Aquatic Sciences最新文献

{"title":"Ecomorphological variation in the Corfu killifish and trait overlap with the invasive mosquitofish: conservation implications","authors":"Yiannis Kapakos,&nbsp;Anthi Oikonomou,&nbsp;Konstantinos Vlachopoulos,&nbsp;Nafsika Karakatsouli,&nbsp;Eleni Kalogianni","doi":"10.1007/s00027-026-01297-0","DOIUrl":"10.1007/s00027-026-01297-0","url":null,"abstract":"<div><p>A functional trait approach in ecology focuses on understanding the relationship between the traits of organisms (e.g. morphology, behaviour, physiology) and their roles in ecosystems, with the aim of connecting these traits to ecological functions and explaining species’ interactions with their environment and other species. In this study, we first compared the ecomorphological traits of three fragmented populations of the rapidly declining Corfu killifish <i>Valencia letourneuxi</i>; then, we compared the functional traits of the Corfu killifish with those of its native sympatric species, i.e. the Thesprotian minnow <i>Pelasgus thesproticus</i> and the Epirus riffle dace <i>Telestes pleurobipunctatus</i>, and of the alien invasive Eastern mosquitofish <i>Gambusia holbrooki</i>, in sympatry with one of the killifish populations. The killifish population in sympatry with the mosquitofish differed from the two killifish populations in mosquitofish-free habitats in pectoral fin position, pectoral fin ratio and pectoral fin surface ratio, which are associated with fish position in the water column, manoeuvrability and propulsion. In addition, the riverine killifish population, in a high flow variability habitat, differed in body mass, throt and caudal fin ratio from the other two populations that occupy hydrologically stable environments, traits associated with differences in hydrodynamics. The Corfu killifish shared only one trait with the native minnow and one with the native riffle dace, indicating they occupy different ecological niches, while it shared several functional traits with the mosquitofish, which related to feeding, prey detection and swimming performance. The notable functional overlap between the Corfu killifish and the invasive mosquitofish underscores the ecological vulnerability of the killifish to mosquitofish impacts, which may lead to further decline and ultimately to its displacement.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00027-026-01297-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147661877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Planktonic response to pulse or continuous inorganic nutrient inputs: temporal variations and monitoring implications","authors":"Warren Meredith,&nbsp;Nuria Perujo,&nbsp;María Antón-Pardo,&nbsp;Anna M. Romaní,&nbsp;Dani Boix,&nbsp;Jordi Compte,&nbsp;María Bas-Silvestre,&nbsp;Xavier D. Quintana,&nbsp;Anna Menció","doi":"10.1007/s00027-026-01299-y","DOIUrl":"10.1007/s00027-026-01299-y","url":null,"abstract":"<div><p>Coastal lagoons are dynamic systems where the mode of nutrient input, continuous or pulsed, or a combination, can significantly affect plankton community structure and function. We conducted a spring field microcosm experiment in a Mediterranean lagoon to evaluate how three nutrient delivery regimes influence planktonic dynamics, using biomass measurements and extracellular enzyme activity (EEA) as functional indicators. Continuous nutrient additions promoted sustained phytoplankton and bacterioplankton growth, indicating bottom-up control and microbial stability. In contrast, pulse treatments saw a brief bacterioplankton bloom followed by delayed phytoplankton increase and a marked decline in zooplankton, suggesting disrupted trophic succession and food quality limitations. The pulse–continuous treatment yielded intermediate responses, confirming that delivery mode, not just nutrient load, modulates ecosystem processes. Elevated β-glucosidase (GLU) and leucine aminopeptidase (LAP) activity under nutrient addition, particularly in continuous treatments, signaled intensified carbon and nitrogen demand and active organic matter mineralization, even when nutrient concentrations appeared low. These findings suggest that, during stable spring conditions, microbial communities rapidly assimilate nutrients, potentially obscuring short-term biogeochemical changes from traditional concentration-based monitoring. Crucially, the timing and frequency of nutrient supply are as influential as total input, with continuous inputs supporting a more stable and efficient microbial loop. This work underscores the ecological importance of recognizing diffuse, low-level nutrient sources, such as groundwater seepage, which may be underrepresented in lagoon management strategies. Integrating functional indicators with delivery mode assessments can improve predictions of eutrophication risks and support more effective conservation planning in shallow coastal systems.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00027-026-01299-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147642848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ostracod (Crustacea: Ostracoda) diversity and environmental drivers in the Iberá Wetlands: insights from a pristine subtropical ecosystem","authors":"Lara Milena Sabater,&nbsp;María Celeste Franceschini,&nbsp;Marina Elizabet Forastier,&nbsp;Alejandra Patricia Pérez","doi":"10.1007/s00027-026-01298-z","DOIUrl":"10.1007/s00027-026-01298-z","url":null,"abstract":"<div><p>The Iberá Wetlands represent one of the largest and least disturbed freshwater ecosystems in South America. Although there has been a long history of research in these wetlands, their ostracod fauna remains unexplored. This study provides the first characterization of ostracod assemblages, analyzing their density, richness, and composition in relation to environmental drivers. Standardized sampling was conducted across littoral, limnetic, and benthic zones using hand nets and dredges. Assemblages were compared between wetland hydrological regimes (lentic versus lotic environments) and two dominant macrophyte species with contrasting architectures (<i>Egeria najas</i> and <i>Pontederia azurea</i>). Although no significant differences in richness were found between lentic and lotic environments, some species exhibited clear habitat preferences. Macrophyte architecture also influenced assemblage composition, with distinct species associated with each plant type. Our findings establish the first regional baseline and constitute valuable data for future monitoring and comparative studies, particularly in the context of global change and the increasing anthropogenic pressures on subtropical freshwater ecosystems.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Daily dissolved oxygen saturation patterns mediated by light and stream discharge in littoral regions of an oligotrophic mountain lake","authors":"Heili E. Lowman,&nbsp;Kelly Loria,&nbsp;Leon Katona,&nbsp;Jasmine Krause,&nbsp;Sudeep Chandra,&nbsp;Sally MacIntyre,&nbsp;John M. Melack,&nbsp;Ramon Naranjo,&nbsp;Joanna R. Blaszczak","doi":"10.1007/s00027-026-01292-5","DOIUrl":"10.1007/s00027-026-01292-5","url":null,"abstract":"<div><p>Nearshore regions of lakes span ecosystem boundaries—terrestrial–aquatic, lotic–lentic, littoral–pelagic—and integrate signals that propagate across these boundaries, yet these regions are undersampled relative to pelagic waters. To examine controls on littoral ecosystem function, we measured high-frequency dissolved oxygen data along the shore of a large, oligotrophic lake during 2 years. We identified two distinct diel oxygen patterns—one whose peak was synchronous with solar noon and another whose peak lagged solar noon—that were distinguished as well by their overall magnitude of dissolved oxygen. We found that these diel oxygen patterns were correlated most strongly with daily light availability when sensors were deployed along a depth gradient and with stream discharge when sensors were in locations close to or far from inflowing streams. These results show that nearshore dissolved oxygen responds variably to climate and physical conditions, that is, light and discharge, depending on the location along the shore. Our approach further highlights the need to apply diverse quantitative methods to develop a better understanding of variability in littoral lake productivity in response to changing environmental conditions, particularly in oligotrophic lakes with low productivity signals that are typically challenging to detect.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147607053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic, morphological and migratory patterns in recovering Atlantic salmon populations","authors":"Paolo M Moccetti,&nbsp;Domino A. Joyce,&nbsp;Jonathan D. Bolland,&nbsp;Jamie R. Dodd,&nbsp;Andy D. Nunn","doi":"10.1007/s00027-026-01288-1","DOIUrl":"10.1007/s00027-026-01288-1","url":null,"abstract":"<div><p>Population recovery is a key goal for conservation, but our understanding of how genetic and phenotypic variation, including local adaptation, emerges in recently recolonised or recovering systems is limited. This complicates the conservation of fitness-related traits that support resilience and long-term population viability. We employed single nucleotide polymorphism markers, geometric morphometrics and acoustic telemetry to investigate the recovery of Atlantic salmon (<i>Salmo salar</i>) in a large river system, which began more than 40 years ago following presumed extirpation in the mid-1900s. We observed genetic differentiation between Atlantic salmon in different tributaries that may reflect natural recolonisation through straying and/or the recovery of remnant populations previously believed to be extinct. Fine-scale philopatry was found to maintain the genetic divergence between tributaries, as confirmed by genetic assignment and telemetry tracking of returning adults, with some individuals displaying ‘search’ behaviour across tributaries. Despite this population structuring, neither consistent genomic signatures of selection nor morphological divergence were detected, indicating no evidence for early stage local adaptation or for differing selective pressures between tributaries. The patterns instead align with stochastic demographic processes (i.e. founder effects and genetic drift), which was further supported by the low contemporary effective population sizes detected across tributaries. These findings highlight the importance of continued genomic and ecological monitoring during population recovery, as improving environmental conditions may promote the re-establishment of remnant populations and/or facilitate recolonisation. This may, in turn, lead to the formation of reproductively isolated units and, over time, the emergence of locally adapted traits of conservation value for Atlantic salmon and other threatened migratory species.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00027-026-01288-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147607310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From natural coexistence to artificial colonisation: habitat use, competition and population structure of sympatric Aegla species","authors":"Harry Boos,&nbsp;Marcio C. A. João,&nbsp;Gilson Stanski,&nbsp;Marcelo A. A. Pinheiro","doi":"10.1007/s00027-026-01296-1","DOIUrl":"10.1007/s00027-026-01296-1","url":null,"abstract":"<div><p>Aeglids are among the most threatened freshwater crustaceans worldwide, restricted to South American watersheds and largely confined to lotic environments. Occurrences in artificial canals have not yet been documented. Here, we investigated two sympatric species, <i>Aegla jarai</i> and <i>Aegla muelleri</i>, in Espingarda Creek, a natural lotic stream, and in an adjacent artificial canal. We assessed population structure, abundance and spatial relationships between the species through monthly sampling from June 2001 to July 2002. We hypothesised that their distinct microhabitat preferences would translate into measurable differences in population parameters between the natural stream and the artificial canal. In Espingarda Creek, <i>A. jarai</i> was consistently more abundant and reached larger sizes than <i>A. muelleri</i>. In the canal, only <i>A. jarai</i> appeared regularly, spanning all ontogenetic stages and attaining larger sizes than conspecifics from the creek. Size–frequency distributions of both species were bimodal, and modal comparisons supported competitive asymmetry under sympatry. The contrasting size structure of <i>A. jarai</i> in the absence of congeners reinforces this hypothesis. Our findings suggest that the apparent dominant competitor in natural streams can also be a successful coloniser in artificial habitats. This pattern does not strictly conform to the classical expectation of a strict competition–colonisation trade‑off and is consistent with extensions of the competition–colonisation theory and with ecological plasticity in <i>A. jarai</i>. Overall, this study provides novel insights into coexistence mechanisms in freshwater decapods and highlights the importance of incorporating artificial habitats into conservation strategies for threatened aquatic invertebrates.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The urban footprint on aquatic ecosystems: comparison of microplastic dynamics in water bodies with divergent usage patterns","authors":"Gülşah Saç,&nbsp;Özgün Deniz Yürekli,&nbsp;Fahrettin Sarcan,&nbsp;Tuğçe Yetim,&nbsp;Müfit Özuluğ","doi":"10.1007/s00027-026-01295-2","DOIUrl":"10.1007/s00027-026-01295-2","url":null,"abstract":"<div><p>Microplastic pollution has become a pervasive threat to aquatic ecosystems, affecting water bodies regardless of their protection status or proximity to urban pressures. This study investigates the impact of urbanization pressure on microplastic (MP) pollution in aquatic ecosystems by comparing two water bodies in the megacity Istanbul: Küçükçekmece Lagoon and the protected freshwater reservoir of Büyükçekmece Lake. Seasonal sampling of surface waters and the eastern sand smelt fish <i>Atherina pontica</i> was conducted in both systems. All samples were (i) digested using hydrogen peroxide (H₂O₂), (ii) followed by visual examination under a stereo microscope and (iii) heat treatment test to identify potential microplastics (MPs). Subsequently, Raman spectroscopy was employed to characterize their polymer compositions. Microplastics obtained were analysed using stereo microscopy and Raman spectroscopy to determine their type, size, colour and polymer composition. The findings revealed that both the MP concentration in surface waters (0.17 items/L) and the prevalence of MPs in fish digestive tracts (38.0%) were significantly higher in Küçükçekmece Lagoon compared with Büyükçekmece Lake (0.05 items/L; 23.0%). Fibre-type MPs dominated both environments, and polymer analyses identified low-density polyethylene (LDPE), polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) as the major polymer types. These results highlight the differences between urban and protected reservoirs, suggesting that anthropogenic factors – potentially including population density, irregular urban development and associated management practices – may influence MP inputs, while protected areas may be more influenced by transport via meteorological processes, surface run-off and recreational activities. The findings also support the suitability of <i>Atherina pontica</i> as an effective bioindicator for assessing MP loads, particularly in lentic water bodies. In conclusion, these observed differences between urban and protected reservoirs suggest that environmental management strategies focusing on potential anthropogenic and meteorological inputs, such as wastewater infrastructure and surface run-off, may be important for reducing the impacts of MPs on aquatic life.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00027-026-01295-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abiotic and biotic patterns of microplastic concentration and potential for food-web uptake along a river continuum","authors":"Janell M. Shah,&nbsp;Clay P. Arango,&nbsp;Paul W. James,&nbsp;Jason T. Irwin","doi":"10.1007/s00027-026-01294-3","DOIUrl":"10.1007/s00027-026-01294-3","url":null,"abstract":"<div><p>Recent microplastic (MP) research establishes rivers as transporters of MP from terrestrial to marine environments. While studies have documented MP consumption in river food webs, few have investigated multiple consumers along a river continuum. We enumerated MP concentration in the water column, biofilm, and four macroinvertebrate families with different feeding strategies across 344 km from the Yakima River headwaters to mouth in Washington, USA. Rigorous procedural controls significantly reduced contamination, highlighting the importance of controlling exogenous plastic sources during environmental MP studies. After contamination corrections, we found MP in 93% of water samples, 96% of biofilm samples, and 68% of insect samples. MP concentration did not increase from headwaters to mouth despite cumulative human population increase, suggesting MP sources other than direct point sources or undocumented sinks in the study area. However, we found significantly different MP concentration within sites, possibly associated with flow dynamics that settle plastic from the water column. Further research is needed to positively identify plastic pollution sources not associated with urban areas and to identify temporary storage dynamics of MP in river systems. Although we found more fibers than fragments in environmental samples, insects consumed more fragments, suggesting a larger role in trophic transfer than fibers. All aquatic insect functional feeding groups had internal plastic, demonstrating that insectivores such as fish or birds are likely vectors of MP movement from the river into nearby terrestrial environments and other consumers through predation.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring a safe operating space for walleye by rebalancing an aquatic community","authors":"Logan W. Sikora,&nbsp;Joseph T. Mrnak,&nbsp;Gregory Matzke,&nbsp;Stephanie L. Shaw,&nbsp;Justin A. VanDeHey,&nbsp;Greg G. Sass","doi":"10.1007/s00027-026-01293-4","DOIUrl":"10.1007/s00027-026-01293-4","url":null,"abstract":"<div><p>Imbalanced fish communities, often driven by the dominance of invasive or overabundant native species, can destabilize aquatic ecosystems, limit management options, and reduce the resilience of desirable fish species. To explore whether reducing a biotic stressor could move a walleye <i>Sander vitreus</i> population into a resilient safe operating space (SOS), we conducted a whole-lake physical removal of overabundant black bullhead <i>Ameiurus melas</i> on Howell Lake, Wisconsin, during 2020–2024. We removed an estimated 779,208 bullhead (46.8 kg/ha), reducing the adult population by 97%. Although bullhead relative abundance (catch-per-unit-effort [CPUE]) significantly declined, walleye natural recruitment failed to meet our safe operating space criteria as hypothesized. Black crappie <i>Pomoxis nigromaculatus</i> CPUE significantly increased following bullhead removal, and age-0 walleye CPUE declined, revealing a threshold-like negative correlation consistent with previous studies. Our results suggest that the system may have transitioned to a new state dominated by black crappie, which are suppressing walleye recruitment despite extensive bullhead removal. Our findings illustrate that managing for resilience through species dominance shifts may yield unpredictable outcomes, highlighting the importance of anticipating compensatory responses of nontarget species and addressing multiple stressors when attempting to restore imperiled fish populations to an SOS.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water quality and trophic dynamics under contrasting hydrological conditions in the lower Usumacinta River basin: potential influence of floodplain wetlands","authors":"Ismael Soria-Reinoso,&nbsp;Javier Alcocer,&nbsp;Salvador Sánchez-Carrillo,&nbsp;Luis A. Oseguera,&nbsp;Daniel Cuevas-Lara,&nbsp;Montserrat Rivera-Herrera,&nbsp;Martín Merino-Ibarra","doi":"10.1007/s00027-026-01289-0","DOIUrl":"10.1007/s00027-026-01289-0","url":null,"abstract":"<div><p>Tropical river–floodplain systems are increasingly threatened by land-use change, hydrological alterations, and climate variability, yet integrated assessments of their ecological condition remain scarce. This study evaluates seasonal and spatial patterns in water quality and trophic status in the lower Usumacinta River basin (southeastern Mexico) and examines the influence of hydrological variability and floodplain wetlands within the Centla Wetlands Biosphere Reserve. Surface water was analyzed at eight stations, both inside and outside the reserve, during a high-discharge rainy season (2017) and a low-discharge dry season (2018), using two complementary multimetric indices: the Water Quality Index (WQI) and the Trophic Index (TRIX). Hydrological state was the primary organizing gradient. During the rainy season, elevated discharge increased suspended solids and total nutrient loads, lowered dissolved oxygen, and heightened eutrophication signals, particularly in floodplain and estuarine reaches. In contrast, the dry season showed improved overall water quality but higher dissolved inorganic nitrogen and stronger phosphorus limitation. Spatially, the San Pedro River maintained oligotrophic conditions and high ecological integrity, whereas the Grijalva River remained persistently eutrophic, reflecting cumulative anthropogenic pressures. Although floodplain wetlands were associated with localized nutrient attenuation under certain hydrological conditions, their regulatory influence was context-dependent and constrained by discharge and land-use gradients. By integrating hydrological context with multimetric indices, this study demonstrates that seasonal connectivity, rather than simple dilution, governs water quality responses in large tropical rivers. These findings provide a basin-scale framework for anticipating eutrophication risk under intensifying hydroclimatic and anthropogenic pressures.</p></div>","PeriodicalId":55489,"journal":{"name":"Aquatic Sciences","volume":"88 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00027-026-01289-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}