Limnology and Oceanography: Methods最新文献

{"title":"The IceShark, an effective method for sampling plankton under sea ice","authors":"Eleanor A. Barry,&nbsp;Susan Ziegler,&nbsp;Joey Angnatok,&nbsp;Emma J. Harrison,&nbsp;Uta Passow","doi":"10.1002/lom3.70029","DOIUrl":"https://doi.org/10.1002/lom3.70029","url":null,"abstract":"<p>Seasonal sea ice plays a crucial role in shaping coastal ecosystem dynamics throughout the circumpolar region. Of particular interest to oceanographers is the ice-ocean interface which functions as a multidimensional habitat, supporting both sympagic algae and pelagic phytoplankton in the under-ice surface waters. Varying both spatially and temporally, these primary producers support and sustain zooplankton populations, forming the foundation of the arctic and subarctic coastal food webs. Current climate-driven shifts in sea ice extent, duration, and thickness along the coast of Nunatsiavut, the homelands of Labrador Inuit in eastern Arctic-subarctic Canada, are expected to disrupt plankton communities, potentially triggering cascading effects across higher trophic levels. Despite these ramifications, research focusing on plankton dynamics at the ice-ocean interface is limited, largely due to restrictions associated with access and isolation of under-ice surface waters, as well as difficulties in undertaking work in subzero conditions. In an effort to address this gap, we introduce a new sampling methodology, using a recently designed apparatus, dubbed the IceShark. With a compact size and targeted design, the IceShark collects plankton directly below the ice, running at an average speed of 0.91 ± 0.15 m s⁻¹, filtering an average volume of 8.61m³ (± 1.37) over 20-min of operation (0.41 m³/min). Here we discuss the design and fabrication of the IceShark and evaluate its performance during pilot deployments along a fjord system in Nunatsiavut.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148047557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Chemical stabilization of glass microfiber type F filters for measuring particulate phosphorus using the extra high-temperature dry combustion method","authors":"Ying-Yu Hu,&nbsp;Andrew J. Irwin,&nbsp;Zoe V. Finkel","doi":"10.1002/lom3.70030","DOIUrl":"https://doi.org/10.1002/lom3.70030","url":null,"abstract":"<p>Accurate quantification of particulate phosphorus is critical for understanding biogeochemical processes in aquatic systems. Extra high-temperature dry combustion at 800°C improves phosphorus recovery by ~ 11% compared to lower-temperature methods. Glass microfiber type F (GF/F) filters are often used for particulate carbon, nitrogen, and phosphorus analysis but melt at 800°C, entrapping phosphorus within the melted matrix and leading to poor phosphorus recovery, thereby limiting their compatibility with the extra high-temperature dry combustion method. To address this limitation, we show that adding 3200 <i>μ</i>mol of magnesium sulfate (MgSO₄) yields statistically equivalent recoveries of total particulate phosphate from both laboratory-grown phytoplankton and seawater particulate matters collected on 25 mm GF/F filters, comparable to recoveries from 25 or 47 mm polycarbonate filters. We hypothesize that MgSO₄ reacts with SiO₂ in the GF/F filter matrix to form crystalline MgSiO₃, increasing the thermal stability of the filters (melting point &gt;1000°C). This transformation preserves filter structure during the 800°C combustion and enables complete recovery of KH₂PO₄ and particulate phosphorus. Structural and chemical changes to the GF/F filter due to MgSO₄ addition were confirmed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The addition of MgSO₄ to GF/F increases their thermal stability, making them suitable for the extra high-temperature dry combustion method; consequently, particulate carbon, nitrogen and phosphorus samples can all be collected and analyzed on 25 mm GF/F filters, improving the consistency of particulate C : N : P estimates in aquatic biogeochemistry.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148046443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Ocean acidification at the crossroads I: Harmonizing unpurified and purified meta-cresol purple spectrophotometric pHT measurements based on absorbance data","authors":"Marta Álvarez,&nbsp;Maribel I. García-Ibáñez,&nbsp;Rubén Acerbi,&nbsp;Rocío Santiago-Domenech,&nbsp;Elisa F. Guallart,&nbsp;Noelia M. Fajar,&nbsp;Lisandro Arbilla","doi":"10.1002/lom3.70023","DOIUrl":"https://doi.org/10.1002/lom3.70023","url":null,"abstract":"<p>Consistent monitoring of seawater spectrophotometric pH on the total hydrogen ion scale (pH_T) has been questioned by an evolving method, with changes in parameterization and the purity of the meta-cresol purple (mCP). Using real seawater samples, we demonstrate that spectrophotometric pH_T measurements obtained with unpurified (UNPUR) and purified (PUR) mCP can be harmonized to within 0.003 pH units, the climate-goal threshold. This agreement is only achieved when mCP impurities at 434 nm are quantified for both the UNPUR and PUR mCP, assuming no impurities affect 545 nm absorbances, and impurity-corrected absorbance data at 434 nm are used in the same parameterization to calculate pH_T. We applied this approach to a ship-based pH_T time series transitioning from UNPUR to PUR mCP measurements. Our results show that previous claims suggesting that UNPUR mCP underestimates pH_T in the upper pH range are misleading, as they were based on the inappropriate use of absorbances obtained with UNPUR mCP with a parameterization developed for PUR mCP. In fact, our data reveal better agreement between UNPUR and PUR pH_T in the upper pH range of seawater, while UNPUR mCP tends to overestimate pH_T in the lower pH range. These findings highlight the urgent need for the global chemical oceanography community to establish a spectrophotometric pH_T method with full traceability to the International System of Units (SI), along with affordable and distributed certified reference materials and characterized purified mCP. This work supports the need for harmonization efforts to ensure the reliability of pH_T data in global synthesis products.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148048446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Sediment trap preservative choice impacts particle-associated microbial community composition","authors":"Nicola L. Paul,&nbsp;Colleen A. Durkin,&nbsp;Sebastian Sudek,&nbsp;Matthieu Bressac,&nbsp;Philip W. Boyd,&nbsp;Eric J. Tappa,&nbsp;Claudia R. Benitez-Nelson,&nbsp;Alyson E. Santoro","doi":"10.1002/lom3.70026","DOIUrl":"https://doi.org/10.1002/lom3.70026","url":null,"abstract":"<p>Understanding and quantifying the microbial contribution to particulate organic matter (POM) flux and carbon cycling in the ocean relies largely on the collection of sinking POM. A critical aspect of evaluating microbial communities on sediment trap-collected POM is their preservation until recovery and sample processing. While RNA<i>later</i> has emerged as a recent preservative in sediment trap studies, no comparisons have been made between RNA<i>later</i> and the more established preservative, formalin, to determine their effectiveness in capturing POM-attached microbial communities. Our work evaluates these preservatives through laboratory testing and sediment trap deployments (lasting days to months). Formalin-fixed POM required decrosslinking (undoing bonds between DNA and proteins) to extract DNA. When decrosslinking was included, no community differences were observed from subsequent DNA extraction or amplification when preserved in the lab. However, when preservatives were deployed inside sediment traps, significant differences were observed among unpreserved, RNA<i>later</i>-preserved, and formalin-preserved POM. In these samples, some copiotrophs, such as Gammaproteobacteria, Verrucomicrobiae, and Flavobacteria, demonstrated greater relative abundances in RNA<i>later</i>, and the overall magnitude of these differences was greater for RNA<i>later</i>-preserved vs. formalin-fixed POM, indicating differing abilities of each preservative to halt microbial activity, contributing to the overrepresentation of some taxa. Together, these results suggest that formalin preservation is the best option for use in sediment traps, especially for long-term deployments (&gt; 5 d), common for moored sediment trap timeseries studies. A skewed view of microbial community structure on POM has implications for our understanding of the taxa and metabolisms contributing to carbon turnover in the ocean.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148050572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Development of a moored radium in situ sampler to measure annual time series","authors":"Lauren Kipp,&nbsp;Matthew A. Charette,&nbsp;Paul Henderson,&nbsp;Joshua Benedict,&nbsp;Igor Polyakov,&nbsp;Andrey Pnyushkov","doi":"10.1002/lom3.70020","DOIUrl":"https://doi.org/10.1002/lom3.70020","url":null,"abstract":"<p>Radium is a useful tracer of sediment-derived materials, improving our understanding of the geochemical cycling of elements at ocean boundaries. We have developed an autonomous in situ sampler to collect time series samples of radium isotopes on mooring deployments. Samplers were deployed for 2 yr in the Arctic Ocean, a region particularly hard to access outside of the summer season, and collected monthly samples to create the first annual time series of radium-228 and radium-226 in the Arctic. Results from the Laptev Slope show increased radium-228 and radium-228/radium-226 ratios in spring/summer, concomitant with increased meteoric water and brine influence. Together, these tracers indicate seasonal periods of increased influence of shelf- and river-derived materials, findings which would not be possible to discern from summertime shipboard surveys alone. The development of this in situ sampler has therefore expanded our capability to use radium as a tracer to discern temporal changes in the geochemistry of remote areas of the ocean.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 3","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147653193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Improved COI taxonomic assignment workflow enhances detection of invertebrates in environmental DNA","authors":"Yuanyu Cheng,&nbsp;David Walsh,&nbsp;Joanna Gauthier,&nbsp;Marie-Eve Monchamp,&nbsp;Daniel T. Selbie,&nbsp;Irene Gregory-Eaves","doi":"10.1002/lom3.70021","DOIUrl":"https://doi.org/10.1002/lom3.70021","url":null,"abstract":"<p>Environmental DNA (eDNA) metabarcoding is an increasingly popular and powerful tool in ecology, offering a non-invasive method to assess biodiversity and monitor ecosystem health across diverse environments. While the mitochondrial cytochrome <i>c</i> oxidase subunit I (COI) gene is one of the most widely used markers for studying eukaryotic community dynamics, its taxonomic assignment process often suffers from low confidence and inconsistent results. In this study, we employed COI metabarcoding to investigate changes in invertebrate communities in Cultus Lake (British Columbia, Canada), over a 36-month time series. To enhance taxonomic accuracy, we developed an enhanced COI workflow incorporating: (1) bacterial-inclusive reference databases, (2) protein-level alignment and cleanup procedures, and (3) taxon-specific nucleotide refinements, thereby accounting for bacterial sequences, codon degeneracy, pseudogenes, and other erroneous sequences. Compared to 18S rRNA metabarcoding of the same samples, our improved COI workflow detected greater invertebrate diversity in Arthropoda and Rotifera, provided higher taxonomic resolution, and showed stronger correlations with microscopic zooplankton counts. Based on these findings, we recommend COI metabarcoding with our enhanced workflow for eDNA-based studies of aquatic invertebrate communities.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 3","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147653257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Predicting potential Arctic kelp distribution and lower-depth biomass from seafloor irradiance","authors":"Laura Castro de la Guardia,&nbsp;Inka Bartsch,&nbsp;Haakon Hop,&nbsp;Sarina Niedzwiedz,&nbsp;Luisa Düsedau,&nbsp;Nora Diehl,&nbsp;Dorte Krause-Jensen,&nbsp;Mikael Sejr,&nbsp;Thomas Gjerfluff Ager,&nbsp;Jean-Pierre Gattuso,&nbsp;Robert W. Schlegel,&nbsp;Cale A. Miller,&nbsp;Karen Filbee-Dexter,&nbsp;Pedro Duarte","doi":"10.1002/lom3.70018","DOIUrl":"https://doi.org/10.1002/lom3.70018","url":null,"abstract":"<p>Kelps have an extensive distribution in Arctic coastal waters. However, quantifying their role in the Arctic food web and carbon cycle is challenged by the scarcity of documented geographical distribution, standing stocks and production. Here we present a framework based on an empirical function to predict the potential kelp distribution and their summer biomass as a function of seafloor irradiance and bathymetry. Predictions of biomass were limited to the lower-depth, light-limited range of the kelp distribution, where the fit of the empirical function was significant (from the depth of maximum biomass to the deepest kelp extent). The model was developed and tested in Kongsfjorden, Svalbard, and applied in six additional fjords in the Arctic. The predicted potential kelp biomass in the fjords ranged from 0.6 to 4.7 kg WW m⁻² and was in good agreement with published values. The resulting kelp standing stock ranged from 0.4 to 300 Gg DW, corresponding to 0.2–109 Gg C. These potential estimates account for light limitation, but do not consider substrata or other factors limiting the kelp distribution area. We identified fjord-specific dependencies between predicted standing stocks and seafloor irradiance and between seafloor irradiance and its drivers (surface irradiance and water column light attenuation) but found no significant change between 2004 and 2022. Our framework provides a baseline for estimating potential kelp biomass from seafloor irradiance, which is expected to change with increasing sediment runoff causing coastal darkening.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 3","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.1002/lom3.70018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147653274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 3","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148080052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The first application of secondary ion mass spectrometry for the analysis of δ18O in otoliths of larval fish","authors":"Alanna Mnich,&nbsp;Mingming Zhang,&nbsp;Trika Gerard,&nbsp;Patricia Reglero,&nbsp;Steven X. Cadrin,&nbsp;Mark Altabet","doi":"10.1002/lom3.70016","DOIUrl":"https://doi.org/10.1002/lom3.70016","url":null,"abstract":"<p>The stable isotope ratio of oxygen (δ¹⁸O) stored in otoliths is a common and reliable tool for studying life history events including natal origin and migratory behavior of marine fish species. This approach is useful particularly in cases where traditional tagging is impossible, such as in early larval stages. However, small amounts of available otolith material have historically precluded analysis of δ¹⁸O in individual larval otoliths by traditional isotope ratio mass spectrometer (IRMS). The use of secondary ion mass spectrometer (SIMS) resolves this challenge, allowing users to obtain δ¹⁸O signatures in otoliths at the scale of tens of microns. This paper presents a method for the preparation of larval fish otoliths compatible with SIMS δ¹⁸O analysis through placement of larval otoliths (~ 20 to ~ 150 <i>μ</i>m diameter) on a single epoxy mount and use of a Cesium ion beam, ¹³³Cs⁺, of 12 <i>μ</i>m in diameter with 1 <i>μ</i>m penetration depth to excite source larval otolith material. In this pilot study, otoliths from Atlantic bluefin tuna (<i>Thunnus thynnus</i>) larvae were used to assess the efficacy of generating quality δ¹⁸O data using the newly developed preparation method for establishing spawning site baselines. The applied methods led to usable δ¹⁸O signatures in &gt; 90% of the otoliths selected for analysis. Challenges and unanticipated considerations that became apparent during the use of this method include the inverse relationship between ¹⁶OH⁻/¹⁶O⁻, an indicator of hydrogen content, and δ¹⁸O, resulting in a limitation of using otoliths from preflexion larvae, as well as a statistically significant difference in δ¹⁸O (−0.17‰) after storage in Type B immersion oil.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 3","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147626377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A refined method for phosphite detection in freshwater ecosystems","authors":"Songjie Han,&nbsp;Wenqiang Zhang,&nbsp;Chunfu Li,&nbsp;Shengguang Yuan,&nbsp;Baoqing Shan","doi":"10.1002/lom3.70019","DOIUrl":"10.1002/lom3.70019","url":null,"abstract":"<p>The prevalent existence of phosphite in the contemporary, oxidizing aquatic environments is noteworthy, and its overlooked role in the phosphorus cycle needs further elucidation. While existing methods for quantifying phosphite have limited applicability due to inherent constraints. We propose a novel approach that integrates various techniques, termed diffusive gradients in thin films (DGT)–ion chromatography (IC)–inductively coupled plasma mass spectrometry (ICP-MS/MS), which differs from traditional high-performance liquid chromatography (HPLC)–ICP-MS. This method converts the detection target of P⁺ (<i>m</i>/<i>z</i> = 31) to PO⁺ (<i>m</i>/<i>z</i> = 47), effectively mitigating MS interference and enhancing detection performance, enabling the method detection limit to 0.033 <i>μ</i>g P L⁻¹, significantly lower than that of the HPLC–ICP-MS. Under the premise of separation of IC, the precision (coefficient of variation= 0.6–1.4%) and accuracy (recovery = 98.2–99.6%) were tested as excellent for the phosphite measurement range from low to high concentration. When combined with the enrichment of DGT, even the amount of phosphite below the method detection limit can be determined, applications of this method to the natural samples with complex matrix ensure that the &gt; 95.2% recovery accurately quantifies phosphite. This method reduced the method detection limit for phosphite and realized the accurate quantitative analysis, providing an important basis for further studys of phosphite in freshwater ecosystems.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":"24 3","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147330719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}