimp feed, the factors affecting their feeding, and the acoustic characteristics of the feeding process, and reviews the latest research progress and application of PAM technology in detecting acoustic signals of shrimp feeding, as well as the challenges faced by the technology in its development. The advantages and limitations of PAM technology in shrimp aquaculture are analyzed, and the future development direction is proposed to address the problems of this technology. To provide a reference for the automatic feeding system to move towards intelligence, to promote the sustainable development of shrimp aquaculture. [ABSTRACT FROM AUTHOR]

We compared the effects of lambda‐cyhalothrin as the pure active ingredient and as a formulated product (Zero®), on the larval stage of the autochthonous species Boana pulchella. We evaluated ecotoxicological endpoints, behavioral and developmental alterations, and the biochemical detoxifying, neurotoxic, and oxidative stress responses, covering a wide concentration range from environmental to high application levels. Both pyrethroid preparations displayed similar ecotoxicity (median lethal concentration of ~0.5 mg/L), with the lethal effect of Zero® being more pronounced than that of the active ingredient. Sublethal behavioral alterations in natatory activity were observed at 1000 times lower concentrations, indicating the ecological hazard of tadpole exposure to this pyrethroid at environmentally relevant concentrations. Biochemical endpoints in B. pulchella larvae showed significant responses to lambda‐cyhalothrin in the ng/L range; these responses were different for the pure or the formulated product, and they were variable at higher concentrations. Principal components analysis confirmed the prevalence of biochemical responses as early endpoints at the lowest lambda‐cyhalothrin concentrations; the Integrated Biomarker Response Index proportionally increased with pyrethroid concentration in a similar way for the pure and the formulated products. We conclude that lambda‐cyhalothrin is of concern from an environmental perspective, with particular emphasis on autochthonous anuran development. The battery of biochemical biomarkers included in our study showed a consistent integrated biomarker response, indicating that this is a potent tool for monitoring impacts on amphibians. Environ Toxicol Chem 2024;43:2134–2144. © 2024 SETAC [ABSTRACT FROM AUTHOR]

High emissions of greenhouse gases to the atmosphere via human activities have caused climate change and ocean warming. The rising water temperature is an abiotic factor that may negatively affect various biological and physiological processes of aquatic organisms, such as growth, digestion, immunity, and survival. Orange mud crab (Scylla olivacea) are commercially important crustacean species of coastal countries along the Indo-Pacific region. Their predominant habitat—the coastal zones make—them vulnerable to ocean warming. This study aimed to understand the impact of temperature increase on the physiology and gut microbial alteration of S. olivacea. Adults of S. olivacea were subjected to present-day water temperature and warming scenarios (∆T = + 4 °C) for 14 days. Growth (weight gain and specific growth rate), oxygen consumption, and serotonin levels of S. olivacea showed a significant increase under warming scenario. However, exposure to higher temperatures did not induce higher feed consumption, feed conversion rate, hepatosomatic index, and hemolymph glucose level in S. olivacea. The thermal coefficient was 3.5232 on day 7 and decreased to 1.2534 on day 15. Furthermore, Vibrio species bacteria were more abundant in the intestines of S. olivacea under warming scenario. These results suggest that S. olivacea exposed to the warming scenario may positively impact the aquaculture industry (higher weight gain), but also bring risk of disease outbreak caused by Vibrio spp. Further studies are needed to better understand the long-term effect of warming scenario on the growth and health of coastal crustacean species, especially species being threatened by fishing pressure. [ABSTRACT FROM AUTHOR]

Object detection adopting deep-learning has strongly promoted the development of intensive aquaculture. However, shrimp larvae, as an important aquatic organism, are more difficult to be detected than others. On the one hand, they have indeed small sizes, which will cause them to be easily ignored due to the background noise pollution. On the other hand, affected by environmental factors and the fact that shrimp larvae like to move fast as jumping, the images of shrimp larvae often appear blurry. In order to obtain better shrimp larvae detection performance, we propose an improved anchor-free method called CAGNet in this paper. Compared with YOLOX_s, three structures including backbone, neck, and head have been improved in the proposed method. Firstly, we ameliorate the backbone by adding a coordinate attention module to extract more location information and semantic information of shrimp larvae at different levels. Secondly, an adaptively spatial feature fusion module is introduced to the neck. It can adaptively integrate effective shrimp larvae features from different levels and suppress the interference of conflicting information arising from the background. Moreover, in the head, we use GIoU module instead of conventional IoU for more accurate bounding box regression. We conducted experiments by collecting shrimp larvae data from a real aquaculture farm. Compared with the general object detection methods and previous related research, CAGNet has achieved better performance in Precision, Recall, F1 Score, and AP@0.5:0.95. Hence, the proposed method can be effectively applied to shrimp larvae detection in intensive aquaculture. [ABSTRACT FROM AUTHOR]

Microplastics have frequently been regarded as a threat to aquatic organisms due to their potential to enhance the accessibility of organic pollutants. However, studies of microplastics as "carriers" in the process of bioaccumulation have only been conducted on a few organic contaminants. In this study, we employed machine learning algorithms to predict the sorption capacity of 83 exogenous organic pollutants (in CCL4) on microplastics, the prediction model exhibits exceptional predictive performance, achieving R2 values of 0.8651 and 0.6962, RMSE values of 0.4625 and 0.1841 for the sorption coefficients Kf and n, respectively, and quantitatively estimated the contribution of microplastics to the bioaccumulation levels of organic pollutants in Gadus morhua. By considering both natural and microplastic-ingesting pathways, we demonstrated that the ingestion of microplastics containing organic pollutants facilitates the entry of organic pollutants into Gadus morhua. However, due to their robust sorption capacity, microplastics transport the organic pollutants accumulated through the natural pathway out of the fish, thereby preventing bioaccumulation. These findings elucidate the "cleaning" mechanism of microplastics concerning various organic pollutants in aquatic organisms, providing valuable insights for accurately assessing the risk of microplastics in aquatic environments. [ABSTRACT FROM AUTHOR]

There are substantial gaps in our empirical knowledge of the effects of chemical exposure on aquatic life that are unlikely to be filled by traditional laboratory toxicity testing alone. One possible alternative of generating new toxicity data is cross-species extrapolation (CSE), a statistical approach in which existing data are used to predict the effect of a chemical on untested species. Some CSE models use relatedness as a predictor of chemical sensitivity, but relatively little is known about how strongly shared evolutionary history influences sensitivity across all chemicals. To address this question, we conducted a survey of phylogenetic signal in the toxicity data from aquatic animal species for a large set of chemicals using a phylogeny inferred from taxonomy. Strong phylogenetic signal was present in just nine of thirty-six toxicity datasets, and there were no clear shared properties among those datasets with strong signal. Strong signal was rare even among chemicals specifically developed to target insects, meaning that these chemicals may be equally lethal to non-target taxa, including chordates. When signal was strong, distinct patterns of sensitivity were evident in the data, which may be informative when assembling toxicity datasets for regulatory use. Although strong signal does not appear to manifest in aquatic toxicity data for most chemicals, we encourage additional phylogenetic evaluations of toxicity data in order to guide the selection of CSE tools and as a means to explore the patterns of chemical sensitivity across the broad diversity of life. [ABSTRACT FROM AUTHOR]

In Egypt, while many studies have focused on the radiometry and mineralogy of black sands, research on their effects on nearby aquatic organisms is rare. This study aimed to assess the combined effects of heat stress (HS) and black sand nanoparticles (BS-NPs) on renal function, antioxidant responses (TAC, SOD, CAT), neuro-stress indicators (AchE, cortisol), and to conduct histopathological investigations in the kidney and spleen tissues of African catfish Clarias gariepinus over a 15-day period to exposure to control, HS (32 °C), BS (6.4 g/kg diet) and HS + BS groups. The outcomes revealed that thermal stress alone showed no significant difference from the control. However, creatinine and uric acid levels were significantly higher in the BS-NPs and HS + BS-NPs groups (p < 0.001). Antioxidant markers (TAC, SOD, and CAT) were substantially reduced across all treated groups (0.05 ≥ p < 0.0001). AchE levels were significantly elevated in BS-NPs and HS + BS-NPs (p < 0.001), while cortisol levels were higher in these groups but not significantly different in HS. Degeneration and necrosis in the white and red pulps, scattered lymphocytes, and increased collagen fiber surrounding blood vessels and the lining of the ellipsoid structure were all evident in the spleen, along with the enlargement of the melanomacrophage centers with big granular, irregular, and brown pigments (hemosiderin). Our study, therefore, provides new insights into how heat stress, an abiotic environmental factor, influences the toxicity of black sand nanoparticles in catfish. [ABSTRACT FROM AUTHOR]

Bycatch is one of the leading threats facing aquatic organisms, worldwide. Pesticide bycatch can occur when nontarget species are incidentally killed during chemical application targeting noxious species. The common mudpuppy (Necturus maculosus) is a river‐dwelling salamander that is susceptible to bycatch from 3‐trifluoromethyl‐4‐nitrophenol (TFM) applications. However, the long‐term consequences of TFM bycatch on mudpuppy populations are not well understood. We used population viability analysis to reveal potential impacts of TFM application on a mudpuppy population in Ohio's Grand River under plausible bycatch scenarios. We found that the population was more sensitive to increased juvenile mortality and rapid declines occurred when both adults and juveniles were impacted at high bycatch rates (≥5% of the population) or more frequent TFM intervals (≥5 years). Our results suggest that continued use of TFM could pose a risk to mudpuppy population persistence if bycatch occurs at moderate to high levels and affects both juveniles and adults. Future TFM use and management decisions should be directed with these potential nontarget impacts in mind. [ABSTRACT FROM AUTHOR]

Simple Summary: The use of Artemia as a supplement to commercial feed during the nursery period, i.e., from post-larvae 10 up to post-larvae 30, is a common procedure in the shrimp industry. This practice provides larger and more resilient post-larvae (PL) that perform better in grow-out ponds. However, the production of brine shrimp is limited to a few natural salt lakes or man-made salt ponds worldwide, subject to strongly fluctuating yields and product quality. Therefore, ongoing research is focused on finding adequate live food alternatives. Nematodes, commonly known as worms, are animals that greatly fulfil the requirements to be used as live feed for aquatic organisms. Nematodes can be reactivated from their desiccated state by simple rehydration. Additionally, they are rich in protein and fatty acids, making them a favorable nutritional diet for shrimp larvae culture. This study demonstrated that nematodes can substitute Artemia in a co-feeding regime for the nursery of shrimp in a biofloc system, increasing the survival of the post-larvae after 20 days. This study evaluated nematodes as an alternative to live Artemia when provided in a co-feeding regime to Pacific white shrimp (Penaeus vannamei) post-larvae (PL) reared in a biofloc nursery system. A 20-day experiment employing PL11 was performed for an evaluation of four dietary groups: control [C] (fed exclusively with a dry commercial feed); artificial Artemia [AA] (dry feed composed of extracted and processed Artemia cysts and dry commercial feed); live Artemia and dry commercial feed [LA]; and nematodes and dry commercial feed [N] (Panagrolaimus sp. dry nematodes). The diets were provided twice a day, with the remaining six feed provisions being a commercial dry feed for all experimental groups. A biofloc system was chosen as it offers a potentially sustainable approach to intensive shrimp farming. Alkalinity and pH in the [N] group were significantly higher in the last 5 days of the experiment (p < 0.05), likely causing the significantly lower nitrite levels observed in that same group (p < 0.05). Total and volatile suspended solids were significantly lower in the two live feed groups when compared with [C] and [AA] (p < 0.05). Although PL fed the dry diets exhibited higher growth rates (p < 0.05), the [N] and [LA] groups presented significantly higher final survivals (p < 0.05). No differences were found for survival after a salinity stress test (p ≥ 0.05). These results suggest that nematodes can successfully substitute Artemia in a co-feeding regime for P. vannamei PL reared in biofloc nursery systems. [ABSTRACT FROM AUTHOR]

Human pythiosis is a rarely encountered yet potentially harmful infectious disease. It is mostly caused by Pythium insidiosum, an aquatic fungal‐like organism, and primarily manifests in tropical locales such as India and Thailand. Cutaneous/subcutaneous pythiosis accounts for a small proportion of all clinical forms. The relationship between cutaneous pythiosis and hemoglobinopathy remains uncertain, unlike the vascular form. The histopathology of the disease demonstrates eosinophilic granulomatous inflammation and dense eosinophilic material enveloping the organism, known as the Splendore–Hoeppli phenomenon. These histopathologic characteristics resemble those observed in entomophthoromycosis. Until now, the histopathology of human cutaneous pythiosis has been scarcely delineated in the literature. Herein, we report a case of cutaneous pythiosis in an adult thalassemic agricultural worker who presented with a 2‐month history of a progressive, painful, erythematous infiltrative plaque on the left leg. The definitive diagnosis was ascertained through histopathologic examination and the identification of anti‐P. insidiosum antibodies in the serum utilizing enzyme‐linked immunosorbent assay. This report demonstrates the exquisite histopathologic findings of a rare case of human cutaneous pythiosis. [ABSTRACT FROM AUTHOR]

We examined the ecological and toxicological implications of the microplastic, Cyanox®53, found in sediments and varnish clams across seven beaches in Burrard Inlet, British Columbia (BC). Using the simulation models embedded within Estimation Programs Interface (EPI) Suite™, the potential persistence, bioaccumulation, and toxicity of Cyanox®53 was assessed to evaluate the risk to varnish clams foraging on sediment containing this contaminant. Moreover, we used a bioenergetic model, based on the blue-listed surf scoter species, to estimate the risk of daily ingestion of Cyanox®53 per body weight in overwintering seabirds. Our findings indicate that varnish clams collected from Burrard Inlet accumulate on average 0.46 particles of Cyanox®53/clam, and based on bioenergetic modeling, results in surf scoters potentially consuming 78 (for males) to 83 (for females) pieces of Cyanox®53 daily from foraged varnish clams. EPI Suite™ predicted Cyanox®53 to be persistent, however, unlikely to bioaccumulate as a "traditional" chemical. Furthermore, the estimation of potential acute and chronic toxicity of Cyanox®53 to aquatic organism surrogates, such as fish, Daphnia magna, and green algae, was inconclusive due to model variability and limitations within EPI Suite™. To fully understand the potential risks of Cyanox®53 further investigation is warranted. [ABSTRACT FROM AUTHOR]

Vibrio coralliilyticus is a pathogen of coral and shellfish, leading to devastating economic and ecological consequences worldwide. Although rising ocean temperatures correlate with increased V. coralliilyticus pathogenicity, the specific molecular mechanisms and determinants contributing to virulence remain poorly understood. Here, we systematically analyzed the type VI secretion system (T6SS), a contact-dependent toxin delivery apparatus, in V. coralliilyticus. We identified 2 omnipresent T6SSs that are activated at temperatures in which V. coralliilyticus becomes virulent; T6SS1 is an antibacterial system mediating interbacterial competition, whereas T6SS2 mediates anti-eukaryotic toxicity and contributes to mortality during infection of an aquatic model organism, Artemia salina. Using comparative proteomics, we identified the T6SS1 and T6SS2 toxin arsenals of 3 V. coralliilyticus strains with distinct disease etiologies. Remarkably, T6SS2 secretes at least 9 novel anti-eukaryotic toxins comprising core and accessory repertoires. We propose that T6SSs differently contribute to V. coralliilyticus's virulence: T6SS2 plays a direct role by targeting the host, while T6SS1 plays an indirect role by eliminating competitors. Vibrio coralliilyticus is a pathogen of coral and shellfish that is becoming more virulent as ocean temperatures rise, causing significant damage. This study shows that V. coralliilyticus has two type VI secretion systems (T6SSs) that are activated at high temperatures; one targets bacterial competitors, while the other launches up to 9 novel toxins against eukaryotic hosts like shrimps. [ABSTRACT FROM AUTHOR]

Salting of roadways contaminates local waterways via snowmelt and precipitation runoff, eliciting various toxicological impacts on aquatic ecosystems. Recently, “eco‐friendly” deicing alternatives have been introduced in hopes of mitigating environmental impacts of deicing agents, while maintaining human safety. These “eco‐friendly” alternatives may pose their own set of environmental concerns that require further study. While the potential toxicity of road salts has been evaluated for various aquatic species, the environmental factors that may influence this toxicity are less understood; and for emerging deicing alternatives, there is a lack of literature documenting these potential implications. For aquatic organisms, the highest exposure to road salts may coincide with reduced food availability, namely during the winter months. The present study evaluates the effect of a conditioning diet on the sensitivity of adult Hyalella azteca to an “eco‐friendly”‐labeled beet deicer (Snow Joe MELT Beet‐IT). Various conditioning diets were examined, including TetraMinTM, TetraMin and diatom (Thalassiosira weissflogii) combinations, and TetraMin and conditioned Acer sacharum leaves. For each diet type, 48‐ and 96‐h water‐only toxicity bioassays were conducted with adult H. azteca. These results were compared to organisms which experienced a 96‐h starvation period prior to exposure and culture organisms. Diet types representing excess quality and quantity of food significantly decreased the toxicity of beet deicer to the organisms. However, starvation likely increases the toxicity of road salts to H. azteca. Therefore, the quantity and quality of food available to H. azteca may influence their sensitivity to deicing agents. Environ Toxicol Chem 2024;00:1–8. © 2024 SETAC [ABSTRACT FROM AUTHOR]

Visual signals are involved in many fitness‐related tasks and are therefore essential for survival in many species. Aquatic organisms are ideal systems to study visual evolution, as the high diversity of spectral properties in aquatic environments generates great potential for adaptation to different light conditions. Flatfishes are an economically important group, with over 800 described species distributed globally, including halibut, flounder, sole, and turbot. The diversity of flatfish species and wide array of environments they occupy provides an excellent opportunity to understand how this variation translates to molecular adaptation of vision genes. Using models of molecular evolution, we investigated how the light environments inhabited by different flatfish lineages have shaped evolution in the rhodopsin gene, which is responsible for mediating dim‐light visual transduction. We found strong evidence for positive selection in rhodopsin, and this was correlated with both migratory behavior and several fundamental aspects of habitat, including depth and freshwater/marine evolutionary transitions. We also identified several mutations that likely affect the wavelength of peak absorbance of rhodopsin, and outline how these shifts in absorbance correlate with the response to the light spectrum present in different habitats. This is the first study of rhodopsin evolution in flatfishes that considers their extensive diversity, and our results highlight how ecologically‐driven molecular adaptation has occurred across this group in response to transitions to novel light environments. [ABSTRACT FROM AUTHOR]

In mariculture facilities, bacterial infections pose significant production challenges, with potentially catastrophic impacts on fish species. Bacterial co-infections are a widespread phenomenon in the natural marine environment, although their impact on aquatic organisms remains poorly investigated. This study aimed to detail the pathological findings associated with a natural bacterial co-infection caused by three different pathogens, namely Photobacterium damselae subsp. piscicida, Tenacibaculum maritimum and Vibrio sp., as the cause of mass mortality in European sea bass. The fish had been reared in open-net cages in Sicily and later transferred for experimental research purposes to a user establishment after immunization with an inactivated vaccine. Macroscopic, cytological and histopathological examinations were performed on 109 animals, and bacterial species were identified by the 16S rRNA gene. Overall, ulcerative skin lesions, necrotizing myositis and tail rot with occasional tail loss were associated with tenacibaculosis and vibriosis, while P. damselae subsp. piscicida mainly caused granulomatous inflammation in the spleen and head kidney. Finally, an injection site reaction due to the oil-adjuvanted vaccine administered intraperitoneally was observed in the abdominal fat. Understanding the impact of bacterial pathogens is essential to manage the health and welfare of farmed fish, and the importance of a good health monitoring program cannot be overstated to avoid outbreaks and the possible emergence of new pathogens due to the intensification of the production systems, antibiotic resistance and climate changes. The study would also highlight the importance of the quarantine period when animals supplied for research come from aquaculture farms and how the main goal in the near future should be to better define the procedures to provide completely pathogen-free animals. [ABSTRACT FROM AUTHOR]

Heavy metals have serious negative effects on various aquatic organisms, and therefore rapid and accurate ecotoxicological assessments of heavy metals are necessary. Fish-derived cells sensitive to heavy metals have been used as valuable tools for ecotoxicological assessments. However, this method requires a minimum toxicity treatment time of 96 h, which limits its use when rapid ecotoxicological assessments are required or ecotoxicological assessments of a large number of toxicants are performed. In this study, these limitations were overcome by adjusting parameters including the concentration of fetal bovine serum (FBS) in the medium and the treatment time of the toxicant. Specifically, we found that the maximum time for fish cells to remain unstarved was 6 h when using a medium containing 1% FBS. We applied both parameters to the ecotoxicological assessment (using a medium containing 1% FBS for the toxicity assessment and treating the toxicant for only 6 h). Surprisingly, these adjusted parameters allowed us to obtain faster and more accurate data than the traditional assessment. This improvement was due to the new assessment conditions that minimized the possibility that the growth-inducing effects of nutrients present in excess in the medium could interfere with the cellular response to the toxicant. The accuracy of this assessment was not limited to measuring the toxicity of heavy metals. In conclusion, we have established an ecotoxicity assessment that can generate rapid and accurate data on heavy metals. This new platform will become the cornerstone of rapid and accurate ecotoxicity assessments of heavy metals. [ABSTRACT FROM AUTHOR]

To better understand the limitations of dormancy on Odontomyia Meigen, 1803 (Diptera: Stratiomyidae) survival and body condition, we conducted a series of laboratory-based microcosm experiments. We found that Odontomyia larvae can survive at least two extended dry periods (≥30 days) through dormancy. The presence of moisture in the substrate during dormancy is not necessary to survive and had no effect on survival or larval body mass in our experiments. Energy and bodily water loss likely limit survival in dormant stages. Although these results suggest Odontomyia are fairly resistant to drying, more data is needed on body mass, pupation, and reproductive success across hydroregimes. The more we understand about the survival limitations of rock pool aquatic invertebrates, the more successful conservation efforts will be for their unique aquatic biota. [ABSTRACT FROM AUTHOR]

• TMA+ exposure significantly inhibited the swimming activities of larval zebrafish. • Swimming path angle is the most sensitive endpoint in response to TMA+ exposure. • Neurobehavior endpoints of larvae were significantly related with oxidative stress. • The calculated 96 h-LC 50 of TMA+ was lower for zebrafish juveniles than larvae. • TMA+ evoked greater inhibitions on multi-biomarkers of juveniles than larvae. Tetramethylammonium hydroxide (TMAH) is an important compound that utilized and released by the rapidly expanding semiconductor industry, which could hardly be removed by the conventional wastewater treatment techniques. As a cholinergic agonist, the tetramethylammonium ion (TMA+) has been reported to induce toxicity to muscular and respiratory systems of mammals and human, however the toxicity on aquatic biota remains poorly known. We investigated the neurotoxic effects of TMA+ exposure on zebrafish, based on neurobehavior tests and a series of biomarkers. Significant inhibitions on the swimming distance of zebrafish larvae were observed when the exposure level exceeded 50 mg/L, and significant alterations on swimming path angles (straight and deflective movements) occurred even at 10 mg/L. The tested neurobehavioral endpoints of zebrafish larvae were significantly positively correlated with reactive oxygen species (ROS) and malondialdehyde (MDA), significantly negatively related with the activities of antioxidant enzymes, but not significantly correlated with the level of acetylcholinesterase (AChE). Such relationship indicates that the observed neurotoxic effects on swimming behavior of zebrafish larvae is mainly driven by oxidative stress, rather than the alterations of neurotransmitter. At the highest exposure concentration (200 mg/L), TMA+ evoked more severe toxicity on zebrafish juveniles, showing significantly stronger elevation on the MDA activity, and greater inhibitions on the activities of antioxidant enzymes and AChE, suggesting juveniles were more susceptible to TMA+ exposure than larval zebrafish. [Display omitted] [ABSTRACT FROM AUTHOR]

This study examines microplastic contamination in river macroinvertebrates and fish within a rapidly urbanising tropical catchment, and provides data on the quantity of microplastics ingested by various taxonomic and functional feeding groups.We employed both a widely used low‐resolution visual inspection method, capable of identifying microplastics ranging from 0.1 to 5 mm, and a novel automated method specifically designed to identify smaller plastics in the nano size range, from 0.004 to 0.1 mm.Analysis using the low‐resolution method indicated that a significant portion of fish (95%) and macroinvertebrates (44%) contained larger microplastics. The composition of microplastic within the animals differed from that in river water and on the river bed: microplastics in the water and on the bed were predominantly fibres (98% and 92% respectively), whereas the animals exhibited a more even mix of fibres (c. 35%), fragments (c. 43%), and film (c. 22%).Microplastic loads in aquatic organisms correlated with feeding group and body size, although patterns were not always consistent. Larger individuals generally contained more microplastic, especially among macroinvertebrates, but this trend was not observed uniformly among fish species. Additionally, differences in body loads among macroinvertebrate taxa and feeding groups varied depending on whether loads were expressed per individual or per unit weight.Use of the high‐resolution enumeration method revealed a substantially higher microplastic count compared to the low‐resolution method, highlighting the potential underestimation of contamination levels by the latter. The study underscores the non‐random uptake of microplastics by aquatic biota, influenced by feeding mode, and stresses the necessity of high‐resolution sample processing for accurate quantification of contamination levels and risk assessment for smaller organisms. [ABSTRACT FROM AUTHOR]

Due to intensified human activities like hydropower development, biodiversity in the upper Yellow River faces severe threats. In 2019, we conducted a survey across all reservoirs in the river section from Longyangxia to Liujiaxia in the upper Yellow River, focusing on key aquatic organisms such as benthic macroinvertebrates and fish. The benthic index of biotic integrity (B-IBI) and the fish stocking index (FSI) were used to assess the river's biotic integrity. We collected 54 macroinvertebrate species with an average biomass of 1.28g/m², predominantly featuring species like Gammarus sp. and Palaemon modestus. Additionally, 39 fish species were captured, with Gymnocypris eckloni, Pseudorasbora parva, and Triplophysa pappenheimi being the most common, with an average weight of 43.27 g per individual. The B-IBI scores ranged from 1.06 to 3.04, averaging 78; the number of native fish species varied from 3 to 15 per location, resulting in an FSI score of 69. This indicated that the biotic integrity of the Longyangxia to Liujiaxia section was common yet still significantly impacted by human activities. This study highlights the impacts of human activities on the river's ecosystem and aims to guide ecological protection and restoration efforts in the upper Yellow River. [ABSTRACT FROM AUTHOR]

Fish skin acts as the first immune barrier against pathogens from external environments. Recently, fish skin immunity research has gradually become a hot topic in aquaculture disease control. Interestingly, the skin can do air-breathing in some bimodal respiration fish. However, there is no comprehensive understanding of these two functions. In this study, the skin regeneration of loach (Paramisgurnus dabryanus) was investigated through morphological and histological observations. Then, original skins (OS) and the regenerated skins (RS) when their capillaries were the most abundant during healing, were collected for transcriptomic analysis. 285,899,386 clean reads with a total length of 42.34 Gb were obtained. A total of 1282 differentially expressed genes (DEGs) were detected, including 1030 DEGs up-regulated and 252 DEGs down-regulated in the comparison of RS vs. OS. Fc gamma R-mediated phagocytosis (containing gelsolin (Gsn)), chemokine signaling pathway (containing C--C motif chemokine ligand 28 (Ccl28)), and B cell receptor signaling pathway (containing CD80 molecule (Cd81)) were closely related to skin immune response of the loach. PI3K-Akt signaling pathway [containing fibronectin 1 (Fn1) and lysyl oxidase-like 2b (Loxl2b)], TGF-beta signaling pathway [containing thrombospondin 1 (Thbs1)], ECM-receptor interaction [containing integrin alpha 7 (Itga7), Itgb8, Itgb10 and Itgb5], and dilated cardiomyopathy [containing laminin subunit alpha1 (Lama1)] were closely associated with skin air-breathing of the loach. This study is conducive to explore the molecular mechanisms of skin immune response during its regeneration and air-breathing of bimodal respiration fish. This study will benefit for the aquaculture of P. dabryanus and its related species. [ABSTRACT FROM AUTHOR]

Marine aquaculture is currently the fastest-growing seafood industry globally, offering a potential solution to overfishing problems, while enhancing food security and income generation. South Sulawesi, a province in Indonesia, is rich in aquaculture resources, one of which is lobster. The two commonly used aquaculture systems are the floating-net cage (KJA) and fixed-net cage (KJD). The growing market demand and rising lobster prices pose a threat to resource sustainability due to overexploitation. This is issue have to be addressed to achieve sustainable fishery development. Sustainability is the primary focus on global fishery development. According to the United Nations, sustainable development encompasses three dimensions: the economy, social and ecology. Therefore, sustainable fishery, particularly aquaculture, relies on obtaining significant benefits while minimizing environmental damage. Hence, this study aimed to analyze the sustainability level of the pearl lobster (Panulirus ornatus) aquaculture in South Sulawesi, based on the provided background information. The study included a sample of 62 farmers. The sample selection involved the use of the stratified sampling method, with 51 farmers from (KJA) and 11 farmers from (KJD). The sustainability analysis, conducted through assessment of based farmers' perceptions, served as the analytical method. The findings revealed that pearl lobster (Panulirus ornatus) aquaculture has a medium level of sustainability. Employing Integrated Multi Tropic Aquaculture (IMTA) and Regional Integrated Multi Tropic Aquaculture (RIMTA) techniques is a recommended sustainability level. [ABSTRACT FROM AUTHOR]

The Yangtze River is the mother river of China. To promote the aquatic ecosystem protection of the great river, the Project of Yangtze Fisheries Resources and Environment Investigation (2017-2021) supported by the Ministry of Agriculture and Rural Affairs, P. R. China carried out by 24 institutes and universities that located in the Yangtze River basin surveys the status of (1) fish species composition and spatial distribution, (2) current fish abundance, (3) endangered fishes, (4) Yangtze finless porpoise, (5) aquatic eco-environments, (6) water-level fluctuation areas, (7) capture fisheries and recreational fisheries of the Yangtze River mainstream and 10 of its main tributaries, including Yalong River, Heng River, Min River (including Dadu River), Chishui River, Tuo River, Jialing River, Wu River, Han River, Dongting Lake and Poyang Lake. The results showed that there were 443 fish species (belonging to 163 genus, 37 families, and 18 orders) before 2017, but only 323 fish species (including 15 new recorded exotic species) were recorded in the project of 2017-2021. Among them, Cyprinus carpio, Carassius auratus, Hypophthalmichthys molitrix, Pelteobagrus fulvidraco, Coilia brachygnathus, Silurus asotus, Saurogobio dabryi, Ctenopharyngodon idellus, Pelteobagrus nitidus, Hemiculter leucisculus, Siniperca chuatsi, Coreius heterodon, Culter alburnus, Parabramis pekinensis, and Aristichthys nobilis were the dominant species across the whole Yangtze River system. It is estimated that there were 886 million individuals weighing 124.8 million kg, merely equivalent to 27.3% of the resources in 1950s, 30.9% of the resources in 1960s, or 58.7% of the resources in 1980s. In the new list of protected fishes that recorded in the Yangtze River system, only 15 of 29 were collected in this project of 2017-2021. Psephurus gladius has been affirmed to be Extinct by International Union for Conservation of Nature (IUCN). The wild individuals of Tenualosa reevesii and Luciobrama macrocephalus have disappeared for many years and maybe have been extinct already. Acipenser dabryanus has been affirmed to be Extinct in the Wild by IUCN. The natural propagations of A. sinensis, Myxocyprinus asiaticus and Trachidermus fasciatus have been interrupted for many years. The populations of Yangtze finless porpoise in the Yangtze River mainstream, Dongting Lake and Poyang Lake have steadily rising sizes and expanding distributions in 2017-2021. Parts of them migrate from one region to another with the seasons, which would result in the fluctuation of Yangtze finless porpoise population within some regions. The conventional indicators of water quality in the Yangtze River system were good and conformed to the water quality criteria of fishery in 2017-2021. In the last 40 years, the maximum surface water area in the Yangtze River basin extended to approximately 63,360 km2, the minimum surface water area covered approximately 26,396 km2, and the seasonal water-level fluctuation areas occupied approximately 36,964 km2. Compared with 1984-2000 period, the 2001-2020 period witnessed an overall decreasing trend in the frequency of surface water occurrence within about 25,869 km2 of aquatic areas. From 1984 to 2000 period to 2001-2020 period, permanent surface water has decreased by nearly 8,750 km2. In 2017, the fishermen were mainly 40-60 years old and their educational levels were mainly lower than junior high school. In 2017, most anglers were older than 40 and used hand rod and/or sea rod. Their average catch of each time was mainly less than 1 kg. Results suggested that the fishing ban in key waters of the Yangtze River basin is not only an ecological project of aquatic ecosystem conservation, but also a livelihood project for the fisherman to embrace industrial transformation and improve their living conditions. After the implementation of the fishing ban, the fisheries resources would gradually recover, and the Yangtze finless porpoise population size would also see a steady increase. However, the endangered species would remain threatened for a long time. The degraded waterbodies and water-level fluctuation areas would be the key restrictive factors for future aquatic ecosystem recovery in the Yangtze River basin. Since this survey was carried out before the fishing ban, the current results could provide a baseline for future evaluation of the effect of the Yangtze River fishing ban. [ABSTRACT FROM AUTHOR]

Aquatic risk assessment is essential to guarantee the sustainable use of pesticides and the conservation of water resources near agricultural fields. This article discusses a proposal for a tiered regulatory framework for the aquatic risk assessment of pesticides in Brazil. The first step is problem formulation, which includes establishing general and specific protection goals. In the exposure assessment, the Estimated Environmental Concentrations in water should be calculated based on realistic worst‐case assumptions regarding application rate and frequency, the entry into the edge‐of‐field water body, and fate in the water body, using scenario‐dependent models suggested by the Brazilian Environmental Agency. These calculations can be refined by including Efate studies with variable exposures to reflect realistic environmental conditions accurately and include mitigation measures that impact the modeling. In the hazard assessment, ecotoxicological data for toxicity to fish, aquatic invertebrates, algae, and aquatic plants should be required for all pesticides based on standardized protocols and species. Tier 2 has several refinement options, including incorporating toxicity data from additional test species and effect modeling. In Tier 3, population‐ and community‐level effects are evaluated using semi‐field studies. Considering the case study in Brazil, Tier 1 demonstrated that, from the 12 pesticides that were assessed, seven (58%) failed based on the value of the Risk Quotient. In Tier 2, when exposure refinement options and mitigation measures such as buffer zones are considered, all seven pesticides, for which Tier 1 indicated risk, still failed the assessment. The risk for four of these seven pesticides could be refined by considering toxicity information from additional species. Refinement options and mitigation measures that could be applied to the agricultural scenario in Brazil were discussed. In conclusion, the proposed tiered risk assessment is a feasible way to evaluate whether a pesticide will pose an unacceptable risk to aquatic organisms. Integr Environ Assess Manag 2024;20:1514–1528. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: This article proposes a tiered regulatory framework for aquatic risk assessment of pesticides in Brazil; the framework involves problem formulation, exposure assessment, and hazard assessment, focusing on realistic worst‐case scenarios and refined calculations.The application of the proposed tiered approach in a Brazilian case study revealed that 58% of assessed pesticides failed the Tier 1 assessment.Refinement options and mitigation measures that could be applied to the agricultural scenario in Brazil were discussed. [ABSTRACT FROM AUTHOR]

Warming water temperatures as a result of climate change pose a major threat to coldwater organisms. However, the rate of warming is not spatially uniform due to surface‐ground‐water interactions and stream and watershed characteristics. Coldwater habitats that are most resistant to warming serve as thermal refugia and identifying their locations is critical to regional aquatic conservation planning. We quantified the thermal sensitivity of 203 streams providing current and potential habitat for brook trout (Salvelinus fontinalis) across nearly 1000 linear km of their native range in the southern and central Appalachian Mountains region, USA, and characterized their spatial variability with landscape variables available in the National Hydrography Dataset. Using the Bayesian framework, we calculated the maximum slope of the logistic function relating paired weekly mean air temperature and stream temperature as an index of stream thermal sensitivity. Streams differed greatly in thermal sensitivity and those with more resistant water temperature regimes (i.e., thermal refugia) were consistently characterized by southerly latitudes and groundwater input. Landscape variables derived from a principal component analysis explained 16% of the variation in thermal sensitivity, indicating that the existing landscape variables were modestly successful in explaining spatial thermal heterogeneity. Using our model and spatial interpolation, we predicted thermal sensitivity at 8695 stream segments potentially suitable for brook trout in the study region. Thermal refugia were more common southward presumably due to higher elevations, but elsewhere they were also clustered at finer spatial scales. Our analysis informs prioritizing habitat conservation and restoration of this native salmonid and other aquatic organisms that depend on coldwater habitats in a warming world. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) and microplastics (MPs) are toxic environmental pollutants that severely risk ecosystems and living organisms. The interactions of these pollutants in the aquatic environment can impact their bioavailability, toxicity, and bioaccumulation potential in organisms. Various factors, including temperature, pH, salinity, polymer type, particle size and microbial abundance, influence these interactions and are likely to increase their influence on aquatic biota and human beings. MPs have been recognized as heavy metal transporters in aquatic environments that exhibit various harmful effects. However, MP interactions with heavy metals are poorly understood. Hence, it is important to understand the detailed mechanism, mainly absorption vs ingestion, MPs degradation with metal fate and combined effects on living organisms. To tackle and reduce the harmful effects on biodiversity, it is essential to comprehend the underlying mechanisms (e.g. adsorption, desorption, bio-uptake, and synergistic effects). Also, more research is required to comprehend the intricate connections between MPs and HMs in an array of environmental situations, which could lead to innovative solutions for mitigating their detrimental environmental consequences. This review paper discusses microplastic's prevalence, concentration, adsorption, and dissociation characteristics concerning HMs in aquatic ecosystems that must be understood to reduce their deleterious effects on aquatic biodiversity. Understanding these complex interactions between MPs and HMs is critical to assessing the ecotoxic effects and preventing environmental pollution. This review paper also underscores the nature of environmental pollutants, including the interaction mechanisms of MPs and HMs, emphasizing the importance of multifaceted approaches that need to be adapted to mitigate their combined effects. [ABSTRACT FROM AUTHOR]

Qatar and other Gulf States have a diverse range of marine vegetation that is adapted to the stressful environmental conditions of seawater. The industrial wastewater produced by oil and gas activities adds further detrimental conditions for marine aquatic photosynthetic organisms on the Qatari coastlines. Thus, these organisms experience severe stress from both seawater and industrial wastewater. This review discusses the biodiversity in seawater around Qatar, as well as remediation methods and metabolic pathways to reduce the negative impacts of heavy metals and petroleum hydrocarbons produced during these activities. The role of microorganisms that are adjacent to or associated with these aquatic marine organisms is discussed. Exudates that are released by plant roots enhance the role of microorganisms to degrade organic pollutants and immobilize heavy metals. Seaweeds may have other roles such as biosorption and nutrient uptake of extra essential elements to avoid or reduce eutrophication in marine environments. Special attention is paid to mangrove forests and their roles in remediating shores polluted by industrial wastewater. Seagrasses (Halodule uninervis, Halophila ovalis, and Thalassia hemprichii) can be used as promising candidates for phytoremediation or bioindicators for pollution status. Some genera among seaweeds that have proven efficient in accumulating the most common heavy metals found in gas activities and biodegradation of petroleum hydrocarbons are discussed. [ABSTRACT FROM AUTHOR]

A rapid and timely response to the impacts of mercury chloride, which is indispensable to the chemical industry, on aquatic organisms is of great significance. Here, we investigated whether the YOLOX (improvements to the YOLO series, forming a new high-performance detector) observation system can be used for the rapid detection of the response of Daphnia magna targets to mercury chloride stress. Thus, we used this system for the real-time tracking and observation of the multidimensional motional behavior of D. magna. The results obtained showed that the average velocity ( v ¯ ), average acceleration ( a ¯ ), and cumulative travel (L) values of D. magna exposed to mercury chloride stress changed significantly under different exposure times and concentrations. Further, we observed that v ¯ , a ¯ and L values of D. magna could be used as indexes of toxicity response. Analysis also showed evident D. magna inhibition at exposure concentrations of 0.08 and 0.02 mg/L after exposure for 10 and 25 min, respectively. However, under 0.06 and 0.04 mg/L toxic stress, v ¯ and L showed faster toxic response than a ¯ , and overall, v ¯ was identified as the most sensitive index for the rapid detection of D. magna response to toxicity stress. Therefore, we provide a strategy for tracking the motile behavior of D. magna in response to toxic stress and lay the foundations for the comprehensive screening of toxicity in water based on motile behavior. [ABSTRACT FROM AUTHOR]

Chiral pesticides account for about 40% of the total pesticides. In the process of using pesticides, it will inevitably flow into the surface water and even penetrate into the groundwater through surface runoff and other means, as a consequence, it affects the water environment. Although the enantiomers of chiral pesticides have the same physical and chemical properties, their distribution, ratio, metabolism, toxicity, etc. in the organism are often different, and sometimes even show completely opposite biological activities. In this article, the selective fate of different types of chiral pesticides such as organochlorine, organophosphorus, triazole, pyrethroid and other chiral pesticides in natural water bodies and sediments, acute toxicity to aquatic organisms, chronic toxicity and other aspects are summarized to further reflect the risks between the enantiomers of chiral pesticides to non-target organisms in the water environment. In this review, we hope to further explore its harm to human society through the study of the toxicity of chiral pesticide enantiomers, so as to provide data support and theoretical basis for the development and production of biochemical pesticides. [ABSTRACT FROM AUTHOR]

Yancheng coastal wetland, the largest coastal wetland in the west coast of the Pacific Ocean and the margin of the Asian continent, has significant environmental, economic and social effects on local human beings. The extensive contamination and potential risk of quinolone antibiotics (QNs) on local aquaculture and human health are still not clear until now. In this study, 52 surface sediment samples were collected to investigate the contamination status and polluted sources, and evaluate ecological risks of QNs in the south of Yancheng coastal wetland. The total contents of QNs ranged from 0.33 to 21.60 ng/g dw (mean value of 4.51 ng/g dw), following the detection frequencies of QNs ranging from 19.23 to 94.23%. The highest content of QNs occurred around an aquaculture pond dominated by flumequine. The total organic carbon contents of sediment were positively correlated with sarafloxacin and lomefloxacin (p < 0.05), indicating the enhanced absorption of these QNs onto sediments. Partial QNs, such as lomefloxacin, enrofloxacin, sarafloxacin and flumequine, presented the homology features originating from the emission of medical treatment and aquaculture. There was no potential risk of QNs to human beings but a potential risk to aquatic organisms (algae > plant > invertebrate). Totally, the management and protection of Yancheng coastal wetland should be of concern with aquaculture as the important industry. [ABSTRACT FROM AUTHOR]

The use of some organophosphate insecticides is restricted or even banned in paddy fields due to their high toxicity to aquatic organisms. The aim of this study is to elucidate the main pathways and target organs of organophosphate insecticide toxicity to fish exposed via different routes by integrating histopathological and biochemical techniques. Using malathion as the model drug, when the dosage is 20–60 mg/L, the toxicity of whole body and head immersion drugs to zebrafish is much higher than that of trunk immersion drugs. A dose of 21.06–190.44 mg/kg of malathion feed was fed to adult zebrafish. Although the dosage was already high, no obvious toxicity was observed. Therefore, we believe that the drug mainly enters the fish body through the gills. When exposed to a drug solution of 20 mg/L and 60 mg/L, the fish showed significant neurological behavioral abnormalities, and the pathological damage to key organs and brain tissue was the most severe, showing obvious vacuolization and the highest residual amount (8.72–47.78 mg/L). The activity of acetylcholinesterase was the most inhibited (54.69–74.68%). Therefore, brain tissue is the key toxic target organ of malathion in fish. In addition, we compared the bioaccumulation effects of different water-soluble organophosphorus insecticides in fish and their toxic effects. We found that the higher the water solubility of organophosphorus insecticides, the lower their toxicity to fish. [ABSTRACT FROM AUTHOR]

Among aquatic organisms, filter feeders are particularly exposed to the ingestion of microplastics (MPs) and nanoplastics (NPs). The present study investigates the effect of environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized plastic debris collected in the Garonne River (France), and polystyrene NPs (PS NPs) on the freshwater bivalve Corbicula fluminea. Organisms were exposed to plastic particles at three concentrations: 0.008, 10, and 100 μg L−1 for 21 days. Gene expression measurements were conducted in gills and visceral mass at 7 and 21 days to assess the effects of plastic particles on different functions. Our results revealed: (i) an up-regulation of genes, mainly involved in endocytosis, oxidative stress, immunity, apoptosis, and neurotoxicity, at 7 days of exposure for almost all environmental plastic particles and at 21 days of exposure for PS NPs in the gills, (ii) PS NPs at the three concentrations tested and ENV MPs at 0.008 μg L−1 induced strong down-regulation of genes involved in detoxication, oxidative stress, immunity, apoptosis, and neurotoxicity at 7 days of exposure in the visceral mass whereas ENV MPs at 10 and 100 μg L−1 and all ENV NPs induced less pronounced effects, (iii) overall, PS NPs and ENV MPs 0.008 μg L−1 did not trigger the same effects as ENV MPs 10 and 100 μg L−1 and all ENV NPs, either in the gills or the visceral mass at 7 and 21 days of exposure. This study highlighted the need to use MPs and NPs sampled in the environment for future studies as their properties induce different effects at the molecular level to living organisms. [ABSTRACT FROM AUTHOR]

Aeromonas veronii is an important pathogen in the co-occurrence of humans and fish, causing significant mortality in various aquatic organisms, posing a major threat to aquaculture and public health care. The type III secretion system (T3SS) is one of the most critical virulence mechanisms in determining the pathogenicity of Aeromonas species. The transcription factor ExsA of AraC family serves as the main regulatory factor and activates T3SS assembly and effector protein secretion in response to changes in environmental conditions. In order to explore the effect of exsA on the pathogenicity of the A. veronii, this study constructed an exsA gene knockout strain using homologous recombination strategy and tested its biofilm formation, adhesion capabilities, as well as the cytotoxicity of the spent cultural supernatant. The results showed that the deletion of the exsA gene in A. veronii led to a significant decrease of its biofilm formation capability, its adhesion to ex vivo host tissues, and the cytotoxicity of the spent culture supernatants. Compared with the wild type, the ability of the exsA knockout strain to form biofilm was reduced by 1.5 folds. The adhesion to epithelial cells was not significantly changed in exsA knockout strain as compared with the wild type, while the adhesion to ex vivo mouse intestinal tissues decreased by 3.4 folds and the cytotoxicity of bacterial culture supernatants decreases by 1.2 folds. These results proved that exsA plays an important regulatory role in the virulence mechanism of bacterial pathogen, laying a solid foundation for further research on the function of T3SS in the pathogenic mechanism of A. veronii and provided clues for establishing strategies for the control of the aquatic infection. [ABSTRACT FROM AUTHOR]

Sulfamethoxazole (SMX) and trimethoprim (TRIM) are two of the most used antibiotics in the last 50 years, to prevent and treat bacterial infections; however, the available literature about toxicity to non-target organisms is quite discrepant and incomplete. This study aims to assess the SMX and TRIM ecotoxicological effects in standard species: Aliivibrio fischeri (bioluminescence inhibition), Escherichia coli ATCC 25922 (growth inhibition), Lemna minor (growth inhibition and biochemical biomarkers), Daphnia magna (immobilization/mortality, life history traits, and biochemical biomarkers), and Danio rerio (survival, hatching, abnormalities, and biochemical biomarkers). The species tested showed different acute sensitivities to SMX (A. fischeri < D. magna < E. coli < L. minor) and TRIM (L. minor < A. fischeri < D. magna < E. coli). Overall, TRIM reveals less toxicity than SMX, except for E. coli (Ecotoxicological approach based on Antimicrobial Susceptibility Testing – EcoAST procedure). Both antibiotics affect individually (e.g., growth and survival) and sub-individually (e.g., antioxidant defenses) L. minor, D. magna, and D. rerio. This study allowed us to generate relevant data and fill gaps in the literature regarding the effects of SMX and TRIM in aquatic organisms. The here-obtained results can be used to (i) complete and re-evaluate the Safety Data Sheet to improve the assessment of environmental safety and management of national and international entities; (ii) clarify the environmental risks of these antibiotics in aquatic ecosystems reinforcing the inclusion in the 4th Watch List of priority substances to be monitored in whole inland waters by the Water Framework Directive; and (iii) combat the development of antimicrobial resistance, as well as supporting the definition of environmental measurements in the context of European One Health Action Plan. However, it is essential to continue studying these antibiotics to better understand their toxicity at ecologically relevant concentrations and their long-term effects under different climatic change scenarios. [ABSTRACT FROM AUTHOR]

Environmental release of wastewater that contains cytostatic drugs can cause genotoxic impact, since these drugs act directly on the genetic material of aquatic organisms. Thus, the aim of this study was to evaluate the removal of the cytostatic drugs cytarabine (CTR) and methotrexate (MTX) using different physico-chemical methods individually (i.e. US, O3, H2O2 and UV) and combined (i.e. O3/US, US/H2O2, O3/H2O2 and O3/US/H2O2) under different pH conditions (4, 7 and 10). In the degradation tests, the efficiency of the methods applied was found to be dependent on the pH of the solution, with the degradation of CTR being better at pH 4 and MTX at pH 7 and pH 10. The US, H2O2 and US + H2O2 methods were the least efficient in degrading CTR and MTX under the pH conditions tested. The highest MTX degradation rate after 16 min of treatment at pH 7 was achieved by the O3 + H2O2 method (97.05% – C/C0 = 0.0295). For CTR, the highest degradation rate after 16 min of treatment was achieved by the O3 process (99.70% – C/C0 = 0.0030) at pH 4. In conclusion, most of the treatment methods tested for the degradation of CTR and MTX are effective. Notably, ozonolysis is an efficient process applied alone. Also, in combination with other methods (US + O3, O3 + H2O2 and O3 + H2O2 + US) it increases the degradation performance, showing a rapid removal rate of 70–94% in less than 4 min of treatment. [ABSTRACT FROM AUTHOR]

Ultraviolet radiation (UVR) is the photochemically most reactive waveband of incident solar irradiation. Despite high absorption in aquatic environments, UVR causes numerous biochemical, genetic, and cytotoxic effects in aquatic organisms. To counteract UVR stress, many of those species are able to synthesize, accumulate, or acquire UV-sunscreen compounds for photoprotection from their diet. The most abundant UV sunscreens in marine and freshwater organisms are mycosporine-like amino acids (MAAs), which exhibit high molar extinction coefficients in the UVR range along with a strong photo- and heat stability. In this study, we investigated the qualitative and quantitative MAA distribution patterns in the eyes of 39 fish species, mainly from the temperate northern hemisphere (Baltic Sea, Northern Atlantic), using state-of-the-art analytical methods. The fish eyes of the most investigated species (33 taxa) contained MAAs, between one and seven different compounds. The MAAs palythine, asterina-330, palythene, and usujirene were present (as previously reported), and three new compounds, aplysiapalythine A, porphyra-334, and shinorine, were identified. Total MAA concentrations covered a wide range from trace amounts to > 4.2 mg g-1 dry weight, thereby providing the first quantitative data on MAAs in fish eyes. The highest MAA contents were measured in Sprattus sprattus, which are comparable to those of intertidal red seaweeds. The trophic transfer of MAAs from primary producers via zooplankton to the fish is discussed, along with the localization in the fish eye as well as possible additional functions. [ABSTRACT FROM AUTHOR]

Ad libitum feeding of laboratory zebrafish has potential benefits for colony management, but would require a new type of diet, such as a gel that remains in the tank. We hypothesized that adult zebrafish fed a gel diet would have similar body size and reproductive success compared with those fed a standard micro-pellet diet. The gel diet's impact on water quality was determined to be safe for zebrafish prior to starting a 12-week feeding study. Two hundred adult AB zebrafish of mixed sex were randomly assigned to be fed exclusively either gel or micro-pellet diet. Fish body length and mass were measured every two weeks, and fish were bred within each feed group to assess fecundity. Zebrafish consumed less gel diet than expected. Body length, mass, and breeding success were lower in the gel diet fish than in the micro-pellet diet fish. Low consumption of the gel diet and/or nutritional differences between the two diets may have contributed to reduced growth and fecundity. Though the gel diet could reduce time personnel spend feeding and be safer for fish in static tanks, the tested formulation was not a satisfactory alternative to the control micro-pellet diet in a research zebrafish colony. [ABSTRACT FROM AUTHOR]

The role of large frugivores in the dispersal of tropical trees has been well‐studied, whereas the importance of the world's largest rodents for plant dispersal has previously been ignored. We studied plant dispersal by gut passage (endozoochory) in Neotropical wetlands by the largest extant rodent, the capybara Hydrochoerus hydrochaeris. We compared it with another of the world's 10 largest rodents, the nutria or coypu Myocastor coypus.We collected 96 faecal samples (50 capybara, 46 nutria) from 10 sites within the Taim Ramsar site in southern Brazil, and extracted intact propagules from 10 g subsamples. Propagules from 27 plant taxa (24 angiosperms, and three aquatic ferns) were recovered, representing 13 plant families. Whole Spirodela (duckweed) plants were dispersed. Seeds from 14 angiosperm taxa were germinated in the laboratory.Taxonomic composition of propagules was significantly different for the two mammals, but propagule size was not. Capybara dispersed more terrestrial propagules per sample, and nutrias more aquatic propagules. When total faecal production was taken into account, an estimated 1025 propagules (including 133 fern spores) were dispersed by each capybara per day, compared with 691 propagules for nutrias (including 566 fern spores). Capybaras have larger home ranges and likely dispersed plants over a greater distance.Synthesis: This is the first demonstration that rodents disperse aquatic pteridophytes as well as flowering plants. Our results suggest that capybaras and nutrias play important, complementary roles in dispersing a variety of aquatic and terrestrial plant species within Neotropical wetlands. Our study indicates that the role of herbivorous mammals as vectors of plants with small seeds and non‐fleshy fruits has been overlooked in the neotropics and that defaunation of large herbivores can have negative consequences, in a manner similar to that previously highlighted for frugivores. [ABSTRACT FROM AUTHOR]

Simple Summary: The individual-rearing method has proven beneficial for detailed studies on the growth and feeding of aquatic organisms, helping to minimize the impact of non-dietary factors such as cannibalism. The Kuruma shrimp Penaeus japonicus occupies a significant niche in global aquaculture, but there is still a gap in the research on its nutrient supply, particularly in comparing the nutritional impacts of live feed and pellet diets. This study employed an individual-rearing method to investigate the effects of live feed (Perinereis aibuhitensis), formulated pellet diets, and their combinations on the growth and health of P. japonicus. The results revealed that live feed can enhance shrimp growth performance compared to pellet diets and provide a healthier and more stable intestinal flora. Growth and feeding performance on a mixed diet were comparable to live feed while also reducing costs. And the individual-rearing method allowed us to find inter-individual differences in growth and feeding, with daily intake varying cyclically with the molting cycle. These findings elucidate the feed preferences as well as the growth and feeding characteristics of shrimp, offering novel methodologies for shrimp feed selection, trait collection, and breeding strategies. This has the potential to significantly enhance aquacultural practices. This study developed an individual-rearing method to compare the effects of live feed (sandworms Perinereis aibuhitensis), formulated pellet diets, and a mixture of live feed and formula feed on the Kuruma shrimp Penaeus japonicus, aiming to minimize the influence of non-dietary factors on the growth of P. japonicus, like cannibalism. Results indicated that live feed, with its higher protein, essential amino acids, and fatty acid content, led to significantly better growth and feeding performance in P. japonicus (p < 0.05) compared to pellet diets. A mixed diet resulted in a lower average daily protein intake yet maintained a growth and feeding performance comparable to live feed. The intestinal microbiota of shrimp, dominated by Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria, showed significant shifts with diet changes. Specifically, formulated feed increased the relative abundance of Vibrio and Photobacterium while decreasing Shimia and Rhodobacterales (p < 0.05), and feeding live food resulted in a more complex and stable bacterial network. Notably, individual variances in growth and feeding were observed among shrimps, with some on formulated diets showing growth comparable to those on live feed. Each shrimp's final weight, specific growth rate, protein efficiency rate, and average daily food intake positively correlated with its initial body weight (p < 0.05), and daily intake varied cyclically with the molting cycle. These findings suggest that individual-rearing is an effective approach for detailed feed evaluation and monitoring in P. japonicus, contributing to improved feed selection, development, and feeding strategies. [ABSTRACT FROM AUTHOR]

Anthropic eutrophication leads to water quality degradation because it may cause the development of harmful cyanobacterial blooms, affecting aquatic biota and threatening human health. Because in the natural environment zooplankters are exposed continuously or intermittently to cyanotoxins in the water or through cyanobacterial consumption, this study aimed to assess the effects of the toxigenic Microcystis aeruginosa VU-5 by different ways of exposure in Daphnia curvirostris. The acute toxicity produced by the cells, the aqueous crude extract of cells (ACE), and the cell-free culture medium (CFM) were determined. The effect on the survival and reproduction of D. curvirostris under continuous and intermittent exposure was determined during 26 d. The LC50 was 407,000 cells mL−1; exposure to the ACE and CFM produced mortality lower than 20%. Daphnia survivorship and reproduction were significantly reduced. Continuous exposure to Microcystis cells caused 100% mortality on the fourth day. Exposure during 4 and 24 h in 48 h cycles produced adult mortality, and reproduction decreased as the exposure time and the Microcystis concentrations increased. The higher toxicity of cells than the ACE could mean that the toxin's absorption is higher in the digestive tract. The temporary exposure to Microcystis cells produced irreversible damage despite the recovery periods with microalgae as food. The form and the continuity in exposure to Microcystis produced adverse effects, warning about threats to the zooplankton during HCBs. [ABSTRACT FROM AUTHOR]

As new pesticides continue to emerge in agricultural systems, understanding their environmental behavior is crucial for effective risk assessment. Tiafenacil (TFA), a promising novel pyrimidinedione herbicide, was the focus of this study. We developed an efficient QuEChERS-UHPLC-QTOF-MS/MS method to measure TFA and its transformation products (TP1, TP2, TP3, TP4, and TP5) in soil. Our calibration curves exhibited strong linearity (R2 ≥ 0.9949) ranging from 0.015 to 2.0 mg/kg within a low limit of quantification (LOQ) of 2.0 µg/kg. Inter-day and intra-day recoveries (0.10 to 2.0 mg/kg, 80.59% to 110.05%, RSD from 0.28% to 12.93%) demonstrated high sensitivity and accuracy. Additionally, TFA dissipation under aerobic conditions followed first-order kinetics, mainly yielding TP1 and TP4. In contrast, TP1 and TP2 were mainly found under sterilized and anaerobic conditions, and TFA dissipation followed second-order kinetics. Moreover, we predicted the transformation pathways of TFA using density functional theory (DFT) and assessed the toxicity levels of TFA and its TPs to aquatic organisms using ECOSAR. Collectively, these findings hold significant implications for a better understanding of TFA fate in diversified soil, benefiting its risk assessment and rational utilization. [ABSTRACT FROM AUTHOR]

Cryptochromes (Crys) represent a multi-facetted class of proteins closely associated with circadian clocks. They have been shown to function as photoreceptors but also to fulfill light-independent roles as transcriptional repressors within the negative feedback loop of the circadian clock. In addition, there is evidence for Crys being involved in light-dependent magneto-sensing, and regulation of neuronal activity in insects, adding to the functional diversity of this cryptic protein class. In mammals, Crys are essential components of the circadian clock, but their role in other vertebrates is less clear. In invertebrates, Crys can function as circadian photoreceptors, or as components of the circadian clock, while in some species, both light-receptive and clock factor roles coexist. In the current study, we investigate the function of Cry proteins in zebrafish (Danio rerio), a freshwater teleost expressing 6 cry genes. Zebrafish peripheral circadian clocks are intrinsically light-sensitive, suggesting the involvement of Cry in light-resetting. Echinoderms (Strongylocentrotus purpuratus) represent the only class of deuterostomes that possess an orthologue (SpuCry) of the light-sensitive Drosophila melanogaster Cry, which is an important component of the light-resetting pathway, but also works as transcriptional repressor in peripheral clocks of fruit flies. We therefore investigated the potential of different zebrafish cry genes and SpuCry to replace the light-resetting and repressor functions of Drosophila Cry by expressing them in fruit flies lacking endogenous cry function. Using various behavioral and molecular approaches, we show that most Cry proteins analyzed are able to fulfill circadian repressor functions in flies, except for one of the zebrafish Crys, encoded by cry4a. Cry4a also shows a tendency to support light-dependent Cry functions, indicating that it might act in the light-input pathway of zebrafish. [ABSTRACT FROM AUTHOR]