Frontiers in Freshwater Science最新文献

{"title":"Disentangling the simultaneous effects of habitat degradation and introduced species on naturally depauperate riverine fish communities","authors":"Christopher G. Meijer, Michael J. H. Hickford, Duncan P. Gray, D. Schiel","doi":"10.3389/ffwsc.2024.1398975","DOIUrl":"https://doi.org/10.3389/ffwsc.2024.1398975","url":null,"abstract":"Global change is a multi-faceted issue putting many species at risk. The broad range of potentially interacting environmental stressors is problematic for effective and efficient conservation and management. In freshwater systems, habitat degradation and introduced species have been repeatedly recognized for their extensive impacts on native ecosystems. However, the simultaneous impacts of these environmental stressors on naturally depauperate and inherently vulnerable communities are poorly understood.In southern New Zealand, the fish communities in 14 tributaries of three lowland lakes were surveyed to quantify the within- and between-community changes along gradients of habitat complexity and abundance of introduced species, specifically brown trout (Salmo trutta Linnaeus) and redfin perch (Perca fluviatilis Linnaeus).Stable isotope analyses identified that trophic diversity increased with habitat complexity and an abundance of native eels (Anguilla spp.) but was unaffected by introduced species. Within each community, only perch exhibited distinct dietary shifts along all environmental gradients, whereas trout and the native fish had consistent, generalist diets. When supported with length–weight regressions, these impacts became increasingly size-dependent. For example, among the native fish, only the larger eels were unaffected by habitat and achieved greater body conditions with increased numbers of eels and perch; however, more trout were detrimental to eel body condition. In contrast, the smaller bodied natives, including elvers, all had improved body conditions from increased habitat complexity and reduced numbers of trout and perch. For the introduced species, perch weights were consistent regardless of the local environment due to their variable diet, but larger trout generally increased in weight with reduced habitat complexity and greater numbers of introduced fish, although high eel densities were detrimental.Overall, our results highlight how the responses to environmental stressors, even in depauperate communities, are complicated and generally species-specific. Nonetheless, habitat degradation had the most wide-ranging negative impacts on native fish, with perch numbers only affecting the smaller bodied natives and trout only affecting one native species. We conclude that focusing on habitat restoration in conservation strategies will provide the most efficient and effective use of resources, although the realized benefits for native species will be limited if introduced species are overly abundant.","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":" 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141673664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adopting a reductionist approach to advance acoustic deterrents in fish conservation","authors":"Amelia Holgate, Paul R. White, T. Leighton, Paul Kemp","doi":"10.3389/ffwsc.2024.1320582","DOIUrl":"https://doi.org/10.3389/ffwsc.2024.1320582","url":null,"abstract":"Deterrents that use acoustics to guide fish away from dangerous areas (e.g., water intakes) depend on the elicitation of avoidance in the target species. Background noise is often neglected when testing acoustic deterrents, but it is important to account for its effects as freshwater environments present a wide variety of ambient soundscapes.Using the widely studied goldfish (Carassius auratus) as a suitable experimental model, this study adopted a reductionist approach to investigate the relationship between the startle response to a pure tone signal and background noise. Under laboratory conditions, the startle responses of individual goldfish exposed to 120 ms tones at 250 Hz and four Sound Pressure Levels (SPLs: 115, 125, 135, 145 dB re 1 μPa) were quantified in the presence (treatment) and absence (ambient - control) of band-limited random noise (105 dB re 1 μPa).When observing the dose-response relationship, the proportion of fish that startled to the signal increased with SPL in both the treatment and control, although there was no difference between them, suggesting that the signal-to-noise ratio was not influential under the conditions tested. However, further analysis using Signal Detection Theory indicated that the was higher in the noisy treatment than the control when responding to both false alarms (startle during a pre-signal period) and hits (startle to an external stimulus during the pre-signal period). Furthermore, fish were better able to discriminate (d?) external stimuli over time (during the pre-signal period) in the treatment than control. There is a need to consider the role of background noise when designing acoustic fish deterrents that depend on the exhibition of avoidance behaviors.","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":"32 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140077551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fish conservation in streams of the agrarian Mississippi Alluvial Valley: conceptual model, management actions, and field verification","authors":"K. Killgore, Jan Jeffrey Hoover, L. E. Miranda, W. T. Slack, David R. Johnson, Neil H. Douglas","doi":"10.3389/ffwsc.2024.1365691","DOIUrl":"https://doi.org/10.3389/ffwsc.2024.1365691","url":null,"abstract":"The effects of agriculture and flood control practices accrued over more than a century have impaired aquatic habitats and their fish communities in the Mississippi Alluvial Valley, the historic floodplain of the Lower Mississippi River prior to leveeing. As a first step to conservation planning and adaptive management, we developed and tested a conceptual model of how changes to this floodplain have affected stream environments and fish assemblages. The model is deliberately simple in structure because it needs to be understood by stakeholders ranging from engineers to farmers who must remain engaged to ensure effective conservation. Testing involved multivariate correlative analyses that included descriptors of land setting, water quality, and fish assemblages representing 376 stream samples taken over two decades and ranging in Strahler stream order from 1 to 8. The conceptual model was adequately corroborated by empirical data, but with unexplained variability that is not uncommon in field surveys where gear biases, temporal biases, and scale biases prevent accurate characterizations. Our conceptual model distinguishes three types of conservation actions relevant to large agricultural floodplains: reforestation of large parcels and riparian zone conservation, in-channel interventions and connectivity preservation, and flow augmentation. Complete restoration of the floodplain may not be an acceptable option to the agriculture community. However, in most cases the application of even the most basic measures can support the return of sensitive aquatic species. We suggest that together these types of conservation actions can bring improved water properties to impacted reaches, higher reach biodiversity, more intolerant species, and more rheophilic fishes.","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":"31 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139960480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Incorporating the riverscape into models of river–floodplain function","authors":"James E. Garvey, M. Whiles","doi":"10.3389/ffwsc.2023.1265423","DOIUrl":"https://doi.org/10.3389/ffwsc.2023.1265423","url":null,"abstract":"Rivers and their flooded alluvial plains integrate physical, biological, and human processes at the scale of continents. Despite their ecological and economic values, these complex ecosystems are poorly understood and highly modified by humans. A primary problem is that most research in fluvial ecosystems has been conducted in small streams and then scaled up to rivers. Furthermore, the point where a stream transitions into a river is not well understood. Although many conceptual models exist, the role that large river–floodplain complexes play within these frameworks is lacking. These models focus on flooding as a temporary reset to river ecosystems, but floodplains and rivers may continue to interact long after floodwaters recede. We revisit the concept of the riverscape, a unique mosaic of perennially interacting wetland and channel habitats that have unique ecological properties during both non-flood and flooding periods relative to the small tributary streams within the riverscape network. This strong bidirectional interaction within low-lying alluvial plains may define large rivers. To determine whether a riverscape is indeed a useful unit of study for river ecology, conservation, and restoration, baseline conditions with measurable, comparable metrics, such as primary and secondary production need to be established. Responses of these metrics to multiple stressors and restoration such as levee setbacks, wetland mitigation, and dam removals will inform both basic models of riverscape function and future management actions. Because humans currently affect nearly all aspects of the environmental structure and function of riverscapes, human perceptions of riverscape value and threat need to be considered as a fundamental component of riverscape ecology.","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":"414 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139204814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fish life-history traits predict abundance-occupancy patterns in artificial lakes","authors":"L. E. Miranda","doi":"10.3389/ffwsc.2023.1270939","DOIUrl":"https://doi.org/10.3389/ffwsc.2023.1270939","url":null,"abstract":"Life-history traits of a species have been postulated as a factor in abundance and occupancy patterns. Understanding how traits contribute to the ubiquity and rarity of taxa can facilitate the development of effective conservation policy by establishing a connection between species requirements and resource. The goal was to evaluate fish assemblages in artificial lakes for evidence of the abundance-occupancy patterns reported in natural environments and, if evident, to explore if observed patterns of abundance and occupancy could be attributed to species traits. Fish abundance and occupancy were estimated over 1990–2018 in 22 artificial lakes impounded within the Tennessee River basin, USA. Consistent with reports for many other taxonomic groups in natural environments, there was a positive association amidst 114 fish species between abundance and occupancy in artificial lakes ( R 2 = 0.78). This result indicates that the fish assemblages that develop in these anthropized environments follow the fundamental abundance-occupancy patterns uncovered in natural environments, despite assemblages having been disfigured by the dramatic rearrangement of habitats brought by impoundment. Moreover, a redundancy analysis focusing mostly on reproductive and habitat traits adequately predicted abundance-occupancy patterns of fish assemblages in artificial lakes ( R 2 = 0.69). Species abundance-occupancy is influenced by the interplay between life-history traits and habitat availability, even in artificial lakes, and by extension, possibly other artificial ecosystems.","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":"695 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tipping points in freshwater ecosystems: an evidence map","authors":"Ana Hernández Martínez de la Riva, Meagan Harper, Trina Rytwinski, Angeli Sahdra, Jessica J. Taylor, Brittany Bard, Joseph R. Bennett, Declan Burton, Irena F. Creed, Laura S. E. Haniford, Dalal E. Hanna, Evaline J. Harmsen, Courtney D. Robichaud, John P. Smol, Myra Thapar, Steven J. Cooke","doi":"10.3389/ffwsc.2023.1264427","DOIUrl":"https://doi.org/10.3389/ffwsc.2023.1264427","url":null,"abstract":"Freshwater ecosystems face numerous threats, including habitat alteration, invasive species, pollution, over extraction of resources, fragmentation, and climate change. When these threats intensify and/or combine with each other, their impacts can shift the ecosystem past a tipping point, producing a major and potentially irreversible shift in state, called a regime shift. We generated an evidence map to assess the current state of knowledge on tipping points in freshwater ecosystems. Our evidence mapping exercise revealed large knowledge gaps. Specifically, there are relatively few studies that explore the effects of tipping points in relation to (1) lotic systems (i.e., rivers, streams), (2) amphibians, mammals, or reptiles, and (3) the interactive impacts of multiple threats. In addition, most studies tended to have short study durations (<1 year), and few studies explored the reversibility of an ecosystem change after a tipping point was crossed. Concentrating future research on these gaps to improve understanding of tipping points in freshwater ecosystems in a holistic manner is important to help develop tools to forecast (and thus mitigate) the emergence and effects of tipping points, as well as to guide restoration actions.","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136210139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Facing our freshwater crisis via fluid and agile communication: A grand challenge","authors":"Leandro E. Miranda","doi":"10.3389/ffwsc.2023.1068115","DOIUrl":"https://doi.org/10.3389/ffwsc.2023.1068115","url":null,"abstract":"COPYRIGHT © 2023 Miranda. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Facing our freshwater crisis via fluid and agile communication: A grand challenge","PeriodicalId":388502,"journal":{"name":"Frontiers in Freshwater Science","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120950495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}