Martin A. Wilkes, Mansi Mungee, Marc Naura, Vicky A. Bell, Lee E. Brown
The Global Biodiversity Framework established ambitious goals for nature recovery which governments must now incorporate into national legislation. In England, legally binding targets require authorities to halt the decline in species abundance by 2030 and reverse the decline by 2042. Riverine invertebrates represent a substantial proportion of the species contributing towards the targets. Thus, understanding the response of these species to potential river restoration actions is key to target delivery. We model counts for 188 riverine invertebrate taxa using zero-inflated generalized Poisson models, applying the models to both inform river restoration planning and set expected values for use in ecological assessment. We identify catchment-specific restoration strategies that combine one or more actions involving the removal of channel modifications, reductions in nitrate concentrations and reductions in total dissolved phosphorus concentrations as the most likely to deliver species abundance targets across three joint climate–socioeconomic scenarios. By hindcasting species abundances under alternative target frameworks, we also demonstrate a new approach to setting expected values in ecological assessment, accounting for changes in water temperature and hydrology that confound historical reference models presently used by regulators. Our findings represent the first systematic attempt to prioritise major actions to deliver species abundance targets in England, providing valuable insights for policymakers, river restoration practitioners and authorities responsible for monitoring river ecosystems.
{"title":"Predicting nature recovery for river restoration planning and ecological assessment: A case study from England, 1991–2042","authors":"Martin A. Wilkes, Mansi Mungee, Marc Naura, Vicky A. Bell, Lee E. Brown","doi":"10.1002/rra.4282","DOIUrl":"https://doi.org/10.1002/rra.4282","url":null,"abstract":"The Global Biodiversity Framework established ambitious goals for nature recovery which governments must now incorporate into national legislation. In England, legally binding targets require authorities to halt the decline in species abundance by 2030 and reverse the decline by 2042. Riverine invertebrates represent a substantial proportion of the species contributing towards the targets. Thus, understanding the response of these species to potential river restoration actions is key to target delivery. We model counts for 188 riverine invertebrate taxa using zero-inflated generalized Poisson models, applying the models to both inform river restoration planning and set expected values for use in ecological assessment. We identify catchment-specific restoration strategies that combine one or more actions involving the removal of channel modifications, reductions in nitrate concentrations and reductions in total dissolved phosphorus concentrations as the most likely to deliver species abundance targets across three joint climate–socioeconomic scenarios. By hindcasting species abundances under alternative target frameworks, we also demonstrate a new approach to setting expected values in ecological assessment, accounting for changes in water temperature and hydrology that confound historical reference models presently used by regulators. Our findings represent the first systematic attempt to prioritise major actions to deliver species abundance targets in England, providing valuable insights for policymakers, river restoration practitioners and authorities responsible for monitoring river ecosystems.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"35 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140571697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many river reaches have transitioned to heavily vegetated systems following the regulation of their flow regime. Vegetation recruitment and survival are key to these transformations. We propose a novel predictive approach to detect how changes in the flow regime may affect conditions for successful vegetation recruitment and survival in channelized rivers with alternate bars. Our approach combines elements of existing vegetation recruitment models (Recruitment Box and Window of Opportunity) with simplified morphodynamic predictions of alternate bar migration. The approach is illustrated by applying it to a reach of the regulated Isère river, SE France, which has transitioned from migrating, unvegetated to steady, vegetated alternate bars over two decades following flow regulation associated with hydropower development. Our modelling approach identifies a strong impact of modified summer flows on vegetation recruitment since 1950 when major flow regulation began. An increase of up to 1 cm year−1 (after 1990) has occurred in the vertical extent of vegetation recruitment bands on the bars. This has been accompanied by an almost 20 m total increase (since 1950) in the horizontal extent of the recruitment bands, and a 1.5 times reduction in the frequency of high flows capable of promoting bar migration. Our modelling also suggests viable flow restoration options to limit widespread vegetation colonisation. Comparing outcomes from our modelling approach with those from the Bertagni et al. (2018) model suggests that the Isère may have been highly prone to vegetation colonisation even before flow regulation and close to some threshold for a shift from an unvegetated to a vegetated state.
{"title":"Modelling flow regulation effects on vegetation recruitment and survival on alternate bars in channelized rivers","authors":"Alyssa Serlet, Angela Gurnell, Guido Zolezzi","doi":"10.1002/rra.4278","DOIUrl":"https://doi.org/10.1002/rra.4278","url":null,"abstract":"Many river reaches have transitioned to heavily vegetated systems following the regulation of their flow regime. Vegetation recruitment and survival are key to these transformations. We propose a novel predictive approach to detect how changes in the flow regime may affect conditions for successful vegetation recruitment and survival in channelized rivers with alternate bars. Our approach combines elements of existing vegetation recruitment models (Recruitment Box and Window of Opportunity) with simplified morphodynamic predictions of alternate bar migration. The approach is illustrated by applying it to a reach of the regulated Isère river, SE France, which has transitioned from migrating, unvegetated to steady, vegetated alternate bars over two decades following flow regulation associated with hydropower development. Our modelling approach identifies a strong impact of modified summer flows on vegetation recruitment since 1950 when major flow regulation began. An increase of up to 1 cm year<sup>−1</sup> (after 1990) has occurred in the vertical extent of vegetation recruitment bands on the bars. This has been accompanied by an almost 20 m total increase (since 1950) in the horizontal extent of the recruitment bands, and a 1.5 times reduction in the frequency of high flows capable of promoting bar migration. Our modelling also suggests viable flow restoration options to limit widespread vegetation colonisation. Comparing outcomes from our modelling approach with those from the Bertagni et al. (2018) model suggests that the Isère may have been highly prone to vegetation colonisation even before flow regulation and close to some threshold for a shift from an unvegetated to a vegetated state.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"6 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140571703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A philosophical and communication shift is needed in river management if we are to meet sustainable development goals and tackle environmental challenges brought about by ongoing anthropogenic and climate change. In some parts of the world, recovery‐enhancement approaches to river management have been adopted, communicated and used for many years. At the heart of these approaches lies an understanding of the biogeomorphic forms, processes and evolutionary trajectories of rivers that differs philosophically from notions of restoration, rewilding or creation of a utopian natural state. Instead, recovery‐enhancement approaches aim to improve the biogeomorphic condition of rivers, recognising that they are dynamic entities and new evolutionary trajectories and novel ecosystems are being created that are now part of the environment. Accepting shifting baselines and moving targets is inherent as boundary conditions (water, sediment and vegetation interactions) continue to be altered under the influence of anthropogenic and climate change, and the impacts of ‘unprecedented’ wildfires, floods, heatwaves and drought are manifested on the ground. The river management sector has not yet fully adapted to this reality with large amounts of applied science and on‐ground practice still focussed on restoration, re‐engineering and rewilding, words which in themselves produce a false impression of the aims, visions and achievability of river management. Embracing recovery‐enhancement approaches to river management requires a conscious shift in communication strategies and terminology to present more realistic expectations and possibilities for river condition improvement, a responsibility that is incumbent upon us, the scientists and practitioners, who work in the applied science and river management profession. In this Short Communication, I use a case study from eastern Australia to illustrate what biogeomorphic river recovery can look like. I use this to discuss the potential for adoption of a recovery‐enhancement approach to river management more broadly, and call on scientists and practitioners to make a conscious philosophical and communications shift when working in applied science and river management.
{"title":"Leveraging understandings of biogeomorphic river recovery to reframe river management philosophy and communication strategies","authors":"Kirstie Fryirs","doi":"10.1002/rra.4272","DOIUrl":"https://doi.org/10.1002/rra.4272","url":null,"abstract":"A philosophical and communication shift is needed in river management if we are to meet sustainable development goals and tackle environmental challenges brought about by ongoing anthropogenic and climate change. In some parts of the world, recovery‐enhancement approaches to river management have been adopted, communicated and used for many years. At the heart of these approaches lies an understanding of the biogeomorphic forms, processes and evolutionary trajectories of rivers that differs philosophically from notions of restoration, rewilding or creation of a utopian natural state. Instead, recovery‐enhancement approaches aim to improve the biogeomorphic condition of rivers, recognising that they are dynamic entities and new evolutionary trajectories and novel ecosystems are being created that are now part of the environment. Accepting shifting baselines and moving targets is inherent as boundary conditions (water, sediment and vegetation interactions) continue to be altered under the influence of anthropogenic and climate change, and the impacts of ‘unprecedented’ wildfires, floods, heatwaves and drought are manifested on the ground. The river management sector has not yet fully adapted to this reality with large amounts of applied science and on‐ground practice still focussed on restoration, re‐engineering and rewilding, words which in themselves produce a false impression of the aims, visions and achievability of river management. Embracing recovery‐enhancement approaches to river management requires a conscious shift in communication strategies and terminology to present more realistic expectations and possibilities for river condition improvement, a responsibility that is incumbent upon us, the scientists and practitioners, who work in the applied science and river management profession. In this Short Communication, I use a case study from eastern Australia to illustrate what biogeomorphic river recovery can look like. I use this to discuss the potential for adoption of a recovery‐enhancement approach to river management more broadly, and call on scientists and practitioners to make a conscious philosophical and communications shift when working in applied science and river management.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"237 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140571690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brett J. Montgomery, Heather L. Bateman, Fábio S. D. Albuquerque
Arizona toad (Anaxyrus microscaphus) is a stream‐breeding bufonid of conservation concern in Arizona, New Mexico, Utah, and Nevada. We determined the occupancy and habitat use of the Arizona toad throughout its range. We surveyed 500‐m reaches along perennial and intermittent streams during the summers of 2021 and 2022 (n = 232) in Arizona. We recorded the presence of all toad life stages, focusing on larval stages. We related toad occupancy to broadscale environmental variables, including measures of bioclimate, habitat heterogeneity, solar radiation, and topography. We collected fine‐scale variables to summarize vegetation cover and substrate within plots (n = 53). We applied multiple occupancy models. Single‐species model results found low toad occupancy with high detection. Two principal component analyses (PCA) were run on broadscale and fine‐scale variables to reduce the number of variables included in the models. Toad occupancy was best predicted by top models with bioclimatic components; occupancy decreases with extremely hot temperatures and less precipitation. A logistic regression related toad presence to fine‐scale components with top models describing riparian complexity and algae. Arizona toads were selected for areas with foliar canopy cover, shallow water, algae cover, and pebble substrates. Arizona toad is an uncommon species and maintaining riparian forests of complex habitats with shallow and side‐channel flow will be important for toad conservation. Implications of less water cause riparian habitat to dry, which ultimately harms aquatic life.
{"title":"Broadscale and fine‐scale variables predict the occurrence of a stream‐breading bufonid: Habitat use by the Arizona toad (Anaxyrus microscaphus)","authors":"Brett J. Montgomery, Heather L. Bateman, Fábio S. D. Albuquerque","doi":"10.1002/rra.4279","DOIUrl":"https://doi.org/10.1002/rra.4279","url":null,"abstract":"Arizona toad (<jats:italic>Anaxyrus microscaphus</jats:italic>) is a stream‐breeding bufonid of conservation concern in Arizona, New Mexico, Utah, and Nevada. We determined the occupancy and habitat use of the Arizona toad throughout its range. We surveyed 500‐m reaches along perennial and intermittent streams during the summers of 2021 and 2022 (<jats:italic>n</jats:italic> = 232) in Arizona. We recorded the presence of all toad life stages, focusing on larval stages. We related toad occupancy to broadscale environmental variables, including measures of bioclimate, habitat heterogeneity, solar radiation, and topography. We collected fine‐scale variables to summarize vegetation cover and substrate within plots (<jats:italic>n</jats:italic> = 53). We applied multiple occupancy models. Single‐species model results found low toad occupancy with high detection. Two principal component analyses (PCA) were run on broadscale and fine‐scale variables to reduce the number of variables included in the models. Toad occupancy was best predicted by top models with bioclimatic components; occupancy decreases with extremely hot temperatures and less precipitation. A logistic regression related toad presence to fine‐scale components with top models describing riparian complexity and algae. Arizona toads were selected for areas with foliar canopy cover, shallow water, algae cover, and pebble substrates. Arizona toad is an uncommon species and maintaining riparian forests of complex habitats with shallow and side‐channel flow will be important for toad conservation. Implications of less water cause riparian habitat to dry, which ultimately harms aquatic life.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"237 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140571702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this article, we track the evolution of fluvial biogeomorphology from the middle of the 20th century to the present. We consider the emergence of fluvial biogeomorphology as an interdisciplinary research area that integrates knowledge drawn primarily from fluvial geomorphology and plant ecology, but with inputs from hydrology and landscape ecology. We start by assembling evidence for the emergence of the field of fluvial biogeomorphology with a keyword search of the Web of Science and a detailed analysis of papers published in two scientific journals: a geomorphology journal—Earth Surface Processes and Landforms; a multidisciplinary river science journal—River Research and Applications. Based on this evidence, we identify three distinct time periods in the development of fluvial biogeomorphology: the ‘early years’ before 1990; the transitional decade of the 1990s; and the period of rapid expansion and diversification in themes, methods and investigation scales since 2000. Because the literature is vast, we can only summarize developments in each of these time periods, but we refer to recent in‐depth reviews and conceptual perspectives on relevant topics. Thus, rather than a full and deep review, we present an annotated bibliographic overview of the development of fluvial biogeomorphology, whereby the text describes broad trends but is supported by tables of citations that can deliver greater detail. We end with a brief consideration of likely future developments.
在这篇文章中，我们追踪了从 20 世纪中叶至今河川生物地貌学的演变过程。我们认为河川生物地貌学是一个跨学科研究领域，它整合了主要来自河川地貌学和植物生态学的知识，同时也吸收了水文学和景观生态学的知识。我们首先通过对 Web of Science 的关键词搜索和对两份科学杂志上发表的论文的详细分析，收集了河川生物地貌学领域出现的证据：一份地貌学杂志--《地球表面过程与地貌》；一份多学科河流科学杂志--《河流研究与应用》。根据这些证据，我们确定了河川生物地貌学发展的三个不同时期：1990 年前的 "早期"；20 世纪 90 年代的过渡十年；2000 年以来在主题、方法和调查规模方面迅速扩展和多样化的时期。由于文献浩如烟海，我们只能对每个时期的发展进行总结，但我们会参考近期对相关主题的深入评论和概念性观点。因此，与其说是全面而深入的综述，不如说是对河流生物地貌学发展的注释式文献综述，文中描述的是大趋势，但通过引文表可以提供更多细节。最后，我们对未来可能的发展进行了简要探讨。
{"title":"Plants and river morphodynamics: The emergence of fluvial biogeomorphology","authors":"A. M. Gurnell, W. Bertoldi","doi":"10.1002/rra.4271","DOIUrl":"https://doi.org/10.1002/rra.4271","url":null,"abstract":"In this article, we track the evolution of fluvial biogeomorphology from the middle of the 20th century to the present. We consider the emergence of fluvial biogeomorphology as an interdisciplinary research area that integrates knowledge drawn primarily from fluvial geomorphology and plant ecology, but with inputs from hydrology and landscape ecology. We start by assembling evidence for the emergence of the field of fluvial biogeomorphology with a keyword search of the Web of Science and a detailed analysis of papers published in two scientific journals: a geomorphology journal—Earth Surface Processes and Landforms; a multidisciplinary river science journal—River Research and Applications. Based on this evidence, we identify three distinct time periods in the development of fluvial biogeomorphology: the ‘early years’ before 1990; the transitional decade of the 1990s; and the period of rapid expansion and diversification in themes, methods and investigation scales since 2000. Because the literature is vast, we can only summarize developments in each of these time periods, but we refer to recent in‐depth reviews and conceptual perspectives on relevant topics. Thus, rather than a full and deep review, we present an annotated bibliographic overview of the development of fluvial biogeomorphology, whereby the text describes broad trends but is supported by tables of citations that can deliver greater detail. We end with a brief consideration of likely future developments.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"46 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140571722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fish stranding in rivers, due to rapid shoreline dewatering, often occurs during the down‐ramping phase of hydropeaks, which enables peak energy production. Multiple hydropeaking characteristics and river morphology influence stranding, but little is known about the effects of riverbed microstructures. Our goal was to identify how the combination of hydropeaking characteristics and the occurrence of morphological microstructures (e.g., puddles and scour pools) influences fish stranding. For this purpose, we used an extensive dataset of fish stranding observations collected over 3 years in spring at 48 sites along a 50 km‐long reach of the Ain River, France. We aimed (1) to characterize stranding events and their associated fish assemblages and (2) to identify the spatial and temporal determinants of stranding. The occurrence of morphological microstructures was the main factor explaining fish stranding. Scour pools had a strong impact, followed by scour puddles, humid zones, and alluvial puddles. Then, hydropeaking characteristics interacted with morphology and modulated the intensity of stranding. Low flow ranges (low peak flow and low base flow) occurring after periods without hydropeaks induced ‘salmonid fry’ stranding events and ‘super‐stranding’ events (massive stranding of many taxa). Other flow ranges induced ‘regular cyprinid fry’ stranding events. Salmonids were particularly subject to stranding at the beginning of the sampling period. Recommendations are (1) to act in priority on sites where stranding is most likely, by morphological operations or by installing attractive structures in the perennial area and (2) to maintain attractive, perennial habitats in the low flow range of hydropeaks, for example, by increasing base flow.
{"title":"Characterizing the effects of morphological microstructures and hydropeaks on fish stranding in rivers","authors":"Flora Insulaire, Nicolas Lamouroux, Agnès Barillier, Amael Paillex, Hervé Capra, Franck Cattaneo, Véronique Gouraud","doi":"10.1002/rra.4277","DOIUrl":"https://doi.org/10.1002/rra.4277","url":null,"abstract":"Fish stranding in rivers, due to rapid shoreline dewatering, often occurs during the down‐ramping phase of hydropeaks, which enables peak energy production. Multiple hydropeaking characteristics and river morphology influence stranding, but little is known about the effects of riverbed microstructures. Our goal was to identify how the combination of hydropeaking characteristics and the occurrence of morphological microstructures (e.g., puddles and scour pools) influences fish stranding. For this purpose, we used an extensive dataset of fish stranding observations collected over 3 years in spring at 48 sites along a 50 km‐long reach of the Ain River, France. We aimed (1) to characterize stranding events and their associated fish assemblages and (2) to identify the spatial and temporal determinants of stranding. The occurrence of morphological microstructures was the main factor explaining fish stranding. Scour pools had a strong impact, followed by scour puddles, humid zones, and alluvial puddles. Then, hydropeaking characteristics interacted with morphology and modulated the intensity of stranding. Low flow ranges (low peak flow and low base flow) occurring after periods without hydropeaks induced ‘salmonid fry’ stranding events and ‘super‐stranding’ events (massive stranding of many taxa). Other flow ranges induced ‘regular cyprinid fry’ stranding events. Salmonids were particularly subject to stranding at the beginning of the sampling period. Recommendations are (1) to act in priority on sites where stranding is most likely, by morphological operations or by installing attractive structures in the perennial area and (2) to maintain attractive, perennial habitats in the low flow range of hydropeaks, for example, by increasing base flow.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"30 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140572333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jamal Kabir, Giulio Biondi, Kieran J. Gething, Thomas Aspin, Tim Sykes, Rachel Stubbington
Headwater springs and streams often occur in relatively remote areas, reducing their exposure to human influences and thus increasing their collective capacity to support high biodiversity. Their aquatic macroinvertebrate communities can include species of conservation interest, some of which are specialists associated with groundwater inputs, low water temperature or temporary flow. However, the inaccessibility of some spring and stream networks has left their communities poorly characterized, limiting our capacity to implement effective conservation strategies. We characterized the biodiversity and conservation value of macroinvertebrate communities in a network of 51 relatively inaccessible and unimpacted headwater spring and stream sites spanning multiple catchments in a single landscape type: the chalk downland of south England. At each site, we kick sampled macroinvertebrate communities and recorded environmental variables, including flow permanence. To represent each community, we calculated taxa richness, coverage-adjusted Hill-Shannon diversity, the local contribution to beta diversity, and an index of richness and species rarity. We used the latter three metrics to rank sites based on their biodiversity and conservation value and analyzed relationships between metrics and environmental variables. We found specialists of springs, cold waters, groundwaters and temporary flow regimes, including rare species of conservation value. Some metrics responded to environmental variables, but top-ranking sites had highly variable environmental characteristics. We highlight the value of individual headwater streams with contrasting characteristics as contributors to ecologically heterogeneous site networks. Our results can inform landscape-scale management strategies that protect headwaters as refuges that support biodiverse communities, including rare species, as they adapt to global change.
{"title":"Spring forth diversity: Specialist species contribute to the conservation value of headwater springs and streams at the landscape scale","authors":"Jamal Kabir, Giulio Biondi, Kieran J. Gething, Thomas Aspin, Tim Sykes, Rachel Stubbington","doi":"10.1002/rra.4275","DOIUrl":"https://doi.org/10.1002/rra.4275","url":null,"abstract":"Headwater springs and streams often occur in relatively remote areas, reducing their exposure to human influences and thus increasing their collective capacity to support high biodiversity. Their aquatic macroinvertebrate communities can include species of conservation interest, some of which are specialists associated with groundwater inputs, low water temperature or temporary flow. However, the inaccessibility of some spring and stream networks has left their communities poorly characterized, limiting our capacity to implement effective conservation strategies. We characterized the biodiversity and conservation value of macroinvertebrate communities in a network of 51 relatively inaccessible and unimpacted headwater spring and stream sites spanning multiple catchments in a single landscape type: the chalk downland of south England. At each site, we kick sampled macroinvertebrate communities and recorded environmental variables, including flow permanence. To represent each community, we calculated taxa richness, coverage-adjusted Hill-Shannon diversity, the local contribution to beta diversity, and an index of richness and species rarity. We used the latter three metrics to rank sites based on their biodiversity and conservation value and analyzed relationships between metrics and environmental variables. We found specialists of springs, cold waters, groundwaters and temporary flow regimes, including rare species of conservation value. Some metrics responded to environmental variables, but top-ranking sites had highly variable environmental characteristics. We highlight the value of individual headwater streams with contrasting characteristics as contributors to ecologically heterogeneous site networks. Our results can inform landscape-scale management strategies that protect headwaters as refuges that support biodiverse communities, including rare species, as they adapt to global change.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"13 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140571664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joshua Everett Williams, Stan Gregory, Randall Wildman
Understanding complex river floodplains is critical to conserve species of fish and their ecological functions. In 2011 through 2013, longitudinal gradients in fish assemblage were investigated in the Willamette River in western United States. Of 36,586 individual fish collected, 93% were native and 7% non-native. The best predictors of fishes collected with a boat electrofisher were percent embeddedness, macrophytes, longitudinal river distance, average depth, and velocity. Habitat type (mainstem or slough) was also a significant predictor. The best predictor of fishes collected in nearshore habitats with a backpack electrofisher were longitudinal river distance, velocity, and percent embeddedness. Fish communities differed significantly between mainstem and slough habitat. Overall, 25 of 40 species had high fidelities to mainstem or slough habitats. Native species showed a high fidelity to both mainstem and slough habitats while non-native species were significantly related only to slough habitats. Environmental characteristics strongly influenced fish assemblage structure in this large floodplain river. Maintaining and restoring mainstem and off-channel habitats are critical for maximizing native species resilience in the face of non-native species encroachment and a changing environment. Restoring the natural flow regime to the degree possible is needed to increase connectivity between the floodplain and mainstem and provide thermal and flood refuges for native fishes. Understanding habitat relationships provides essential context for fish conservation and management by resource agencies and landowners.
{"title":"Fish assemblage structure and habitat relationships of a large floodplain river in western North America","authors":"Joshua Everett Williams, Stan Gregory, Randall Wildman","doi":"10.1002/rra.4273","DOIUrl":"https://doi.org/10.1002/rra.4273","url":null,"abstract":"Understanding complex river floodplains is critical to conserve species of fish and their ecological functions. In 2011 through 2013, longitudinal gradients in fish assemblage were investigated in the Willamette River in western United States. Of 36,586 individual fish collected, 93% were native and 7% non-native. The best predictors of fishes collected with a boat electrofisher were percent embeddedness, macrophytes, longitudinal river distance, average depth, and velocity. Habitat type (mainstem or slough) was also a significant predictor. The best predictor of fishes collected in nearshore habitats with a backpack electrofisher were longitudinal river distance, velocity, and percent embeddedness. Fish communities differed significantly between mainstem and slough habitat. Overall, 25 of 40 species had high fidelities to mainstem or slough habitats. Native species showed a high fidelity to both mainstem and slough habitats while non-native species were significantly related only to slough habitats. Environmental characteristics strongly influenced fish assemblage structure in this large floodplain river. Maintaining and restoring mainstem and off-channel habitats are critical for maximizing native species resilience in the face of non-native species encroachment and a changing environment. Restoring the natural flow regime to the degree possible is needed to increase connectivity between the floodplain and mainstem and provide thermal and flood refuges for native fishes. Understanding habitat relationships provides essential context for fish conservation and management by resource agencies and landowners.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"28 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140301070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Behnam Balouchi, Nils Rüther, Kordula Schwarzwälder
The river morphology of a braided‐type river is rather complex. High sediment transport rates and frequently changing discharges are the cause of dynamic planform evolution. Over the past few decades, scientific attention has been directed toward understanding the coexistence of alternating bars and the consequent emergence of confluences and divergences, all of which interact intricately with the process of bank erosion. It is still rather challenging to estimate or predict the total sediment transport rate in this type of river, especially by considering various hydrologic data and climate effects. This study is focused on the reach of the Devoll River in Albania, located upstream of the Banja dam. Understanding the morphodynamics of this river reach holds significance due to the expanding delta upstream of the dam reservoir. The objectives of the two‐dimensional depth‐averaged approach of the present study are to investigate the temporal variation of braided intensity of Devoll River and the effect of using a discharge hydrograph from hydrologic data compared to the regulated one from the upstream dam on the morphodynamics and sediment transport of the river. After evaluating various parameters such as 11 different sediment transport functions, the best results were reached for a cell size of 5 × 5 m2, Manning roughness coefficient of 0.03, Meyer‐Peter and Müller's sediment function, Hayashi et al. (1980) hiding function, and Van Rijn bed roughness predictor in this study. In addition, the results of comparing satellite images and modeling the river from 2019 to 2023 show that the braided index decreased, and this can be due to the fact that the real scenario of the river has a regulated discharge compared to the non‐regulated discharge from hydrologic data, in the mentioned period.
{"title":"Temporal variation of braided intensity and morphodynamic changes in a regulated braided river using 2D modeling and satellite images","authors":"Behnam Balouchi, Nils Rüther, Kordula Schwarzwälder","doi":"10.1002/rra.4268","DOIUrl":"https://doi.org/10.1002/rra.4268","url":null,"abstract":"The river morphology of a braided‐type river is rather complex. High sediment transport rates and frequently changing discharges are the cause of dynamic planform evolution. Over the past few decades, scientific attention has been directed toward understanding the coexistence of alternating bars and the consequent emergence of confluences and divergences, all of which interact intricately with the process of bank erosion. It is still rather challenging to estimate or predict the total sediment transport rate in this type of river, especially by considering various hydrologic data and climate effects. This study is focused on the reach of the Devoll River in Albania, located upstream of the Banja dam. Understanding the morphodynamics of this river reach holds significance due to the expanding delta upstream of the dam reservoir. The objectives of the two‐dimensional depth‐averaged approach of the present study are to investigate the temporal variation of braided intensity of Devoll River and the effect of using a discharge hydrograph from hydrologic data compared to the regulated one from the upstream dam on the morphodynamics and sediment transport of the river. After evaluating various parameters such as 11 different sediment transport functions, the best results were reached for a cell size of 5 × 5 m<jats:sup>2</jats:sup>, Manning roughness coefficient of 0.03, Meyer‐Peter and Müller's sediment function, Hayashi et al. (1980) hiding function, and Van Rijn bed roughness predictor in this study. In addition, the results of comparing satellite images and modeling the river from 2019 to 2023 show that the braided index decreased, and this can be due to the fact that the real scenario of the river has a regulated discharge compared to the non‐regulated discharge from hydrologic data, in the mentioned period.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"53 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140199425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biogeomorphological responses to river restoration are rarely reported. Despite a transition in the emphasis and priorities of river management over the last 40 years from controlling river channel forms and processes to restoring and supporting natural processes, forms and functions, remarkably little information is available on project outcomes. Here, using the example of Beverley Brook within Wimbledon Common, Greater London, UK, we illustrate how standardised detailed monitoring information can be assembled at a very low cost using the citizen science MoRPh survey and we demonstrate the importance of having a pre-project vision of likely outcomes that can be tracked by the monitoring programme. We show how a pre-project and five post-project surveys undertaken over 4 years according to a before-after-control-impact (BACI) design provides scientifically robust data. Analysis of the survey data quantifies the nature, abundance and spatial distribution of restoration interventions, the immediate responses to those interventions, and the ensuing trajectory of biogeomorphological adjustments. Changes in the persistence, size, position, abundance and evolution of habitats reveal the degree to which the restoration achieved the pre-project biogeomorphological vision and why the recovery trajectory progressed at the observed rate and to the observed end point over 4 years. Our approach has enormous potential for monitoring the outcomes of river interventions. Whilst our project was limited in its spatial scale and focus on physical habitats, we suggest how these limitations could be overcome whilst still containing costs.
{"title":"Biogeomorphological response to river restoration of a suburban river with large wood: Creating a restoration vision and cost-effectively monitoring the response trajectory using the citizen science MoRPh survey","authors":"Lucy Shuker, Angela Gurnell, Toby Hull","doi":"10.1002/rra.4262","DOIUrl":"https://doi.org/10.1002/rra.4262","url":null,"abstract":"Biogeomorphological responses to river restoration are rarely reported. Despite a transition in the emphasis and priorities of river management over the last 40 years from controlling river channel forms and processes to restoring and supporting natural processes, forms and functions, remarkably little information is available on project outcomes. Here, using the example of Beverley Brook within Wimbledon Common, Greater London, UK, we illustrate how standardised detailed monitoring information can be assembled at a very low cost using the citizen science MoRPh survey and we demonstrate the importance of having a pre-project vision of likely outcomes that can be tracked by the monitoring programme. We show how a pre-project and five post-project surveys undertaken over 4 years according to a before-after-control-impact (BACI) design provides scientifically robust data. Analysis of the survey data quantifies the nature, abundance and spatial distribution of restoration interventions, the immediate responses to those interventions, and the ensuing trajectory of biogeomorphological adjustments. Changes in the persistence, size, position, abundance and evolution of habitats reveal the degree to which the restoration achieved the pre-project biogeomorphological vision and why the recovery trajectory progressed at the observed rate and to the observed end point over 4 years. Our approach has enormous potential for monitoring the outcomes of river interventions. Whilst our project was limited in its spatial scale and focus on physical habitats, we suggest how these limitations could be overcome whilst still containing costs.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":"12 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140147249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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