Anna Stanicka, Jarosław Kobak, Joanna Hildebrand, Anna Cichy, Kamil Wiśniewski, Daniel Szarmach, Kinga Lesiak, Joanna Urbaniak, Mateusz Augustyniak, Zuzanna Dlouhy, Szymon Graczyk, Arkadiusz Grzeczka, Zuzanna Kowaleska, Monika Lewalska, Katarzyna Lichocka, Sebastian Terebiński, Anna Wiśniewska, Elżbieta Żbikowska, Małgorzata Poznańska-Kakareko
Understanding the impact of invaders and parasites/pathogens and their interactions is desirable in an era of global environmental change. Such comprehensive insight is one of the drivers of sound conservation planning for biodiversity on local and global scales. Bivalves have experienced precipitous declines in species diversity and abundance in recent decades. Few threats have been reported for Sphaeriidae, mainly due to significant data deficiency, particularly at the species level.
We used a vulnerable worldwide fingernail clam Sphaerium rivicola as a model to find multi-species associations between the sphaeriid host, its digenean internal parasites, and fouling invasive dreissenid mussels (including potential interactions among the parasites and foulers). Individual clams were collected from the Włocławek Reservoir (Poland), representing a well-defined and representative population. We analysed host traits—shell length (size), wet weight per unit length (condition) and embryo presence (fertility)—in relation to two biotic stressors: digenean infection and fouling by invasive dreissenid mussels. Our aim was to assess their individual and combined effects on the clam host, and to test for potential interactions between parasites and foulers.
Biofouling and digenean infections had negative effects on clam growth and fertility. The combined presence of both stressors intensified the adverse impact compared to either alone. Tetracotyle metacercariae (recorded in bivalves for the first time) were positively associated with digeneans exploiting clams as first intermediate hosts, but negatively associated with echinostome metacercariae. No evidence was found for parasite dilution or facilitation by dreissenid mussels.
Presumably, the negative consequences for individual clam hosts may affect population-level success metrics. Disseminating the issues raised here will be one of the drivers for considering additional protective measures for endangered clam species.
{"title":"Many Evils Are Worse Than One: An Interplay Between Invasive Biofoulers and Parasites Helps Predict the Future of an Endangered Freshwater Fingernail Clam","authors":"Anna Stanicka, Jarosław Kobak, Joanna Hildebrand, Anna Cichy, Kamil Wiśniewski, Daniel Szarmach, Kinga Lesiak, Joanna Urbaniak, Mateusz Augustyniak, Zuzanna Dlouhy, Szymon Graczyk, Arkadiusz Grzeczka, Zuzanna Kowaleska, Monika Lewalska, Katarzyna Lichocka, Sebastian Terebiński, Anna Wiśniewska, Elżbieta Żbikowska, Małgorzata Poznańska-Kakareko","doi":"10.1111/fwb.70125","DOIUrl":"https://doi.org/10.1111/fwb.70125","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Understanding the impact of invaders and parasites/pathogens and their interactions is desirable in an era of global environmental change. Such comprehensive insight is one of the drivers of sound conservation planning for biodiversity on local and global scales. Bivalves have experienced precipitous declines in species diversity and abundance in recent decades. Few threats have been reported for Sphaeriidae, mainly due to significant data deficiency, particularly at the species level.</li>\u0000 \u0000 \u0000 <li>We used a vulnerable worldwide fingernail clam <i>Sphaerium rivicola</i> as a model to find multi-species associations between the sphaeriid host, its digenean internal parasites, and fouling invasive dreissenid mussels (including potential interactions among the parasites and foulers). Individual clams were collected from the Włocławek Reservoir (Poland), representing a well-defined and representative population. We analysed host traits—shell length (size), wet weight per unit length (condition) and embryo presence (fertility)—in relation to two biotic stressors: digenean infection and fouling by invasive dreissenid mussels. Our aim was to assess their individual and combined effects on the clam host, and to test for potential interactions between parasites and foulers.</li>\u0000 \u0000 \u0000 <li>Biofouling and digenean infections had negative effects on clam growth and fertility. The combined presence of both stressors intensified the adverse impact compared to either alone. Tetracotyle metacercariae (recorded in bivalves for the first time) were positively associated with digeneans exploiting clams as first intermediate hosts, but negatively associated with echinostome metacercariae. No evidence was found for parasite dilution or facilitation by dreissenid mussels.</li>\u0000 \u0000 \u0000 <li>Presumably, the negative consequences for individual clam hosts may affect population-level success metrics. Disseminating the issues raised here will be one of the drivers for considering additional protective measures for endangered clam species.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145469933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yue Wu, Siwen Chen, Qi Ye, Lei Jiang, Yiheng Chang, Wei Huang, Cheng Liu, Shuzhan Ma, Rong Jiang, Dandan Fei, Hongliang Xu, Xiaoli Shi, Kaining Chen
Submerged macrophytes influence sediment microbial communities in shallow lakes; however, the ecological roles of their community-level characteristics remain underexplored. In this study, we examined the relationships between macrophyte community coverage and diversity and the composition of sediment bacterial communities in Dongshan Bay, Lake Taihu.
We combined high-throughput sequencing, functional prediction, and multivariate statistical modelling to analyse sediment bacterial composition, potential metabolic functions, community assembly proceses, and their associations with macrophyte communities and environmental factors.
Macrophyte community structure explained more variation in sediment bacterial community structure than seasonal dynamics. Higher coverage and diversity were related to improved water clarity, elevated sediment nutrient concentrations, and enhanced bacterial metabolic potential. In macrophyte-dominated zones, bacterial communities were primarily structured by homogeneous selection, and microbial co-occurrence networks became less complex.
Our results indicate that species richness, diversity, and coverage most effectively capture the ecological functions of submerged macrophyte communities, and collectively influence sediment bacterial communities through multiple pathways, including habitat modification and altered selection pressures.
This study underscores the ecological role of macrophyte diversity and coverage in shaping sediment microbiota, offering insights for lake restoration strategies.
{"title":"Influence of Coverage and Diversity of Submerged Macrophytes on the Sediment Bacterial Community in Dongshan Bay, Lake Taihu","authors":"Yue Wu, Siwen Chen, Qi Ye, Lei Jiang, Yiheng Chang, Wei Huang, Cheng Liu, Shuzhan Ma, Rong Jiang, Dandan Fei, Hongliang Xu, Xiaoli Shi, Kaining Chen","doi":"10.1111/fwb.70120","DOIUrl":"https://doi.org/10.1111/fwb.70120","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Submerged macrophytes influence sediment microbial communities in shallow lakes; however, the ecological roles of their community-level characteristics remain underexplored. In this study, we examined the relationships between macrophyte community coverage and diversity and the composition of sediment bacterial communities in Dongshan Bay, Lake Taihu.</li>\u0000 \u0000 \u0000 <li>We combined high-throughput sequencing, functional prediction, and multivariate statistical modelling to analyse sediment bacterial composition, potential metabolic functions, community assembly proceses, and their associations with macrophyte communities and environmental factors.</li>\u0000 \u0000 \u0000 <li>Macrophyte community structure explained more variation in sediment bacterial community structure than seasonal dynamics. Higher coverage and diversity were related to improved water clarity, elevated sediment nutrient concentrations, and enhanced bacterial metabolic potential. In macrophyte-dominated zones, bacterial communities were primarily structured by homogeneous selection, and microbial co-occurrence networks became less complex.</li>\u0000 \u0000 \u0000 <li>Our results indicate that species richness, diversity, and coverage most effectively capture the ecological functions of submerged macrophyte communities, and collectively influence sediment bacterial communities through multiple pathways, including habitat modification and altered selection pressures.</li>\u0000 \u0000 \u0000 <li>This study underscores the ecological role of macrophyte diversity and coverage in shaping sediment microbiota, offering insights for lake restoration strategies.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145469390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Changes in Diversity With Stream Order in Particle-Associated and Free-Living Bacteria From Headwater Streams","authors":"Tadashi Ookami, Shunsuke Matsuoka, Tomohiro Yokobe, Ryunosuke Tateno","doi":"10.1111/fwb.70123","DOIUrl":"https://doi.org/10.1111/fwb.70123","url":null,"abstract":"<p>\u0000 \u0000 </p>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fwb.70123","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145469431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Timothy D. Jardine, Francisco Villamarín, Joseph E. Hawes, Joao Campos-Silva, Cristina M. Jacobi, Stephen Srayko, Alexander Pelletier, William E. Magnusson
{"title":"Seasonal Forest Resources Support Fish Biomass in Floodplain Lakes of an Amazonian Tributary","authors":"Timothy D. Jardine, Francisco Villamarín, Joseph E. Hawes, Joao Campos-Silva, Cristina M. Jacobi, Stephen Srayko, Alexander Pelletier, William E. Magnusson","doi":"10.1111/fwb.70121","DOIUrl":"https://doi.org/10.1111/fwb.70121","url":null,"abstract":"<p>\u0000 \u0000 </p>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fwb.70121","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145407266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information - Cover and Ed Board","authors":"","doi":"10.1111/fwb.14284","DOIUrl":"https://doi.org/10.1111/fwb.14284","url":null,"abstract":"","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fwb.14284","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145385013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mian Adnan Kakakhel, Nishita Narwal, Sanaullah Khan, Alam Khan, Majid Rasta, Shi Xiaotao, Yujiao Wu
Hydraulic engineering alters freshwater fish swimming performance by affecting fish physiology; however, the mechanistic links between water flow-induced bacterial shift and locomotor impairment remain poorly understood.
This study investigated the effects of varying flow velocities on intestinal microbiota composition, immune gene expression, and swimming performance in grass carp (Ctenopharyngodon idella), a commercially important freshwater species. Fish were exposed to three flow regimes: low, medium, and high water velocity in a controlled open recirculation system over a defined exposure period.
Swimming performance was significantly impaired under increasing flow velocity (R2 = 0.9128; p < 0.001), indicating reduced locomotive efficiency.
High-flow exposure also induced notable gut microbial dysbiosis (p = 0.0010; Adonis R2 = 0.2529), with elevated relative abundance of opportunistic and potentially pathogenic bacteria, including Aeromonas, Acinetobacter, and Vibrio spp. (p < 0.05***). This microbial imbalance was paralleled by the significant upregulation of key immune response genes (p < 0.001), reflecting a systemic stress-induced immunomodulatory effect.
These findings identify water flow velocity as a critical but underrecognized abiotic factor that not only impairs physical performance, also disrupts microbial homeostasis and triggers host immune responses. This study provides novel insights into the complex interactions among chronic hydrodynamic stress, host-associated microbiota, and immune regulation in freshwater fish. The obtained findings have far-reaching implications for aquaculture system design, environmental risk assessment, and the conservation of freshwater biodiversity under changing flow regimes.
{"title":"Hydraulic Engineering Affects Freshwater Fish Swimming Performance by Shifting Intestinal Bacterial Composition. A Microbiological Mechanism","authors":"Mian Adnan Kakakhel, Nishita Narwal, Sanaullah Khan, Alam Khan, Majid Rasta, Shi Xiaotao, Yujiao Wu","doi":"10.1111/fwb.70122","DOIUrl":"https://doi.org/10.1111/fwb.70122","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Hydraulic engineering alters freshwater fish swimming performance by affecting fish physiology; however, the mechanistic links between water flow-induced bacterial shift and locomotor impairment remain poorly understood.</li>\u0000 \u0000 \u0000 <li>This study investigated the effects of varying flow velocities on intestinal microbiota composition, immune gene expression, and swimming performance in grass carp (<i>Ctenopharyngodon idella</i>), a commercially important freshwater species. Fish were exposed to three flow regimes: low, medium, and high water velocity in a controlled open recirculation system over a defined exposure period.</li>\u0000 \u0000 \u0000 <li>Swimming performance was significantly impaired under increasing flow velocity (<i>R</i><sup>2</sup> = 0.9128; <i>p</i> < 0.001), indicating reduced locomotive efficiency.</li>\u0000 \u0000 \u0000 <li>High-flow exposure also induced notable gut microbial dysbiosis (<i>p</i> = 0.0010; Adonis <i>R</i><sup>2</sup> = 0.2529), with elevated relative abundance of opportunistic and potentially pathogenic bacteria, including <i>Aeromonas</i>, <i>Acinetobacter</i>, and <i>Vibrio</i> spp. (<i>p</i> < 0.05***). This microbial imbalance was paralleled by the significant upregulation of key immune response genes (<i>p</i> < 0.001), reflecting a systemic stress-induced immunomodulatory effect.</li>\u0000 \u0000 \u0000 <li>These findings identify water flow velocity as a critical but underrecognized abiotic factor that not only impairs physical performance, also disrupts microbial homeostasis and triggers host immune responses. This study provides novel insights into the complex interactions among chronic hydrodynamic stress, host-associated microbiota, and immune regulation in freshwater fish. The obtained findings have far-reaching implications for aquaculture system design, environmental risk assessment, and the conservation of freshwater biodiversity under changing flow regimes.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145385012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lucas Pereira-Moura, Carolina Gomes Viana, Lucas Ferreira Colares, Karina Dias da Silva, Everton Cruz da Silva, Myckey Kenzy Silva Gonçalves, Lenize Batista Calvão, José Max Barbosa Oliveira-Junior, Leandro Juen, Sheyla Regina Marques Couceiro
Extinction processes driven by habitat loss at multiple scales can lead to changes in the taxonomic and functional rarity of biological communities. However, evidence on the direction of these changes remains limited, making more accurate extrapolations about ecosystem functioning difficult. Therefore, our objective was to assess how rarity, functional groups, and species traits of adult Odonata communities change across extinction scenarios at local and regional scales. We tested the following hypotheses: (i) Functional rarity will decrease as species vulnerable to habitat loss go extinct at local and regional scales; (ii) the average body size of adult Odonata will increase as vulnerable species are lost at local and regional scales; and (iii) the loss of functional groups will occur earlier if the species more vulnerable to habitat loss go extinct, because these species are expected to perform unique ecological roles that may vanish with their disappearance.
We sampled a total of 128 streams in the Eastern Amazon, recording 4031 individuals representing 42 genera and 141 species. After determining the extinction risk and functional rarity of the community, we simulated three extinction scenarios at both local and regional scales (1—extinction of species more vulnerable to habitat loss, 2—extinction of species more tolerant to habitat loss, and 3—random extinction), calculated our response variables, and tested the observed differences using a nonparametric Friedman test.
Our results indicated that communities at local and regional scales tend to lose functional rarity as species vulnerable to habitat loss become extinct, supporting H1. At the local scale, average body size decreased as species more vulnerable to habitat loss became extinct, and at the regional scale, the opposite occurred; that is, there was an increase in average body size as they became extinct, partially supporting our H2. We also observe the loss of multiple functional groups as species vulnerable to habitat loss become extinct, supporting our H3.
These results support the hypothesis that species vulnerable to habitat loss are also important in maintaining unique functions within ecosystem processes. Functional groups associated with endophytic oviposition and thermal conformer thermoregulation were the most likely to be lost, possibly due to their strong association with environments of higher ecological integrity.
Thus, if species vulnerable to habitat loss maintain unique functions in ecosystems and they are extirpated from a landscape, this will lead to the disappearance of entire functional groups and potentially ecosystem services (if they are not performed by other species).
{"title":"Extinctions Associated With Sensitivity to Habitat Loss Promote Functional Homogenisation and Body Size Increase of Odonata in Amazonian Streams","authors":"Lucas Pereira-Moura, Carolina Gomes Viana, Lucas Ferreira Colares, Karina Dias da Silva, Everton Cruz da Silva, Myckey Kenzy Silva Gonçalves, Lenize Batista Calvão, José Max Barbosa Oliveira-Junior, Leandro Juen, Sheyla Regina Marques Couceiro","doi":"10.1111/fwb.70119","DOIUrl":"https://doi.org/10.1111/fwb.70119","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Extinction processes driven by habitat loss at multiple scales can lead to changes in the taxonomic and functional rarity of biological communities. However, evidence on the direction of these changes remains limited, making more accurate extrapolations about ecosystem functioning difficult. Therefore, our objective was to assess how rarity, functional groups, and species traits of adult Odonata communities change across extinction scenarios at local and regional scales. We tested the following hypotheses: (i) Functional rarity will decrease as species vulnerable to habitat loss go extinct at local and regional scales; (ii) the average body size of adult Odonata will increase as vulnerable species are lost at local and regional scales; and (iii) the loss of functional groups will occur earlier if the species more vulnerable to habitat loss go extinct, because these species are expected to perform unique ecological roles that may vanish with their disappearance.</li>\u0000 \u0000 \u0000 <li>We sampled a total of 128 streams in the Eastern Amazon, recording 4031 individuals representing 42 genera and 141 species. After determining the extinction risk and functional rarity of the community, we simulated three extinction scenarios at both local and regional scales (1—extinction of species more vulnerable to habitat loss, 2—extinction of species more tolerant to habitat loss, and 3—random extinction), calculated our response variables, and tested the observed differences using a nonparametric Friedman test.</li>\u0000 \u0000 \u0000 <li>Our results indicated that communities at local and regional scales tend to lose functional rarity as species vulnerable to habitat loss become extinct, supporting H1. At the local scale, average body size decreased as species more vulnerable to habitat loss became extinct, and at the regional scale, the opposite occurred; that is, there was an increase in average body size as they became extinct, partially supporting our H2. We also observe the loss of multiple functional groups as species vulnerable to habitat loss become extinct, supporting our H3.</li>\u0000 \u0000 \u0000 <li>These results support the hypothesis that species vulnerable to habitat loss are also important in maintaining unique functions within ecosystem processes. Functional groups associated with endophytic oviposition and thermal conformer thermoregulation were the most likely to be lost, possibly due to their strong association with environments of higher ecological integrity.</li>\u0000 \u0000 \u0000 <li>Thus, if species vulnerable to habitat loss maintain unique functions in ecosystems and they are extirpated from a landscape, this will lead to the disappearance of entire functional groups and potentially ecosystem services (if they are not performed by other species).</li>\u0000 ","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145385011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Terrestrial invertebrates are important food resources for fish in forested streams, and understanding their origins as fish prey—whether from air-canopy or ground surface-soil environments within the forest—is essential for the management of headwater catchments. However, the contribution of ground-dwelling invertebrates to fish food resources remains unclear because few studies have quantified their inputs to streams. Here, we investigated the input pathways and composition of terrestrial invertebrates supplied to a channel and preyed upon by fish in a small forested stream in a cool-temperature area of western Japan and evaluated the importance of ground-dwelling invertebrates as a food resource for stream fish.
We used pan-traps placed in the central part of the channel (instream traps) and along the channel margins (bankside traps) to clarify the input pathways of terrestrial invertebrates (vertical pathway via air and canopy; lateral pathway via ground surface and soil). Additionally, terrestrial invertebrates were identified at the class, order, and family levels to determine their typical habitat and compare mass-based composition in terrestrial inputs and fish stomach contents.
The mass of terrestrial invertebrates captured by traps at the channel margin was equivalent to approximately 10 times that in the central part of the channel, mainly due to ground-dwelling invertebrates common in bankside traps but rare in instream traps.
Based on an assessment at the reach scale, the proportion of ground-dwelling invertebrates to total terrestrial inputs (58%) was comparable to their proportion in fish stomach contents (58%). These findings indicate that bankside traps effectively address the methodological limitations of relying solely on instream traps and highlight ground-dwelling invertebrates as an essential component of potential fish prey. However, the correlation between the inputs and stomach contents was notably weaker for ground-dwelling invertebrates (r = 0.47) than for air- and canopy-dwelling invertebrates (r = 0.78). This weak correlation might stem from the complex prey–fish processes, such as the spatial heterogeneity of ground-dwelling invertebrate inputs, their underwater behaviours, and/or fish prey selections.
Our results emphasise the need for quantitative analysis of the lateral movement of ground-dwelling invertebrates to better understand forest–stream ecological linkages through terrestrial invertebrate inputs. Therefore, we conclude that conserving the forest floor and soil environment in riparian areas, as well as vegetation, is crucial for maintaining stream ecosystems.
{"title":"Lateral Movement of Ground-Dwelling Invertebrates Resolves Discrepancies Between Fish Diet and Terrestrial Input Data","authors":"Takehiro Kubo, Hirokazu Haga","doi":"10.1111/fwb.70110","DOIUrl":"https://doi.org/10.1111/fwb.70110","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Terrestrial invertebrates are important food resources for fish in forested streams, and understanding their origins as fish prey—whether from air-canopy or ground surface-soil environments within the forest—is essential for the management of headwater catchments. However, the contribution of ground-dwelling invertebrates to fish food resources remains unclear because few studies have quantified their inputs to streams. Here, we investigated the input pathways and composition of terrestrial invertebrates supplied to a channel and preyed upon by fish in a small forested stream in a cool-temperature area of western Japan and evaluated the importance of ground-dwelling invertebrates as a food resource for stream fish.</li>\u0000 \u0000 \u0000 <li>We used pan-traps placed in the central part of the channel (instream traps) and along the channel margins (bankside traps) to clarify the input pathways of terrestrial invertebrates (vertical pathway via air and canopy; lateral pathway via ground surface and soil). Additionally, terrestrial invertebrates were identified at the class, order, and family levels to determine their typical habitat and compare mass-based composition in terrestrial inputs and fish stomach contents.</li>\u0000 \u0000 \u0000 <li>The mass of terrestrial invertebrates captured by traps at the channel margin was equivalent to approximately 10 times that in the central part of the channel, mainly due to ground-dwelling invertebrates common in bankside traps but rare in instream traps.</li>\u0000 \u0000 \u0000 <li>Based on an assessment at the reach scale, the proportion of ground-dwelling invertebrates to total terrestrial inputs (58%) was comparable to their proportion in fish stomach contents (58%). These findings indicate that bankside traps effectively address the methodological limitations of relying solely on instream traps and highlight ground-dwelling invertebrates as an essential component of potential fish prey. However, the correlation between the inputs and stomach contents was notably weaker for ground-dwelling invertebrates (<i>r</i> = 0.47) than for air- and canopy-dwelling invertebrates (<i>r</i> = 0.78). This weak correlation might stem from the complex prey–fish processes, such as the spatial heterogeneity of ground-dwelling invertebrate inputs, their underwater behaviours, and/or fish prey selections.</li>\u0000 \u0000 \u0000 <li>Our results emphasise the need for quantitative analysis of the lateral movement of ground-dwelling invertebrates to better understand forest–stream ecological linkages through terrestrial invertebrate inputs. Therefore, we conclude that conserving the forest floor and soil environment in riparian areas, as well as vegetation, is crucial for maintaining stream ecosystems.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145406705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coexistence of submerged macrophytes is crucial for maintaining ecosystem health and biodiversity in shallow lake ecosystems. The modern coexistence theory (MCT) has been extensively used to explain species coexistence in grasslands and microbial communities by considering average fitness differences and niche differences at local scales. However, this theory has not yet been applied to investigate the coexistence of submerged macrophytes. In freshwater ecosystems, fish play a vital role in regulating the structure of the submerged macrophytes community. Fish could affect inter/intra specific competition of submerged macrophytes by indirectly changing the water environment or directly acting as herbivores, which might be described as apparent competition.
Here, we employed a short-term mesocosm experiment to explore how omnivorous fish (Rhodeus ocellatus) and herbivorous fish (Megalobrama amblycephala) affect the co-existence of rosette-forming macrophytes (Vallisneria denseserrulata) and canopy-forming macrophytes (Myriophyllum spicatum), based on the MCT. We hypothesised that both herbivorous fish and omnivorous fish could influence the co-existence dynamics of these macrophytes through apparent competition, that is two macrophytes interact indirectly through their shared grazer.
In the absence of fish or with only omnivorous fish present, V. denseserrulata and M. spicatum couldn't stably coexist, with V. denseserrulata exhibiting stronger growth and clonal reproductive with more ramets, winning the interspecific competition according to the prediction of MCT. However, the herbivorous fish, with preferential grazing, altered their fitness and niche differences between the macrophytes, promoting their coexistence.
Our results reveal a case study of apparent competition between submerged macrophytes via fish presence, which provides insightful solutions for maintaining high species diversity of submerged macrophytes in restored shallow lakes.
{"title":"Apparent Competition Between Two Submerged Macrophytes via Fish: Evidence From a Mesocosm Study","authors":"Manli Xia, Wei Liu, Chaoyu Tian, Cheng Daomin, Wei Li, Yu Cao","doi":"10.1111/fwb.70116","DOIUrl":"https://doi.org/10.1111/fwb.70116","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>The coexistence of submerged macrophytes is crucial for maintaining ecosystem health and biodiversity in shallow lake ecosystems. The modern coexistence theory (MCT) has been extensively used to explain species coexistence in grasslands and microbial communities by considering average fitness differences and niche differences at local scales. However, this theory has not yet been applied to investigate the coexistence of submerged macrophytes. In freshwater ecosystems, fish play a vital role in regulating the structure of the submerged macrophytes community. Fish could affect inter/intra specific competition of submerged macrophytes by indirectly changing the water environment or directly acting as herbivores, which might be described as apparent competition.</li>\u0000 \u0000 \u0000 <li>Here, we employed a short-term mesocosm experiment to explore how omnivorous fish (<i>Rhodeus ocellatus</i>) and herbivorous fish (<i>Megalobrama amblycephala</i>) affect the co-existence of rosette-forming macrophytes (<i>Vallisneria denseserrulata</i>) and canopy-forming macrophytes (<i>Myriophyllum spicatum</i>), based on the MCT. We hypothesised that both herbivorous fish and omnivorous fish could influence the co-existence dynamics of these macrophytes through apparent competition, that is two macrophytes interact indirectly through their shared grazer.</li>\u0000 \u0000 \u0000 <li>In the absence of fish or with only omnivorous fish present, <i>V</i>. <i>denseserrulata</i> and <i>M. spicatum</i> couldn't stably coexist, with <i>V</i>. <i>denseserrulata</i> exhibiting stronger growth and clonal reproductive with more ramets, winning the interspecific competition according to the prediction of MCT. However, the herbivorous fish, with preferential grazing, altered their fitness and niche differences between the macrophytes, promoting their coexistence.</li>\u0000 \u0000 \u0000 <li>Our results reveal a case study of apparent competition between submerged macrophytes via fish presence, which provides insightful solutions for maintaining high species diversity of submerged macrophytes in restored shallow lakes.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145367080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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