Martin Berggren, Mayra P. D. Rulli, Ann-Kristin Bergström, Ryan A. Sponseller, Geert Hensgens
{"title":"Does Dissolved Organic Matter Composition Help Explain the Concentrations of Bioavailable Macronutrients in Organic Matter-Rich Freshwaters?","authors":"Martin Berggren, Mayra P. D. Rulli, Ann-Kristin Bergström, Ryan A. Sponseller, Geert Hensgens","doi":"10.1111/fwb.70141","DOIUrl":"https://doi.org/10.1111/fwb.70141","url":null,"abstract":"<p>\u0000 \u0000 </p>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fwb.70141","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145619059","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":"Cyanobacterial Bloom Development, Nitrogen Fixation and Community Change: Insights on Rapid Change From a Shallow Lake","authors":"Lisa M. Boyer, Scott N. Higgins, Helen M. Baulch","doi":"10.1111/fwb.70131","DOIUrl":"https://doi.org/10.1111/fwb.70131","url":null,"abstract":"<p>\u0000 \u0000 </p>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fwb.70131","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145572604","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}
Chao Guo, Wei Li, Adam G. Hansen, Shiqi Li, Jie Ke, Erik Jeppesen, Chuansong Liao, Jing Yuan, Tanglin Zhang, Chuanbo Guo, Jiashou Liu
The proliferation of small-bodied fishes and their foraging effects within food webs can limit the growth of submerged macrophytes and degrade water quality in shallow lake ecosystems. The foraging habits of small-bodied fishes vary, and, therefore, ecosystem responses may differ depending on which species or feeding guild that dominates the fish community. Yet, species and feeding guild-specific foraging effects remain poorly understood.
Here, we used an experimental mesocosm to evaluate how water quality and submerged macrophytes respond to different species of small-bodied fishes, including omnivorous bitterling Acheilognathus macropterus (AMA), crucian carp Carassius auratus (CAU), sharpbelly Hemiculter leucisculus (HLE), zooplanktivorous thin sharpbelly Toxabramis swinhonis (TSW) and their mixes (1:1:1:1) (MIX).
Our results showed that the mean weekly total nitrogen, total phosphorus, turbidity, chlorophyll-a and trophic level index values were significantly higher in treatments with fish compared to fish-free controls during the experiment. At the end of the experiment, mean values for the number of submerged macrophyte shoots, leaf number, dry mass and the relative growth rate of shoots were significantly lower in the treatments with than without fish. In addition, mean values for leaf height, leaf width and the dry mass of submerged macrophytes in the TSW treatment were significantly greater than in the CAU, HLE and AMA treatments. Structural equation modelling revealed that small-bodied omnivorous fishes (i.e., crucian carp, sharpbelly and bitterling) affected submerged macrophyte growth more than zooplanktivorous fishes (i.e., thin sharpbelly), driven by their different foraging habits.
Our findings indicated that high abundances of small-bodied fishes have negative effects on water quality and the growth of submerged macrophytes in subtropical shallow lake ecosystems, but the effects differed with fish foraging guild. Control of overabundant small-bodied fishes (especially omnivorous fishes) may facilitate maintenance or effective restoration of submerged macrophytes and subtropical shallow lake ecosystem structure and function.
{"title":"Diverse Foraging in Small-Bodied Fishes: Effects on Water Quality and Submerged Macrophytes in Shallow Subtropical Lake Ecosystems","authors":"Chao Guo, Wei Li, Adam G. Hansen, Shiqi Li, Jie Ke, Erik Jeppesen, Chuansong Liao, Jing Yuan, Tanglin Zhang, Chuanbo Guo, Jiashou Liu","doi":"10.1111/fwb.70136","DOIUrl":"https://doi.org/10.1111/fwb.70136","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>The proliferation of small-bodied fishes and their foraging effects within food webs can limit the growth of submerged macrophytes and degrade water quality in shallow lake ecosystems. The foraging habits of small-bodied fishes vary, and, therefore, ecosystem responses may differ depending on which species or feeding guild that dominates the fish community. Yet, species and feeding guild-specific foraging effects remain poorly understood.</li>\u0000 \u0000 \u0000 <li>Here, we used an experimental mesocosm to evaluate how water quality and submerged macrophytes respond to different species of small-bodied fishes, including omnivorous bitterling <i>Acheilognathus macropterus</i> (AMA), crucian carp <i>Carassius auratus</i> (CAU), sharpbelly <i>Hemiculter leucisculus</i> (HLE), zooplanktivorous thin sharpbelly <i>Toxabramis swinhonis</i> (TSW) and their mixes (1:1:1:1) (MIX).</li>\u0000 \u0000 \u0000 <li>Our results showed that the mean weekly total nitrogen, total phosphorus, turbidity, chlorophyll-<i>a</i> and trophic level index values were significantly higher in treatments with fish compared to fish-free controls during the experiment. At the end of the experiment, mean values for the number of submerged macrophyte shoots, leaf number, dry mass and the relative growth rate of shoots were significantly lower in the treatments with than without fish. In addition, mean values for leaf height, leaf width and the dry mass of submerged macrophytes in the TSW treatment were significantly greater than in the CAU, HLE and AMA treatments. Structural equation modelling revealed that small-bodied omnivorous fishes (i.e., crucian carp, sharpbelly and bitterling) affected submerged macrophyte growth more than zooplanktivorous fishes (i.e., thin sharpbelly), driven by their different foraging habits.</li>\u0000 \u0000 \u0000 <li>Our findings indicated that high abundances of small-bodied fishes have negative effects on water quality and the growth of submerged macrophytes in subtropical shallow lake ecosystems, but the effects differed with fish foraging guild. Control of overabundant small-bodied fishes (especially omnivorous fishes) may facilitate maintenance or effective restoration of submerged macrophytes and subtropical shallow lake ecosystem structure and function.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145572605","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}
David J. Gallagher, Payton E. Johnson, Sara M. Kangas, Dylan J. McNulty, Mary A. Thelen, Brian R. Herwig, David F. Staples, Kyle D. Zimmer
Larger trophic niches may contribute to the adaptive capacity of food webs by facilitating shifts in resource use during environmental change, but niche size patterns across lakes and fish species remain poorly known.
We sampled 14 fish species across 17 Minnesota lakes and used stable isotopes ẟ13C (littoral carbon use, hereafter littoral C) and ẟ15N (trophic position) to estimate isotopic niche size (SEAb) for each species in each lake. We tested for relationships between niche size and lake characteristics using common species. We also tested whether niche size differed among and within species and evaluated whether differences could be explained by trophic (e.g., trophic position, littoral C use) or morphological (e.g., total length, length range) variables.
Results showed mean niche size varied four-fold among lakes and was inversely related to lake surface area, total phosphorus, and hypoxic depth. Niches were smaller in larger, more productive lakes with more suitable dissolved oxygen due to reduced littoral C use variation, indicating fish populations focus on more similar habitats along these gradients. Niche size varied over three-fold among species. Niches were largest in bluegill (Lepomis macrochirus) and yellow perch (Perca flavescens) and smallest in walleye (Sander vitreus) and three prey fish species. Niche size showed dome-shaped quadratic relationships with length, trophic position, and littoral C across all populations, but species identity explained more variation. Length range had a positive effect on niche size within all species.
Niche size and potential flexibility in resource use is greatest in small, unproductive lakes with more extensive hypoxic conditions, in species with intermediate trophic positions, and in populations with large length ranges. These results suggest populations contribute differently to the adaptive capacity of food webs depending on lake, trophic, and morphological characteristics.
Overall, our study demonstrates how niche size changes predictably across lakes and species, an important step for understanding lake food web dynamics and managing fish populations.
{"title":"Variables Associated With Isotopic Niche Size in Fish Communities Across North-Temperate Lakes","authors":"David J. Gallagher, Payton E. Johnson, Sara M. Kangas, Dylan J. McNulty, Mary A. Thelen, Brian R. Herwig, David F. Staples, Kyle D. Zimmer","doi":"10.1111/fwb.70142","DOIUrl":"https://doi.org/10.1111/fwb.70142","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Larger trophic niches may contribute to the adaptive capacity of food webs by facilitating shifts in resource use during environmental change, but niche size patterns across lakes and fish species remain poorly known.</li>\u0000 \u0000 \u0000 <li>We sampled 14 fish species across 17 Minnesota lakes and used stable isotopes ẟ<sup>13</sup>C (littoral carbon use, hereafter littoral C) and ẟ<sup>15</sup>N (trophic position) to estimate isotopic niche size (SEA<sub>b</sub>) for each species in each lake. We tested for relationships between niche size and lake characteristics using common species. We also tested whether niche size differed among and within species and evaluated whether differences could be explained by trophic (e.g., trophic position, littoral C use) or morphological (e.g., total length, length range) variables.</li>\u0000 \u0000 \u0000 <li>Results showed mean niche size varied four-fold among lakes and was inversely related to lake surface area, total phosphorus, and hypoxic depth. Niches were smaller in larger, more productive lakes with more suitable dissolved oxygen due to reduced littoral C use variation, indicating fish populations focus on more similar habitats along these gradients. Niche size varied over three-fold among species. Niches were largest in bluegill (<i>Lepomis macrochirus</i>) and yellow perch (<i>Perca flavescens</i>) and smallest in walleye (<i>Sander vitreus</i>) and three prey fish species. Niche size showed dome-shaped quadratic relationships with length, trophic position, and littoral C across all populations, but species identity explained more variation. Length range had a positive effect on niche size within all species.</li>\u0000 \u0000 \u0000 <li>Niche size and potential flexibility in resource use is greatest in small, unproductive lakes with more extensive hypoxic conditions, in species with intermediate trophic positions, and in populations with large length ranges. These results suggest populations contribute differently to the adaptive capacity of food webs depending on lake, trophic, and morphological characteristics.</li>\u0000 \u0000 \u0000 <li>Overall, our study demonstrates how niche size changes predictably across lakes and species, an important step for understanding lake food web dynamics and managing fish populations.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145581196","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}
Yao Zhang, Qingji Zhang, Xiaolong Wang, Zhiqiang Tan, Jinqiao Mao, Yongjiu Cai
<div> <p> </p><ol> <li>Molluscs are a vital component of floodplain wetland ecosystems worldwide, playing key roles in water purification and nutrient cycling. However, the increasing frequency and intensity of global droughts, particularly flash drought (FD) events, have led to widespread mollusc mortality. <i>Bellamya aeruginosa</i>, a dominant freshwater mollusc, has demonstrated remarkable tolerance to extreme drought (ED) conditions. Yet, the underlying mechanisms enabling drought resilience remain unclear. To bridge this gap, we combined field surveys with controlled indoor simulation experiments to assess changes in the density and biomass of <i>B. aeruginosa</i> before and after ED (Pre-ED and Post-ED), and to explore its molecular responses to drought stress.</li> <li>At the population level, no surviving individuals were found on the soil surface during the ED phase. However, as rewetting duration increased, the density and biomass of <i>B. aeruginosa</i> gradually rose and eventually recovered to pre-ED levels. Laboratory experiments revealed that <i>B. aeruginosa</i> crawls into moist, shaded crevices during extreme drought, entering a dormant state by burrowing upside down with its operculum facing upward to endure harsh aridity. During the rewetting phase, its ovoviviparous reproductive strategy enables rapid population recovery.</li> <li>At the molecular level, drought stress led to a statistically significant change in biochemical parameters. Glycogen and protein contents, along with lactate dehydrogenase activity (LDH), were significantly elevated, whereas triglycerides (TG) and antioxidant parameters declined markedly in both the normal drought (ND) and ED groups during drought stress.</li> <li>Metabolomic analyses revealed that combined hypoxia and desiccation stress induced substantial shifts in metabolic pathways. Notably, metabolites involved in glycolysis, fatty acid metabolism and the tricarboxylic acid (TCA) cycle were significantly affected. Key metabolites, including Pyruvaldehyde, Carnitine, Arginine, Histidine, Sphingosine, Ile-Pro and Acetylcholine, were downregulated, while Malate and Pantothenol were upregulated. Furthermore, metabolites related to nucleotide metabolism, such as Inosine, 2′-deoxycytidine 5′-monophosphate, Pseudouridine and Uracil, showed consistent downregulation with increasing drought severity.</li> <li>Overall, <i>B. aeruginosa</i> employs a combination of behavioural strategies, physiological adaptations and rapid reproductive capabilities to endure and recover from extreme drought, thereby enhancing the resistance and resilience of floodplain wetland ecosystems. These findings highlight the importance of conserving microhabitats with residual moisture and offer a scient
{"title":"How Does a Freshwater Snail (Bellamya aeruginosa) Tolerate Extreme Drought in Floodplain Wetlands? Insights From Field Surveys, Biochemical Indicators and Metabolomics","authors":"Yao Zhang, Qingji Zhang, Xiaolong Wang, Zhiqiang Tan, Jinqiao Mao, Yongjiu Cai","doi":"10.1111/fwb.70138","DOIUrl":"https://doi.org/10.1111/fwb.70138","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Molluscs are a vital component of floodplain wetland ecosystems worldwide, playing key roles in water purification and nutrient cycling. However, the increasing frequency and intensity of global droughts, particularly flash drought (FD) events, have led to widespread mollusc mortality. <i>Bellamya aeruginosa</i>, a dominant freshwater mollusc, has demonstrated remarkable tolerance to extreme drought (ED) conditions. Yet, the underlying mechanisms enabling drought resilience remain unclear. To bridge this gap, we combined field surveys with controlled indoor simulation experiments to assess changes in the density and biomass of <i>B. aeruginosa</i> before and after ED (Pre-ED and Post-ED), and to explore its molecular responses to drought stress.</li>\u0000 \u0000 \u0000 <li>At the population level, no surviving individuals were found on the soil surface during the ED phase. However, as rewetting duration increased, the density and biomass of <i>B. aeruginosa</i> gradually rose and eventually recovered to pre-ED levels. Laboratory experiments revealed that <i>B. aeruginosa</i> crawls into moist, shaded crevices during extreme drought, entering a dormant state by burrowing upside down with its operculum facing upward to endure harsh aridity. During the rewetting phase, its ovoviviparous reproductive strategy enables rapid population recovery.</li>\u0000 \u0000 \u0000 <li>At the molecular level, drought stress led to a statistically significant change in biochemical parameters. Glycogen and protein contents, along with lactate dehydrogenase activity (LDH), were significantly elevated, whereas triglycerides (TG) and antioxidant parameters declined markedly in both the normal drought (ND) and ED groups during drought stress.</li>\u0000 \u0000 \u0000 <li>Metabolomic analyses revealed that combined hypoxia and desiccation stress induced substantial shifts in metabolic pathways. Notably, metabolites involved in glycolysis, fatty acid metabolism and the tricarboxylic acid (TCA) cycle were significantly affected. Key metabolites, including Pyruvaldehyde, Carnitine, Arginine, Histidine, Sphingosine, Ile-Pro and Acetylcholine, were downregulated, while Malate and Pantothenol were upregulated. Furthermore, metabolites related to nucleotide metabolism, such as Inosine, 2′-deoxycytidine 5′-monophosphate, Pseudouridine and Uracil, showed consistent downregulation with increasing drought severity.</li>\u0000 \u0000 \u0000 <li>Overall, <i>B. aeruginosa</i> employs a combination of behavioural strategies, physiological adaptations and rapid reproductive capabilities to endure and recover from extreme drought, thereby enhancing the resistance and resilience of floodplain wetland ecosystems. These findings highlight the importance of conserving microhabitats with residual moisture and offer a scient","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145572546","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}
Huan Zhang, Yulu Wang, Peiyu Zhang, Lars-Anders Hansson, Jorge García Molinos, Konghao Zhu, Hailu Li, Huan Wang, Hongxia Wang, Yingchun Gong, Liang He, Min Zhang, Jun Xu
Climate warming, nutrient loading, and pesticide pollution are major anthropogenic stressors affecting community dynamics and trophic interactions in aquatic ecosystems. However, the complex interplay among these stressors remains poorly understood as most studies focus on a single stressor and overlook the effects of temporal variations.
To address this knowledge gap, we first conducted a long-term outdoor experiment to examine the effects of climate warming, nutrient loading, and a neonicotinoid pesticide (imidacloprid) on the responses of the common predator–prey pair cyclopoid copepods and rotifers. Additionally, a follow-up laboratory experiment was conducted to assess the dose-dependent impact of imidacloprid on the predation rate of cyclopoid copepods on rotifers, and to explore mechanistic alterations in biotic interactions resulting from predator responses to varying neonicotinoid concentrations.
The neonicotinoid pesticide was the most influential stressor, significantly reducing cyclopoid copepod populations thereby positively affecting rotifer abundances due to a release from predation. Nutrient loading boosted copepod abundances but weakened their top-down control on rotifer prey, disrupting predator–prey dynamics. Warming had negligible effects on copepod abundances, but ultimately increased rotifer abundances.
Warming predominantly influenced rotifer abundances during the establishment phase, whereas the effects of the pesticide became more pronounced during subsequent growth and reproduction phases. Conversely, the neonicotinoid pesticide consistently emerged as the primary stressor impacting cyclopoid copepods throughout the experiment.
Our study underscores the importance of considering temporal dynamics when assessing the combined effects of multiple stressors for understanding responses among interacting organisms and highlights the significance of organism life history stages in their distinct reactions to specific compounded threats over time.
{"title":"Multiple Stressors From Climate Warming, Neonicotinoid Pesticide, and Nutrient Loading Alter Zooplankton Predator–Prey Dynamics in Freshwaters","authors":"Huan Zhang, Yulu Wang, Peiyu Zhang, Lars-Anders Hansson, Jorge García Molinos, Konghao Zhu, Hailu Li, Huan Wang, Hongxia Wang, Yingchun Gong, Liang He, Min Zhang, Jun Xu","doi":"10.1111/fwb.70132","DOIUrl":"https://doi.org/10.1111/fwb.70132","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Climate warming, nutrient loading, and pesticide pollution are major anthropogenic stressors affecting community dynamics and trophic interactions in aquatic ecosystems. However, the complex interplay among these stressors remains poorly understood as most studies focus on a single stressor and overlook the effects of temporal variations.</li>\u0000 \u0000 \u0000 <li>To address this knowledge gap, we first conducted a long-term outdoor experiment to examine the effects of climate warming, nutrient loading, and a neonicotinoid pesticide (imidacloprid) on the responses of the common predator–prey pair cyclopoid copepods and rotifers. Additionally, a follow-up laboratory experiment was conducted to assess the dose-dependent impact of imidacloprid on the predation rate of cyclopoid copepods on rotifers, and to explore mechanistic alterations in biotic interactions resulting from predator responses to varying neonicotinoid concentrations.</li>\u0000 \u0000 \u0000 <li>The neonicotinoid pesticide was the most influential stressor, significantly reducing cyclopoid copepod populations thereby positively affecting rotifer abundances due to a release from predation. Nutrient loading boosted copepod abundances but weakened their top-down control on rotifer prey, disrupting predator–prey dynamics. Warming had negligible effects on copepod abundances, but ultimately increased rotifer abundances.</li>\u0000 \u0000 \u0000 <li>Warming predominantly influenced rotifer abundances during the establishment phase, whereas the effects of the pesticide became more pronounced during subsequent growth and reproduction phases. Conversely, the neonicotinoid pesticide consistently emerged as the primary stressor impacting cyclopoid copepods throughout the experiment.</li>\u0000 \u0000 \u0000 <li>Our study underscores the importance of considering temporal dynamics when assessing the combined effects of multiple stressors for understanding responses among interacting organisms and highlights the significance of organism life history stages in their distinct reactions to specific compounded threats over time.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145572544","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}
Raymond M. Lee, Scott Collins, Erin F. Jones, Gabriella Lawson, Sarah Chan, Rachel L. Wood, Neil Hansen, Benjamin W. Abbott, Gregory T. Carling, Michelle A. Baker, Zachary T. Aanderud
Cyanobacterial proliferation in inland waters can degrade water quality and harm human health. Cyanobacterial proliferation is determined largely by nitrogen and phosphorus supply, though nutrient conditions in the impacted lake or reservoir and its inflow(s) are not always sufficient for explaining/mitigating the bloom. Other factors may include fluvial seeding of cyanobacteria, in-lake sediment release then entrainment of nutrients and species preference for nutrients (e.g., diazotrophic vs. non-diazotrophic).
We studied diverse aquatic systems (drinking water reservoir to throughflow and endorheic lakes along a freshwater to hypersaline gradient) to investigate (a) how nutrients supported cyanobacterial blooms (blooms were defined by the outsized relative abundance of a given cyanobacterial species); (b) which factors besides external nutrient loading supported blooms; and (c) if/how all these processes changed across limnologic conditions in successively downstream systems.
Results showed that blooms occurred in different patterns despite being located in the same basin with the same regional climate. Blooms were controlled by nitrogen at the freshwater reservoir (Phormidium spp. succeeded by Microcystis spp.), phosphorus at the brackish lake (Aphanizomenon flos-aquae) and inflow at the hypersaline endorheic lake (Nodularia spp.). At the reservoir, there were spatial and temporal shifts in dominance from diazotrophic (historically) to non-diazotrophic species (currently) that occurred likely due to successful watershed management of phosphorus loading; at the endorheic lake, the bay dried up completely, likely due to high water consumption, which reduced inflow over time.
Results suggested that bloom characteristics and controls changed at each study lake due to different local human activities, so strategies for nutrient and bloom mitigation should be site-specific rather than uniform for the region.
The concept of a cyanobacterial ‘bloom’ is ambiguous because it can be defined by different thresholds of different specimens (e.g., chlorophyll concentration, cyanobacterial cell count/density, cyanotoxin concentration or perceived/actual harm or risk thereof). Here, we defined a bloom as excessive cyanobacterial relative abundance, which is a novel way to track the life cycles of dominant cyanobacterial species in the context of limnologic and nutrient controls. This approach allowed us to identify significant and different anthropogenic changes to controlling factors of blooms in diverse settings.
{"title":"Anthropogenic Changes to Factors Controlling Cyanobacterial Blooms Along a Chain of Fresh to Hypersaline Water Bodies","authors":"Raymond M. Lee, Scott Collins, Erin F. Jones, Gabriella Lawson, Sarah Chan, Rachel L. Wood, Neil Hansen, Benjamin W. Abbott, Gregory T. Carling, Michelle A. Baker, Zachary T. Aanderud","doi":"10.1111/fwb.70135","DOIUrl":"https://doi.org/10.1111/fwb.70135","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Cyanobacterial proliferation in inland waters can degrade water quality and harm human health. Cyanobacterial proliferation is determined largely by nitrogen and phosphorus supply, though nutrient conditions in the impacted lake or reservoir and its inflow(s) are not always sufficient for explaining/mitigating the bloom. Other factors may include fluvial seeding of cyanobacteria, in-lake sediment release then entrainment of nutrients and species preference for nutrients (e.g., diazotrophic vs. non-diazotrophic).</li>\u0000 \u0000 \u0000 <li>We studied diverse aquatic systems (drinking water reservoir to throughflow and endorheic lakes along a freshwater to hypersaline gradient) to investigate (a) how nutrients supported cyanobacterial blooms (blooms were defined by the outsized relative abundance of a given cyanobacterial species); (b) which factors besides external nutrient loading supported blooms; and (c) if/how all these processes changed across limnologic conditions in successively downstream systems.</li>\u0000 \u0000 \u0000 <li>Results showed that blooms occurred in different patterns despite being located in the same basin with the same regional climate. Blooms were controlled by nitrogen at the freshwater reservoir (<i>Phormidium</i> spp. succeeded by <i>Microcystis</i> spp.), phosphorus at the brackish lake (<i>Aphanizomenon flos-aquae</i>) and inflow at the hypersaline endorheic lake (<i>Nodularia</i> spp.). At the reservoir, there were spatial and temporal shifts in dominance from diazotrophic (historically) to non-diazotrophic species (currently) that occurred likely due to successful watershed management of phosphorus loading; at the endorheic lake, the bay dried up completely, likely due to high water consumption, which reduced inflow over time.</li>\u0000 \u0000 \u0000 <li>Results suggested that bloom characteristics and controls changed at each study lake due to different local human activities, so strategies for nutrient and bloom mitigation should be site-specific rather than uniform for the region.</li>\u0000 \u0000 \u0000 <li>The concept of a cyanobacterial ‘bloom’ is ambiguous because it can be defined by different thresholds of different specimens (e.g., chlorophyll concentration, cyanobacterial cell count/density, cyanotoxin concentration or perceived/actual harm or risk thereof). Here, we defined a bloom as excessive cyanobacterial relative abundance, which is a novel way to track the life cycles of dominant cyanobacterial species in the context of limnologic and nutrient controls. This approach allowed us to identify significant and different anthropogenic changes to controlling factors of blooms in diverse settings.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145572297","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}
Bradley J. Pusey, Mark J. Kennard, Leah S. Beesley, Tsz Wai Ho, Aaron M. Davis, Michael M. Douglas
<div> <p> </p><ol> <li>Intact riparian vegetation plays an important role in the energetics of freshwater ecosystems. Plant and animal biomass from the riparian zone may be directly consumed by freshwater organisms without intermediary processing by microbial or metazoan communities. This study examined the extent and importance of such direct consumption by Australian freshwater fishes.</li> <li>We assembled a data set that spanned the Australian continent and examined the extent of terrestrial contributions to freshwater fish diets for 137 species (i.e., approximately one half of Australia's fish fauna). Using a range of multivariate methods we examined variation in reliance on terrestrial material (leaves, fruit, invertebrates and vertebrates) between species and families and between different regions of Australia, particularly focussing on differences between temperate and tropical Australia. We also examined whether particular aspects of morphology were related to increased consumption of terrestrially-derived material.</li> <li>Overall, terrestrial invertebrates contributed 10% or more of the diet of about one quarter of all species and families examined. Most families contained at least one species for which consumption of terrestrial invertebrates was high (> 20%) but only two families, Galaxiidae and Melanotaeniidae, exhibited consistently high consumption across most species. Terrestrial vegetation, principally fruit, contributed 10% or more of the diet in three species from two families only (Terapontidae and Ariidae). There was little regional variation in reliance on terrestrial invertebrates as a food source, but species in south-western Western Australia consistently consumed more than did species elsewhere. Frugivory, in contrast, was significantly more common in the wet-dry tropical northern Australia as reported elsewhere for other tropical regions.</li> <li>Australian freshwater fishes appear to rely more on terrestrial invertebrates than do freshwater fishes elsewhere although data is largely lacking to make broader comparisons with other continents. Morphological correlates with the consumption of terrestrial material were individually and collectively limited, but species with a pelagic habit and an upturned (supraterminal) mouth consumed significantly more such material than did species within other habit/mouth orientation combinations.</li> <li>The present study further confirms the importance of the riparian zone to lotic ecosystem function with direct contributions of terrestrially derived material contributing significantly to the diet of many species and of some families in particular. Although data is lacking for large-scale (i.e., continental) assessments of the importance of terrestrial su
{"title":"Eating In or Out? Terrestrial Contributions to the Diet of Australian Freshwater Fish","authors":"Bradley J. Pusey, Mark J. Kennard, Leah S. Beesley, Tsz Wai Ho, Aaron M. Davis, Michael M. Douglas","doi":"10.1111/fwb.70129","DOIUrl":"https://doi.org/10.1111/fwb.70129","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Intact riparian vegetation plays an important role in the energetics of freshwater ecosystems. Plant and animal biomass from the riparian zone may be directly consumed by freshwater organisms without intermediary processing by microbial or metazoan communities. This study examined the extent and importance of such direct consumption by Australian freshwater fishes.</li>\u0000 \u0000 \u0000 <li>We assembled a data set that spanned the Australian continent and examined the extent of terrestrial contributions to freshwater fish diets for 137 species (i.e., approximately one half of Australia's fish fauna). Using a range of multivariate methods we examined variation in reliance on terrestrial material (leaves, fruit, invertebrates and vertebrates) between species and families and between different regions of Australia, particularly focussing on differences between temperate and tropical Australia. We also examined whether particular aspects of morphology were related to increased consumption of terrestrially-derived material.</li>\u0000 \u0000 \u0000 <li>Overall, terrestrial invertebrates contributed 10% or more of the diet of about one quarter of all species and families examined. Most families contained at least one species for which consumption of terrestrial invertebrates was high (> 20%) but only two families, Galaxiidae and Melanotaeniidae, exhibited consistently high consumption across most species. Terrestrial vegetation, principally fruit, contributed 10% or more of the diet in three species from two families only (Terapontidae and Ariidae). There was little regional variation in reliance on terrestrial invertebrates as a food source, but species in south-western Western Australia consistently consumed more than did species elsewhere. Frugivory, in contrast, was significantly more common in the wet-dry tropical northern Australia as reported elsewhere for other tropical regions.</li>\u0000 \u0000 \u0000 <li>Australian freshwater fishes appear to rely more on terrestrial invertebrates than do freshwater fishes elsewhere although data is largely lacking to make broader comparisons with other continents. Morphological correlates with the consumption of terrestrial material were individually and collectively limited, but species with a pelagic habit and an upturned (supraterminal) mouth consumed significantly more such material than did species within other habit/mouth orientation combinations.</li>\u0000 \u0000 \u0000 <li>The present study further confirms the importance of the riparian zone to lotic ecosystem function with direct contributions of terrestrially derived material contributing significantly to the diet of many species and of some families in particular. Although data is lacking for large-scale (i.e., continental) assessments of the importance of terrestrial su","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521956","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}
Maria Chiara Vulcano, Martin J. Kainz, Georg H. Niedrist, Leopold Füreder
{"title":"The Fundamental Role of Periphyton in Supplying Dietary Energy to Alpine Stream Food Webs: Current Knowledge, Limitations and Future Perspectives","authors":"Maria Chiara Vulcano, Martin J. Kainz, Georg H. Niedrist, Leopold Füreder","doi":"10.1111/fwb.70133","DOIUrl":"https://doi.org/10.1111/fwb.70133","url":null,"abstract":"<p>\u0000 \u0000 </p>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/fwb.70133","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521957","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}
Kexin Zhu, Rong Wang, Bo Qin, Jianan Zheng, Yanjie Zhao, Yu Zhao, Wenxiu Zheng, Jianjun Wang, Xiangdong Yang
Regime shifts in aquatic ecosystems have attracted widespread attention. While research has extensively focused on shallow lakes, such shifts in deep lakes remain less studied. This study investigates the mechanisms influencing regime shifts in Lake Fuxian, China's largest deep freshwater lake, which has experienced cyanobacterial blooms and rapid algal growth despite strict nutrient input regulations.
We examined trends in diatoms, cyanobacteria, and geochemical elements over the past century using rate-of-change analysis, F-statistics and random forest regression models to identify the time of ecological shifts and the factors associated with them.
We found two significant ecological shifts during the 1990s and 2010s. Both were accompanied by increases in TOC, hypolimnetic anoxia and cyanobacterial abundance. The 1990s shift was primarily associated with invasive fish species, whereas the 2010s shift was linked to phosphorus enrichment.
Notably, phosphorus enrichment was not mainly associated with external nutrient inputs but by an internal positive feedback mechanism. Specifically, hypolimnetic anoxia facilitates phosphorus release from sediments, promoting algal growth during mixing periods, which increases oxygen demand. This feedback further alters nutrient dynamics, favouring the proliferation of algal biomass, particularly cyanobacteria, and may ultimately trigger an ecosystem regime shift.
These results suggest that even oligotrophic deep lakes are susceptible to regime shifts, emphasising the importance of disrupting positive feedback mechanisms for effective management.
{"title":"From External Pressure to Internal Drivers: Anthropogenic Disturbance and Positive Feedback Trigger Deep Lake Regime Shifts","authors":"Kexin Zhu, Rong Wang, Bo Qin, Jianan Zheng, Yanjie Zhao, Yu Zhao, Wenxiu Zheng, Jianjun Wang, Xiangdong Yang","doi":"10.1111/fwb.70128","DOIUrl":"https://doi.org/10.1111/fwb.70128","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 \u0000 </p><ol>\u0000 \u0000 \u0000 <li>Regime shifts in aquatic ecosystems have attracted widespread attention. While research has extensively focused on shallow lakes, such shifts in deep lakes remain less studied. This study investigates the mechanisms influencing regime shifts in Lake Fuxian, China's largest deep freshwater lake, which has experienced cyanobacterial blooms and rapid algal growth despite strict nutrient input regulations.</li>\u0000 \u0000 \u0000 <li>We examined trends in diatoms, cyanobacteria, and geochemical elements over the past century using rate-of-change analysis, <i>F</i>-statistics and random forest regression models to identify the time of ecological shifts and the factors associated with them.</li>\u0000 \u0000 \u0000 <li>We found two significant ecological shifts during the 1990s and 2010s. Both were accompanied by increases in TOC, hypolimnetic anoxia and cyanobacterial abundance. The 1990s shift was primarily associated with invasive fish species, whereas the 2010s shift was linked to phosphorus enrichment.</li>\u0000 \u0000 \u0000 <li>Notably, phosphorus enrichment was not mainly associated with external nutrient inputs but by an internal positive feedback mechanism. Specifically, hypolimnetic anoxia facilitates phosphorus release from sediments, promoting algal growth during mixing periods, which increases oxygen demand. This feedback further alters nutrient dynamics, favouring the proliferation of algal biomass, particularly cyanobacteria, and may ultimately trigger an ecosystem regime shift.</li>\u0000 \u0000 \u0000 <li>These results suggest that even oligotrophic deep lakes are susceptible to regime shifts, emphasising the importance of disrupting positive feedback mechanisms for effective management.</li>\u0000 </ol>\u0000 \u0000 </div>","PeriodicalId":12365,"journal":{"name":"Freshwater Biology","volume":"70 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145522189","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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