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Although understanding nutrient limitation of primary productivity in lakes is among the oldest research priorities in limnology, there have been few broad‐scale studies of the characteristics of phosphorus (P)‐, nitrogen (N)‐, and co‐limited lakes and their environmental context. By analyzing 3342 US lakes with concurrent P, N, and chlorophyll a (Chl a) samples, we showed that US lakes are predominantly co‐limited (43%) or P‐limited (41%). Majorities of lakes were P‐limited in the Northeast, Upper Midwest, and Southeast, and co‐limitation was most prevalent in the interior and western United States. N‐limitation (16%) was more prevalent than P‐limitation in the Great Basin and Central Plains. Nutrient limitation was related to lake, watershed, and regional variables, including Chl a concentration, watershed soil, and wet nitrate deposition. N and P concentrations interactively affected nutrient–chlorophyll relationships, which differed by nutrient limitation. Our study demonstrates the value of considering P, N, and environmental context in nutrient limitation and nutrient–chlorophyll relationships. [ABSTRACT FROM AUTHOR]

Freshwater jellyfish (= limnic medusa‐budding hydrozoans, FWJ) are a small group of cnidarians found on all continents except Antarctica in temperate to tropical latitudes. Members of this group belong primarily to three genera: Astrohydra, Craspedacusta, and Limnocnida. While Astrohydra and Limnocnida are typically restricted to the islands of Japan, Africa, and the Indian subcontinent, one species or potential species complex, Craspedacusta sowerbii, became globally invasive. Despite research going back about one‐and‐a‐half centuries, little is known about their phylogeny and ecology compared to marine jellyfish. Recent species distribution modelling, however, showed that by 2050, C. sowerbii will potentially extend their distribution ranges due to global warming to high‐latitude ecosystems and be present (medusa stage) for an extended time in the seasonal limnic production cycle. An increase in their relative ecological importance with temporal and spatial spreading is hypothesised. Only recently, it has been shown that the trophic roles of polyps and medusae and their prey overlap with other ecosystem members. In addition, medusa behaviour may cause trophic cascades and alter vertical nutrient distributions. However, polyps and other benthic life cycle stages are understudied. In globally, changing freshwater ecosystems that may become more accommodating for FWJ, an improved understanding of their population biology and ecosystem ecology is urgently needed. In this integrative review, we, therefore, explore reasons for the hampered historical research progress, contrast developments with those of marine cnidarians, compile and publish alongside an extensive and unprecedented literature database, and formulate avenues for future directions in FWJ research. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive dataset of hydrological information gathered from five key eastern basins in Jalisco, Mexico. The dataset encompasses approximately 50 limnological variables and phytoplankton counts specifically for one of these basins. Water‐quality data were collected by the State Water Commission of Jalisco, adhering to the methods outlined in the Official Mexican Norm 'NOM‐127'. Monthly samplings were conducted to assess environmental variables such as pH, temperature, oxygen, nutrients and heavy metals. Monitoring has been ongoing for three basins since 2009, while the remaining two basins have been monitored since 2015 and 2020. Phytoplankton data were obtained from monthly samples taken by the University of Guadalajara between 2014 and 2019 in Lake Cajititlán. The original data were cleaned and organized using tidy data principles, with codes accessible on GitHub. To facilitate data exploration and visualization, we developed a user‐friendly web application with the Shiny package in R. This application enables users to explore the dataset through summary statistics tables, time series plots and phytoplankton community analysis. The dataset is accessible on Zenodo. The presented data hold significance for environmental and water‐quality assessment and applications in machine learning, neural network models, community ecology and broader environmental research. Notably, the raw data, publicly accessible from the State Water Commission of Jalisco, have been previously utilized for these purposes. This dataset offers value due to its diverse limnological and phytoplankton variables, an extended time frame of availability, a curated and streamlined accessibility process and the inclusion of a web application for intuitive exploration and visualization. [ABSTRACT FROM AUTHOR]

Owing to increased awareness of the value of long-term ecological studies, there have been numerous calls for long-term data. Natural lakes and reservoirs provide ecosystem services and serve as sentinels of change but differ in origin, water movement, and location. We conducted a meta-analysis of study duration for lake and reservoir studies from 1975 to 2015 (6362 studies were initially identified, and 801 met study criteria). Study duration increased among longer studies (> 0.5 quantile) with increases of 20 years for the highest (0.9) quantile, and there were no changes among short-term studies. Increased study duration was inversely related to number of focal areas or metrics (e.g., phytoplankton, zooplankton, vertebrates) with few focal areas or metrics (< 2 metrics) indicating few focal areas for long-term studies. Surprisingly, despite continued construction of reservoirs, the ratio of studies of lakes to reservoirs was 5 to 1 with no change over time, with the dearth of data on reservoirs making it difficult to characterize long-term trends. Increased duration in high quantiles concurrent with static duration of short-term studies suggests limnologists have fundamentally altered the way they approach questions that are influenced by study duration, but also that gaps remain in multifaceted studies and in reservoir studies. [ABSTRACT FROM AUTHOR]

Biodiversity is declining worldwide due to anthropogenic impacts, especially noxious for freshwater ecosystems, considering their close relationship with human activities. Damming is one of the most harmful human impacts that leads to the loss of several riverine fish through habitat loss or change. Herein, we aimed to assess the relationship between the composition of fish assemblages in reservoirs and the availability of littoral habitats, and whether these patterns differ between native and non-native species. Fish assemblages of fifteen reservoirs from up to downstream the Paraíba do Sul river basin were evaluated. Habitat availability was more important for native than for non-native species, after controlling for the influence of reservoir features. Local drivers were crucial for the occurrence of non-native species which thrived in the absence of complex habitats. Macrophytes seemed to play two key but quite antagonistic roles for fish species. They were positively related to native small characids, probably acting as shelter against predation, but they were also related to hypoxic conditions in eutrophic reservoirs. These findings stress the importance of preserving or restoring physically complex habitats as beneficial for native fish species through providing grounds for feeding (catfishes on leaves) and recruitment (juveniles of characids in macrophytes banks). [ABSTRACT FROM AUTHOR]

Nitrification rate measurements provide critical information on the performance of an environmental process central to the N cycle and are best studied using isotope labeling techniques. However, combining the high sensitivity of isotope labeling techniques with selected inhibition of nitrifiers as a whole or of specific nitrifier guilds has not been established in limnology. This can be achieved with different concentrations of the commonly used nitrification inhibitor allylthiourea (ATU). In the 15N‐ammonium oxidation technique, the converted isotope label is typically captured in an excess pool of 14N‐nitrite. Here, we assessed how different storage conditions affect the stability of the nitrite pool in freshwater samples treated with ATU. When stored frozen, the nitrite pool was rapidly destabilized to 25–31% after 7 d of storage and even to less than 5% after storage exceeding 90 d for samples treated with ATU, thus making them unusable for rate determinations in these cost and labor‐intensive experiments. In comparison, this was not the case in marine samples or freshwater samples not treated with ATU, where the nitrite pool remained stable. Building on these results, we tested two options to stabilize nitrite during the storage of freshwater samples. The nitrite pool was stable if samples were stored at 4°C instead of freezing. We recommend this option for short‐term storage. For long‐term storage, samples should be supplemented with 0.5 mmol L−1 NaCl to increase salinity before freezing. As in marine samples, this stabilized the nitrite pool. Our results provide important guidance for the storage of non‐saline samples used for nitrification rate measurements in freshwater environments. [ABSTRACT FROM AUTHOR]

The southeastern edge of the Lake Trout (Salvelinus namaycush) range extends to Nova Scotia (NS), Canada, including Sherbrooke Lake, Lunenburg County. These Lake Trout may be of native origin; however, the putatively native population was historically supplemented by stocking from nonindigenous strains. To determine genetic origin of this population, 25 Lake Trout from Sherbrooke Lake were used to compare genetic likeness to populations that had been stocked into the lake. Lake Trout of Sherbrooke Lake were determined to be highly genetically distinct from source populations in Ontario, Manitoba, New York, and Vermont, suggesting that the extant population is of native origin. To identify suitable habitat of Lake Trout in Sherbrooke Lake, acoustic telemetry was used to track the depth and temperature residency of 11 Lake Trout in tandem with measuring lake bathymetric and water column temperature and oxygen. During spring and summer, 2022, Lake Trout occupied a hypolimnetic residency, ranging from 11 to 22 m of depth and 8.5 to 10.0 °C. Suitable conditions for Lake Trout were available in the south basin. The main basin, containing ~ 80% of the lake's volume, was unstratified and unsuitable for Lake Trout. The effects of Hurricane Fiona caused the hypolimnion in the south basin to shrink via the thermal mixing of the epilimnion, forcing adult Lake Trout to a depth range of 16–18 m for ~ 1 month. During this time, suitable Lake Trout habitat comprised only ~ 0.5% of the total volume of Sherbrooke Lake. [ABSTRACT FROM AUTHOR]

Abstract This study presents a comprehensive dataset of hydrological information gathered from five key eastern basins in Jalisco, Mexico. The dataset encompasses approximately 50 limnological variables and phytoplankton counts specifically for one of these basins. Water‐quality data were collected by the State Water Commission of Jalisco, adhering to the methods outlined in the Official Mexican Norm ‘NOM‐127’. Monthly samplings were conducted to assess environmental variables such as pH, temperature, oxygen, nutrients and heavy metals. Monitoring has been ongoing for three basins since 2009, while the remaining two basins have been monitored since 2015 and 2020. Phytoplankton data were obtained from monthly samples taken by the University of Guadalajara between 2014 and 2019 in Lake Cajititlán. The original data were cleaned and organized using tidy data principles, with codes accessible on GitHub. To facilitate data exploration and visualization, we developed a user‐friendly web application with the Shiny package in R. This application enables users to explore the dataset through summary statistics tables, time series plots and phytoplankton community analysis. The dataset is accessible on Zenodo. The presented data hold significance for environmental and water‐quality assessment and applications in machine learning, neural network models, community ecology and broader environmental research. Notably, the raw data, publicly accessible from the State Water Commission of Jalisco, have been previously utilized for these purposes. This dataset offers value due to its diverse limnological and phytoplankton variables, an extended time frame of availability, a curated and streamlined accessibility process and the inclusion of a web application for intuitive exploration and visualization.

Bullfrog tadpoles were exposed (96 h) to water from two sites (the Ibiúna and the Itupararanga reservoir) on the Sorocaba River (São Paulo, Brazil). Metal concentrations (Ba, Cu, Mn, Sr and Zn) and metallothioneins (MTs) levels were determined in the gills (n = 27) and caudal muscle (n = 18). Metals increased in the gills of the animals exposed to the waters of the Sorocaba River in relation to the control and in relation to the animals exposed to the waters of the Ibiúna point. The levels of MT in gills were higher in animals exposed to the Itupararanga reservoir compared to the control. There was a strong correlation between metals and the presence of MT in gills, indicating that this organ can be used in environmental biomonitoring. The results demonstrate the need to protect the waters of the Sorocaba River, and especially the Itupararanga reservoir, through quality monitoring and reduction of anthropogenic pressure. [ABSTRACT FROM AUTHOR]

The McMurdo Dry Valleys (MDVs) of Antarctica are a mosaic of extreme habitats which are dominated by microbial life. The MDVs include glacial melt holes, streams, lakes, and soils, which are interconnected through the transfer of energy and flux of inorganic and organic material via wind and hydrology. For the first time, we provide new data on the viral community structure and function in the MDVs through metagenomics of the planktonic and benthic mat communities of Lakes Bonney and Fryxell. Viral taxonomic diversity was compared across lakes and ecological function was investigated by characterizing auxiliary metabolic genes (AMGs) and predicting viral hosts. Our data suggest that viral communities differed between the lakes and among sites: these differences were connected to microbial host communities. AMGs were associated with the potential augmentation of multiple biogeochemical processes in host, most notably with phosphorus acquisition, organic nitrogen acquisition, sulfur oxidation, and photosynthesis. Viral genome abundances containing AMGs differed between the lakes and microbial mats, indicating site specialization. Using procrustes analysis, we also identified significant coupling between viral and bacterial communities (p = 0.001). Finally, host predictions indicate viral host preference among the assembled viromes. Collectively, our data show that: (i) viruses are uniquely distributed through the McMurdo Dry Valley lakes, (ii) their AMGs can contribute to overcoming host nutrient limitation and, (iii) viral and bacterial MDV communities are tightly coupled. [ABSTRACT FROM AUTHOR]

The objective of this paper was to assess the physicochemical limnology and water quality assessment of ten surface water bodies in Edo State, Nigeria to determine their suitability for drinking, provide information on water quality status to the concerned public as well as providing baseline information that can be used as reference for further studies using appropriate standard techniques. Results revealed that pH, colour, turbidity, total dissolved solids, electrical conductivity, total alkalinity, total hardness, calcium, magnesium, dissolved oxygen, biochemical oxygen demand, sulphate, nitrate and phosphate 5.52 - 7.06, 1.0 - 5.5 PtCoU, 3.5 - 23.0 NTU, 11.0 -75.5 mg/L, 21.0 - 152.5µS/cm, 25.0 - 106.5 mg/L, 3.0 - 40.8 mg/L, 0.18 - 7.40 mg/L, 0.13 - 2.77 mg/L, 5.76 - 8.92 mg/L, 3.12 - 6.87 mg/L, 9.5 - 24.5 mg/L, 0.2 - 2.60 mg/L and 0.05 - 0.49 mg/L respectively. From the results of the physicochemical analyses, the water quality index score of the rivers was computed using the Weighted Arithmetic Water Quality Index method and the values obtained indicated that 60% of the sampled rivers were classified as having grade C quality (51 - 75), while 40% were of the grade D category (76 -100). Maximum index score (79.72) was recorded at Eruvbi River while the lowest index value (59.32) was redorded at Ugbogor River. Overall, this study found that the water quality of all chosen rivers is poor and unfit for drinking without previous treatment, although they are appropriate for irrigation and industrial usage. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the water quality and phytoplankton abundance in Lake Toba to determine its trophic status. This research was conducted from January to March 2024 at four stations in Lake Toba. Water samples were taken using a UWITEC water sampler and a plankton net and brought to the laboratory for analysis. The study measured physical and chemical water quality and phytoplankton abundance. The results showed a brightness ranging between 5.8 and 6.3 meters, chlorophyll-a content <10 µg/L, total nitrogen <750 µg/L, and phosphorus ranging from 20 µg/L to 30 µg/L. Based on these parameters, the nutrient quality of Lake Toba was classified as mesotrophic. Phytoplankton abundance ranged from 22,514 to 33,475 individuals/L, with 33 genera identified across nine classes: Bacillariophyceae, Chlorophyceae, Cyanophyceae, Coscinodiscophyceae, Dinophyceae, Euglenida, Fragilariophyceae, Mediophyceae, and Zygnemophyceae. The diversity index (H') was 2.631 - 2.723, the uniformity index (E) was 0.828 - 0.872, and the percentage of blue-green algae was 14.75 - 20.85. Zygnemophyceae was the most dominant phytoplankton class, with Staurastrum sp. being the most prevalent species. In conclusion, Lake Toba's waters are categorized as mesotrophic based on the chemical parameters and as eutrophic based on phytoplankton abundance, indicating potential nutrient enrichment issues that warrant further investigation. [ABSTRACT FROM AUTHOR]

East African lakes support the food and water security of millions of people. Yet, a lack of continuous long-term water quality data for these waterbodies impedes their sustainable management. While satellite-based water quality retrieval methods have been developed for lakes globally, African lakes are typically underrepresented in training data, limiting the applicability of existing methods to the region. Hence, this study aimed to (1) assess the accuracy of existing and newly developed water quality band algorithms for East African lakes and (2) make satellite-derived water quality information easily accessible through a Google Earth Engine application (app), named LAndsat water QUality retrieval tool for east African lakes (LAQUA). We collated a dataset of existing and newly collected in situ surface water quality samples from seven lakes to develop and test Landsat water quality retrieval models. Twenty-one published algorithms were evaluated and compared with newly developed linear and quadratic regression models, to determine the most suitable Landsat band algorithms for chlorophyll-a, total suspended solids (TSS), and Secchi disk depth (SDD) for East African lakes. The three-band algorithm, parameterised using data for East African lakes, proved the most suitable for chlorophyll-a retrieval (R2 = 0.717, p < 0.001, RMSE = 22.917 μg/L), a novel index developed in this study, the Modified Suspended Matter Index (MSMI), was the most accurate for TSS retrieval (R2 = 0.822, p < 0.001, RMSE = 9.006 mg/L), and an existing global model was the most accurate for SDD estimation (R2 = 0.933, p < 0.001, RMSE = 0.073 m). The LAQUA app we developed provides easy access to the best performing retrieval models, facilitating the use of water quality information for management and evidence-informed policy making for East African lakes. [ABSTRACT FROM AUTHOR]

Lake Erie's Western Basin is a eutrophic region and likely hotspot for carbon transformation. While this basin has received much attention for its high nutrient loads from the Maumee River and recurring harmful algal blooms, carbon has gone understudied. To investigate the seasonal and spatial variability in inorganic and organic carbon budgets, we completed three surveys in spring, summer, and fall on a transect from the Maumee River to South Bass Island. In each survey, we observed higher spatial variability of all carbon species within 11 km of the Maumee River mouth relative to sites outside of Maumee Bay. This variability was driven by pulses of direct river water carbon, steep nutrient gradients, and patchy bloom conditions. Seasonal variability was also greater in Maumee Bay, with the highest river discharge in June adding large amounts of dissolved inorganic and organic carbon and pCO2 flux out of the water when productivity from the diatom bloom was smaller. In August, when and where we observed a Microcystis bloom, particulate organic carbon increased in concentration, and pCO2 flux switched directions into the water. In October, Chl‐a concentrations and oxygen saturations were lowest, indicating a seasonal slowdown in productivity, and river discharge was the lowest, resulting in the lowest total carbon observed and dissolved organic matter chemistry indicating less contribution from the terrestrial watershed. In the open water outside of Maumee Bay seasonal and spatial carbon budget dynamics were more stable, highlighting the importance of riverine inputs on lake carbon cycling. Plain Language Summary: The Maumee River has a large influence on the water quality of Lake Erie's Western Basin. Past research in this region focused on the connection between nutrients, such as phosphorus and nitrogen, and harmful algal blooms. Carbon, which is a water quality indicator and can serve as a component of greenhouse gases, is less studied. The goal of this project was to quantify changes in carbon over space and time along a gradient from the Maumee River into the Western Basin. We performed research cruises in spring, summer, and fall and collected samples for dissolved inorganic carbon, dissolved organic carbon, and particulate organic carbon. We found the Maumee River influenced the carbon budget due to direct inputs of carbon as well as nutrient inputs that fueled algal blooms. In the spring and summer when the Maumee River had high flow, much of the carbon in Maumee Bay was from the river, but later in the year as flow decreased an larger percent of the carbon came from the algal bloom, which changed which kind of carbon was most common due to photosynthesis. Throughout the study the open water of the basin had less variability in carbon compared to Maumee Bay. Key Points: Carbon in the Western Basin of Lake Erie is heavily influenced by river inputSpatial and temporal variability of inorganic and organic carbon is high in Maumee BaySeasonal bloom dynamics transform carbon [ABSTRACT FROM AUTHOR]

Despite the growing use of Aquatic Ecosystem Models for lake modeling, there is currently no widely applicable framework for their configuration, calibration, and evaluation. Calibration is generally based on direct data comparison of observed versus modeled state variables using standard statistical techniques, however, this approach may not give a complete picture of the model's ability to capture system‐scale behavior that is not easily perceivable in observations, but which may be important for resource management. The aim of this study is to compare the performance of "naïve" calibration and a "system‐inspired" calibration, an approach that augments the standard state‐based calibration with a range of system‐inspired metrics (e.g., thermocline depth, metalimnetic oxygen minima), to increase the coherence between the simulated and natural ecosystems. A coupled physical‐biogeochemical model was applied to a focal site to simulate two key state‐variables: water temperature and dissolved oxygen. The model was calibrated according to the new system‐inspired modeling convention, using formal calibration techniques. There was an improvement in the simulation using parameters optimized on the additional metrics, which helped to reduce uncertainty predicting aspects of the system relevant to reservoir management, such as the occurrence of the metalimnetic oxygen minima. Extending the use of system‐inspired metrics when calibrating models has the potential to improve model fidelity for capturing more complex ecosystem dynamics. Key Points: We assessed the use of system‐inspired metrics in a novel approach to calibrating Aquatic Ecosystem Models (AEMs)The use of system‐inspired metrics in calibration improved model performance relative to traditional calibration methodsImplementation of system‐inspired metrics has the potential to greatly improve model prediction of complex ecosystem dynamics [ABSTRACT FROM AUTHOR]

Numerous policies have been proposed by international and supranational institutions, such as the European Union, to surveil Earth from space and furnish indicators of environmental conditions across diverse scenarios. In tandem with these policies, different initiatives, particularly on both sides of the Atlantic, have emerged to provide valuable data for environmental management such as the concept of essential climate variables. However, a key question arises: do the available data align with the monitoring requirements outlined in these policies? In this paper, we concentrate on Earth Observation (EO) optical data applications for environmental monitoring, with a specific emphasis on ocean colour. In a rapidly changing climate, it becomes imperative to consider data requirements for upcoming space missions. We place particular significance on the application of these data when monitoring lakes and marine protected areas (MPAs). These two use cases, albeit very different in nature, underscore the necessity for higher-spatial-resolution imagery to effectively study these vital habitats. Limnological ecosystems, sensitive to ice melting and temperature fluctuations, serve as crucial indicators of a climate in change. Simultaneously, MPAs, although generally small in size, play a crucial role in safeguarding marine biodiversity and supporting sustainable marine resource management. They are increasingly acknowledged as a critical component of global efforts to conserve and manage marine ecosystems, as exemplified by Target 3 of the Kunming–Montreal Global Biodiversity Framework (GBF), which aims to effectively conserve 30% of terrestrial, inland water, coastal, and marine areas by 2030 through protected areas and other conservation measures. In this paper, we analysed different policies concerning EO data and their application to environmental-based monitoring. We also reviewed and analysed the existing relevant literature in order to find gaps that need to be bridged to effectively monitor these habitats in an ecosystem-based approach, making data more accessible, leading to the generation of water quality indicators derived from new high- and very high-resolution satellite monitoring focusing especially on Chlorophyll-a concentrations. Such data are pivotal for comprehending, at small and local scales, how these habitats are responding to climate change and various stressors. [ABSTRACT FROM AUTHOR]

Understanding the thermal classification of lakes based on mixing regimes is fundamental in limnology. Although this classification has traditionally been considered well-established, recent studies highlight variations in the mixing behaviors of ponds and shallow lakes. This paper introduces the Ardulake temperature profiler, an innovative, simple, and autonomous high-frequency temperature monitoring system designed for shallow to moderately deep lakes (3.5 to 10 m). Utilizing Arduino technology and GPRS telemetry, the system is cost-effective, with electronic components and sensors costing approximately USD 250 and buoy construction and deployment around USD 1000. The Ardulake enables real-time environmental temperature monitoring and data storage on an online platform for subsequent analysis and visualization. The collected data supports ecosystem research and the numerical modeling of thermal behavior in lakes. Key strengths of the system include low production and maintenance costs, replicability, and customization capabilities. Challenges, such as interference from animal activity, are addressed with recommended preventive measures tailored to specific fauna. Overall, the Ardulake temperature profiler offers a practical tool for advancing limnological research, with potential for modification to various environmental monitoring objectives.

Abstract Freshwater jellyfish (= limnic medusa‐budding hydrozoans, FWJ) are a small group of cnidarians found on all continents except Antarctica in temperate to tropical latitudes. Members of this group belong primarily to three genera: Astrohydra, Craspedacusta, and Limnocnida. While Astrohydra and Limnocnida are typically restricted to the islands of Japan, Africa, and the Indian subcontinent, one species or potential species complex, Craspedacusta sowerbii, became globally invasive. Despite research going back about one‐and‐a‐half centuries, little is known about their phylogeny and ecology compared to marine jellyfish. Recent species distribution modelling, however, showed that by 2050, C. sowerbii will potentially extend their distribution ranges due to global warming to high‐latitude ecosystems and be present (medusa stage) for an extended time in the seasonal limnic production cycle. An increase in their relative ecological importance with temporal and spatial spreading is hypothesised. Only recently, it has been shown that the trophic roles of polyps and medusae and their prey overlap with other ecosystem members. In addition, medusa behaviour may cause trophic cascades and alter vertical nutrient distributions. However, polyps and other benthic life cycle stages are understudied. In globally, changing freshwater ecosystems that may become more accommodating for FWJ, an improved understanding of their population biology and ecosystem ecology is urgently needed. In this integrative review, we, therefore, explore reasons for the hampered historical research progress, contrast developments with those of marine cnidarians, compile and publish alongside an extensive and unprecedented literature database, and formulate avenues for future directions in FWJ research.

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]

Lake Tennyson's basin and sedimentary record were assessed for multiple branches of paleoenvironmental research. A geophysical investigation of the lake depositional setting was supported by physical and chemical analysis of multiple sediment cores. The basin reaches 60 m depth and several subaerial landforms identified were likely deposited from seismic activity. Deformed sediments and turbidites in gravity cores are attributed to one or more large (pre)historic earthquakes, and episodic grain size changes in sediment cores are related to either seismic and/or climatic/meteorological processes. A hummocky slump deposit located on the western lake bed margin is linked to widespread sediment deformation that was likely caused by movement of the Awatere Fault. Radiocarbon dating constrains the most recent major deformation event between the late thirteenth century CE and mid-twentieth Century. Folded turbidites in the stratigraphy suggest multiple sedimentary deformation episodes occurred during the last millennium. Micro-XRF elemental signatures suggest proxies of past water column mixing (windiness proxy) can be reconstructed via identification of changing redox conditions. Records from Lake Tennyson show potential for several palaeoenvironmental research applications, and combining them with basin morphostratigraphy and land-based palaeoclimate and palaeoseismic evidence can enhance understanding of environmental change in the northern South Island. [ABSTRACT FROM AUTHOR]

Sources and fluxes of methane to the atmosphere from permafrost are significant but poorly constrained in global climate models. We present data collected from the variable permafrost setting of the outer Mackenzie River Delta, including observations of aquatic methane seepage, core determinations of in situ methane occurrence and seep gas isotope geochemistry. The sources and locations of in situ geologic methane occurrence and aquatic and atmospheric gas release appear to be controlled by the regional geology and permafrost conditions. Where permafrost is >250 m thick, thermogenic gas deposits at depth are isolated by laterally continuous, low permeability ice‐bearing sediments with few through‐going thawed taliks. Thus, the observed in situ methane and aquatic gas seepage appears to be dominated by microbial methane. In contrast, where permafrost is <80 m thick, taliks are more likely to be through‐going, providing permeable conduits from depth and migration pathways for both thermogenic and biogenic gas. Continuous annual fluid sampling of two lakes and a river channel documents aquatic methane flux from microbial sources, more deeply buried thermogenic sources, and mixtures of both. Using estimates of in situ methane concentration from deep core samples and observations of in situ free gas occurrences, we conclude that the reservoir of in situ geologic methane within ice bonded permafrost is substantial and that this methane is presently migrating with ongoing atmospheric release. It is our assessment that the permafrost setting, and processes described are sensitive to future climate change as the permafrost warms. Plain Language Summary: Methane is released from permafrost, yet the amount and sources of the methane are poorly understood. This paper presents data on methane released from water environments and stored in soil from the permafrost areas of the outer Mackenzie River Delta, NWT. It also uses isotope geochemistry to determine the source (type) of the methane ‐ either biogenic (produced by living organisms) or thermogenic (produced by breaking down of organic matter by heat). The sources and locations of the methane gas release appear to be controlled by the regional geology and permafrost conditions. We conclude that the methane stored within and beneath the ice bonded permafrost is substantial and that this methane is presently migrating to aquatic systems with ongoing atmospheric release. It is our assessment that this permafrost setting and the potential for increased methane release are sensitive to future climate change as the permafrost warms. Key Points: A unique annual record of dissolved methane geochemistry documents active microbial and geologic methane sources in a delta lake and channelSeep gas chemistry, geophysical, and core data allow appraisal of permafrost controls on subsurface methane dynamics in the Mackenzie DeltaThe large inventory of stored methane and the dynamic permafrost processes described are potentially responsive to future climate change [ABSTRACT FROM AUTHOR]

Eutrophication represents a major threat to freshwater systems and climate change is expected to drive further increases in freshwater primary productivity. However, long‐term in situ data is available for very few lakes and makes identifying trends and drivers of eutrophication challenging. Using remote sensing data, we conducted a retrospective analysis of long‐term trends in trophic status among lakes greater than 10 ha across the Intermountain West, a region with understudied water quality trends and limited long‐term data sets. We found that most lakes (55%) were not exhibiting shifts in trophic status from 1984 to 2019. Our results also show that increases in eutrophication were rare (3% of lakes) during this period, and that lakes becoming increasingly oligotrophic were more common (17% of lakes). Lakes that were not trending occupied a wide range of lake and landscape characteristics, whereas lakes that were becoming more oligotrophic tended to have larger residence times and were located in catchments with greater clay content and more development. Our results highlight that while there are well‐established narratives that climate change can lead to more eutrophication of lakes, this is not broadly observed in our data set, where we found more lakes in the Intermountain West becoming more oligotrophic than lakes becoming eutrophic. Plain Language Summary: Lakes are often classified by their productivity. Low productivity lakes are generally deep with low nutrient levels and low amounts of algae. Whereas lakes with high levels of productivity support more plant growth and have higher amounts of algae. The accumulation of nutrients in freshwater systems often results in increases in productivity and can lead to the development of algal blooms. Algal blooms are a major concern due to their threat to ecosystem health, recreation, and drinking water sources. Yet the lack of long‐term field data across large scales has resulted in a limited understanding of (a) what are the long‐term trends in lake productivity and how does this relate to trends in algal blooms, and (b) what factors are driving productivity trends and the development of algal blooms across regions. Therefore, there is a pressing need to effectively monitor and understand these trends in order to inform management actions that address their frequency and intensity. Here, we use data obtained from satellite imagery from 1984 to 2019 to document lake productivity trends in 1,169 lakes across the Intermountain West. We show that substantial increases in productivity over this time period were rare, and that the majority of lakes have not undergone widespread change. Key Points: Remote sensing imagery captures long‐term trends in lake productivity across the Intermountain WestThe majority of lakes observed in this data set were not exhibiting shifts in trophic status from 1984 to 2019The incorporation of fine‐scale lake climate data from new deep learning data sets results in substantial improvement to model accuracy [ABSTRACT FROM AUTHOR]

The depositional history of the Bonneville Salt Flats, a perennial saline pan in Utah's Bonneville basin, has poor temporal constraints, and the climatic and geomorphic conditions that led to saline pan formation there are poorly understood. We explore the late Pleistocene to Holocene depositional record of Bonneville Salt Flats cores. Our data challenge the assumption that the saline pan formed from the desiccation of Lake Bonneville, the largest late Pleistocene lake in the Great Basin, which covered this area from 30 to 13 cal ka BP. We test two hypotheses: whether climatic transitions from (1) wet to arid or (2) arid to wet led to saline pan deposition. We describe the depositional record with radiocarbon dating, sedimentological structures, mineralogy, diatom, ostracode, and portable X-ray fluorescence spectrometer measurements. Gypsum and carbonate strontium isotope ratio measurements reflect changes in water sources. Three shallow saline lake to desiccation cycles occurred from >45 and >28 cal ka BP. Deflation removed Lake Bonneville sediments between 13 and 8.3 cal ka BP. Gypsum deposition spanned 8.3 to 5.4 cal ka BP, while the oldest halite interval formed from 5.4 to 3.5 cal ka BP during a wetter period. These findings offer valuable insights for sedimentologists, archaeologists, geomorphologists, and land managers. [ABSTRACT FROM AUTHOR]

This study observed seasonal trends and inferred drivers of CO2 biogeochemistry at the air‐water interface of Lake Superior. Underway carbon dioxide partial pressure (pCO2) was measured in surface water during 69 transects spanning ice free seasons of 2019‐2022. These data comprise the first multiannual pCO2 time series in the Laurentian Great Lakes. Surface water pCO2 was closely tied to increasing atmospheric pCO2 over a 100‐day CO2 equilibration timescale, while seasonal variability was controlled equally by thermal and non‐thermal drivers during the ice‐free season. Comparison to previous modeling efforts indicated that Lake Superior surface pCO2 increased with two decades of rising atmospheric CO2. Spatial heterogeneity in CO2 dynamics was highlighted by a conductivity‐based delineation of "riverine" and "pelagic" regimes, each of which was associated with net CO2 influx over Julian days 100–300 on the order of 25 Gmol C. These findings refine previous estimates of Lake Superior C fluxes, support predictions of anthropogenic CO2 invasion during the ice‐free season, point to new observation strategies for large lakes, and highlight an urgent need for studies of changes to lacustrine C cycling. Plain Language Summary: Carbon dioxide gas concentrations were measured in surface waters of Lake Superior for 4 years, forming the first multi‐year data set of direct observations of carbon dioxide gas concentration in the Laurentian Great Lakes. Lake Superior's surface carbon dioxide concentration was closely tied during the ice‐free season to that of the atmosphere on time scales longer than 1 year. Seasonal variations in carbon dioxide concentration were driven by water temperature, biological activity, river influence, and gas exchange with the atmosphere. Lake Superior released and absorbed carbon dioxide cyclically at different times during the year, absorbing more than it released from April to November. The carbon dioxide gas concentration in mixing surface waters was observed to have increased over a multi‐decade period with that of the atmosphere. This work improves the scientific understanding of carbon cycling in Lake Superior and advances techniques for carbon cycle observation and modeling of other lakes in a time of large‐scale changes to surface water CO2 cycling. Key Points: Underway pCO2 was measured in Lake Superior from 2019 to 2022 to form the first multi‐year pCO2 time series in the Laurentian Great LakesThe seasonal pCO2 cycle showed competition of thermal and non‐thermal drivers and spatial heterogeneity associated with riverine influenceSuperior's CO2 reservoir equilibrated with the atmosphere repeatedly, indicating increasing sea surface pCO2 with rising atmospheric CO2 [ABSTRACT FROM AUTHOR]

Reservoirs are artificial systems that alter the natural conditions of the environment. This transformation process affects the chemical, physical and biological properties of the water body. The objective of this study was to assess the environmental impacts due to the spatial behavior of limnological variables in water reservoirs, using the Espora Hydroelectric Power Plant (HPP) water reservoir as environmental system model. The parameters analyzed were: hydrogen potential (pH), water temperature, turbidity, transparency and chlorophyll-a content. Thirty-four collection points were selected in the model reservoir in four different periods (winter, spring, summer, and autumn). The results were compared to Brazilian legislation standards for fresh water, according to resolution no 357/2005 of the national council for the environment (Conama), and statistically evaluated through principal component analysis (PCA). The limnological parameters indicated that the water body can be classified as class 2. The first two axes of the PCA explain 62.59% of the total variation of the correlations among the physical, chemical, and biological variables, during the four sampling campaigns in the climatic seasons of the study cerrado region. Transparency, water temperature, pH, and chlorophyll-a content were the most significant variables, with correlation coefficients of 0.614, − 0.677, 0.755, and − 0.484, indicating a gradient related to the increase of the primary productivity of aquatic organisms in the reservoir. This work has useful results that can be used for the environmental monitoring of HPP water reservoirs around the world. [ABSTRACT FROM AUTHOR]

The physico-chemical profile of the freshwater reservoir (dam) in Anandpur, Saurashtra, Gujarat, where limnological research was carried out from June 2021 to May 2023, is described in this report. Temperature, transparency, pH, electrical conductivity, dissolved oxygen, biological oxygen demand, acidity, alkalinity, total hardness, calcium hardness, magnesium hardness, chlorides, salinity, and other variables were examined in the surface water of the dam. These components' seasonal fluctuations were examined, and their interrelationships are addressed. Water had an alkaline pH. Summertime saw a rise in EC, whereas the post-monsoon season saw a reduction. Alkalinity and total hardness tended to drop in the winter and summer and to rise during and after the monsoon. The amount of dissolved oxygen was highest in the winter and lowest in the summer. Temperature and EC indicated an inverse connection with dissolved oxygen. Total 36 species of zooplankton were also recorded. The highest arthropodan and rotifer zooplankton species were recorded. [ABSTRACT FROM AUTHOR]

The McMurdo Dry Valleys (MDVs) of Antarctica are a mosaic of extreme habitats which are dominated by microbial life. The MDVs include glacial melt holes, streams, lakes, and soils, which are interconnected through the transfer of energy and flux of inorganic and organic material via wind and hydrology. For the first time, we provide new data on the viral community structure and function in the MDVs through metagenomics of the planktonic and benthic mat communities of Lakes Bonney and Fryxell. Viral taxonomic diversity was compared across lakes and ecological function was investigated by characterizing auxiliary metabolic genes (AMGs) and predicting viral hosts. Our data suggest that viral communities differed between the lakes and among sites: these differences were connected to microbial host communities. AMGs were associated with the potential augmentation of multiple biogeochemical processes in host, most notably with phosphorus acquisition, organic nitrogen acquisition, sulfur oxidation, and photosynthesis. Viral genome abundances containing AMGs differed between the lakes and microbial mats, indicating site specialization. Using procrustes analysis, we also identified significant coupling between viral and bacterial communities (p = 0.001). Finally, host predictions indicate viral host preference among the assembled viromes. Collectively, our data show that: (i) viruses are uniquely distributed through the McMurdo Dry Valley lakes, (ii) their AMGs can contribute to overcoming host nutrient limitation and, (iii) viral and bacterial MDV communities are tightly coupled.

The objective of this paper was to assess the physicochemical limnology and water quality assessment of ten surface water bodies in Edo State, Nigeria to determine their suitability for drinking, provide information on water quality status to the concerned public as well as providing baseline information that can be used as reference for further studies using appropriate standard techniques. Results revealed that pH, colour, turbidity, total dissolved solids, electrical conductivity, total alkalinity, total hardness, calcium, magnesium, dissolved oxygen, biochemical oxygen demand, sulphate, nitrate and phosphate 5.52 – 7.06, 1.0 – 5.5 PtCoU, 3.5 -23.0 NTU, 11.0 -75.5 mg/L, 21.0 – 152.5µS/cm, 25.0 – 106.5 mg/L, 3.0 – 40.8 mg/L, 0.18 – 7.40 mg/L, 0.13 – 2.77 mg/L, 5.76 – 8.92 mg/L, 3.12 – 6.87 mg/L, 9.5 – 24.5 mg/L, 0.2 – 2.60 mg/L and 0.05 – 0.49 mg/L respectively. From the results of the physicochemical analyses, the water quality index score of the rivers was computed using the Weighted Arithmetic Water Quality Index method and the values obtained indicated that 60% of the sampled rivers were classified as having grade C quality (51 – 75), while 40% were of the grade D category (76 -100). Maximum index score (79.72) was recorded at Eruvbi River while the lowest index value (59.32) was redorded at Ugbogor River. Overall, this study found that the water quality of all chosen rivers is poor and unfit for drinking without previous treatment, although they are appropriate for irrigation and industrial usage.

Abstract The aim of this study is to analyze the waterborne metal levels in four lakes (one endorheic and three exorheic) of Harmony Point, Nelson Island, Antarctica. Water samples were analyzed by using a quadrupole type inductively coupled plasma mass spectrometer and an inductively coupled plasma optical emission spectrometer. The levels of As, Cu, Mn, Mo, and V were significantly lower and those of Cr, Mg, Na, and Sr were significantly higher in the endorheic lake than in the other lakes. Most water samples presented levels of Ag, Be, Cd, Pb, Se, Tl, and U below the limit of quantification, while for Ba, Co, and Ni around half of the samples were below this limit. The waterborne metal levels were not significantly different between the exorheic lakes. Waterborne metal levels in the freshwater lakes from Harmony Point did not show any clear relationship with their levels in the soil of the region or with bird guano, and overall, their levels indicate an environment without anthropogenic influence. Apparently, the Na levels are influenced by salt spray from the ocean, as they are related to the distance of the lakes from the ocean.

Rapid warming in the High Arctic has induced changes in terrestrial environments that have included major recent shifts in lakes and ponds. Numerous studies exist of spatial trends in water chemistry, bioindicator groups, and paleoenvironmental change from High Arctic lakes; however, little is known about lake thermal stratification regimes at high latitudes beyond assumptions based on generalized classification schemes. Here, we report on the presence in late July 2022 of positive thermal stratification during open-water conditions in two freshwater lakes near Clements Markham Inlet, on northern Ellesmere Island. These lakes are situated in the polar desert at 82.6°N, >1000 km north of the generally accepted northern limit of summer thermal stratification. Given their location approaching the northernmost land on Earth, the thermal profiles of these lakes suggest that the occurrence of summer stratification may no longer be discounted anywhere in the Northern Hemisphere.

Lake thermal dynamics have been considerably impacted by climate change, with potential adverse effects on aquatic ecosystems. To better understand the potential impacts of future climate change on lake thermal dynamics and related processes, the use of mathematical models is essential. In this study, we provide a comprehensive review of lake water temperature modeling. We begin by discussing the physical concepts that regulate thermal dynamics in lakes, which serve as a primer for the description of process‐based models. We then provide an overview of different sources of observational water temperature data, including in situ monitoring and satellite Earth observations, used in the field of lake water temperature modeling. We classify and review the various lake water temperature models available, and then discuss model performance, including commonly used performance metrics and optimization methods. Finally, we analyze emerging modeling approaches, including forecasting, digital twins, combining process‐based modeling with deep learning, evaluating structural model differences through ensemble modeling, adapted water management, and coupling of climate and lake models. This review is aimed at a diverse group of professionals working in the fields of limnology and hydrology, including ecologists, biologists, physicists, engineers, and remote sensing researchers from the private and public sectors who are interested in understanding lake water temperature modeling and its potential applications. Plain Language Summary: Lake thermal dynamics are fundamental in controlling mixing processes and have significant implications for biological and geochemical processes. Consequently, the impacts of climate change on these dynamics can have severe consequences for the health of lakes and their aquatic ecosystems. In this context, mathematical models are essential for understanding the potential effects of future climate change on lake thermal dynamics and related processes. This manuscript offers a comprehensive review of lake water temperature modeling. It covers the fundamental physical concepts that govern thermal dynamics in lakes and provides an overview of various sources of observational water temperature data, including in situ monitoring and satellite data used in these models. The study evaluates different types of lake water temperature models, including statistical, process‐based, and hybrid models. It explores emerging modeling approaches such as forecasting, digital twins, combining process‐based modeling with deep learning, ensemble modeling, and climate‐lake models coupling. Model performance is also discussed, highlighting suggested evaluation metrics and providing a comprehensive analysis of the state‐of‐the‐art optimization methods to assess model accuracy. This review targets researchers in limnology, hydrology, ecology, biology, physics, engineering, and remote sensing from the private and public sectors interested in lake water temperature modeling and its applications. Key Points: Lake thermal dynamics are central in shaping mixing processes and the health of aquatic ecosystems, and climate change alters these dynamicsMathematical models are essential to understand past and project future climate change impacts on lake thermal dynamicsThis study reviews lake water temperature modeling, covering concepts, data sources, and model evaluation for applications across disciplines [ABSTRACT FROM AUTHOR]

There is a scarcity of long-term chemical monitoring data for lakes in Algonquin Provincial Park (APP), with minimal understanding of the impacts of cottage-leases (e.g., cottage lots, campgrounds, and commercial leases) on lake water chemistry. We examine spatial patterns in water chemistry and landscape features of 32 reference and 22 cottage-lease lakes in APP. Multivariate techniques were used to examine differences in water chemistry, and to identify the subset of landscape features that best explain this variability. Breakpoint analysis was used to examine the relationship between gradients of water chemistry and specific landscape features. Lakes were separated along a primary gradient of ions and pH and a secondary gradient of nutrients and colour. These gradients were best explained by a combination of six landscape features (wetlands, elevation, lake depth, road length, and coniferous trees). Except for chloride, there was no statistically significant difference in water chemistry between cottage-lease and reference lakes. A roughly west-to-east gradient in catchment vegetation and lake chemistry was related to the location of the Algonquin Dome, a natural geological feature in APP, and the park's glacial history. These results emphasize the importance of the park's topography in influencing regional water chemistry. [ABSTRACT FROM AUTHOR]

The 3rd Aquatic Ecosystem Modeling Network—Junior (AEMON‐J) Hacking Limnology Workshop and 4th Virtual Summit: Incorporating Data Science and Open Science in the Aquatic Sciences (DSOS) took place in July 2023. The events aimed to bring together aquatic science practitioners and enthusiasts to exchange knowledge and experiences in the field of data science, open science, remote sensing, and the aquatic sciences. The workshops focused on introducing early career scientists to open datasets and coding skills, while the summit featured speakers presenting on various topics related to data science and open science in the aquatic sciences. The events were accessible to a global audience, with materials and recordings made freely available for asynchronous viewing. The organizers also emphasized diversity, equity, inclusion, and accessibility in the community. The events received positive feedback, but synchronous engagement was lower compared to previous years, possibly due to the decline of COVID-19 restrictions and the increase in face-to-face conferences. The organizers are considering a balance between in-person and virtual engagement for future events and are open to collaborations and self-organized workshops. [Extracted from the article]

Studies on the length–weight relationship (LWR), condition factor (K) and size at first maturity status are important aspects of fish biology and fisheries management. Although many studies have reported about growth parameters of Oreochromis niloticus under various fishery waters and aquaculture systems, a recent invasion of the species in Lake Nakuru (Kenya) is a new case study. Therefore, this paper provides baseline data on LWR, K and Lm50 of O. niloticus in relation to limnological conditions in the lake. Water quality parameters (pH, temperature, conductivity, dissolved oxygen, salinity and total suspended solids) and indicators of eutrophication status (phosphates, nitrates and chlorophyll‐a.) were analysed in November 2020 and November 2021. Fish samples were collected using experimental gillnets with assorted mesh sizes from 2 to 4 in., and their morphometric data was analysed. Results show significant spatial variations (ANOVA; p < 0.05) in all the water quality parameters. These parameters, except the temperature, also significantly differed between the study periods (t‐test; p < 0.05). O. niloticus was the most dominant species, comprising 75.3% and 90.8%, in 2020 and 2021, respectively. Mean total length (19.80 cm) and weight (169 g) of the fish in 2021 were greater than 19.20 cm and 153 g in 2020. Nile tilapia exhibited an isometric LWR (b = 3), better well‐being (K>1), but it matured at smaller sizes (<25 cm) in both sexes. Further monitoring of water quality changes in Lake Nakuru and their future impact on the population of O. niloticus is recommended. [ABSTRACT FROM AUTHOR]

Continuous multiproxy data were generated to understand the mid-late Holocene palaeoenvironmental history of the Kashmir Valley and the biogeochemistry of Wular Lake, India. For this purpose, geochemical and stable isotopic analyses were carried out on sediment samples retrieved from a 160 cm long trench excavated on the eastern bank of Wular Lake located in the Union Territory of Jammu and Kashmir, India. The chronology of the sediment strata developed using 14C dating by accelerator mass spectrometry covered the last ~5600 yr BP. Our results indicated the occurrence of an extended dry climate phase from 4600 to 3800 yr BP, which coincided with the widely recognised Meghalayan Stage, when major civilisations like the Harappa and the Akkadian were known to collapse. The lake biogeochemistry revealed dominance of the emergent macrophytes during this stage. Another dry phase was observed between 3100 and 2200 yr BP. This dry phase peaked at around 2900 yr BP, coinciding with Bond Event 2. Wular Lake faced nutrient limitation due to low runoff around 2500 yr BP caused by the persistent dry and cold climate. Geochemical signatures revealed that anthropogenic activities during the last two millennia might have significantly influenced erosion in the catchment area. [ABSTRACT FROM AUTHOR]

Climate change is driving the loss of alpine glaciers globally, yet investigations about the water quality of rivers stemming from them are few. Here we provide an overview assessment of a biogeochemical data set containing 200+ parameters that we collected between 2019 and 2021 from the headwaters of three such rivers (Sunwapta‐Athabasca, North Saskatchewan, and Bow) which originate from the glacierized eastern slopes of the Canadian Rocky Mountains. We used regional hydrometric data sets to accurately model discharge at our 14 sampling sites. We created a Local Meteoric Water Line (LMWL) using riverine water isotope signatures and compared it to collected regional rain, snow, and glacial ice signatures. Principal component analyses of river physicochemical measures revealed distance from glacier explained more data variability than other spatiotemporal factors (i.e., season, year, or river). Discharge, chemical concentrations, and watershed areas were then used to model site‐specific open water season yields for 25 parameters. Chemical yields followed what would generally be expected along river continuums from glacierized to montane altitudinal life zones, with landscape characteristics driving chemical sources and sinks. For instance, particulate chemical yields were generally highest near source glaciers with proglacial lakes acting as settling ponds, whereas most dissolved yields varied by parameter and site. As these headwaters continue to evolve with glacier mass loss, the data set and analyses presented here can be used as a contemporary baseline to mark future change against. Further, following this initial assessment of our data set, we encourage others to mine it for additional biogeochemical studies. Plain Language Summary: Alpine glaciers are vulnerable to climate change, with their numbers and sizes expected to decline dramatically within the current century. It is known that a decrease in glacier mass will have direct consequences on glacial meltwater quantity, but how this may impact the quality of receiving freshwaters is less understood. Our goal was to record a water quality data set of 200+ physical and chemical parameters for the headwaters of three major rivers draining glaciers on the eastern slopes of the Canadian Rocky Mountains. We first used statistics to model how fast the rivers were flowing at our 14 sampling locations over our 2‐year sampling period. We then looked at how and why water isotopes collected from river, rain, snow, and glacier ice samples differed. We discovered that distance downstream from the glacier explained more statistical variation in our physical and chemical measures than season, year, or river. Finally, at each of our sampling sites, we calculated chemical yields, or the amount of chemical constituent being exported downriver per unit watershed area, and found landscape features like lakes, outwash plains, and forests influence them. We ultimately hope that others use our comprehensive data set to investigate this changing region further. Key Points: We assessed a 200+ parameter data set collected from glacial river headwaters on the eastern slopes of the Canadian Rocky MountainsOur findings can act as a contemporary reference for future investigation of glacial headwaters in rapidly evolving alpine regionsThe possibilities for data exploration of our 260,000+ measure data set are numerous and we encourage others to mine it for new studies [ABSTRACT FROM AUTHOR]

Although scientific research has identified the causes of undesirable ecological changes in fresh waters, translating the results of research into practical conservation and management, and raising awareness of the need for action, is often inadequate.This Viewpoint considers the present coverage of conservation‐related freshwater research, the application of science to conservation, the extent of collaboration between international organizations, and the level of awareness of freshwater ecosystems and the need for their conservation.Far greater attention has been given to conservation in marine than freshwater areas. This is illustrated by the respective number of publications in the scientific literature, an imbalance in the UN Sustainable Development goals, and, until recently, the lack of an explicit reference to freshwater ecosystems in the UN Global Biodiversity Framework.Four case studies are presented as examples of how freshwater conservation can be made more effective: involving local communities in applying nature‐based solutions; bringing scientists and stakeholders together to discuss how to improve freshwater management; collaborating at a global scale in freshwater protection and restoration; and demonstrating how scientists and government can work together to reconcile the competing needs of nature and human society.Producing and implementing effective conservation and management plans needs a recognition of the extensive diversity of freshwater habitats and species, as well as a systematic evaluation of how scientific information can be translated into action at local, regional and global scales.Data on freshwater ecosystems need to be accessible, comprehensible, unambiguous and available to all those working on practical conservation projects. Many international organizations are already active in this field, but greater collaboration would make their work more effective.Raising awareness needs education and training, carefully targeted at a wide range of audiences, and communicated using the full range of media now available. [ABSTRACT FROM AUTHOR]

Water quality improvements in shallow eutrophic lakes are commonly delayed due to loading from legacy phosphorus (P)‐enriched sediments, even with reduced external nutrient loads. It is critical to understand the drivers of internal P loading to suppress or remove this source of P and meet water quality goals. We contrast the drivers of internal P loading in two shallow eutrophic systems (Lake Carmi and Missisquoi Bay). Legacy P dynamics in the unmanipulated systems were compared to Lake Carmi during aeration. In‐situ high frequency water column monitoring along with water and sediment sampling was used to study P dynamics in response to changing lake conditions and aeration. Despite both systems exhibiting P mobility controlled by iron redox cycling, we observed distinct differences in the spatial extent and drivers of internal P loading. Legacy P loading was controlled by seasonal drivers in Lake Carmi, but by spatially variable and highly transient wind driven forcing of hydrodynamics in Missisquoi Bay. Aeration altered the mixing regime of Lake Carmi and shifted loading dynamics to frequent wind‐driven pulses of legacy P to surface waters akin to those of Missisquoi Bay. Mean hypolimnetic dissolved oxygen increased with aeration, but greater oxygen demand rates and periods of anoxia under transient stratification still resulted in internal P loading. Surface P concentrations were higher in summer months with aeration compared to previous years. This research illustrates the dynamic nature of legacy P behavior within and between shallow eutrophic lakes and the challenges in addressing this common water resources threat. Plain Language Summary: Shallow lakes with high amounts of nutrients like phosphorus often experience worsening water quality and harmful algae blooms. Even if less phosphorus enters the lake from the watershed, phosphorus already in the lake can cycle between the water and sediment for decades. It is important to understand how phosphorus moves within lakes to make management decisions. We studied what causes the release of phosphorus from sediment in Lake Carmi and Missisquoi Bay, Lake Champlain. These observations were compared to Lake Carmi during 4 years of whole‐lake aeration designed to limit phosphorus release. We found that the release of phosphorus at both study sites was tied to chemical reactions of iron. The timing of this release was controlled by seasonal changes in Lake Carmi before aeration, and by frequent wind‐driven mixing in Missisquoi Bay. Aeration changed the timing of mixing in Lake Carmi but did not decrease the amount of phosphorus recycled from the sediment. Aeration also increased the rate of oxygen consumption in Lake Carmi which quickly led to phosphorus release during periods of calm wind. This research shows the highly dynamic nature of phosphorus behavior within shallow lakes which is important to understand when making management decisions. Key Points: Legacy phosphorus mobility was driven by either episodic wind‐mediated mixing or seasonal turnover in two proximal shallow eutrophic systemsAeration altered hydrodynamics to change from seasonal to wind‐driven internal loading of legacy phosphorus, but it was not suppressedHeterogeneous spatiotemporal controls on internal legacy phosphorus loading present challenges to achieving water quality goals [ABSTRACT FROM AUTHOR]

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