Ronielson Gaia, Ana Carolina Martins-Pereira, Paulo Ricardo S. Camargo, Virgilio Teixeira Carrijo, Rafael Cunha Bruno, Fagner de Souza, Victor A. Tagliacollo
{"title":"Trophic Redundancy and the Hidden Dietary Overlap Between Native and Invasive Stream Fishes","authors":"Ronielson Gaia, Ana Carolina Martins-Pereira, Paulo Ricardo S. Camargo, Virgilio Teixeira Carrijo, Rafael Cunha Bruno, Fagner de Souza, Victor A. Tagliacollo","doi":"10.1111/eff.70045","DOIUrl":"10.1111/eff.70045","url":null,"abstract":"<p>Biological invasions introduce non-native species into natural ecosystems, often reshaping localcommunities and altering trophic interactions. In freshwater environments, such invasions can intensify resource use and threaten native fish diversity. In the Upper Paraná River basin, a hotspot with the highest number of threatened fishes in the Neotropics, invasions can be a significant threat. Understanding how non-native fish integrate into local food webs, and how their diets overlap or diverge from those of native species, is essential for assessing the risks they pose. This study investigates dietary patterns of the non-native <i>Poecilia reticulata (</i>guppy) with those of its closely related native species <i>Phalloceros harpagos</i> in streams of southeast Brazil. We analysed the stomach contents of 77 individuals (31 <i>Poecilia reticulata</i> and 46 <i>Phalloceros harpagos</i>) sampled, simultaneously, from five streams where the two species coexist. Dietary patterns were evaluated using a combination of ecological approaches, including trophic overlap (i.e., PerMANOVA, nMDS), niche breadth (i.e., Levins' index) and diet composition (i.e., GLMM). Our results indicate that both species rely heavily on dipterans, particularly Chironomidae, exhibiting low niche breadth and high trophic overlap. However, subtle differences in secondary prey consumption suggest a latent dietary overlap, indicating that minor variations in diet may facilitate coexistence despite the strong similarity in primary resources. This dietary partitioning illustrates how reliance on a dominant prey, coupled with opportunistic consumption of less abundant resources, can facilitate coexistence and stabilise trophic interactions in disturbed freshwater streams.</p>","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/eff.70045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147684184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Call for a Holistic, Precautionary Approach When Considering Thermal Tolerance in Pacific Lamprey","authors":"Benjamin J. Clemens, Abel F. Brumo","doi":"10.1111/eff.70044","DOIUrl":"https://doi.org/10.1111/eff.70044","url":null,"abstract":"","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 2","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147579859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. S. Eerola, B. Hayden, A. J. Piro, K. K. Kahilainen
{"title":"Seasonal Variation of δ13C and δ15N in a Boreal Lake Fish Community—Year-Round Patterns and Explanatory Variables","authors":"E. S. Eerola, B. Hayden, A. J. Piro, K. K. Kahilainen","doi":"10.1111/eff.70043","DOIUrl":"https://doi.org/10.1111/eff.70043","url":null,"abstract":"<p>Seasonal changes in freshwater ecosystems influence fish resource use through both environmental and biological factors, but year-round studies that include ice-covered months have been lacking. We investigated seasonal variation in the stable isotope ratios of carbon (δ<sup>13</sup>C) and nitrogen (δ<sup>15</sup>N) using year-round monthly sampling of the fish community in a deep, seasonally ice-covered boreal lake in southern Finland. We simultaneously examined how month and a suite of biological variables (total length, sex, gonadosomatic index, condition factor, stomach fullness, C:N ratio of fish muscle) varied across the same period and assessed their relationship with isotope ratios of fish. We found seasonal variations in both δ<sup>13</sup>C and δ<sup>15</sup>N, although the patterns differed among fish species. Three percids: pikeperch (<i>Sander lucioperca</i>), perch (<i>Perca fluviatilis</i>) and ruffe (<i>Gymnocephalus cernua</i>) were enriched in <sup>15</sup>N in the winter, while no change was evident in the cyprinid species. Conversely, roach (<i>Rutilus rutilus</i>) and pikeperch <sup>13</sup>C values were enriched in autumn and winter, while no change was detected for perch and ruffe. Total length, month and C:N ratio explained most of the variation in isotope ratios in most species. Results confirm that all four abundant species with year-round samples of muscle stable isotope ratios are subject to seasonal changes in the studied boreal lake, suggesting that this variation should be taken into account in future spatial and temporal studies.</p>","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 2","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/eff.70043","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147564128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Correction to “Brown Trout Abundance in Boreal Streams With Large Wood”","authors":"","doi":"10.1111/eff.70042","DOIUrl":"https://doi.org/10.1111/eff.70042","url":null,"abstract":"<p>Alisa, K., T. Sara, V. Reetta, and S. Jukka Tapani. 2026. “Brown Trout Abundance in Boreal Streams With Large Wood.” <i>Ecology of Freshwater Fish</i> 35, no. 2: e70040. https://doi.org/10.1111/eff.70040.</p><p>In the originally published article, the authors names were reversed. The correct names are shown below. The online version of the article has been corrected.</p><p>Incorrect:</p><p>Koski Alisa; Taskinen Sara; Väätäinen Reetta; Syrjänen Jukka Tapani</p><p>Correct:</p><p>Alisa Koski, Sara Taskinen, Reetta Väätäinen, Jukka Tapani Syrjänen</p><p>We apologize for this error.</p>","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 2","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/eff.70042","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146217320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonison Vieira Pinheiro, Osmar J. Luiz, Vinicius Giglio
{"title":"Trends and Knowledge Gaps in Amazonian Fish Ecology Research: A Topic Modelling Review","authors":"Jonison Vieira Pinheiro, Osmar J. Luiz, Vinicius Giglio","doi":"10.1111/eff.70041","DOIUrl":"https://doi.org/10.1111/eff.70041","url":null,"abstract":"<p>The Amazon basin is home to one of the richest aquatic ecosystems, playing a key role in maintaining global biodiversity and ecosystem services. Despite extensive studies on fish diversity in the region, gaps remain in understanding broad processes to inform management strategies, such as the socioeconomic aspects of fisheries and the long-term effects of environmental change on fish populations. We used topic modelling, a machine learning technique, to analyse 400 peer-reviewed articles on Amazonian fish ecology published over the last 50 years. We identified 13 distinct topics, grouped into five main themes: Ecosystem dynamics, Evolutionary ecology, Hydrological processes, Impact assessments, and Management and Conservation. Results revealed an emphasis on Trophic ecology and Feeding dynamics, Fisheries management, and Evolutionary and Molecular ecology, which make up a large part of the literature. However, topics like Functional extinction and ecosystem consequences and Flood pulse dynamics are less represented, indicating important research gaps. Temporal analysis revealed a shift from early emphases on hydrological processes and participatory management toward contemporary priorities centered on functional ecology, trophic dynamics, and applied management. These findings offer insights for future research and underscore the need for integrated, interdisciplinary approaches to address the region's complex ecological challenges and promote evidence-based conservation and management strategies.</p>","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 2","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/eff.70041","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146197055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Koski Alisa, Taskinen Sara, Väätäinen Reetta, Syrjänen Jukka Tapani
{"title":"Brown Trout Abundance in Boreal Streams With Large Wood","authors":"Koski Alisa, Taskinen Sara, Väätäinen Reetta, Syrjänen Jukka Tapani","doi":"10.1111/eff.70040","DOIUrl":"https://doi.org/10.1111/eff.70040","url":null,"abstract":"<p>Large wood has been found to be a crucial component in riverine ecosystems. However, due to the heavy channelization of rivers and intensive forestry practices over the past few decades, the amount of large wood in these ecosystems has decreased worldwide. River restoration aims to mitigate the effects of channelization and restore the channel closer to its original, pre-channelized form, but large wood has been an overlooked component in restoration. In this study, we investigated the effect of large wood on the density of brown trout (<i>Salmo trutta</i> L.) parr in several natural rivers in southern Finland and Sweden. The density of 0-year-old parr was higher in areas with a high concentration of large wood, but no difference was found in the densities of 1-year-old or ≥ 2-year-old parr or other fish species. Other microenvironmental factors did not influence parr density. Due to the apparent positive impact of large wood on 0-year-old parr density, it is recommended as a part of river restoration.</p>","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 2","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/eff.70040","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146096590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xuemei Chen, Thomas Mehner, Lei Yang, Sandra Bibiana Correa, Xiang Ji, Jing Yuan, Chao Guo, Chuansong Liao, Chuanbo Guo, Jiashou Liu
{"title":"Density-Dependent Reproduction of Two Dominant Small-Bodied Fish Species in Reservoirs and Their Top-Down Effects on Plankton Biomass","authors":"Xuemei Chen, Thomas Mehner, Lei Yang, Sandra Bibiana Correa, Xiang Ji, Jing Yuan, Chao Guo, Chuansong Liao, Chuanbo Guo, Jiashou Liu","doi":"10.1111/eff.70038","DOIUrl":"https://doi.org/10.1111/eff.70038","url":null,"abstract":"<div>\u0000 \u0000 <p>In recent years, small-bodied fishes have become increasingly dominant in many subtropical reservoirs due to climate change and overfishing of predatory species. Their rising populations can disrupt aquatic ecosystem balance and increase eutrophication risk. This study investigated the density-dependent effects on the reproductive traits of two dominant small-bodied fish species (sharpbelly <i>Hemiculter leucisculus</i> and thin sharpbelly <i>Toxabramis swinhonis</i>), and their subsequent impacts on plankton biomass in three large Chinese reservoirs during 2022–2023. We observed significant variation in reproductive traits of the two fish species; both species exhibited the lowest fecundity, largest egg diameter, and smallest length at 50% maturity in the Liuxihe Reservoir, which had the highest density of thin sharpbelly. Density-dependent responses differed between species: sharpbelly fecundity was primarily affected by interspecific competition with thin sharpbelly, whereas thin sharpbelly fecundity was mainly influenced by intraspecific competition. Both species affected realised zooplankton biomass (as indicated by the ratio of zooplankton biomass to phytoplankton biomass) and positively promoted realised phytoplankton biomass (as indicated by the ratio of chlorophyll a to total phosphorus content). These results suggest that both species exert top-down control on zooplankton, which indirectly promote phytoplankton growth and negatively affect water quality. Our findings highlight that the reproductive traits of these small-bodied fish species were closely linked to species-specific densities, which in turn drove top-down impacts within freshwater food webs. These findings underscore the ecological risks posed by high densities of small zooplanktivorous fish and emphasise the importance for population regulation in freshwater ecosystems management.</p>\u0000 </div>","PeriodicalId":11422,"journal":{"name":"Ecology of Freshwater Fish","volume":"35 2","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145987181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}