The introduction of non-native species is a major driver of biodiversity loss and poses a growing threat to the health and functioning of freshwater ecosystems globally. In recent decades, the pet trade and aquarophilia have become lucrative industries, accelerating the spread of new non-native fishes. This includes various species of Asian loaches that have recently been detected outside their native range in several European countries as well as in the United States and Australia. Using species distribution models, we aim to evaluate the potential of the large-scale loach Paramisgurnus dabryanus and the dojo weatherloach Misgurnus anguillicaudatus to become globally invasive, and explore their impacts on the threatened European weatherfish Misgurnus fossilis. Our results indicate that both loaches have a high potential to become globally invasive, with M. anguillicaudatus appearing more capable of invading broader areas than P. dabryanus. Identified as most vulnerable were temperate regions in Europe, North America, and the south-eastern coast of Australia. The range expansion of these two Asian loaches in Europe could significantly increase their distribution overlap with populations of the native M. fossilis, with projections showing P. dabryanus increasing from a current overlap of 0.5% to 11.8% and M. anguillicaudatus from 0.9% to 90.5%. These findings highlight that the introduction of non-native loaches can pose a substantial threat to M. fossilis, but also other native and especially benthic fishes, as well as macroinvertebrate prey. To halt the spread of these highly invasive fishes, it is essential to prevent new introduction events and conduct further research on their ecology and current global distribution.

The introduction of non-native species is a major driver of biodiversity loss and poses a growing threat to the health and functioning of freshwater ecosystems globally. In recent decades, the pet trade and aquarophilia have become lucrative industries, accelerating the spread of new non-native fishes. This includes various species of Asian loaches that have recently been detected outside their native range in several European countries as well as in the United States and Australia. Using species distribution models, we aim to evaluate the potential of the large-scale loach Paramisgurnus dabryanus and the dojo weatherloach Misgurnus anguillicaudatus to become globally invasive, and explore their impacts on the threatened European weatherfish Misgurnus fossilis. Our results indicate that both loaches have a high potential to become globally invasive, with M. anguillicaudatus appearing more capable of invading broader areas than P. dabryanus. Identified as most vulnerable were temperate regions in Europe, North America, and the south-eastern coast of Australia. The range expansion of these two Asian loaches in Europe could significantly increase their distribution overlap with populations of the native M. fossilis, with projections showing P. dabryanus increasing from a current overlap of 0.5% to 11.8% and M. anguillicaudatus from 0.9% to 90.5%. These findings highlight that the introduction of non-native loaches can pose a substantial threat to M. fossilis, but also other native and especially benthic fishes, as well as macroinvertebrate prey. To halt the spread of these highly invasive fishes, it is essential to prevent new introduction events and conduct further research on their ecology and current global distribution.

Freshwater ecosystems face significant threats from various anthropogenic pressures, including pollution, habitat loss, invasive species, and climate change. To address these challenges, protective regulations and restoration efforts have been implemented at national and international levels, resulting in overall improvements in freshwater biodiversity. However, population recovery of macroinvertebrates at impacted or restored sites is greatly affected by the life-history traits and the dispersive abilities of species. This study focuses on understanding the complex relationship between the ecological quality of stream habitats and the dispersal capacity of macroinvertebrate communities in Europe. More specifically, we investigate the role of overall dispersal capacity metric, and specific dispersal traits, in shaping community recovery and degradation processes.Using a comprehensive dataset of 1,327 time series on macroinvertebrate communities ranging from 1968 to 2021 across 23 European countries, this research investigates how changes in ecological quality influence the dispersal capacity of these communities. The findings reveal that recovering sites with improving ecological quality tend to have more dispersive macroinvertebrate communities, characterized by species with more dispersive traits (e.g. active aquatic and aerial dispersers, species with frequent propensity to drift, insects with two similar-sized pair of wings or with larger wings). By contrast, degrading sites show a reduction in the proportion of strong dispersers. However, our results showed this response varied extensively among regions, and thus, some communities that have increased their ecological quality have not gained macroinvertebrates with higher dispersal capacity.This study emphasizes the importance of considering dispersal capacity when planning and implementing freshwater ecosystem restoration projects. Management strategies should focus on enhancing landscape connectivity to create accessible “source” areas and refugia for sensitive taxa, especially as climate change reshapes habitat suitability. Additionally, biodiversity initiatives must incorporate adaptive decision-making approaches that account for the site-specific responses of macroinvertebrate communities to changes in ecological quality.

Freshwater ecosystems face significant threats from various anthropogenic pressures, including pollution, habitat loss, invasive species, and climate change. To address these challenges, protective regulations and restoration efforts have been implemented at national and international levels, resulting in overall improvements in freshwater biodiversity. However, population recovery of macroinvertebrates at impacted or restored sites is greatly affected by the life-history traits and the dispersive abilities of species. This study focuses on understanding the complex relationship between the ecological quality of stream habitats and the dispersal capacity of macroinvertebrate communities in Europe. More specifically, we investigate the role of overall dispersal capacity metric, and specific dispersal traits, in shaping community recovery and degradation processes.Using a comprehensive dataset of 1,327 time series on macroinvertebrate communities ranging from 1968 to 2021 across 23 European countries, this research investigates how changes in ecological quality influence the dispersal capacity of these communities. The findings reveal that recovering sites with improving ecological quality tend to have more dispersive macroinvertebrate communities, characterized by species with more dispersive traits (e.g. active aquatic and aerial dispersers, species with frequent propensity to drift, insects with two similar-sized pair of wings or with larger wings). By contrast, degrading sites show a reduction in the proportion of strong dispersers. However, our results showed this response varied extensively among regions, and thus, some communities that have increased their ecological quality have not gained macroinvertebrates with higher dispersal capacity.This study emphasizes the importance of considering dispersal capacity when planning and implementing freshwater ecosystem restoration projects. Management strategies should focus on enhancing landscape connectivity to create accessible “source” areas and refugia for sensitive taxa, especially as climate change reshapes habitat suitability. Additionally, biodiversity initiatives must incorporate adaptive decision-making approaches that account for the site-specific responses of macroinvertebrate communities to changes in ecological quality.

Article DOI: 10.1111/faf.12832Eighty years ago, George S. Myers classified inland fishes in three divisions (primary, secondary and peripheral) based on their salinity tolerance and eco-evolutionary history. Although this classification has been followed by many fish studies, it has also received considerable criticism. Here, we aim to test for differences in salinity and thermal tolerance, species traits and distribution patterns among the three divisions using data for about 21,000 species. We found that primary fishes have much less salinity tolerance than secondary and peripheral species, with some secondary fishes displaying the highest tolerances (> 100 ppt). We also provide, for the first time, evidence of significant phylogenetic signal of salinity tolerance, comparable in magnitude to conservative traits, and show that studied peripheral and secondary species have maintained or even developed salinity tolerance, in contrast to primary fishes. Although peripheral fishes are the most different, and despite the large variability observed within some families, primary and secondary species also show differences in morphology and life history traits. The distribution ranges and genetic diversity of primary and secondary fish divisions are similar and differ from peripheral species, suggesting that although there is evidence of oceanic dispersal of a few secondary fishes at evolutionary time scales, it is a rare contemporary phenomenon. Importantly, a few findings outlined in this study, namely differences in salinity tolerance, rely on limited data. Thus, we urge for additional empirical research on the salinity tolerance of freshwater fish, which remains largely unexplored, to help clarify differences among and within clades.

Article DOI: 10.1111/faf.12832Eighty years ago, George S. Myers classified inland fishes in three divisions (primary, secondary and peripheral) based on their salinity tolerance and eco-evolutionary history. Although this classification has been followed by many fish studies, it has also received considerable criticism. Here, we aim to test for differences in salinity and thermal tolerance, species traits and distribution patterns among the three divisions using data for about 21,000 species. We found that primary fishes have much less salinity tolerance than secondary and peripheral species, with some secondary fishes displaying the highest tolerances (> 100 ppt). We also provide, for the first time, evidence of significant phylogenetic signal of salinity tolerance, comparable in magnitude to conservative traits, and show that studied peripheral and secondary species have maintained or even developed salinity tolerance, in contrast to primary fishes. Although peripheral fishes are the most different, and despite the large variability observed within some families, primary and secondary species also show differences in morphology and life history traits. The distribution ranges and genetic diversity of primary and secondary fish divisions are similar and differ from peripheral species, suggesting that although there is evidence of oceanic dispersal of a few secondary fishes at evolutionary time scales, it is a rare contemporary phenomenon. Importantly, a few findings outlined in this study, namely differences in salinity tolerance, rely on limited data. Thus, we urge for additional empirical research on the salinity tolerance of freshwater fish, which remains largely unexplored, to help clarify differences among and within clades.

Article DOI: 10.1111/faf.12832Eighty years ago, George S. Myers classified inland fishes in three divisions (primary, secondary and peripheral) based on their salinity tolerance and eco-evolutionary history. Although this classification has been followed by many fish studies, it has also received considerable criticism. Here, we aim to test for differences in salinity and thermal tolerance, species traits and distribution patterns among the three divisions using data for about 21,000 species. We found that primary fishes have much less salinity tolerance than secondary and peripheral species, with some secondary fishes displaying the highest tolerances (> 100 ppt). We also provide, for the first time, evidence of significant phylogenetic signal of salinity tolerance, comparable in magnitude to conservative traits, and show that studied peripheral and secondary species have maintained or even developed salinity tolerance, in contrast to primary fishes. Although peripheral fishes are the most different, and despite the large variability observed within some families, primary and secondary species also show differences in morphology and life history traits. The distribution ranges and genetic diversity of primary and secondary fish divisions are similar and differ from peripheral species, suggesting that although there is evidence of oceanic dispersal of a few secondary fishes at evolutionary time scales, it is a rare contemporary phenomenon. Importantly, a few findings outlined in this study, namely differences in salinity tolerance, rely on limited data. Thus, we urge for additional empirical research on the salinity tolerance of freshwater fish, which remains largely unexplored, to help clarify differences among and within clades.

Cano‐Barbacil, C., Radinger, J., & García‐Berthou, E. (2020). Reliability analysis of fish traits reveals discrepancies among databases. Freshwater Biology, 65(5), 863-877. https://doi.org/10.1111/fwb.13469
Fish trait data from 19 different data sources of 99 freshwater Iberian fish (native and alien) and consensus database.

Cano‐Barbacil, C., Radinger, J., & García‐Berthou, E. (2020). Reliability analysis of fish traits reveals discrepancies among databases. Freshwater Biology, 65(5), 863-877. https://doi.org/10.1111/fwb.13469
Fish trait data from 19 different data sources of 99 freshwater Iberian fish (native and alien) and consensus database.

Estimates of species’ niche position and breadth is considered fundamental to understanding their ecological and evolutionary responses to natural and anthropogenic environmental change. Methodological challenges arise from the fact that macroecological inference is substantially affected by the selection of a certain geographical extent. This is particularly relevant for understanding alien species introduction success and associated species’ niche characteristics which can be estimated either from their invaded region, their native region, or both. However, surprisingly little is known regarding how the estimation of species niche breadth and position is affected by the geographical extent of investigation, especially for alien species. Here we estimate and compare climatic niche metrics of native and alien Iberian inland fishes using the outlying mean index (OMI) at three different geographical extents spanning from regional to global. Furthermore, we investigate how the introduction date of alien species affects niche characterisation. Our results show that niche metrics differed depending on the geographical extent of the investigation, as well as with respect to species nativity (native vs. alien). Differences in climatic niche position between native and alien species observed at a global scale vanished at a regional scale. The niche breadth of widely distributed alien species was highly underestimated when only considering the invaded region, and further mediated by species’ introduction date into the invaded area. In conclusion, estimating niches of freshwater species, especially of alien invaders should carefully consider the geographical extent of the investigation. We suggest that analyses that jointly consider regional and global scales will improve the estimation of niche characteristics of widely distributed organisms, particularly regarding the climatic niche, and the assessment of the invasive potential of species.