Unravelling large-scale patterns and drivers of biodiversity in dry rivers.

More than half of the world's rivers dry up periodically, but our understanding of the biological communities in dry riverbeds remains limited. Specifically, the roles of dispersal, environmental filtering and biotic interactions in driving biodiversity in dry rivers are poorly understood. Here, we conduct a large-scale coordinated survey of patterns and drivers of biodiversity in dry riverbeds. We focus on eight major taxa, including microorganisms, invertebrates and plants: Algae, Archaea, Bacteria, Fungi, Protozoa, Arthropods, Nematodes and Streptophyta. We use environmental DNA metabarcoding to assess biodiversity in dry sediments collected over a 1-year period from 84 non-perennial rivers across 19 countries on four continents. Both direct factors, such as nutrient and carbon availability, and indirect factors such as climate influence the local biodiversity of most taxa. Limited resource availability and prolonged dry phases favor oligotrophic microbial taxa. Co-variation among taxa, particularly Bacteria, Fungi, Algae and Protozoa, explain more spatial variation in community composition than dispersal or environmental gradients. This finding suggests that biotic interactions or unmeasured ecological and evolutionary factors may strongly influence communities during dry phases, altering biodiversity responses to global changes.

The global contribution of vultures towards ecosystem services and sustainability: An experts' perspective.

The ecosystem services framework is essential for biodiversity conservation, emphasizing the role of nature in achieving sustainable development goals (SDGs). This study offers a global view on vulture-associated ecosystem services and their SDG contributions, based on insights from 206 experts. The findings reveal global consensus on the importance of vultures in regulation and maintenance services, such as waste recycling and disease control. Cultural services attributed to vultures are moderate and vary regionally. Provisioning services are consistently rated low across all regions. Experts' views on vultures' key ecosystem roles are often biased toward well-known services and may not align with all scientific evidence. The study emphasizes vultures' role in achieving SDGs, particularly impacting life on land and health, and calls for reevaluating their contribution to sustainable practices. It stresses the need to customize conservation to regional values and perceptions, recognizing vultures' critical role in ecological balance, public health, and sustainable development.

Drivers of species knowledge across the tree of life.

Knowledge of biodiversity is unevenly distributed across the Tree of Life. In the long run, such disparity in awareness unbalances our understanding of life on Earth, influencing policy decisions and the allocation of research and conservation funding. We investigated how humans accumulate knowledge of biodiversity by searching for consistent relationships between scientific (number of publications) and societal (number of views in Wikipedia) interest, and species-level morphological, ecological, and sociocultural factors. Across a random selection of 3019 species spanning 29 Phyla/Divisions, we show that sociocultural factors are the most important correlates of scientific and societal interest in biodiversity, including the fact that a species is useful or harmful to humans, has a common name, and is listed in the International Union for Conservation of Nature Red List. Furthermore, large-bodied, broadly distributed, and taxonomically unique species receive more scientific and societal attention, whereas colorfulness and phylogenetic proximity to humans correlate exclusively with societal attention. These results highlight a favoritism toward limited branches of the Tree of Life, and that scientific and societal priorities in biodiversity research broadly align. This suggests that we may be missing out on key species in our research and conservation agenda simply because they are not on our cultural radar.

Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter.

Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico-chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%-98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.

Freshwater macroinvertebrate samples from a water quality monitoring network in the Iberian Peninsula.

This dataset gathers information about the macroinvertatebrate samples and environmental variables collected on rivers of the Ebro River Basin (NE Iberian Peninsula), the second largest catchment in the Iberian Peninsula. The collection is composed of 1,776 sampling events carried out between 2005 and 2015 at more than 400 sampling sites. This dataset is part of a monitoring network set up by the Ebro Hydrographic Confederation, the official body entrusted with the care of the basin, to fulfill the requirements of the European Water Framework Directive. Biological indices based on the freshwater macroinvertebrate communities were used to evaluate the ecological status of the water bodies within the basin. Samples were qualitatively screened for all occurring taxa. Then, all individuals from all taxa in a quantitative subsample of each sample were counted. Biological indices were calculated to estimate water quality at each sampling site. All samples are kept at the Museum of Zoology of the University of Navarra.