Limnology and Oceanography Letters最新文献

{"title":"Stage-specific vulnerability: Ocean acidification and hypoxia impair copepod recruitment through a naupliar bottleneck","authors":"Weijia Chen,&nbsp;Kunshan Gao","doi":"10.1002/lol2.70181","DOIUrl":"10.1002/lol2.70181","url":null,"abstract":"<p>Progressive ocean acidification and deoxygenation are expected to threaten many marine zooplankton, but their combined effects across life stages remain poorly understood. We investigated stage-specific responses of the egg-carrying copepod <i>Pseudodiaptomus annandalei</i> to changes in pH_T (5.97–8.05) and dissolved oxygen (DO; 0.90–8.20 mg L⁻¹). Nauplii were the most sensitive stage in 24-h exposures, with survival dropping below 40% at pH_T 6.1 and declining to 55–70% when DO fell below 1 mg O₂ L⁻¹. Under combined stress, naupliar survival declined to about 65% in the most severe treatment (pH_T 7.11, DO 1.74 mg O₂ L⁻¹), whereas copepodites and adults showed no significant short-term survival response. In contrast, moderate combined stress (pH_T 7.62, DO 4.11 mg O₂ L⁻¹) produced sublethal effects, increasing development time by approximately 70%, reducing development success from 86% to 28%, and decreasing nauplii production by approximately one-third. Thus, nauplii form a critical bottleneck for recruitment under combined stress.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70181","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extreme coastal El Niño reduces ocean carbon outgassing off Peru","authors":"Weixian Zeng,&nbsp;Enhui Liao,&nbsp;Xueming Zhu,&nbsp;Jiaxu Zhang","doi":"10.1002/lol2.70176","DOIUrl":"10.1002/lol2.70176","url":null,"abstract":"<p>The southeastern tropical Pacific exhibits strong El Niño–Southern Oscillation (ENSO)-driven interannual carbon variability. Previous studies have established carbon response to basin-scale El Niño, but the response to coastal El Niño, a distinct mode confined to the Peruvian coast, remains poorly constrained. Using observation-based <i>p</i>CO₂ products and a forced global physical-biogeochemical ocean model at ~ 0.5° horizontal resolution, we quantify and decompose the carbon response to the 2017 coastal El Niño. During this event, nearshore CO₂ flux decreased by as much as 14.65 TgC yr⁻¹, comparable to the extreme basin-scale events. This reduction was driven by weakened coastal winds that lowered gas transfer efficiency and suppressed upwelling of CO₂-rich subsurface waters. Mean cross-shore circulation further transported low-<i>p</i>CO₂ waters into the open ocean. This wind-driven and spatially confined coastal pathway is distinct from basin-scale El Niño, which suppresses outgassing through thermocline deepening, highlighting coastal El Niño as a distinct mode of carbon variability.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70176","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148902399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small- and large-scale patches shape benthic microbial community structure and functional gene composition in streams at the subcontinental scale","authors":"Richard LaBrie,&nbsp;Rebecca L. Maher,&nbsp;Kelly S. Aho,&nbsp;Brittni L. Bertolet,&nbsp;Nicholas E. Ray,&nbsp;Paula C.J. Reis,&nbsp;Andrew L. Robison,&nbsp;Shannon L. Speir","doi":"10.1002/lol2.70149","DOIUrl":"10.1002/lol2.70149","url":null,"abstract":"<p>Streams process organic matter as water moves along the land-to-ocean continuum, making important contributions to global biogeochemical cycles. Yet, predicting stream microbial metabolism associated with biogeochemical transformations at broad spatial scales remains challenging. Using the National Ecological Observatory Network database, we investigated ecological relationships between microbial communities and environmental conditions at the subcontinental scale. We found that microbial community composition and function were best explained by site and substrate type. However, when field replicates were combined, stream physico-chemical characteristics became strong predictors. Additionally, oxic and anoxic nitrogen- and methane-related gene abundances varied with substrate type and coexisted in epipsammon samples, but not in epilithon. Overall, water quality appeared to act as a subcontinental scale environmental filter on microbial communities. However, this influence was secondary to the high spatial heterogeneity induced by small-scale patches. Thus, nested spatial scales must be considered to fully understand benthic microbial communities' role in stream biogeochemistry.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70149","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does nutrient scarcity select for Synechococcus clade III in the Mediterranean Sea?","authors":"Xiaodong Zhang,&nbsp;Shunyan Cheung,&nbsp;Hoi Yau Chan,&nbsp;Sangwook Scott Lee,&nbsp;Ioulia Santi,&nbsp;Paraskevi Pitta,&nbsp;Jiawei Chen,&nbsp;Hongbin Liu","doi":"10.1002/lol2.70175","DOIUrl":"10.1002/lol2.70175","url":null,"abstract":"<p><i>Synechococcus</i> inhabit both nutrient-rich estuaries and oligotrophic waters, yet exhibit distinct niche segregation across phylogenetic clades. Previous studies indicated clade III predominated in the ultraoligotrophic Mediterranean Sea. However, the mechanisms underlying clade III's dominance over other clades in ultraoligotrophic waters remain unclear. Here, we measured bulk and clade-specific growth rates of <i>Synechococcus</i> using a dilution approach during a mesocosm experiment in the Eastern Mediterranean Sea. Clade III exhibited higher growth rates than competing clades and competitive superiority for limited nutrients in mesocosms amended with ammonium and phosphate. Genomic analyses revealed clade III possessed more nitrogen/phosphorus transporters than other clades (except clade VIII and S5.2), which may contribute to their competitive advantage in ultraoligotrophic conditions. Compared to clade VIII/S5.2, clade III's lower GC content and smaller genome size are consistent with adaptation to oligotrophic systems. The unique adaptive genomic traits of clade III <i>Synechococcus</i> may facilitate their ecological success in ultraoligotrophic waters.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70175","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using a large language model to automate harmful algal bloom prediction","authors":"Ming Li,&nbsp;Jorge Z. Verduzco,&nbsp;Xiaohong Wang,&nbsp;Pedro R. Costa,&nbsp;Patricia M. Glibert","doi":"10.1002/lol2.70177","DOIUrl":"10.1002/lol2.70177","url":null,"abstract":"&lt;p&gt;Machine learning (ML) can transform aquatic science and environmental research by enabling the analysis of large datasets, pattern recognition, time series prediction, and decision support (Sadaiappan and Balakrishnan &lt;span&gt;2023&lt;/span&gt;; Konya and Nematzadeh &lt;span&gt;2024&lt;/span&gt;; Gorski et al. &lt;span&gt;2024&lt;/span&gt;; Allen et al. &lt;span&gt;2025&lt;/span&gt;). ML models are capable of capturing complex, nonlinear relationships among physical, chemical, and biological processes that vary across multiple temporal and spatial scales using growing volumes of observational data. However, it is challenging to apply ML to aquatic science due to the difficulty of mastering both ML and domain knowledge (Zhu et al. &lt;span&gt;2023&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;Large language models (LLMs) have the potential to make ML more accessible to the aquatic science community (Zhu et al. &lt;span&gt;2023&lt;/span&gt;; An et al. &lt;span&gt;2024&lt;/span&gt;). Based on transformer architectures and trained on massive text and code datasets (Vaswani et al. &lt;span&gt;2017&lt;/span&gt;), LLMs such as ChatGPT can generate and summarize text, write and debug computer code, and assist with reasoning and data analysis (Brown et al. &lt;span&gt;2020&lt;/span&gt;; Wei et al. &lt;span&gt;2022&lt;/span&gt;; OpenAI &lt;span&gt;2023&lt;/span&gt;). These capabilities can substantially streamline ML model development and lower the barrier to applying AI in aquatic and environmental research. For example, An et al. (&lt;span&gt;2024&lt;/span&gt;) developed a ChatGPT-assisted machine learning framework for air quality prediction.&lt;/p&gt;&lt;p&gt;Harmful algal blooms (HABs) are increasing in frequency and severity worldwide. Filter-feeding organisms such as shellfish can accumulate HAB-produced toxins, becoming vectors for human exposure (Costa et al. &lt;span&gt;2019&lt;/span&gt;). ML is being increasingly used for HAB prediction (Li et al. &lt;span&gt;2021&lt;/span&gt;; Park et al. &lt;span&gt;2024&lt;/span&gt;). Commonly applied ML methods include random forests, support vector machines, gradient boosting models, artificial neural networks such as multilayer perceptron (MLP), and deep learning architectures such as convolutional neural networks (CNN) and recurrent neural networks (RNN), including long short-term memory (LSTM), that are well suited for time series prediction (Cruz et al. &lt;span&gt;2021&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;Here we demonstrate the use of ChatGPT to automate the generation of ML regression and classification models for the HABs toxin prediction. HAB species such as &lt;i&gt;Dinophysis&lt;/i&gt; spp.—producers of diarrhetic shellfish poisoning (DSP) toxins—are common in European waters (Reguera et al. &lt;span&gt;2012&lt;/span&gt;; Braga et al. &lt;span&gt;2023&lt;/span&gt;). The Portuguese Institute for the Sea and Atmosphere (IPMA) has conducted routine monitoring of marine biotoxins along the Portuguese coast since 1986. The program currently covers 37 classified shellfish production areas (Vale et al. &lt;span&gt;2008&lt;/span&gt;), with weekly analyses of shellfish tissues for major toxin groups, including DSP toxins in the mussel &lt;i&gt;Mytilus galloprovincialis&lt;/i&gt;. Concurrent monitor","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70177","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A dual role of phycoerythrin in the nitrogen-fixing cyanobacterium Crocosphaera watsonii: From light-harvesting to nitrogen reservoir","authors":"Takako Masuda,&nbsp;Grzegorz Konert,&nbsp;Dominik Pinkas,&nbsp;Marie Vancová,&nbsp;Vlada Filimonenko,&nbsp;Radek Kaňa,&nbsp;Ondřej Prásil","doi":"10.1002/lol2.70172","DOIUrl":"10.1002/lol2.70172","url":null,"abstract":"<p>Unicellular diazotrophic cyanobacteria contribute up to ~50% of marine N₂ fixation, and <i>Crocosphaera watsonii</i>, characterized by high phycoerythrin (PE) content, is among one of the key species in tropical and subtropical oceans. Although recent observations have revealed heterogeneous N₂ fixation activity within <i>C. watsonii</i> populations, the mechanisms behind its heterogeneity remain unresolved. Here, we hypothesize that PE's structural state is associated with the regulation of N₂ fixation. Using single-cell fluorescence spectroscopy, we observed that photosystem-uncoupled free PE was exclusively present under diazotrophic conditions and localized to the central cytoplasmic region. While mean PE fluorescence remained unchanged, PE : allophycocyanin ratios declined at the periphery in the night. These findings suggest an additional role for PE, potentially as a temporary nitrogen reservoir to buffer cellular N levels during active N₂ fixation, beyond its established light-harvesting function.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70172","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Salinization induced under‐ice benthic warming, hypoxia, and reduced spring mixing in a rural lake with low road density","authors":"Ryan W. Scott,Joshua Culpepper,Ryan H. S. Hutchins,James A. Rusak,Mathew G. Wells,Sapna Sharma","doi":"10.1002/lol2.70179","DOIUrl":"https://doi.org/10.1002/lol2.70179","url":null,"abstract":"Abstract The stratification of ice‐covered lakes is currently understood as either cryomictic (mixing near 0°C) or cryostratified (inverse stratification reaching 4°C). However, internal or external salt sources may alter these patterns, creating stable stratification with high under‐ice bottom water temperatures, a condition we term cryohalostratification, which may lead to anoxia and interference with spring mixing. We measured stratification and water quality over two winters in a rural Canadian Shield lake exposed to a highway. We found high under‐ice water temperatures (&gt; 4°C) and low dissolved oxygen (&lt; 2 mg L −1 ) because of increases in chloride and sodium. Following a cold winter, stability remained high after ice‐off, preventing mixing and prolonging seasonal hypoxia. Lake stability estimates showed that the stability of the lake was enhanced by wind sheltering from the surrounding forest, suggesting that even rural lakes with low road density are susceptible to salinization.","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"3 1","pages":""},"PeriodicalIF":7.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"No evidence of Calanus reorganization across three Northeast Atlantic transects during 30 years of monitoring","authors":"Johanna M. Aarflot,&nbsp;Cecilie Broms,&nbsp;Magnus Reeve,&nbsp;Morten D. Skogen","doi":"10.1002/lol2.70173","DOIUrl":"10.1002/lol2.70173","url":null,"abstract":"<p>Reports have suggested dramatic shifts in the calanoid assemblage of the Northeast Atlantic, with warm-water species expanding northwards at the expense of cold-water congeners. This is considered a serious threat to lipid-fueled higher trophic levels, as warm-water copepods are typically smaller with lower lipid content. Nevertheless, ecosystem dynamics may vary substantially among this vast region. Here, we analyze 30 years of abundance data for temperate <i>Calanus helgolandicus</i> and sub-Arctic <i>C. finmarchicus</i> along three oceanographic transects in the Norwegian zone, spanning temperate (northern North Sea) to sub-Arctic (southwestern Barents Sea) conditions. Contrary to expectations, we find no evidence of a copepod reorganization. Following a decline toward 2010, <i>C. finmarchicus</i> has returned to historical levels, while <i>C. helgolandicus</i> remains roughly an order of magnitude less abundant at all transects. Our results caution against extrapolation of regional plankton dynamics to the Northeast Atlantic, emphasizing the value of sustained, spatially distributed monitoring programs.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148861050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tropical cyclone-induced estuarine destratification and protracted recovery","authors":"Jiayao Zhang,&nbsp;Leiping Ye,&nbsp;Zhaohui Deng,&nbsp;Jiaxue Wu","doi":"10.1002/lol2.70171","DOIUrl":"10.1002/lol2.70171","url":null,"abstract":"<p>Estuarine stratification regulates nutrient cycling and ecosystem dynamics, yet its resilience to extreme meteorological events remains poorly understood. Here, we combine high-resolution observations and numerical modeling to capture the full-cycle physical response of an estuary to a summer typhoon. Results show that within 48 h, vigorous vertical mixing driven by typhoon wind stress erased salinity-driven stratification and homogenized the water column. A salinity budget reveals vertical mixing as the dominant destratification mechanism. Following the typhoon, the system entered a prolonged recovery exceeding 7 d, during which gradually re-established stratification. Notably, we document significant decoupling in recovery timescales: surface freshwater plume signatures began recovering within days, whereas bottom water property shifts lagged by ~ 6 d. This depth-dependent recovery underscores that estuarine restoration after extreme mixing is a multi-stage process. It improves understanding of estuarine stratification responding to and recovering from tropical cyclones, and highlights the importance of considering depth-dependent recovery processes when assessing post-storm estuarine conditions.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70171","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148836255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentary lycopane/n-C31 ratio as a proxy for bottom water hypoxia in coastal ocean","authors":"Qingnan Song,&nbsp;Huamao Yuan,&nbsp;Jinming Song,&nbsp;Guiling Zhang,&nbsp;Fengmin Pan,&nbsp;Xuegang Li,&nbsp;Liqin Duan","doi":"10.1002/lol2.70167","DOIUrl":"10.1002/lol2.70167","url":null,"abstract":"<p>Bottom-water hypoxia on continental shelves is intensifying under climate change and eutrophication, yet long-term records remain scarce. Here we show that the sedimentary lycopane/n-C₃₁ ratio reliably records bottom-water oxygenation in the seasonally hypoxic Yangtze River Estuary. In surface sediments, lycopane/n-C₃₁ correlates negatively with dissolved oxygen, reflecting preferential preservation of lycopane under low-oxygen conditions. Despite multiple potential sources, sedimentary lycopane is dominated by bottom particulate deposition, making the ratio a robust redox proxy in dynamic coastal margins. Sediment core records reveal a progressive intensification of hypoxia since 2005, consistent with trace-metal enrichment factors (Mo_EF/U_EF) and complementary biomarkers. This deoxygenation coincides with warming, reduced sediment supply, and enhanced export production. Our results suggest that lycopane/n-C₃₁ is a sensitive indicator of bottom-water oxygen variability in the Yangtze River Estuary, with potential for reconstructing modern decadal-scale hypoxia trends in seasonally hypoxic coastal systems.</p>","PeriodicalId":18128,"journal":{"name":"Limnology and Oceanography Letters","volume":"11 5","pages":""},"PeriodicalIF":7.3,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lol2.70167","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148836256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}