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Aquatic macrophytes serve as shelter and a direct source of food for invertebrates, in addition to indirectly providing items such as algae, detritus, and microorganisms. Thus, aquatic macrophytes act as habitat structuring elements, requiring a distinction between habitat complexity (physical formations such as fractal dimensions, density and biomass) and habitat heterogeneity (diversity of these structures). Here we explore the effects of habitat complexity and habitat heterogeneity on the invertebrate community.We collected macrophytes and invertebrates from 28 sampling sites along a 13.7‐km stretch of the Baía River in Brazil, and examined specific groups (insects, microcrustaceans, and other invertebrates). Environmental variables in the sites were also measured. We aimed to explore the effects of habitat complexity (measured by macrophyte biomass) and habitat heterogeneity (evaluated through macrophyte functional diversity) on the richness and abundance of invertebrates.We found that overall invertebrate richness was positively influenced solely by habitat heterogeneity. For invertebrate abundance, intermediate habitat complexity had more invertebrates, while habitat heterogeneity had a positive impact. Environmental variables influenced only the abundance. For specific groups, insect richness was positively influenced by habitat heterogeneity, while insect abundance decreased with high complexity and increased with high heterogeneity. Microcrustacean abundance was positively influenced by habitat complexity. Richness and abundance of other invertebrates was positively influenced by habitat heterogeneity.Invertebrates prefer macrophyte stands with intermediate complexity and high heterogeneity. Abundance is linked to structural complexity and heterogeneity, while species richness is more strongly associated with heterogeneity. Furthermore, the impact of these factors varies among invertebrate groups.These findings emphasise the importance of integrating a broad range of metrics, such as macrophyte biomass and functional diversity, to gain a thorough understanding of invertebrate community dynamics in future studies. Additionally, our study demonstrates that preserving macrophyte stands with high heterogeneity significantly enhances the diversity of associated invertebrate species. [ABSTRACT FROM AUTHOR]

Understanding how the causal feedback between phytoplankton and environmental drivers controlling the chlorophyll a (Chl a, as a proxy of phytoplankton biomass)–nutrient relationships are modulated under different ecosystem conditions is a major challenge in aquatic ecology. Using an empirical dynamic model (convergent cross mapping) on a 20‐yr dataset on 20 Danish lakes, we quantified hypothesized causal feedback networks for each lake and related them to lake system properties (e.g., mean water depth, nutrient concentrations and extent of reduction, climate warming) vs. the Chl a–nutrient relationship (estimated from generalized least square models). The results showed prevalent causal feedback across the studied lakes, which demonstrated clear patterns for the tested ecosystem variations. Weaker causal feedbacks were found in deeper lakes and lakes with larger warming trends, while stronger causal feedbacks appeared in lakes experiencing greater reductions of TP (total phosphorus) and TN (total nitrogen). Moreover, these causal feedbacks showed a strong and positive coupled pattern. Most of the causal feedbacks worked as enhancement loops, which promote the sensitivity of phytoplankton to TP, not least in shallow lakes with a high TP reduction, and as regulatory loops, which force a shift in the Chl a–TN relationship from a more negative slope in lakes experiencing a high nutrient reduction and weak warming to a positive slope in lakes with low nutrient reduction and stronger warming. Our findings suggest a mechanistic explanation of how internal feedbacks regulate the Chl a–nutrient relationships across a broad gradient of nutrient reductions, climate warming, and lake morphologies. [ABSTRACT FROM AUTHOR]

Skin microbiomes provide vital functions, yet knowledge about the drivers and processes structuring their species assemblages is limited—especially for non‐model organisms. In this study, fish skin microbiome was assessed by high throughput sequencing of amplicon sequence variants from metabarcoding of V3–V4 regions in the 16S rRNA gene on fish hosts subjected to the following experimental manipulations: (i) translocation between fresh and brackish water habitats to investigate the role of environment; (ii) treatment with an antibacterial disinfectant to reboot the microbiome and investigate community assembly and priority effects; and (iii) maintained alone or in pairs to study the role of social environment and inter‐host dispersal of microbes. The results revealed that fish skin microbiomes harbour a highly dynamic microbial composition that was distinct from bacterioplankton communities in the ambient water. Microbiome composition first diverged as an effect of translocation to either the brackish or freshwater habitat. When the freshwater individuals were translocated back to brackish water, their microbiome composition converged towards the fish microbiomes in the brackish habitat. In summary, external environmental conditions and individual‐specific factors jointly determined the community composition dynamics, whereas inter‐host dispersal had negligible effects. The dynamics of the microbiome composition was seemingly non‐affected by reboot treatment, pointing towards high resilience to disturbance. The results emphasised the role of inter‐individual variability for the unexplained variation found in many host‐microbiome systems, although the mechanistic underpinnings remain to be identified. [ABSTRACT FROM AUTHOR]

Mangroves are implemented as nature‐based solutions (NbS) for coastal protection, climate change mitigation (carbon sequestration) and other services. They play a core role in providing benefits for biodiversity, livelihoods and human well‐being. Ecological research has informed the use of mangroves as NbS, but failure of NbS projects has often been due to misconceptions about mangrove ecology and the limited use of the wide range of ecological knowledge available. Enhanced knowledge of the spatial and temporal variation in ecological processes, and differentiation among mangrove tree species and assemblages (including fauna and microbial communities) in the provision of ecosystem functions and services, will support successful use of mangroves as NbS. Knowledge of mangrove responses to the interacting pressures of climate change and human uses of the coastal zone will support resilient NbS projects. Synthesis. The success of mangroves as NbS can be improved with increased incorporation of knowledge of the ecology of mangrove plants, animals and microbes and by sharing and co‐producing knowledge within mangrove societies. [ABSTRACT FROM AUTHOR]

The development of hydroelectric projects has adversely affected the reproductive activities of downstream fish species. To facilitate the natural reproduction of fish and restore spawning grounds post‐dam construction, it is imperative to explore the ecological factors crucial for their reproduction. Currently, various research methods with different advantages and limitations are employed for this purpose. Using identified spawning locations and periods as clues, we quantitatively investigate the flow velocity, water depth, water temperature, and riverbed substrate required for spawning. The results are validated using habitat simulation methods, aiming to establish a more scientific approach to explore ecological factors affecting fish reproduction. This study provides a more scientific, systematic, and detailed report on the ecological factors required for the spawning of Gymnocypris eckloni: flow velocity ranging from 0.19 to 0.97 m/s, water depth from 0.28 to 1.12 m, water temperature between 11.4 and 15.2°C, and predominantly gravel substrate. The reliability of the results was verified in another spawning ground, with good verification results. This research provides crucial data for the bio‐mimetic reproductive technology of Gymnocypris eckloni and the restoration of spawning grounds for natural fish reproduction post‐dam construction. It addresses the lack of suitable ecological factor data for protective fish species in the upper reaches of the Yellow River. The method exhibits strong scientific, accurate, and implementable characteristics. [ABSTRACT FROM AUTHOR]

Carrion ecology, i.e. the decomposition and recycling of dead animals, has traditionally been neglected as a key process in ecosystem functioning. Similarly, despite the large threats that inland aquatic ecosystems (hereafter, aquatic ecosystems) face, the scientific literature is still largely biased towards terrestrial ecosystems. However, there has been an increasing number of studies on carrion ecology in aquatic ecosystems in the last two decades, highlighting their key role in nutrient recirculation and disease control. Thus, a global assessment of the ecological role of scavengers and carrion in aquatic ecosystems is timely. Here, we systematically reviewed scientific articles on carrion ecology in aquatic ecosystems to describe current knowledge, identify research gaps, and promote future studies that will deepen our understanding in this field. We found 206 relevant studies, which were highly biased towards North America, especially in lotic ecosystems, covering short time periods, and overlooking seasonality, a crucial factor in scavenging dynamics. Despite the low number of studies on scavenger assemblages, we recorded 55 orders of invertebrates from 179 families, with Diptera and Coleoptera being the most frequent orders. For vertebrates, we recorded 114 species from 40 families, with birds and mammals being the most common. Our results emphasise the significance of scavengers in stabilising food webs and facilitating nutrient cycling within aquatic ecosystems. Studies were strongly biased towards the assessment of the ecosystem effects of carrion, particularly of salmon carcasses in North America. The second most common research topic was the foraging ecology of vertebrates, which was mostly evaluated through sporadic observations of carrion in the diet. Articles assessing scavenger assemblages were scarce, and only a limited number of these studies evaluated carrion consumption patterns, which serve as a proxy for the role of scavengers in the ecosystem. The ecological functions performed by carrion and scavengers in aquatic ecosystems were diverse. The main ecological functions were carrion as food source and the role of scavengers in nutrient cycling, which appeared in 52.4% (N = 108) and 46.1% (N = 95) of publications, respectively. Ecosystem threats associated with carrion ecology were also identified, the most common being water eutrophication and carrion as source of pathogens (2.4%; N = 5 each). Regarding the effects of carrion on ecosystems, we found studies spanning all ecosystem components (N = 85), from soil or the water column to terrestrial vertebrates, with a particular focus on aquatic invertebrates and fish. Most of these articles found positive effects of carrion on ecosystems (e.g. higher species richness, abundance or fitness; 84.7%; N = 72), while a minority found negative effects, changes in community composition, or even no effects. Enhancing our understanding of scavengers and carrion in aquatic ecosystems is crucial to assessing their current and future roles amidst global change, mainly for water–land nutrient transport, due to changes in the amount and speed of nutrient movement, and for disease control and impact mitigation, due to the predicted increase in occurrence and magnitude of mortality events in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Andean glaciers are losing mass rapidly but a centennial‐scale context to those rates is lacking. Here we show the extent of >5,500 glaciers during the Little Ice Age chronozone (LIA; c. 1,400 to c. 1,850) and compute an overall area change of −25% from then to year 2000 at an average rate of −36.5 km2 yr−1 or −0.11% yr−1. Glaciers in the Tropical Andes (Peru, Bolivia) have depleted the most; median −56% of LIA area, and the fastest; median −0.16% yr−1. Up to 10 × acceleration in glacier area loss has occurred in Tropical mountain sub‐regions comparing LIA to 2,000 rates to post‐2000 rates. Regional climate controls inter‐regional variability, whereas local factors affect intra‐region glacier response time. Analyzing glacier area change by river basins and by protected areas leads us to suggest that conservation and environmental management strategies should be re‐visited as proglacial areas expand. Plain Language Summary: Andean glaciers are melting fast but how that rate compares in a longer‐term context is unknown. In this study we mapped the extent of >5,500 glaciers during the Little Ice Age, which was the last major glacial advance culminating about c. 150 years ago. We analyzed the change in glacier size and computed overall area change of −25% from the LIA to year 2000 at a rate of −36.5 km2 per year or −0.11% per year. Glaciers within Peru and Bolivia have shrunk the most by median −56% of LIA area, and the fastest by median −0.16% per year. We discuss that these glaciers are depleting and retreating due to climate change but that response is compounded by glacier size, shape and terminus environment effects. As glaciers melt they reveal proglacial landscapes that tend to be highly unstable, impacting water resources, natural hazards and terrestrial and aquatic ecology. Key Points: Little Ice Age (LIA) chronozone extent of >5,500 glaciers mapped from geomorphological evidenceOverall glacier area change of −25% to year 2000 at a rate of −36.5 km2 yr−1 or −0.11% yr−1Up to 10 × acceleration in glacier area loss for Tropical sub‐regions comparing LIA to 2,000 with post‐2000 rates [ABSTRACT FROM AUTHOR]

Aquatic birds are notable among the global avifauna for living in environments exposed to large amounts of light. Despite growing evidence that visual adaptations to light underly the ecology and evolution of the avian tree of life, no comprehensive comparative analysis of visual acuity as approximated by eyes size exists for the global aquatic avifauna. Here, I use Stanley Ritland's unpublished dataset of measurements for axial length collected from museum specimens to explore the ecology and evolution of eye size variation for half of the aquatic avifauna (N = 464 species). After correcting for body mass allometry and incorporating phylogenetic relationships, aquatic species had significantly smaller eyes compared to terrestrial species. Furthermore, species using hyperopic foraging manoeuvres, exhibiting carnivorous and insectivorous diets, and displaying nocturnal behaviour had larger eyes. Plunge‐divers (e.g. boobies and tropic birds) and stalkers (e.g. herons) had the largest relative eye sizes, especially species identifying prey at higher altitudes or longer distances. Underwater pursuit‐divers foraging at greater depths had larger eyes, likely due to the dramatic attenuation of light in the deep ocean. Overall, residual eye size was phylogenetically conserved (l = 0.94), with phylogeny alone explaining 62% of residual eye size variation. Collectively, these results suggest that the relatively bright environments found in aquatic ecosystems negate the adaptive benefits of costly metabolic investments associated with developing and maintaining larger eyes, while also reducing the potential occurrence of disability glare. Strong correlations between eye size and foraging ecology in different aquatic environments corroborate similar comparative studies of terrestrial birds and underscore the central role that vision has played in driving the ecology and evolution of the global avifauna. [ABSTRACT FROM AUTHOR]

The document is a report of the February 2024 ESA Council Meeting, held on Zoom. The meeting began with introductions and a welcome from Emilie Graves and Catherine O'Riordan. President Shahid Naeem discussed the new Council format and strategic planning efforts. President-elect Stephanie Hampton presented a draft of a new strategic plan, which was discussed in breakout rooms focusing on equity and inclusion, community building, and operational excellence. Updates were given on ESA publications and funding opportunities. The creation of new ESA sections for Climate Adaptation and Coastal & Marine Ecology was approved. Recommendations for standardizing governance and activities were presented, and the meeting concluded with information on the next Speaker-Elect and closing remarks. [Extracted from the article]

Eco‐evolutionary experiments are typically conducted in semi‐unnatural controlled settings, such as mesocosms; yet inferences about how evolution and ecology interact in the real world would surely benefit from experiments in natural uncontrolled settings. Opportunities for such experiments are rare but do arise in the context of restoration ecology—where different "types" of a given species can be introduced into different "replicate" locations. Designing such experiments requires wrestling with consequential questions. (Q1) Which specific "types" of a focal species should be introduced to the restoration location? (Q2) How many sources of each type should be used—and should they be mixed together? (Q3) Which specific source populations should be used? (Q4) Which type(s) or population(s) should be introduced into which restoration sites? We recently grappled with these questions when designing an eco‐evolutionary experiment with threespine stickleback (Gasterosteus aculeatus) introduced into nine small lakes and ponds on the Kenai Peninsula in Alaska that required restoration. After considering the options at length, we decided to use benthic versus limnetic ecotypes (Q1) to create a mixed group of colonists from four source populations of each ecotype (Q2), where ecotypes were identified based on trophic morphology (Q3), and were then introduced into nine restoration lakes scaled by lake size (Q4). We hope that outlining the alternatives and resulting choices will make the rationales clear for future studies leveraging our experiment, while also proving useful for investigators considering similar experiments in the future. [ABSTRACT FROM AUTHOR]

Researchers are increasingly using biologging equipment (e.g., telemetry receivers, temperature loggers) to characterize the ecology of aquatic ecosystems. This equipment is commonly deployed at a wide range of water depths and greatly expands our capacity to remotely monitor aquatic ecosystems; however, equipment retrieval can be a major challenge. Here, we describe a technological solution to this challenge that uses a combination of live imaging sonar and a remotely operated vehicle to efficiently locate and recover equipment across a wide range of conditions (e.g., turbid water, range of water depths). We provide details on our specific equipment setup (total cost < Can$15,000) used for the recovery of acoustic fish tracking receivers moored to the benthos of Stoney Lake, Ontario, Canada. There are some limitations to this approach, which are discussed. With technological advances and increases in affordability of commercially available products, this approach may be widely applicable to recover biologgers from depth. [ABSTRACT FROM AUTHOR]

Lakes host a high level of biodiversity, especially in their littoral zone, and provide various ecological and socio‐economic services. Lake ecosystems are impacted by a combination of pressures from different human activities (industry, hydroelectricity, agriculture, recreational activities, domestic and urban uses). Anthropic pressures can lead to alterations and dysfunctions in lakes, particularly in the littoral zone.The 2000 EU Water Framework Directive led to considerable efforts to improve the ecological status of European water bodies. However, in France, measures implemented by lake managers to counteract, limit or suppress anthropogenic impacts are still poorly identified. Moreover, their effects on hydromorphology, physico‐chemistry and biotic communities are often only partially reported (the monitoring being incomplete or heterogeneous, if not missing).This paper proposes a framework to harmonize the monitoring of habitat improvement actions conducted in the littoral zone of lakes. The monitoring method is presented as well as the sampling protocols and techniques set out to survey both the restored and control zones at the European French territory scale.Long‐term monitoring of hydromorphological, biological and physicochemical features is expected to improve our understanding of recolonization mechanisms following restoration. The proposed approach will therefore guide practitioners to identify the best restoration options and ultimately contribute to the conservation of recipient populations and communities. [ABSTRACT FROM AUTHOR]

The expansion of scientific image data holds great promise to quantify individuals, size distributions and traits. Computer vision tools are especially powerful to automate data mining of images and thus have been applied widely across studies in aquatic and terrestrial ecology. Yet marine benthic communities, especially infauna, remain understudied despite their dominance of marine biomass, biodiversity and playing critical roles in ecosystem functioning.Here, we disaggregated infauna from sediment cores taken throughout the spring transition (April–June) from a near‐natural mesocosm setup under experimental warming (Ambient, +1.5°C, +3.0°C). Numerically abundant mudsnails were imaged in batches under stereomicroscopy, from which we automatically counted and sized individuals using a superpixel‐based segmentation algorithm. Our segmentation approach was based on clustering superpixels, which naturally partition images by low‐level properties (e.g., colour, shape and edges) and allow instance‐based segmentation to extract all individuals from each image.We demonstrate high accuracy and precision for counting and sizing individuals, through a procedure that is robust to the number of individuals per image (5–65) and to size ranges spanning an order of magnitude (<750 μm to 7.4 mm). The segmentation routine provided at least a fivefold increase in efficiency compared with manual measurements. Scaling this approach to a larger dataset tallied >40k individuals and revealed overall growth in response to springtime warming.We illustrate that image processing and segmentation workflows can be built upon existing open‐access R packages, underlining the potential for wider adoption of computer vision tools among ecologists. The image‐based approach also generated reproducible data products that, alongside our scripts, we have made freely available. This work reinforces the need for next‐generation monitoring of benthic communities, especially infauna, which can display differential responses to average warming. [ABSTRACT FROM AUTHOR]

Traditionally, trophic ecology research on aquatic ecosystems has focused more on the quantity of dietary energy flow within food webs rather than food quality and its effects on organisms at various trophic levels. Recent studies emphasize that food quality is central to consumer growth and reproduction, and the importance of food quality for aquatic ecosystems has become increasingly well recognized. It is timely to synthesise these findings and identify potential future research directions. We conducted a systematic review of omega‐3 polyunsaturated fatty acids (ω3‐PUFAs) as a crucial component of high‐quality food sources in freshwater ecosystems to evaluate their impact on a variety of consumers, and explore the effects of global change on these high‐quality food sources and their transfer to higher trophic consumers within and across ecosystems. In freshwater ecosystems, algae rich in ω3 long‐chain PUFAs, such as diatoms, dinoflagellates and cryptophytes, represent important high‐quality food sources for consumers, whereas cyanobacteria, green algae, terrestrial vascular plants and macrophytes low in ω3 long‐chain PUFAs are low‐quality food sources. High‐quality ω3‐PUFA‐containing food sources usually lead to increased growth and reproduction of aquatic consumers, e.g. benthic invertebrates, zooplankton and fish, and also provide ω3 long‐chain PUFAs to riparian terrestrial consumers via emergent aquatic insects. Consumers feeding on high‐quality ω3‐PUFA‐containing foods in turn represent high‐quality food for their own predators. However, the ω3‐PUFA content of food sources is sensitive to global environmental changes. Warming, eutrophication, increased light intensity (e.g. from loss of riparian shading), and pollutants potentially inhibit the synthesis of algal ω3‐PUFAs while at the same time promoting the growth of lower‐quality foods, such as cyanobacteria and green algae. These factors combined could lead to a significant reduction in the availability of ω3‐PUFAs for consumers and constrain their overall fitness. Although the effect of individual environmental factors on high‐quality ω3‐PUFA‐containing food sources has been investigated, multiple environmental factors (e.g. climate change, human activities, pollution) will act in combination and any synergistic effects on aquatic food webs remain unclear. Identifying the sources and fate of ω3‐PUFAs within and across ecosystems could represent an important approach to understand the impact of multiple environmental factors on trophic relationships and the implications for populations of freshwater and riparian consumers. Maintaining the availability of high‐quality ω3‐PUFA‐containing food sources may also be key to mitigating freshwater biodiversity loss due to global change. [ABSTRACT FROM AUTHOR]

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The Indus River dolphin (Platanista minor) is a severely threatened species of freshwater dolphin that occurs only in the lower Indus River system of Pakistan and India. The dolphin's range has declined by 80% since the 1870s, and total species abundance is estimated as approximately 2000 individuals.In 2007, a remnant population of Indus dolphins was discovered above Harike Barrage, in the Beas River in India, 600 km away from all other individuals of its species. This paper provides an overview of the conservation status of Indus dolphins in the Beas River, details the threats they face, and suggests priorities for their conservation and management.Between 2011 and 2022, 40 dolphin direct count surveys were conducted. Indus dolphins occur only in the lower third of the Beas River and reported counts have been from one to eight individuals. The data do not indicate an increase in abundance, and instead suggest a potential decrease; however, sightings of calves continue to be reported annually indicating reproduction is still taking place.Threats to the Beas River dolphin population include accidental entanglement in fishing gear, pollution, escapement downstream of Harike barrage, altered and depleted river flow regimes' and the effects of a very small population size. Urgent conservation measures are essential if this small, but important satellite population is to persist.Recommended management actions include the complete removal of fishing nets from dolphin habitat, reducing pollution, ensuring adequate river discharge to sustain aquatic ecology including dolphins, evaluating and monitoring dolphin movement through Harike barrage and into canals, and engaging riverside communities to protect dolphins. In addition, the possibility of conservation translocations to supplement this population with individuals from larger healthy populations elsewhere in the range of the species should be explored. [ABSTRACT FROM AUTHOR]

Warming has broad and often nonlinear impacts on organismal physiology and traits, allowing it to impact species interactions like predation through a variety of pathways that may be difficult to predict. Predictions are commonly based on short‐term experiments and models, and these studies often yield conflicting results depending on the environmental context, spatiotemporal scale, and the predator and prey species considered. Thus, the accuracy of predicted changes in interaction strength, and their importance to the broader ecosystems they take place in, remain unclear. Here, we attempted to link one such set of predictions generated using theory, modeling, and controlled experiments to patterns in the natural abundance of prey across a broad thermal gradient. To do so, we first predicted how warming would impact a stage‐structured predator–prey interaction in riverine rock pools between Pantala spp. dragonfly nymph predators and Aedes atropalpus mosquito larval prey. We then described temperature variation across a set of hundreds of riverine rock pools (n = 775) and leveraged this natural gradient to look for evidence for or against our model's predictions. Our model's predictions suggested that warming should weaken predator control of mosquito larval prey by accelerating their development and shrinking the window of time during which aquatic dragonfly nymphs could consume them. This was consistent with data collected in rock pool ecosystems, where the negative effects of dragonfly nymph predators on mosquito larval abundance were weaker in warmer pools. Our findings provide additional evidence to substantiate our model‐derived predictions while emphasizing the importance of assessing similar predictions using natural gradients of temperature whenever possible. [ABSTRACT FROM AUTHOR]

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Disregarding the importance of groundwater as an ecosystem ignores its critical role in preserving surface biomes. To foster timely global conservation of groundwater, we propose elevating the concept of keystone species into the realm of ecosystems, claiming groundwater as a keystone ecosystem that influences the integrity of many dependent ecosystems. Our global analysis shows that over half of land surface areas (52.6%) has a medium‐to‐high interaction with groundwater, reaching up to 74.9% when deserts and high mountains are excluded. We postulate that the intrinsic transboundary features of groundwater are critical for shifting perspectives towards more holistic approaches in aquatic ecology and beyond. Furthermore, we propose eight key themes to develop a science‐policy integrated groundwater conservation agenda. Given ecosystems above and below the ground intersect at many levels, considering groundwater as an essential component of planetary health is pivotal to reduce biodiversity loss and buffer against climate change. [ABSTRACT FROM AUTHOR]

Zooplankton analysis represents a bottleneck in marine ecology studies due to the difficulty to obtain zooplankton data. The last decades have seen the intense development of zooplankton imaging systems, to increase the zooplankton data spatio‐temporal resolution as well as enabling the combination of size, taxonomy, and functional traits in aquatic ecology studies. Here, we propose a benchmark between the ZooScan, a commercially available, laboratory‐based scanner, which analyses zooplankton preserved samples, and the ZooCAM, an in‐flow imaging system designed for on‐board live zooplankton imaging. Sixty‐one zooplankton samples collected over the Bay of Biscay in environments ranging from estuarine to offshore blue waters were imaged with both instruments. Zooplankton Normalized Biovolume‐Size Spectra slopes, mean sizes, abundances, and zooplankton community biogeographical patterns were computed for each instrument and compared at the taxonomic group, the sampling stations and the Bay of Biscay scales. Both instruments produced similar zooplankton variables by stations and by taxa and described similar zooplankton community compositions and biogeographical patterns, on the large mesozooplankton size range, i.e., [0.3–3.39] mm ESD. We conclude that the ZooCAM and the ZooScan data can be combined to generate long term or spatially resolved zooplankton time series. Our study shows that benchmarking imaging instruments or techniques (1) offers a robust assessment of interoperability between instruments, mitigating possible instrumental biases, and (2) may be of great interest in the case of instrumental obsolescence or breakdown, to choose the most conservative replacement solution in a long term time series framework. [ABSTRACT FROM AUTHOR]

Eurasian perch Perca fluviatilis has been a popular model species for decades in the fields of aquatic ecology, community dynamics, behaviour, physiology and ecotoxicology. Yet, despite extensive research, the progress of integrating genomic perspective into existing ecological knowledge in perch has been relatively modest. Meanwhile, the emergence of high‐throughput sequencing technologies has completely changed the methods for genetic variation assessment and conducting biodiversity and evolutionary research. During the last 5 years, three genome assemblies of P. fluviatilis have been generated, allowing substantial advancement of our understanding of the interactions between ecological and evolutionary processes at the whole‐genome level. We review the past progress, current status and potential future impact of the genomic resources and tools for ecological research in Eurasian perch focusing on the utility of recent whole‐genome assemblies. Furthermore, we demonstrate the power of genome‐wide approaches and newly developed tools and outline recent cases where genomics have contributed to new ecological and evolutionary knowledge. We explore how the availability of reference assembly enables the efficient application of various statistical tools, and how genomic approaches can provide novel insights into resource polymorphism, host–parasite interactions and to genetic and phenotypic changes associated with climate change and harvesting‐induced evolution. In summary, we call for increased integration of genomic tools into ecological research for perch, as well as for other fish species, which is likely to yield novel insights into processes linking the adaptation and plasticity to ecosystem functioning and environmental change. [ABSTRACT FROM AUTHOR]

CONCLUDING REMARKS This new paper by Fong et al. makes an exciting and relevant contribution to the emerging field of trait-based seaweed ecology, leading to new opportunities in trait-based seaweed research. In this issue, Fong et al. show how the use of categorical traits can greatly accelerate progress in the emerging field of seaweed trait-based ecology (Fong et al., [3]). Keywords: aquatic plant ecology; categorical traits; determinants of plant community diversity and structure; functional traits; Macroalgae; plant development and life-history traits; trait-based ecology EN aquatic plant ecology categorical traits determinants of plant community diversity and structure functional traits Macroalgae plant development and life-history traits trait-based ecology 1844 1847 4 09/07/23 20230901 NES 230901 In this issue, Fong et al. show how the use of categorical traits can greatly accelerate progress in seaweed trait-based ecology. [Extracted from the article]

While trait‐based approaches have been effectively leveraged by plant ecologists to advance our understanding of community responses to major global challenges, such as climate change and invasive species, the study of marine macroalgae is still mired in a functional group (FG) framework developed in the 1980s.In this paper, we used predominantly categorical data for 18 macroalgal traits that were accessible in public databases and/or the literature to explore their usefulness in a trait‐based framework for marine macroalgae. Species were clustered into emergent, data‐driven groups using a Gower dissimilarity matrix, then a k‐medoid clustering approach called partitioning around the medoids.We identified 14 emergent groups (EGs) that captured a spectrum of strategies used by different macroalgal species. However, significant 'gaps' in trait space may identify evolutionary constraints to algal adaptive strategies. Multivariate analysis showed how the 18 traits created trait space and drove the clustering. A spectrum of strategies and the influence of multiple traits imply that algal strategies are likely governed by complex multivariate, not bivariate, trade‐offs. Finally, we found that our EGs appeared to reflect multivariate trade‐offs and diverse ecological strategies more than the traditional FG model for macroalgae. We tested the usefulness of our EGs by comparing real‐world spatial distributions of species across habitats with known strong environmental filters to their area occupied in trait space. We found significant separation in trait space and divergent occupancy patterns across global distributions, attachment substrates and elevational zones. These results support the use of categorical data accessible in the literature as a useful step towards developing trait‐based ecology for marine macroalgae.Synthesis. Our findings indicate that readily accessible categorical traits produce emergent FGs that reflect environmental filtering and therefore demonstrate the power of trait‐based approaches over the current FG framework. Furthermore, we posit that categorical traits are a valuable and potentially complementary addition to a newly developing database of continuous traits because they encompass a broader, more globally accessible set of traits. [ABSTRACT FROM AUTHOR]

We define coral reef BCMs as a functional grouping that broadly encompasses taxonomically and functionally rich, conspicuous benthic consortia primarily comprised of prokaryotic members of the phyla Cyanobacteria (dominating the construction and maintenance of mat structural complexity), Proteobacteria, and Bacteroidetes (Cissell & McCoy, [7]; Stuij et al., [20]). Keywords: bacteriophage; coral reef; Cyanobacteria; microbial mat; molecular ecology; species interactions; top-down; trophic control EN bacteriophage coral reef Cyanobacteria microbial mat molecular ecology species interactions top-down trophic control 1 6 6 09/05/23 20230901 NES 230901 Benthic cyanobacterial mats (BCMs) are becoming increasingly dominant members of coral reef communities worldwide due to the influence of both local and global stressors (Cissell & McCoy, [8]; de Bakker et al., [11]; Ford et al., [13]). The proliferation of BCMs on coral reefs is both a product of and itself exacerbates reef degradation, with feedback among BCM cover and major drivers of reef decline such as shifting reef carbon chemistry and coral disease transmission (Brocke, Polerecky, et al., [3]; Cissell et al., [6]). Sampling during the collapse of an extensive BCM bloom event on a coral reef in Moreton Bay, Australia, revealed viruses as a potential driver of rapid bloom mortality (Hewson et al., [15]). [Extracted from the article]

Despite the considerable social and economic benefits of hydropower dams, they can cause total dissolved gas (TDG) supersaturation downstream of hydropower dams, which can harm fish through gas bubble trauma (GBT) and cause issues with aquatic ecology. This paper systematically reviewed the generation and release mechanism of TDG supersaturation, including three stages of TDG generation and release, to broaden the research ideas of TDG supersaturation and encourage the construction of environmentally friendly dams and other hydropower projects. The factors affecting the generation and release were summarized from the three stages of TDG generation and release, including temperature, momentum difference at the water‐air interface, and effective depth of bubble arrival. The research methods were introduced from four aspects: theoretical methods, field observations, experiments, and numerical simulations. The advantages, disadvantages, and application scopes of different research methods were outlined. Finally, the abatement measures in the three stages of TDG generation and release were introduced from the engineering and non‐engineering perspectives, and the future research directions were pointed out from the four aspects of TDG supersaturation generation and release mechanism, research methods, abatement measures, and management methods, including in‐depth study of whether gas‐liquid transfer through bubble surfaces or free surfaces dominates, consideration of bubble coalescence and rupture to improve the accuracy of numerical methods in TDG supersaturation prediction, the combination of engineering and non‐engineering measures to optimize TDG supersaturation abatement measures and consideration of artificial intelligence technology to improve hydropower project management methods. Plain Language Summary: Generally, the dissolved amount of total dissolved gas (TDG) in water and that in the atmosphere is in balance, and the state at this time is called the phase equilibrium state. When the dissolved gas concentration in water is higher than the equilibrium concentration, TDG supersaturation will occur. TDG supersaturation often occurs in dam flood discharge, and its adverse effect is to harm fish through gas bubble trauma and cause issues with aquatic ecology. This paper systematically reviewed the generation and release mechanism of TDG supersaturation, including three stages of TDG generation and release, to broaden the research ideas of TDG supersaturation and encourage the construction of environmentally friendly dams and other hydropower projects. Key Points: The review covers the generation and release mechanism and abatement measures for total dissolved gas (TDG) supersaturationSummarize the factors affecting TDG supersaturationThe advantages, disadvantages, and application scopes of different research methods are highlighted [ABSTRACT FROM AUTHOR]

Lake water clarity is an indicator of water quality, trophic status, and habitat condition. Changes in clarity impact lake ecosystems and may reflect land use changes or presence of invasive species. Quantifying temporal changes in water clarity can be challenging because clarity varies seasonally, annually, and spatially within and among lakes. We developed a hierarchical generalized additive model to quantify trends in water clarity (Secchi depth) from 1979 to 2018 for 909 Minnesota lakes, accounting for seasonal and spatial variability. Water clarity increased by 0.41 m across lakes from 1984 to 1988 and 2014 to 2018. Lake‐specific clarity trends varied: clarity did not change significantly in 59.0% of lakes, increased in 34.5% of lakes, and decreased in 6.5% of lakes. Water clarity dynamics caused considerable variability in littoral area between seasons and years. Our results have wide applications in aquatic ecology, including understanding changes to food webs, assessing fish habitat, and evaluating impacts of invasive species. [ABSTRACT FROM AUTHOR]

Robustness analysis can support the design and operation of large‐scale water infrastructure projects confronting deeply uncertain futures. However, diverse actors, contextual specificities, sectoral interests, and risk attitudes make it difficult to identify an appropriate robustness metric to rank decision alternatives under deep uncertainty. Here, we clarify how methodological choices affect robustness evaluation using the multi‐actor, multi‐sector Inchampalli‐Nagarjuna Sagar water transfer megaproject in Southern India. We compare a suite of water transfer strategies discovered using evolutionary multi‐objective direct policy search (EMODPS), a strategy proposed by regional authorities and the status quo of no water transfer. We stress‐test these strategies across scenarios that capture climatic and socioeconomic uncertainties and rank them using robustness metrics representing sectoral perspectives and priorities of different actors with varying risk attitudes. Results show a considerable impact of metric choices on robustness rankings of strategies, with compromise solution discovered via EMODPS as robust. The no‐transfer strategy results in the worst water supply robustness with an average volumetric deficit of 17% of total historical demands but emerges as a robust alternative for 6 out of 12 combinations of actor‐sectors with high risk aversion. Also, changes in the amplitude of the Indian Summer Monsoon is identified as the most important uncertain factor determining the failure of strategies. Our findings highlight that the selection of robust solutions should be guided by an understanding of how assumed risk attitudes shape stakeholders' perceptions of vulnerabilities. These findings are generalizable to large infrastructure projects with diverse stakeholders and multisectoral impacts. Plain Language Summary: Climate change and growing multi‐sectoral competition for water resources are motivating the design and evaluation of infrastructure‐based adaptation actions. Here, we explore the Inchampalli‐Nagarjuna Sagar (INS) mega water transfer project; a multi‐actor and a multi‐sector project that aims to transfer water from the Godavari basin to the Krishna basin in Southern India. The project will affect multiple sectors including agriculture, domestic water supply, and downstream aquatic ecology of both rivers and involves multiple actors—the donor, recipient basin and the combined system. It is critical to understand if the INS mega water transfer can robustly meet its intended benefits while limiting unintended consequences in the future. We formally explore different combinations of actors and sectors' objectives, their risk attitudes, and scenario sampling strategies providing a rich context for understanding conflicts and limiting the unintended consequences of myopic analyses. Results show emergent tradeoffs between the ecological requirements of the donor and the water supply needs of the recipient. Our analysis indicates that large‐scale water infrastructure projects need to employ broad exploratory robustness analyses that better engage with conflicting stakeholder objectives and that help to clarify how differences in risk aversion shape the vulnerabilities of preferred actions. Key Points: Multi actor and sector robustness trade‐offs are often not explored due to narrowly defined robustness metricsRobustness rankings for decision alternatives across robustness metrics shed light on trade‐offs across actors, sectors, and risk attitudesClarify donor‐recipient conflicts between ecological needs and socio‐economic development for a proposed water transfer mega‐project [ABSTRACT FROM AUTHOR]

The alligator snapping turtle (Macrochelys temminckii) is a long‐lived species that is widely distributed across the southeastern United States. Both these characteristics make monitoring its occupancy and abundance particularly challenging. In 2020 and 2021, we conducted hoop trap surveys at 51 permanent water bodies across the Texas, USA, range of the species to estimate occupancy and average abundance with site occupancy models and multinomial N‐mixture models, respectively. We confirmed the species to be present at 61% of surveyed locations. Mean detection probability was 0.77, and was influenced methodologically by the spacing of traps, and environmentally by lunar phase and water flow velocity. Mean occupancy probability was 0.82, and mean estimated abundance was 7.57 turtles/site. Our data provided evidence that the species has a higher occurrence probability in waters of highly forested catchments, and is most probable to occur in highest abundances at median latitudes within its Texas range. Despite known microhabitat preferences of the species, instream habitat characteristics (e.g., canopy coverage, depth, sinuosity) did not strongly influence its occupancy or abundance. Spatial dynamics of the occupancy and abundance of the species in Texas are influenced by landscape features more than local habitat. These results further corroborate the importance of watershed land cover to aquatic organisms, and our methods provide a standardized template for monitoring and quantifying important demographic parameters of the species across multiple locations while accounting for imperfect detection. [ABSTRACT FROM AUTHOR]

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The advent of metabarcoding (metaB) in aquatic ecology has provided a huge amount of information on plankton biodiversity worldwide. However, the large datasets obtained with that approach are still partially explored, especially for what concerns the study of trophic interactions and food webs. In this study, we analysed a metaB time series from the Long‐Term Ecological Research station MareChiara (LTER‐MC) in the Gulf of Naples, Mediterranean Sea, Italy, to describe the link between plankton diversity and food‐web structure. We derived co‐occurrence networks from metaB time series, identified putative trophic interactions among co‐occurrences based on biological information (body size and trophic habit) available for planktonic organisms detected by metaB, and converted co‐occurrence networks into conceptual models of food webs. The latter showed structural properties resembling ecological processes, because network modularity (the presence of semi‐independent sub‐networks) paralleled trophic hierarchy (the dimensional difference between predator and prey). We also analysed the role of planktonic organisms in maintaining network modularity. The largest predators occupied distinct modules, suggesting niche partitioning, whereas the smallest preys worked as fundamental connectors between larger predators (and different modules). Overall, the presence of trophic hierarchy and modularity shown herein supports the view of the high ecological resilience of plankton, pursued via food‐web rewiring, to environmental shifts. [ABSTRACT FROM AUTHOR]

Resurrection studies can answer some fundamental questions in aquatic ecology and evolutionary biology. For phytoplankton resting stages, longevity of thousands to millions of years has recently been reported. However, contamination during sediment sampling could distort these estimates, and this risk has not been systematically evaluated. Here we used 4.5 μm diameter microspheres to quantify contamination while reviving the resting stages of seven abundant estuarine diatom and cyanobacterial taxa. We observed a sharp decline in resting stages abundance from 106 (g wet sediment)−1 at the surface to < 0.8 (g wet sediment)−1 at 12.5 cm depth. Added microspheres (~ 4.5 × 107 cm−2) were translocated even deeper down the sediment and could well explain the vertical distributions and abundances of revived cells. Without this control, we could have claimed to have revived seven multi‐decades to centennial‐old taxa. Our findings suggest that improved contamination controls are needed for sediment core sampling of rare cells, microfossils, or DNA molecules. [ABSTRACT FROM AUTHOR]

Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integrative approach to explain these differences by linking impacts to four fundamental processes that structure communities: dispersal, speciation, species‐level selection and ecological drift. Our goal is to provide process‐based insights into why human impacts, and responses to impacts, may differ across ecosystem types using a mechanistic, eco‐evolutionary comparative framework. To enable these insights, we review and synthesise (i) how the four processes influence diversity and dynamics in terrestrial versus freshwater communities, specifically whether the relative importance of each process differs among ecosystems, and (ii) the pathways by which human impacts can produce divergent responses across ecosystems, due to differences in the strength of processes among ecosystems we identify. Finally, we highlight research gaps and next steps, and discuss how this approach can provide new insights for conservation. By focusing on the processes that shape diversity in communities, we aim to mechanistically link human impacts to ongoing and future changes in ecosystems. [ABSTRACT FROM AUTHOR]

All aquatic organisms rely on chemical stimuli at some point during their life cycles. These stimuli are typically associated with essential functions such as food-, mate-, or habitat-finding, or predator avoidance. Historically, research on sensory ecology and behavior of aquatic organisms has been conducted using two-channel choice flumes, which have many limitations when utilized on small organisms. Here, we describe functional features and results of pilot tests of an aquatic olfactometer, adapted from olfactometers used in studies on terrestrial arthropods, which eliminates these limitations. The initial implementation of this olfactometer is described. The structural integrity, hydrodynamics, and basic function of the olfactometer were tested and verified. The ability to clearly record the movements of a small organism within was also tested. Our experiments verify that the flow rate of water within the choice arena was accurate, water behaved as theorized in prior modeling, and chemical concentrations within each "zone" were distributed as expected based on computer simulations. We further show that video data could be obtained and analyzed using Ethovision XT to provide large amounts of raw data, including position, velocity, and acceleration, which can be used to investigate many potential questions associated with behavior. This olfactometer has the potential to become the new standard for research on chemotaxis and chemical ecology of small aquatic organisms. [ABSTRACT FROM AUTHOR]

The management and protection of the world's major river basins have received increasing attention, and a series of related measures, including fishing bans and ecological engineering restoration, has been pioneered in the Yangtze River Basin (YRB). This paper provides a quantitative and qualitative analysis of research trends and hotspots in the water environment of the YRB through bibliometric means. The database period was from its inception to December 31, 2020. This review combines the changing trends in the water environment of the YRB in the form of keywords. The results show that the governance of the YRB is based on the relationship between "water" and "sediment" as an entry point, focusing on changes in the "temporal" and "spatial" allocation of water resources; further, when considering the problem of "eutrophication" caused by the release of "nitrogen" and "phosphorus" from "sediments," water quality factors such as "heavy metal pollution" and "organic pollution" are becoming more prominent; then water quality factor affects "biodiversity," aquatic ecology becomes more and more concerned, and "ecological risk" factor is taken into consideration. Therefore, future management of the YRB requires consideration of all elements of the basin, including water resources, water quality, and aquatic ecology, and how to coordinate these all material elements is the obstacle and breakthrough point. In addition, further studies on research frontiers have revealed that ecological risk, emerging bioinformatics technologies, and, source apportionment will become the new and popular directions and trends in research. This review is intended to provide insights into the management of other large river basins around the world. [ABSTRACT FROM AUTHOR]

The escalating anthropogenic activities in recent decades are constantly affecting the aquatic ecology and posing a threat to freshwater species. In this study, a two‐dimensional ecohydraulic model and multiple criteria decision analysis (MCDA) coupled framework is employed in the Dikhow River, India, to investigate the favourable habitat condition for the nearly threatened Notopterus chitala fish locally known as Chital fish. The habitat residence suitability and habitat suitability indices are calculated at the observed and ecological flows. The ecological flow rates are computed from flow duration curve shifting and flow duration curve analysis methods. The hydrodynamic computations are carried out using a 1D‐2D coupled MIKE FLOOD model. The habitat assessment of the targeted species is carried out by constructing the suitability curves from the computed hydraulic parameters at different environmental management conditions. Results from the habitat assessment curves indicate that the maximum habitat suitability index is found for the targeted fish species at average annual flow. Based on the MCDA analysis, the outer banks of the meander zones are identified as not suitable residence regions for the target species. This study revealed that the coupled approach could be useful to regulate the stream restoration strategies and identify potential habitat preference locations in the domain. [ABSTRACT FROM AUTHOR]

The biodiversity–ecosystem function hypothesis postulates that higher biodiversity is correlated with faster ecosystem process rates and increased ecosystem stability in fluctuating environments. Exhibiting high spatiotemporal habitat diversity, floodplains are highly productive ecosystems, supporting communities that are naturally resilient and highly diverse.We examined linkages among floodplain wetland habitats, invertebrate communities and their associated traits, and ecosystem function across 60 sites within the floodplain wetlands of the lower Wolastoq | Saint John River, New Brunswick, using structural equation modelling and Threshold Indicator Taxa ANalysis.We identified key environmental filters structuring invertebrate communities, by linking increased niche differentiation through shoreline change, flood pulse dynamics, and macrophyte bed complexity with increased taxa and functional diversity.Examination of traits linked to ecosystem functions revealed that more resilient wetlands with balance between primary productivity and decomposition as carbon sources were associated with greater functional evenness and richness, while habitat patches with elevated decomposition rates had lower functional richness, reflecting a simplified, more disturbed habitat.While our more complex overarching SEM model was ultimately compromised by an overspecified number of pathways, our results nevertheless are indicative of a divergence between wetland and riverine ecosystems in their relationships linking biodiversity and ecosystem function, illustrating how to define ecosystem health in wetland habitats, and demonstrating how critical functions support healthy wetland habitats by providing increased resilience to disturbance. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Climate warming is a ubiquitous stressor in freshwater ecosystems, yet its interactive effects with other stressors are poorly understood. We address this knowledge gap by testing the ability of three contrasting null models to predict the joint impacts of warming and a range of other aquatic stressors using a new database of 296 experimental combinations. Despite concerns that stressors will interact to cause synergisms, we found that net impacts were usually best explained by the effect of the stronger stressor alone (the dominance null model), especially if this stressor was a local disturbance associated with human land use. Prediction accuracy depended on stressor identity and how asymmetric stressors were in the magnitude of their effects. These findings suggest we can effectively predict the impacts of multiple stressors by focusing on the stronger stressor, as habitat alteration, nutrients and contamination often override the biological consequences of higher temperatures in freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Mixing processes downstream of river confluences impacts the ecology and the related environmental management of river networks. A clear understanding of such processes is challenging, especially for confluences having width‐to‐depth ratios larger than 100, due to the limited available field data. In this study, four field surveys based on hydro‐acoustic and conductivity measurements were conducted near the confluence between the Yangtze River and the Poyang Lake, which are the largest river and freshwater lake in China, respectively. It was found that mixing dynamics at the confluence were controlled by a complex interaction among the momentum flux ratio, secondary flow and the lock‐exchange flow associated to the density contrast between the two tributaries. Slow mixing was observed during high‐flow conditions that generated dual counter‐rotating secondary cells, with the downwelling flow acting as a barrier in the post‐confluence channel. In contrast, more rapid mixing was observed during low‐flow conditions when only a single channel‐scale secondary flow was identified. The mixing processes were also affected by the lock‐exchange flow associated to the density difference between the two confluent flows. Such lock‐exchange enhanced mixing when the Yangtze River waters had higher temperature, that is, lower density than that of the Poyang Lake. In low flow condition, the penetration of the much larger momentum flux of Yangtze River created a "two‐layers" structure with the contribution of the density difference, which further enhanced the curvature‐induced helicity. The findings from the present study improve our current understanding of mixing dynamics in large river confluences. Plain Language Summary: The confluence between the Yangtze River and the Poyang Lake, which are the largest river and the largest freshwater lake in China, respectively, is one of the largest on the Earth. Understanding this mixing processes at such large‐scale river confluence is significantly important for local flood control and aquatic ecology management, but even challenging due to the lack of detailed field data. Four field surveys were conducted to investigate hydrodynamics, water quality and mixing at the confluence of the Yangtze River and Poyang Lake. The effect of momentum and density difference between the two rivers and large‐scale secondary flow on mixing processes was identified. The results of the present study indicated that such density difference can produce different patterns of vertical stratification which are related to the mixing between the Yangtze River and the Poyang Lake. Key Points: Four field surveys on the mixing process downstream of a large river confluence were conductedDifferent mixing patterns were distinguished based on conductivity and hydro‐acoustic measurementsMixing dynamics around the confluence were controlled by the momentum flux ratio, secondary flow and the lock‐exchange [ABSTRACT FROM AUTHOR]

The capability of Scenedesmus dimorphus for biodegradation of crude oil components is evaluated using biological and biochemical techniques. After exposure of the algal cells to different concentrations of crude oil for 21 day, growth parameters such as cell number as well as fresh and dry weights have increased at low concentrations of crude oil (up to 0.04%) in comparison with control samples. However, growth criteria have decreased in response to the increase in crude oil concentration (0.08%–1%). Similar trends are observed in the content of chlorophylls, carotenoids, flavonoids, anthocyanins, and phenols. Crude oil treatment induces the production of H2O2 and thiobarbituric acid reacting substances. Moreover, enhancing crude oil concentration results in increasing activities of superoxide dismutase, polyphenol oxidase, peroxidase, and lipoxygenase. In comparison, the activities of catalase, ascorbate peroxidase, and phenylalanine ammonia lyase increase at low concentrations (up to 0.02%) and then decrease. Using gas chromatography–mass spectrometry analysis several biodegradation intermediate compounds are recognized in the culture media over treatment time. Altogether, S. dimorphus shows considerable potential for biodegradation of crude oil components particularly at concentrations lower than 0.08%. Thus, this microalga can be used as a competent phytoplankton in removal of crude oil from contaminated water supplies. [ABSTRACT FROM AUTHOR]

Animal migration is one of the most spectacular and visible behavioural phenomena in nature with profound implications for a range of ecological and evolutionary processes. Successful migration hinges on the ability to exploit temporary resources (e.g. food) and evade threats (e.g. predators) as they arise, and thus the timing of migration is often regarded as a dominant predictor of individual migratory success.However, with the exception of intensively studied taxa (mainly birds), relatively few studies have investigated inter‐individual annual and seasonal variation in migratory timing and performance, or tested predictions on how migration across high and low predation‐risk habitats may exert selection on migratory timing. In particular, studies that assess the survival consequences of variation in migratory timing remain rare, which is most likely due to the logistical challenges associated with monitoring survival success and population‐level characteristics simultaneously.Here, we address the above‐mentioned questions using roach Rutilus rutilus, a fish that migrates from lakes characterised by high predation risk into low‐risk streams during winter. Specifically, we used individual‐based tracking of roach in two European lake systems over multiple migration periods (9 and 7 years respectively), to obtain highly detailed (year‐round scheduling, repeat journeys and the fate of individuals) data on the variability/synchrony of migratory timing in spring and autumn respectively.We report seasonal differences in the variability of migratory timing, with lower variance and higher migration synchrony in spring lake arrival timing as compared to autumn lake departure timing. Furthermore, the timing of autumn migration is more variable across years than the timing of spring migration. Second, we find that later arrival to the lake habitat is positively associated with apparent survival from 1 year to the next, whereas we found no effect of lake departure timing on survival probability.These findings represent rare evidence showing how intraspecific variation in timing in migratory fish differs across years and seasons, and how variation in timing can translate into survival consequences for prey in systems characterised by high predation risk. [ABSTRACT FROM AUTHOR]

Seldom investigated for its biodiversity, the biomonitoring of Lake Ahémé is expected to increase in future and a prerequisite is the design of an appropriate sampling strategy. Here, we assessed macroinvertebrate assemblages in relation to environmental conditions in Lake Ahémé during the short and long wet seasons (SWS and LWS, respectively). This will help optimise sampling strategies for the future, when sampling only during the SWS or the LWS. A total of 4049 macroinvertebrates from 28 families and 32 genera were collected. Abundance was significantly higher at sites sampled during the SWS. Molluscs were the most dominant taxon and accounted for 92.8% of individuals collected during this study. This was followed by annelids, insects and crustaceans representing 3.7%, 3.2% and 0.3% of the total abundance, respectively. Biodiversity indices showed a significantly higher diversity in the SWS and higher spatial variation in the macroinvertebrate community. The first three axes of the non‐metric multidimensional scaling revealed spatial changes in the macroinvertebrate community during the SWS and LWS. These changes were driven by salinity, conductivity, pH, temperature, dissolved oxygen and water depth. No taxa could be assigned as indicators in the LWS whereas diverse brackish and freshwater species characterised the SWS. As a result, when considering sampling during the wet seasons, SWS sampling should suffice for a qualitative study whereas an accurate ecological investigation requires both SWS and LWS. [ABSTRACT FROM AUTHOR]

1. Fine-scale tracking with passive acoustic telemetry can yield great insights into the movement ecology of aquatic animals. To predict fine-scale positions of tagged animals in continuous space from spatially-discrete detection data, state-space modelling through the R package YAPS provides a promising alternative to frequently used positioning algorithms. However, YAPS cannot currently classify multiple kinds of movement that may be used as proxies for individual behaviours of study animals (behavioural states), an endeavour that is of increasing interest to movement ecologists. 2. We advance YAPS by incorporating the functionality to predict behavioural states by using an iterative maximization framework. Our model, which we call YAMS, occurs in continuous time and therefore we adapt current hidden Markov model (HMM) machinery to accommodate this while remaining within a likelihood framework that provides rapid fitting. We test our model using simulations and approximately 6 days’ worth of Northern pike data from Hald Lake, Denmark. 3. YAMS is shown to produce accurate parameter estimates and random effect predictions when model results were compared to simulated data, with behavioural state accuracies of 0.94 and 0.79 for two-and three-state models, respectively, and location state root mean squared errors of 1.8 m for both models. In addition, the behavioural states are shown to reflect varying speeds of the pike, yielding a highly interpretable classification. 4. This research has the potential to be broadly applicable to both ecologists interested in identifying fine-scale space use and behavioural states from acoustic telemetry data, as well as to statisticians who may wish to use standard HMM machinery to fit continuous-time HMMs to animal movement data. [ABSTRACT FROM AUTHOR]

Leveraging big, open data is the next frontier in ecology. The National Ecological Observatory Network (NEON) is a network of monitoring sites collecting ecological data from across the United States. Using a case study approach, we provide examples of how NEON data can be applied to address a few big questions in aquatic ecology. First, we examined spatial patterns in stream water chemistry, to determine whether sites tend to cluster into regions based on geographic proximity. We found that this was not the case, likely because the hydrologic, geologic, and anthropogenic factors that drive heterogeneity in stream water chemistry vary across smaller spatial scales. Second, we examined temporal variability in stream water chemistry. We determined that the majority of catchments are relatively chemostatic (i.e., discharge varies by orders of magnitude more than concentrations) and that differences between catchments are likely to shift across decades due to changes in network conductivity. Third, we tested predictions of the River Continuum Concept (RCC) along a gradient from a second‐order stream to a seventh‐order river. We found that longitudinal patterns in metabolism, carbon chemistry, and macroinvertebrate community composition generally follow the patterns predicted by the RCC. NEON is only in its third year of full operations, with a planned 30‐year life. The studies presented here show the utility of NEON data, while only using a subset of the many data products that NEON produces. The massive amounts and types of data NEON generates, in conjunction with other national‐scale datasets, will allow the research community to better understand how aquatic ecosystems function and respond to drivers of long‐term change. [ABSTRACT FROM AUTHOR]

The relative capacity for watersheds to eliminate or export reactive constituents has important implications on aquatic ecosystem ecology and biogeochemistry. Removal efficiency depends on factors that affect either the reactivity or advection of a constituent within river networks. Here, we characterized Damköhler number (Da) for dissolved organic carbon (DOC) uptake in global river networks. Da equals the advection to reaction timescale ratio and thus provides a unitless indicator for DOC reaction intensity during transport within river networks. We aim to demonstrate the spatial and temporal patterns and interplays among factors that determine DOC uptake across global river networks. We show that watershed size imposes a primary control on river network DOC uptake due to a three orders of magnitude difference in water residence time (WRT) between the smallest and largest river networks. DOC uptake capacity in tropical river networks is 2–6 times that in temperate and the Arctic river networks, coinciding with larger DOC removals in warm than in cold watersheds. River damming has a profound impact on DOC uptake due to significantly extended WRTs, particularly in temperate watersheds where most constructed dams are situated. Global warming is projected to increase river network DOC uptake by ca. 19% until year 2100 under the RCP4.5 scenario. Plain Language Summary: Dissolved organic carbon (DOC) transported by river networks is either removed during transport or exported to downstream receiving basins. The capacity for river networks to remove DOC is determined by the relative balance between its transport and reaction timescales. Damköhler number measures the transport to a reaction timescale ratio and provides a common framework for evaluating the spatial and temporal variations in DOC uptake across global river networks. We show that large river networks have higher DOC uptake because of orders of magnitude longer advection time than in small river networks. Tropical river networks have higher DOC uptake than temperate and the Arctic river networks because of higher reaction rates in warm than in cold watersheds. Damming significantly prolongs water advection and increases DOC uptake within river networks. Global warming is also projected to increase river network DOC uptake because of enhanced DOC uptake rates under a warmer climate. Key Points: Watershed size imposes a primary control on the Damköhler number (Da) for dissolved organic carbon (DOC) uptake in global river networksThe Da for DOC uptake in tropical river networks is 2–6 fold that in temperate and the Arctic river networksDamming and climatic warming significantly enhance the Da for DOC uptake in global river networks [ABSTRACT FROM AUTHOR]

Nontarget management effects Nontarget management effects refer to the situation in which management actions implemented to benefit one species (species A) negatively affect the state of another species (species B; Figure 2). Keywords: conflict resolution; decision-making; fishery management; invasive species control; unintended consequences; control de especies invasoras; consecuencias no deseadas; manejo de pesquerías; resolución de conflictos; toma de decisiones EN conflict resolution decision-making fishery management invasive species control unintended consequences control de especies invasoras consecuencias no deseadas manejo de pesquerías resolución de conflictos toma de decisiones 1 14 14 03/02/22 20220201 NES 220201 INTRODUCTION Wildlife provide multiple benefits to humans, including recreational, economic, health, historic, and scientific benefits (Conover, 2002). Conflict-generating species In situations with conflict-generating species, there is a trade-off when management of an intermediate species (species C) benefits one species (species A) and negatively affects another (species B; Figure 1). In this case, management efforts to increase a target species (species A; Figure 2) are either hindered by the other species (species B; Figure 2 prey focused), or can be achieved by reducing the state of the other species (species B; Figure 2 competitor and predator focused). Single-species management Management narrowly focused on a single species may miss the consequences of single-species decisions on other important species (e.g., bycatch [Gilman et al., 2019]) and can create perceived trade-offs due to incomplete knowledge of community structure and interspecific interactions (e.g., Caribbean spiny lobster [ I Panulirus argus i ] and grey snapper [ I Lutjanus griseus i ] vs. goliath grouper [ I Epinephelus itajara i ] [Frias-Torres, 2013]). [Extracted from the article]

Body size is a decisive functional trait in many organisms, especially for phytoplankton, which span several orders of magnitude in cell volume. Therefore, the analysis of size as a functional trait driving species' performance has received wide attention in aquatic ecology, amended in recent decades by studies documenting changes in phytoplankton size in response to abiotic or biotic factors in the environment.We performed a systematic literature review to provide an overarching, partially quantitative synthesis of cell size as a driver and sentinel of phytoplankton ecology. We found consistent and significant allometric relationships between cell sizes and the functional performance of phytoplankton species (cellular rates of carbon fixation, respiration and exudation as well as resource affinities, uptake and content). Size scaling became weaker, absent or even negative when addressing C‐ or volume‐specific rates or growth. C‐specific photosynthesis and population growth rate peaked at intermediate cell sizes around 100 µm3.Additionally, we found a rich literature on sizes changing in response to warming, nutrients and pollutants. Whereas small cells tended to dominate under oligotrophic and warm conditions, there are a few notable exceptions, which indicates that other environmental or biotic constraints alter this general trend. Grazing seems a likely explanation, which we reviewed to understand both how size affects edibility and how size structure changes in response to grazing. Cell size also predisposes the strength and outcome of competitive interactions between algal species. Finally, we address size in a community context, where size‐abundance scaling describes community composition and thereby the biodiversity in phytoplankton assemblages.We conclude that (a) size is a highly predictive trait for phytoplankton metabolism at the cellular scale, with less strong and nonlinear implications for growth and specific metabolism and (b) size structure is a highly suitable sentinel of phytoplankton responses to changing environments. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Freshwater systems are critical to life on earth, yet they are threatened by the increasing rate of synthetic chemical pollution. Current predictions of the effects of synthetic chemicals on freshwater ecosystems are hampered by the sheer number of chemical contaminants entering aquatic systems, the diversity of organisms inhabiting these systems, the myriad possible direct and indirect effects resulting from these combinations, and uncertainties concerning how contaminants might alter ecosystem metabolism via changes in biodiversity. To address these knowledge gaps, we conducted a mesocosm experiment that elucidated the responses of ponds composed of phytoplankton and zooplankton to standardized concentrations of 12 pesticides, nested within four pesticide classes, and two pesticide types. We show that the effects of the pesticides on algae were consistent within herbicides and insecticides and that responses of over 70 phytoplankton species and genera were consistent within broad taxonomic groups. Insecticides generated top‐down effects on phytoplankton community composition and abundance, which were associated with persistent increases in ecosystem respiration. Insecticides had direct toxic effects on cladocerans, which led to competitive release of copepods. These changes in the zooplankton community led to a decrease in green algae and a modest increase in diatoms. Herbicides did not change phytoplankton composition but reduced total phytoplankton abundance. This reduction in phytoplankton led to short‐term decreases in ecosystem respiration. Given that ponds release atmospheric carbon and that worldwide pesticide pollution continues to increase exponentially, scientists and policy makers should pay more attention to the ways pesticides alter the carbon cycle in ponds via changes in communities, as demonstrated by our results. Our results show that these predictions can be simplified by grouping pesticides into types and species into functional groups. Adopting this approach provides an opportunity to improve the efficiency of risk assessment and mitigation responses to global change. [ABSTRACT FROM AUTHOR]

To help store water, facilitate navigation, generate energy, mitigate floods, and support industrial and agricultural production, people have built and continue to build obstructions to natural flow in rivers. However, due to the long and complex history of constructing and removing such obstructions, we lack a globally consistent record of their locations and types. Here, we used a consistent method to visually locate and classify obstructions on 2.1 million km of large rivers (width ≥30 m) globally. We based our mapping on Google Earth Engine's high resolution images, which for many places have meter‐scale resolution. The resulting Global River Obstruction Database (GROD) consists of 30,549 unique obstructions, covering six different obstruction types: dam, lock, low head dam, channel dam, and two types of partial dams. By classifying a subset of the obstructions multiple times, we are able to show high classification consistency (87% mean balanced accuracy) for the three types of obstructions that fully intersect rivers: dams, low head dams, and locks. The classification of the three types of partial obstructions are somewhat less consistent (61% mean balanced accuracy). Overall, by comparing GROD to similar datasets, we estimate GROD likely captured >90% of the obstructions on large rivers. We anticipate that GROD will be of wide interest to the hydrological modeling, aquatic ecology, geomorphology, and water resource management communities. Plain Language Summary: Many obstructions (e.g., dams and locks) have been built on rivers across the globe to help store water, facilitate navigation, generate energy, mitigate floods, and support industrial and agricultural production. However, the lack of publicly available information on where these obstructions are reduces our ability to assess their environmental impact. In this study, we used publicly available satellite data from Google to manually identify river obstructions on all large rivers across the globe (width ≥30 m) to develop the Global River Obstruction Database, or GROD. GROD consists of 30,549 unique obstructions assigned to one of the six types: dam, low head dam, lock, channel dam (a dam that obstructs one channel of a multi‐channel river), and two types of partial dams (dam that extends partially across a river). By repeatedly classifying subsets of GROD obstructions, we estimate high classification consistency. And by comparing GROD to five other obstruction datasets, we estimate that GROD contains >90% obstructions for the rivers studied. We anticipate that the release of GROD will help people around the world better understand and manage human impacts on rivers. Key Points: We manually identified 30,549 river obstructions on 2.1 million km of large rivers across the globeThe Global River Obstruction Database provides rich new context for understanding human impacts on riversGROD identifies many in‐river structures missed by other global dam databases [ABSTRACT FROM AUTHOR]

Keywords: clam shrimps; Crustacea; fairy shrimps; predation; temporary waters EN clam shrimps Crustacea fairy shrimps predation temporary waters 1 5 5 12/03/21 20211201 NES 211201 It is conventionally understood that large branchiopod crustaceans are limited to temporary waters because they are sensitive to fish predation in permanent habitats (Kerfoot and Lynch 1987, Brendonck et al. 2008). We simultaneously subjected field-collected populations of the commonly occurring fairy shrimp Streptocephalus bidentatus and the clam shrimp Cyzicus sp. to predation by the co-occurring killifish Nothobranchius furzeri. Clam shrimps tend to occur later than fairy shrimps in the sequence of ecological succession (Jocque et al. 2007, Brendonck et al. 2017), and our results show that they are less susceptible to killifish predation, at least when more vulnerable fairy shrimp prey are present. To each of the tanks, 5 small killifish, 20 fairy shrimp, and 11 clam shrimps were added during the first trial and 4 large killifish, 15 fairy shrimp, and 10 clam shrimps in the second trial. [Extracted from the article]

Rationale: Stable isotopes are used to study trophic and movement ecology in aquatic systems, as they provide spatially distinct, time-integrated signatures of diet. Stable isotope ecology has been used to quantify species-habitat relationships in many important fisheries species (e.g., penaeid prawns), with approaches that typically assume constant values for diet-tissue discrimination and diet-tissue steady state, but these can be highly variable. Here we provide the first report of these processes in Metapenaeus macleayi (eastern school prawn). Methods: Here we explicitly measure and model carbon (δ13C) and nitrogen (δ15N) diet-tissue discrimination and turnover in eastern school prawn muscle tissue as a function of experimental time following a change in diet to an isotopically distinct food source. Results: Diet-tissue discrimination factors were 5 and 0.6‰ for δ13 C and δ15N, respectively. Prawn muscle tissue reached an approximate steady state after approximately 50 and 30 days for δ13C and δ15N. Half-lives indicated faster turnover of δ15 N(~8 days) than δ13C(~14 days). Conclusions: Our diet-tissue discrimination factors deviate from 'typical' values with larger values for carbon than nitrogen isotopes, but are generally similar to those measured in other crustaceans. Similarly, our estimates of isotopic turnover align with those in other penaeid species. These findings confirm muscle tissue as a reliable indicator of long-term diet and movement patterns in eastern school prawn. [ABSTRACT FROM AUTHOR]