Fish and macroinvertebrate assemblages reveal extensive degradation of the world's rivers

Rivers suffer from multiple stressors acting simultaneously on their biota, but the consequences are poorly quantified at the global scale. We evaluated the biological condition of rivers globally, including the largest proportion of countries from the Global South published to date. We gathered macroinvertebrate- and fish-based assessments from 72,275 and 37,676 sites, respectively, from 64 study regions across six continents and 45 nations. Because assessments were based on differing methods, different systems were consolidated into a 3-class system: Good, Impaired, or Severely Impaired, following common guidelines. The proportion of sites in each class by study area was calculated and each region was assigned a Köppen-Geiger climate type, Human Footprint score (addressing landscape alterations), Human Development Index (HDI) score (addressing social welfare), % rivers with good ambient water quality, % protected freshwater key biodiversity areas; and % of forest area net change rate. We found that 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired, respectively. The poorest biological conditions occurred in Arid and Equatorial climates and the best conditions occurred in Snow climates. Severely Impaired conditions were associated (Pearson correlation coefficient) with higher HDI scores, poorer physico-chemical water quality, and lower proportions of protected freshwater areas. Good biological conditions were associated with good water quality and increased forested areas. It is essential to implement statutory bioassessment programs in Asian, African, and South American countries, and continue them in Oceania, Europe, and North America. There is a need to invest in assessments based on fish, as there is less information globally and fish were strong indicators of degradation. Our study highlights a need to increase the extent and number of protected river catchments, preserve and restore natural forested areas in the catchments, treat wastewater discharges, and improve river connectivity

The relationships between biotic uniqueness and abiotic uniqueness are context dependent across drainage basins worldwide

[EN] Context: Global change, including land-use change and habitat degradation, has led to a decline in biodiversity, more so in freshwater than in terrestrial ecosystems. However, the research on freshwaters lags behind terrestrial and marine studies, highlighting the need for innovative approaches to comprehend freshwater biodiversity. Objectives: We investigated patterns in the relationships between biotic uniqueness and abiotic environmental uniqueness in drainage basins worldwide. Methods: We compiled high-quality data on aquatic insects (mayflies, stoneflies, and caddisflies at genus-level) from 42 drainage basins spanning four continents. Within each basin we calculated biotic uniqueness (local contribution to beta diversity, LCBD) of aquatic insect assemblages, and four types of abiotic uniqueness (local contribution to environmental heterogeneity, LCEH), categorized into upstream land cover, chemical soil properties, stream site landscape position, and climate. A mixed-effects meta-regression was performed across basins to examine variations in the strength of the LCBD-LCEH relationship in terms of latitude, human footprint, and major continental regions (the Americas versus Eurasia). Results: On average, relationships between LCBD and LCEH were weak. However, the strength and direction of the relationship varied among the drainage basins. Latitude, human footprint index, or continental location did not explain significant variation in the strength of the LCBD-LCEH relationship. Conclusions: We detected strong context dependence in the LCBD-LCEH relationship across the drainage basins. Varying environmental conditions and gradient lengths across drainage basins, land-use change, historical contingencies, and stochastic factors may explain these findings. This context dependence underscores the need for basin-specific management practices to protect the biodiversity of riverine systemsSIOpen Access funding provided by University of Oulu (including Oulu University Hospital). The work for this article was supported by the Academy of Finland’s grant to JHeino for the project GloBioTrends (Grant No. 331957). JGG was funded by the European Union Next Generation EU/PRTR (Grant No. AG325). Work by LMB has been continuously supported by the National Council for Scientifc & Technological Development (CNPq) and Fundação de Amparo à Pesquisa do Estado de Goiás (FAPEG) (grants 308974/2020–4 and 465610/2014–5). PB and ZC were fnancially supported by the National Research Development and Innovation Ofce (NKFIH FK 135 136), and PB was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences BO-00106–21. LB thanks the National Council for Scientifc and Technological Development (CNPq) for the Scientifc Initiation Fellowship for JVASS and the productivity fellowship in research to LSB (process nº. 305929/2022–4). MC was awarded National Council for Scientifc & Technological Development (CNPq) research productivity grant 304060/2020–8 and received grants (PPM 00104–18, APQ-00261–22) from the Fundação de Amparo à Pesquisa do Estado de Minas Gerais. SD and JRGM acknowledge funding by the Leibniz Competition (Grant No. J45/2018) and the German Federal Ministry of Education and Research (BMBF grant agreement number no. 033W034A). DRM was supported by National Council for Scientifc & Technological Development (CNPq) (Grant No. PQ-309763–2020-7). DMPC received a postdoctoral scholarship from P&D Aneel- Cemig GT-611. PH was partially funded by the eLTER PLUS project (Grant Agreement No. 871128). LJ is grateful to 33 Forest, CIKEL Ltd. and Instituto de Floresta Tropical (IFT), Biodiversity Research Consortium Brazil-Norway (BRC), and Norsk Hydro for the fnancial and logistical support for sampling. Brazilian National Council for Scientifc and Technological Development (CNPq) is acknowledged for fnancing the projects and for granting a research productivity fellowship to LJ (304710/2019–9). APJF was supported by Conselho Nacional de Desenvolvimento Científco e Tecnológico (CNPq, Brazil, process no. 449315/2014–2 and 481015/2011–6). RL also received a research productivity fellowship from CNPq (grant # 312531/2021–4). MSL received a postdoctoral scholarship from ANEEL/CEMIG (Project GT-599). Part of feld sampling and aquatic insects processing were funded by Conselho Nacional de Desenvolvimento Científco e Tecnológico (CNPq; 403758/2021–1); Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM; Programa Biodiversa) and INCT ADAPTA II – (CNPq: 465540/2014–7; FAPEAM: 062.1187/2017). NH (308970/2019–5) received productivity fellowships from CNPq. RTM received a fellowship from Biodiversa/FAPEAM (01.02.016301.03271/2021–93). KLM acknowledges fnancial support from the Swiss Federal Ofce for the Environment to undertake data collection. Funding for the Segura River basin project was provided by the Seneca Foundation and the European Fund of Regional Development (PLP10/FS/97). FOR was supported by CNPq research grant. TS was partially funded by grant 13/50424–1 and 21/00619–7 from the São Paulo Research Foundation (FAPESP), and by grant 309496/2021–7 from the Conselho Nacional de Desenvolvimento Científco e Tecnológico (CNPq). FVN was supported by grant #2021/13299–0, São Paulo Research Foundation (FAPESP). ALA acknowledges Brazilian National Council for Scientifc and Technological Development (CNPq, Brazil) for granting a postdoctoral scholarship to her (process number: 167873/2022–9

Development of a multimetric index based on aquatic macroinvertebrates to assess the biological integrity in streams of the Bolivian inter-Andean valleys

Se presenta un índice multimétrico que permite discriminar la variabilidad ambiental natural de la antropogénica en 91 sitios (63 sitios de referencia y 28 sitios perturbados) distribuidos de manera uniforme a lo largo de la cuenca alta del Río Grande (Bolivia). En este procedimiento se utilizaron inicialmente 12 métricas que reflejan distintos atributos de la estructura y el funcionamiento de la comunidad de macroinvertebrados acuáticos, por su potencial como indicadoras de alteración de ambientes acuáticos. En principio, usando los sitios de referencia, se desarrollaron modelos estadísticos que describen la respuesta de las distintas métricas a la variabilidad ambiental natural. Luego se utilizaron estos modelos para predecir la respuesta de las métricas en condiciones alteradas, para lo cual se usaron los sitios que presentaban distintos tipos de perturbación antropogénica (i.e., perturbación por actividad agrícola, urbana y minera). De las 12 métricas iniciales se conservaron sólo cinco para elaborar el índice final (riqueza total, abundancia total, riqueza de Ephemeroptera, Plecoptera y Trichoptera (EPT), porcentaje en abundancia de EPT y porcentaje en abundancia de raspadores). Estas métricas resultaron las más efectivas al responder de manera significativa al gradiente de perturbación. Este índice distinguió con claridad los sitios de referencia de los perturbados, y mostró una relación lineal negativa significativa frente a un gradiente de perturbaciones físicas y químicas. Esta aproximación puede servir como herramienta de biomonitoreo para evaluar la integridad biótica y la biodiversidad acuática en los ríos de la región de los valles interandinos de Bolivia.We developed a multimetric index that could discriminate natural from anthropogenic variability in 91 sites (63 reference sites and 28 disturbed sites) fairly evenly distributed across the upper Grande River Basin (Bolivia). To do so, we examined 12 candidate metrics for their potential to indicate degradation and reflecting different aspects of macroinvertebrate assemblage structure and function. Initially, using the reference sites, we developed statistical models describing the response of the different metrics to the natural environmental variability. In a second step, using sites experiencing three types of anthropogenic disturbances (i.e., agriculture, urban and mining activities), we quantified the deviation in the response of each metric model between reference and disturbed conditions. From the initial 12 metrics, we retained only 5 metrics in the final index (total richness, total abundance, richness of Ephemeroptera, Plecoptera and Trichoptera (EPT), percentage of EPT abundance and percentage of scrapers abundance). These metrics were the most effective ones in responding to anthropogenic disturbances. Our final index performed well in discriminating between reference and disturbed sites, giving a significant negative linear response to a gradient of physical and chemical anthropogenic disturbances. This index can be used as a monitoring tool to evaluate the biological integrity and aquatic biodiversity of the Bolivian inter-Andean valleys streams.Fil: Moya, Nabor. Universidad Mayor de San Simón; BoliviaFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Goitia, Edgar. Universidad Mayor de San Simón; BoliviaFil: Oberdorff, Thierry. Muséum National d'Histoire Naturelle; Franci

Comparison of aquatic macroinvertebrate communities from Intermittent and perennial bolivian headwater andean Streams: implications for future climate change

El impacto de la estacionalidad de los ríos sobre las comunidades de macroinvertebrados fue estudiado en ríos de la zona Altoandina de Bolivia, durante la época de transición y época seca del año 2008. En nueve arroyos intermitentes y nueve permanentes se colectaron muestras de macroinvertebrados y parámetros ambientales. A traves de análisis multivariados, se determinaron relaciones entre variables biológicas (según riqueza, abundancia, composición trófica y rasgos biológicos) con las variables ambientales. La estacionalidad no tuvo efecto significativo sobre la riqueza ni densidad de macroinvertebrados, tampoco se encontraron efectos notorios sobre la composición trófica ni los rasgos biológicos (tipo de respiración), pero sí encontramos diferencias significativas en la composición taxonómica, especialmente en la proporción de Ephemeroptera, Plecoptera y Trichoptera (EPT); asimismo, encontramos que existen otras variables ambientales como la profundidad, solidos disueltos y pH que tienen mayor efecto que la intermitencia en la riqueza y densidad total. De acuerdo a datos climáticos de la región Andina de Bolivia se sabe que en el futuro habrá una disminución del agua, incluso la desecación temporal en varios ríos de la zona, esto debido a la disminución de los glaciares. De esta manera, el futuro cambio climático reflejado a través de la estacionalidad de los ríos, tendrá mayor efecto en los cambios de la estructura taxonómica que en la estructura funcional, lo que indica que probablemente tendrá implicaciones más fuertes en la conservación de taxa que en la composición de los rasgos de la comunidad de macroinvertebrados.The impact of hydrologic non-permanence (intermittent streams) on benthic macroinvertebrate communities was investigated in Bolivian head Andean streams. Samples of benthic macroinvertebrates and environmental variables were taken in nine intermittent and nine permanent streams during dry and transition to dry seasons during 2008. Using different multivariate analyses, we determined relationships between biological variables (richness, density, trophic composition and biological traits) and environmental variables. Hydrologic non-permanence had no significant effect on total species richness, total density, trophic composition or physiological traits (i.e. respiration). However, significant effects were found on taxonomic composition, specifically on taxonomic richness of Ephemeroptera, Plecoptera and Trichoptera. Likewise, we found that environmental variables such as profundity, total dissolved solids and pH have more important effects on total richness and density than hydrologic non-permanence itself. Thus, climate change would likely have stronger implications for taxa conservation than for the functional characteristics of stream macroinvertebrate communities.Fil: Moya, Nabor. Universidad Mayor de San Simón; BoliviaFil: Gibon, François Marie. Muséum National d'Histoire Naturelle; FranciaFil: Oberdorff, Thierry. Muséum National d'Histoire Naturelle; FranciaFil: Rosales, Claudio. Universidad Mayor de San Andrés; BoliviaFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentin

Context-dependent resistance of freshwater invertebrate communities to drying

International audienceMore freshwater ecosystems are drying in response to global change thereby posing serious threat to freshwater biota and functions. The production of desiccation-resistant forms is an important adaptation that helps maintain biodiversity in temporary freshwa-ters by buffering communities from drying, but its potential to mitigate the negative effects of drying in freshwater ecosystems could vary greatly across regions and ecosystem types. We explored this context dependency by quantifying the potential contribution of desiccation-resistance forms to invertebrate community recovery across levels of regional drying prevalence (defined as the occurrence of drying events in freshwaters in a given region) and ecosystem types (lentic, lotic) in temporary neotropical freshwaters. We first predicted that regional drying prevalence influences the selection of species with desiccation-resistant forms from the regional species pools and thus increases the ability of communities to recover from drying. Second, we predicted lentic freshwaters harbor higher proportions of species with desiccation-resistant forms compared to lotic, in response to contrasted hydrologic connectivity. To test these predictions, we used natural experiments to quantify the contribution of desiccation-resistant forms to ben-thic invertebrate community recovery in nine intermittent streams and six geographically isolated temporary wetlands from three Bolivian regions differing in drying prevalence. The contribution of desiccation-resistant forms to community recovery was highest where regional drying prevalence was high, suggesting the species pool was adapted to regional disturbance regimes. The contribution of desiccation-resistant forms to community recovery was lower in streams than in wetlands, emphasizing the importance of hydrologic connectivity and associated recolonization processes from in-stream refuges to recovery in lotic systems. In all regions, the majority of functional traits were present in desiccation-resistant taxa indicating this adaptation may help maintain ecosystem functions by buffering communities from the loss of functional traits. Accounting for regional context and hydrologic connectivity in community recovery processes following drying can help refine predictions of freshwater biodiversity response to global change

Assemblage-based biomonitoring of freshwater ecosystem health via multimetric indices: A critical review and suggestions for improving their applicability

Freshwater biota are more comprehensive and direct indicators of biological impacts, and more meaningful to the public than water quality or physical habitat surrogates. Freshwater biotic data and the multiple biological indicators developed from them offer a much richer array of data for assessing the impacts of pollution controls than a limited set of physical or chemical measures. In recent decades, assemblage-based assessments by ecologists, environmental scientists, and water quality agencies have been employed globally for determining the condition of, and threats to, freshwater ecosystems. A key step in this advance has been the development of multimetric indices (MMIs) or indices of biotic integrity (IBIs) based on quantitative assessments of algae, macrophyte, macroinvertebrate, fish or riparian bird assemblages. In Europe, where biological assemblages are mandated for assessing freshwater ecosystem health, many indices are multimetric. However, the proliferation of MMIs globally has not always occurred through the application of rigorous study designs and monitoring protocols, nor have they always effectively incorporated functional metrics, stressor assessments, and statistical analyses. Therefore, in this review, we discuss eleven major concerns with the development and application (including logistical limitations) of multimetric indicators based on freshwater biota to encourage more rigorous and widely applicable (transferable) MMI use and implementation. Specifically, our concerns focus on reference conditions; sampling effort, methods, and season; trophic guild definition; metric comprehensiveness, options, screening and scoring; and MMI validation. MMIs could also benefit from increased attention to ecological mechanisms and metric development, to further improve our understanding of anthropogenic impacts as well as rehabilitation effects on freshwater ecosystems globally. Paying closer attention to study designs, ecological mechanisms and metric development should further improve our understanding of anthropogenic impacts and better facilitate rehabilitation of degraded freshwater ecosystems, as well as aiding in the conservation of healthy freshwater ecosystems globally

Securing Biodiversity, Functional Integrity, and Ecosystem Services in Drying River Networks (DRYvER)

International audienceRiver networks are among Earth’s most threatened hot-spots of biodiversity and provide key ecosystem services (e.g., supply drinking water and food, climate regulation) essential to sustaining human well-being. Climate change and increased human water use are causing more rivers and streams to dry, with devastating impacts on biodiversity and ecosystem services. Currently, more than a half of the global river networks consist of drying channels, and these are expanding dramatically. However, drying river networks (DRNs) have received little attention from scientists and policy makers, and the public is unaware of their importance. Consequently, there is no effective integrated biodiversity conservation or ecosystem management strategy of DRNs. A multidisciplinary team of 25 experts from 11 countries in Europe, South America, China and the USA will build on EU efforts to assess the cascading effects of climate change on biodiversity, ecosystem functions and ecosystem services of DRNs through changes in flow regimes and water use. DRYvER (DRYing riVER networks) will gather and upscale empirical and modelling data from nine focal DRNs (case studies) in Europe (EU) and Community of Latin American and Caribbean States (CELAC) to develop a meta-system framework applicable to Europe and worldwide. It will also generate crucial knowledge-based strategies, tools and guidelines for economically-efficient adaptive management of DRNs. Working closely with stakeholders and end-users, DRYvER will co-develop strategies to mitigate and adapt to climate change impacts in DRNs, integrating hydrological, ecological (including nature-based solutions), socio-economic and policy perspectives. The end results of DRYvER will contribute to reaching the objectives of the Paris Agreement and placing Europe at the forefront of research on climate change