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Wildfire smoke often covers areas larger than the burned area, yet the impacts of smoke on nearby aquatic ecosystems are understudied. In the summer of 2018, wildfire smoke covered Castle Lake (California, USA) for 55 days. We quantified the influence of smoke on the lake by comparing the physics, chemistry, productivity, and animal ecology in the prior four years (2014–2017) to the smoke year (2018). Smoke reduced incident ultraviolet-B (UV-B) radiation by 31% and photosynthetically active radiation (PAR) by 11%. Similarly, underwater UV-B and PAR decreased by 65 and 44%, respectively, and lake heat content decreased by 7%. While the nutrient limitation of primary production did not change, shallow production in the offshore habitat increased by 109%, likely due to a release from photoinhibition. In contrast, deep-water, primary production decreased and the deep-water peak in chlorophyll a did not develop, likely due to reduced PAR. Despite the structural changes in primary production, light, and temperature, we observed little significant change in zooplankton biomass, community composition, or migration pattern. Trout were absent from the littoral-benthic habitat during the smoke period. The duration and intensity of smoke influences light regimes, heat content, and productivity, with differing responses to consumers.

In recent decades, invasive quagga mussels have expanded to the Western United States from the Great Lakes region of North America. Most studies that evaluate the invasion potential of quagga mussels in western water bodies have utilized physiological and life history information from zebra mussels, a related taxon. Few studies have assessed the potential for invasion using specific information from quagga mussel life history or experiments that test for their survival in the fresh and saline waters of the western United States. We investigated quagga mussel survival, growth, and reproduction using semi-natural experiments under temperature and light controlled conditions across a gradient of water salinity (fresh to brackish) and pH (8.4-11). Water from Lake Mead was used as a positive control in our experiment, and water from Pyramid Lake and the Truckee River was used as brackish and freshwater treatments, respectively. The mussels used in the experiments were collected from Lake Mead. After 12 h in brackish water (4 ppt, pH 9.3), we observed 100% mortality of adult mussels. The swelling and disintegration of body tissues and high mortality rates indicated that high potassium, sodium, and chloride concentrations were the likely causes of death in brackish water treatments. In contrast, mussels were able to survive, grow, and reach sexual maturity in freshwater (0.1 ppt) with a low calcium concentration (17 mg L ) after 57 days. Mussels died after 2 days at pH 11 and after 12 days at pH 10; during the 14-day monitoring period, no mortality was detected at pH 9.0, 9.3, or 9.5 and mussels did not exhibit any visual indications of stress. Understanding quagga mussel physiological and environmental tolerances appears to be essential for assessing their invasion potential in aquatic habitats.

Abstract The world's 1.4 million lakes (≥10 ha) provide many ecosystem services that are essential for human well‐being; however, only if their health status is good. Here, we reviewed common lake health issues and classified them using a simple human health‐based approach to outline that lakes are living systems that are in need of oxygen, clean water and a balanced energy and nutrient supply. The main reason for adopting some of the human health terminology for the lake health classification is to increase the awareness and understanding of global lake health issues. We show that lakes are exposed to various anthropogenic stressors which can result in many lake health issues, ranging from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning. Of particular concern for human well‐being is the widespread lake drying, which is a severe circulatory issue with many cascading effects on lake health. We estimated that ∼115,000 lakes evaporate twice as much water as they gain from direct precipitation, making them vulnerable to potential drying if inflowing waters follow the drying trend, putting more than 153 million people at risk who live in close vicinity to those lakes. Where lake health issues remain untreated, essential ecosystem services will decline or even vanish, posing a threat to the well‐being of millions of people. We recommend coordinated multisectoral and multidisciplinary prevention and treatment strategies, which need to include a follow‐up of the progress and an assessment of the resilience of lakes to intensifying threats. Priority should be given to implementing sewage water treatment, mitigating climate change, counteracting introductions of non‐native species to lakes and decreasing uncontrolled anthropogenic releases of chemicals into the hydro‐, bio‐, and atmosphere.

Evaluating progress toward achieving freshwater conservation and sustainability goals requires transforming diverse types of data into useful information for scientists, managers, and other interest groups. Despite substantial increases in the volume of freshwater data collected worldwide, many regions and ecosystems still lack sufficient data collection and/or data access. We illustrate how these data challenges result from a diverse set of underlying mechanisms and propose solutions that can be applied by individuals or organizations. We discuss creative approaches to address data scarcity, including the use of community science, remote‐sensing, environmental sensors, and legacy datasets. We highlight the importance of coordinated data collection efforts among groups and training programs to improve data access. At the institutional level, we emphasize the power of prioritizing data curation, incentivizing data publication, and promoting research that enhances data coverage and representativeness. Some of these strategies involve technological and analytical approaches, but many necessitate shifting the priorities and incentives of organizations such as academic and government research institutions, monitoring groups, journals, and funding agencies. Our overarching goal is to stimulate discussion to narrow the data disparities hindering the understanding of freshwater processes and their change across spatial scales. Resumen Evaluar el progreso hacia el alcance de los objetivos de conservación y sustentabilidad del agua dulce requiere la transformación de diversos tipos de datos para hacerlos información útil para los científicos, gestores de recursos y otros tomadores de decisiones. A pesar de que el volumen de datos recolectados alrededor del mundo en cuerpos de agua dulce ha incrementado sustancialmente, muchas regiones y ecosistemas aún no cuentan con suficiente recolección y/o acceso a datos. Ilustramos como los desafíos respecto a la generación y accesibilidad a los datos son el resultado de un conjunto diverso de mecanismos subyacentes y proponemos soluciones que pueden ser aplicadas por individuos y organizaciones. Discutimos diferentes opciones para enfrentar la escasez de datos, incluyendo el uso de ciencia comunitaria, sensores remotos, sensores ambientales y revalorización de conjuntos de datos históricos. Resaltamos la importancia de coordinar los esfuerzos para la recolección de datos entre grupos y programas de monitoreo para mejorar el acceso a los datos. A nivel institucional enfatizamos la necesidad de priorizar el procesamiento de los datos, incentivando la publicación de los datos y promoviendo investigaciones que fortalezca una mayor cobertura y representatividad de los diferentes ecosistemas. Algunas de las estrategias institucionales incluyen aproximaciones tecnológicas y analíticas, pero muchas requieren de un cambio de prioridades e incentivos dentro de las organizaciones, tales como las instituciones de investigación académicas y gubernamentales, grupos de monitoreo, revistas científicas y agencias de financiamiento. Nuestro objetivo es estimular la discusión para reducir las disparidades de datos que dificultan la comprensión de los procesos en cuerpos de agua dulce y sus cambios a través de las diferentes escalas espaciales.

Wildfire smoke covers entire continents, depositing aerosols and reducing solar radiation fluxes to millions of freshwater ecosystems, yet little is known about impacts on lakes. Here, we quantified trends in the spatial extent of smoke cover in California, USA, and assessed responses of gross primary production and ecosystem respiration to smoke in 10 lakes spanning a gradient in water clarity and nutrient concentrations. From 2006 − 2022, the maximum extent of medium or high-density smoke occurring between June-October increased by 300,000 km2. In the three smokiest years (2018, 2020, 2021), lakes experienced 23 − 45 medium or high-density smoke days, characterized by 20% lower shortwave radiation fluxes and five-fold higher atmospheric fine particulate matter concentrations. Ecosystem respiration generally declined during smoke cover, especially in low-nutrient, cold lakes, whereas responses of primary production were more variable. Lake attributes and seasonal timing of wildfires will mediate the effects of smoke on lakes.

The Senguer River basin, located in central Argentinian Patagonia, has its headwater in the Andean Range and ends in extra-Andean Patagonian plains. Within this region, the water bodies may be affected by their localization and the climatic and hydrological seasonality. At the lower basin, there are higher temperatures, evaporation and human impact, and lower precipitation and land cover. In addition, rainfall and runoff are higher during the winter and spring, while temperatures, wind intensity, and evaporation are higher during the summer and autumn. However, the characteristics and dynamics of the water bodies of this basin are not well known. This work aims to study the physical–chemical characteristics of the rivers and lakes of the Senguer River basin to establish their spatial and seasonal variations. During 1 year, seasonally, it was measured the concentration of total, organic and inorganic suspended sediments (TSS, OSS, ISS, respectively), total dissolved solids (TDS), pH, dissolved oxygen (DO), water temperature, chlorophyll a (Chl a), total phosphorus and Secchi disk depth. At the lower basin, water bodies present higher TSS, TDS, Chl a, and turbidity. The seasonal variability has a high impact on TSS (higher on the spring) and water temperature (higher on summer); however, the effect on the other variables is lower relative to the importance of the localization. The two extremes of the basin, Fontana Lake (Fo; located in the Andean zone) and Musters Lake (Mu; located extra-Andean plains), differed in TSS (Fo = 0.4 ± 0.3 mg L−1; Mu = 4.3 ± 2.8 mg L−1), TDS (Fo = 14 ± 1 mg L−1; Mu = 278 ± 9 mg L−1), water transparency (Fo = 11.8 ± 1.2 m; Mu = 3.1 ± 2.4 mg L−1), and Chl a (Fo = 0.42 ± 0.17 μg L−1; Mu = 3.93 ± 2.23 μg L−1). Our results allow a better understanding of the differences between the Andean and extra-Andean water bodies in Patagonia.

Institutional Analysis and Development (IAD) studies how institutions (the rules of the game of a society) determine the performance of a social-economic system. Elinor Ostrom extends the institutional analysis to the collective action for a particular case, the study of the social-ecological systems (SESs) (Ostrom 1990). Any group that attempts to manage a common resource (e.g. aquifers, pastures) for optimal sustainable production must solve a set of problems in order to create institutions to facilitate collective action. Some evidences show that following a set of design principles in creating institutions can lead to overcome these problems. The aim of the paper is to apply the SES framework to an artisanal fishery community in Argentina in order to: 1) describe the principal features, key variables and relations of the small-scale fishery system; 2) detect the principal drivers of a potential common-management and the leading detractors from the current communal performance; and 3) analyze the possibility that a self-governing for sustainable fishery may appear. Several drivers for potential common-management and some detractors from the current common performance are summarized. Artisanal fishery SES is currently at a bifurcation point. A common historical and cultural root, the presence of leaderships, the relevance of local knowledge, the dependence on the resource to sustainable livelihoods and the threat of big-scale fisheries area have generated incentives to collective-action. But, simultaneously, internal conflicts are the most important barrier for an integrated community-based management. The heterogeneity among actors and the relevant external conditions have resulted in two groups diverging in their self-organization. The work is framed by the project COMET-LA (COmmunity-based Management of Environmental challenges in Latin America; European Commission’s Seventh Framework Programme of Research and Development), which aims to identify sustainable community-based governance for the management of natural resources that can be used in different social-ecological systems in a context of climate change and increasing competition in the use of resources.

Community-based natural resource management (CBNRM) is a concept critical to managing social-ecological systems but whose implementation needs strengthening. Scenario planning is one approach that may offer benefits relevant to CBNRM but whose potential is not yet well understood. Therefore, we designed, trialed, and evaluated a scenario-planning method intended to support CBNRM in three cases, located in Colombia, Mexico, and Argentina. Implementing scenario planning was judged as worthwhile in all three cases, although aspects of it were challenging to facilitate. The benefits generated were relevant to strengthening CBNRM: encouraging the participation of local people and using their knowledge, enhanced consideration of and adaptation to future change, and supporting the development of systems thinking. Tracing exactly when and how these benefits arose was challenging, but two elements of the method seemed particularly useful. First, using a systematic approach to discuss how drivers of change may affect local social-ecological systems helped to foster systems thinking and identify connections between issues. Second, explicitly focusing on how to use and respond to scenarios helped identify specific practical activities, or “response options,” that would support CBNRM despite the pressures of future change. Discussions about response options also highlighted the need for support by other actors, e.g., policy groups: this raised the question of when and how other actors and other sources of knowledge should be involved in scenario planning, so as to encourage their buy-in to actions identified by the process. We suggest that other CBNRM initiatives may benefit from adapting and applying scenario planning. However, these initiatives should be carefully monitored because further research is required to understand how and when scenario-planning methods may produce benefits, as well as their strengths and weaknesses versus other methods.

The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L−1), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue.

Some biological invasions can result in algae blooms in the nearshore of clear lakes. We studied if an invasive crayfish (Pacifastacus leniusculus) modified the biomass and community composition of benthic macroinvertebrates and therefore led to a trophic cascade resulting in increased periphyton biomass, elevated littoral primary productivity, and benthic algae bloom in a lake with remarkable transparency [Crater Lake, Oregon, USA]. After quantifying the changes in the spatial distribution of invasive crayfish over a 13-year period, we compared biomass and community composition of littoral–benthic macroinvertebrates, periphyton biovolume, community composition, nutrient limitation, and the development of benthic algae bloom in locations with high and low crayfish density. In addition, we determined if the alteration in community structure resulted in directional changes to gross primary production and ecosystem respiration. The extent of crayfish distribution along the shoreline of Crater Lake doubled over a 13-year period, leaving less than 20% of the shoreline free from crayfish. At high crayfish density sites, benthic macroinvertebrate biomass was 99% lower, and taxa richness was 50% lower than at low crayfish areas. High crayfish sites show tenfold greater periphyton biovolume, sixfold higher periphyton biomass (chlorophyll a), twofold higher metabolic productivity, and the presence of large filamentous algae (Cladophora sp.). The invasion of crayfish had negative consequences for a lake protected under the management of the USA National Park Service, with direct impacts on many levels of ecological organization.