Limnology and Oceanography最新文献

{"title":"Zooplankton diel vertical migration drives a major, variable and underestimated carbon sink in the Southern Ocean","authors":"Yilin Ruan,&nbsp;Lv Yan,&nbsp;Xinshang Zhang,&nbsp;Jun Zhao,&nbsp;Guang Yang,&nbsp;Song Sun","doi":"10.1002/lno.70516","DOIUrl":"10.1002/lno.70516","url":null,"abstract":"<p>The biological carbon pump, a key process for oceanic CO₂ sequestration, is primarily attributed to the gravitational sinking of particles. However, vertically migrating zooplankton actively transport carbon to depth through respiration and excretion during diel vertical migration (DVM). Here, we quantify the magnitude and variability of DVM-mediated active carbon flux (AF_DVM) by mesozooplankton in the Southern Ocean and assess its contribution relative to gravitational export. We estimated AF_DVM using paired day–night, vertically resolved net sampling across ecologically contrasting regions of the Southern Ocean during austral summers between 2018 and 2023. Migrating biomass was combined with temperature-dependent metabolic rates to calculate respiratory and excretory carbon fluxes. Regional estimates were compared with modeled particulate organic carbon fluxes and extrapolated to the circumpolar scale using a long-term zooplankton biomass synthesis (1932–2020). Diel vertical migration–mediated active fluxes exhibited strong regional variability, with relatively consistent export in copepod-dominated communities of the Amundsen Sea and substantially higher variability in the Cosmonaut Sea. Across the 27 stations, AF_DVM ranged from 1.1% to 136.6% of modeled gravitational particulate organic carbon fluxes, with a geometric mean of 27.2% and a median of 31.8%. Circumpolar extrapolation indicates that summer AF_DVM reaches approximately 38.9 Mt C (95% uncertainty interval: 27–60 Mt C), representing ~ 13% of total summer carbon export at 200 m depth. Our results demonstrate that DVM constitutes a substantial and previously under-quantified component of the Southern Ocean carbon cycle. Incorporating zooplankton-mediated active transport alongside sinking fluxes is therefore essential for a more complete assessment of carbon export in polar oceans.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 10","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149086129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate warming and aquaculture reclamation activate positive feedback mechanisms for greenhouse gases in a temperate mudflat","authors":"Zihao Wang,&nbsp;Qian Cui,&nbsp;Peng Guo,&nbsp;Can Wang,&nbsp;Heting Zhou,&nbsp;Min Li,&nbsp;Qiuyu Shen,&nbsp;Zongxiao Zhang,&nbsp;Xianbiao Lin","doi":"10.1002/lno.70512","DOIUrl":"10.1002/lno.70512","url":null,"abstract":"<p>Conversion of natural bare mudflats to aquaculture ponds is a prevalent practice that fundamentally alters sediment biogeochemistry and microbial processes. However, its impact on greenhouse gas (GHG) production dynamics and their temperature sensitivity remains inadequately quantified. This study combined laboratory incubation with metagenomic sequencing to investigate the effects of converting bare mudflats to moderate- and high-intensity aquaculture ponds on sediment GHG production potential and thermal response patterns. Aquaculture reclamation suppressed methane production potential by 89.89% but enhanced nitrous oxide and carbon dioxide (CO₂) by 78.08% and 10.40%, respectively, while simultaneously altering their temperature sensitivity. Mechanistically, these shifts were driven by modified redox conditions, carbon/nitrogen substrate availability, and restructuring of microbial metabolic networks, including functional gene abundance and community composition. Counterintuitively, moderate, rather than heavy, aquaculture reclamation provides the strongest stimulus to GHG production potential, a pattern that can be summarized as a transition from the activation of biogeochemical processes at moderate disturbance to the suppression of system functioning at high intensities of stress, in which toxic byproducts of excessive organic loading inhibit the microbial metabolism they are supposed to promote. Model projections under 2°C and 4°C warming scenarios indicated that aquaculture reclamation may elevate sediment CO₂-equivalent production potential by 32.59–67.45% through stimulated heterotrophic respiration, establishing a positive climate feedback loop, which we conceptualize as an “aquaculture reclamation-induced GHG amplification” mechanism. This study establishes a mechanistic framework for linking reclamation-climate interactions with microbial carbon/nitrogen cycling, providing insights for predicting and mitigating GHG production from bare mudflats in warming ecosystems.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 10","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149086162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nutrient thresholds govern carbon dioxide sink–source dynamics in seagrass ecosystems","authors":"Songlin Liu,&nbsp;Zhen Shi,&nbsp;Vincent Saderne,&nbsp;Yuzheng Ren,&nbsp;Derrick Y. F. Lai,&nbsp;Sai Gao,&nbsp;Zhijian Jiang,&nbsp;Hongxue Luo,&nbsp;Shuo Yu,&nbsp;Yunchao Wu,&nbsp;Xia Zhang,&nbsp;Xiaoping Huang,&nbsp;Peter I. Macreadie","doi":"10.1002/lno.70488","DOIUrl":"10.1002/lno.70488","url":null,"abstract":"<p>Nutrient pollution is accelerating in coastal waters, yet its effects on carbon dioxide (CO₂) sink–source dynamics remain poorly constrained. Seagrass ecosystems are globally important blue carbon sinks but can shift to net CO₂ sources under excessive nutrient loading. Here, we present one of the first empirical assessments examining how dissolved inorganic nitrogen, dissolved inorganic phosphorus, and their stoichiometric balance (dissolved inorganic nitrogen/dissolved inorganic phosphorus) regulate seasonal air–sea CO₂ fluxes across tropical seagrass meadows. Using in situ measurements along a nutrient gradient in the South China Sea, we show that CO₂ fluxes respond nonlinearly to nutrient concentrations and exhibit season-specific thresholds. Dissolved inorganic nitrogen enhances CO₂ uptake during spring and summer but promotes CO₂ emissions during autumn and winter. Dissolved inorganic phosphorus consistently reduces CO₂ influx. We identify nutrient “turning points” (maximum CO₂ uptake) and “transition points” (CO₂ sink–source reversals) that offer predictive capacity for managing carbon outcomes. Strategic nutrient management—optimizing dissolved inorganic nitrogen during growing seasons while restricting dissolved inorganic phosphorus year-round—could enhance CO₂ uptake by up to 400% and reduce emissions by 90%. These findings reveal a previously underappreciated vulnerability of seagrass carbon sinks to nutrient pollution and provide actionable thresholds for aligning coastal nutrient management with climate mitigation goals.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 10","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149086163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water mass dynamics drive nitrogen fixation rates and diazotroph community composition in the coastal ocean","authors":"Katherine E. Crider,&nbsp;Corday R. Selden,&nbsp;Kimberly Powell,&nbsp;Sing-how Tuo,&nbsp;Michael Muglia,&nbsp;Patterson Taylor,&nbsp;Margaret R. Mulholland,&nbsp;P. Dreux Chappell","doi":"10.1002/lno.70499","DOIUrl":"https://doi.org/10.1002/lno.70499","url":null,"abstract":"<p>Although significant N₂ fixation rates (NFRs) have been observed throughout mid-Atlantic coastal waters, studies have been limited in their temporal coverage, and the methods used to detect nitrogen fixers (diazotrophs) and their findings have varied. This study investigated NFRs and diazotroph communities in a dynamic coastal setting between Nags Head and Pea Island, North Carolina, USA, during a monthly time series from June 2019 to August 2020, and an August 2019 cruise. We observed movement of the Cape Hatteras Front and distinct NFRs and diazotroph communities in the Mid-Atlantic Bight, South-Atlantic Bight, Chesapeake Bay and Oregon Inlet plume waters, and mixing zones. The highest NFR (42.4 ± 3.0 nmol N L⁻¹ d⁻¹) coincided with the frontal mixing zone, where <i>nifH</i> of assayed targets was most abundant and the <i>nifH</i> community highly diverse. Observations revealed significant seasonal variability in the diazotroph community and NFRs (below detection to 26.1 ± 9.3 nmol N L⁻¹ d⁻¹), with higher NFRs in the late summer and early fall. Furthermore, our comparison of three diazotroph detection methods (<i>nifH</i> gene amplicon sequencing, <i>nifH</i> quantitative PCR, and microscopy) confirms a combined approach is needed to thoroughly survey the diazotroph community, and corroborates previous suggestions that <i>Richelia</i> is selected against by the classical <i>nifH</i> sequencing primers. This study advances our understanding of coastal N₂ fixation by documenting how water mass dynamics affect biogeochemical regimes and diazotroph communities. Our findings have implications for predicting how climate-induced changes in water mass characteristics may impact coastal diazotroph community composition and activity in this region.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 10","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.70499","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"The downward legacy of a phytoplankton bloom in the oligotrophic North Pacific Subtropical Gyre","authors":"Angelicque E. White,&nbsp;Matthew J. Church,&nbsp;Hanna Anderson,&nbsp;Benedetto Barone,&nbsp;Karin M. Björkman,&nbsp;David A. Caron,&nbsp;Edward F. DeLong,&nbsp;Sonya T. Dyhrman,&nbsp;Rhea Foreman,&nbsp;Catherine Garcia,&nbsp;Eric Grabowski,&nbsp;Sheean T. Haley,&nbsp;Fernanda Henderikx Freitas,&nbsp;Andrew J. Hirzel,&nbsp;Reece James,&nbsp;Isha Kalra,&nbsp;Fuyan Li,&nbsp;Lauren Manck,&nbsp;Daniel Muratore,&nbsp;John C. Tracey,&nbsp;Kendra Turk-Kubo,&nbsp;David M. Karl","doi":"10.1002/lno.70489","DOIUrl":"https://doi.org/10.1002/lno.70489","url":null,"abstract":"<p>Ocean particles are a heterogeneous collection, including living and dead cells, feces, mucus-rich aggregates, and mineral shells and frustules. In the well-lit upper ocean, phototrophic processes fuel production of particulate matter; however, only a relatively small percentage (&lt; 10% per day) of this material (mostly detrital) escapes the recycling-intensive upper ocean, transiting downward by gravitational settling. In the North Pacific Subtropical Gyre, sinking particles are considered the major pathway supporting the vertical export of material to the mesopelagic zone. In the summer of 2021, an expedition explored a phytoplankton bloom, constrained within an anticyclonic eddy, that was detected from satellite chlorophyll products. Extensive near-Lagrangian sampling of this bloom revealed a decaying population of diatoms containing diazotrophic symbionts imprinted over a relatively stable population of picocyanobacteria. Strong top-down control appears to have led to the termination of this diazotrophy-fueled growth, as evidenced by the prevalence of empty diatom frustules, incomplete drawdown of inorganic nutrients, and the presence and activity of protistan grazers/parasites coincident with the timing of bloom decline. Sinking rates of diatom frustules were ~ 50–100 m d⁻¹ and drove elevated fluxes of carbon, nitrogen, and silicate into the mesopelagic zone, roughly 2–3× the regular summer fluxes measured at the nearby sampling station of the Hawaii Ocean Time-series. While phytoplankton blooms are regular occurrences in this region, it is rare to sample their decay. The observations from the bloom demise described here highlight the significance of non-steady-state events in a region generally typified as a stable ecosystem.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 10","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.70489","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Vertical structures of marine heatwaves and their impacts on primary production in the South China Sea","authors":"Jingjing Zheng, Peng Xiu, Lili Zeng, Guimei Liu, Xueming Zhu, Shan Gao, Xuanliang Ji, Zhijie Li","doi":"10.1002/lno.70511","DOIUrl":"https://doi.org/10.1002/lno.70511","url":null,"abstract":"Marine heatwaves (MHWs) are extreme warm‐water events that can strongly perturb marine ecosystems. Although MHWs are known to extend into subsurface and deep waters, their vertical structures and biogeochemical consequences remain poorly quantified. Here, we use a physical‐biogeochemical model to characterize the vertical structures of MHWs in the South China Sea (SCS) and to assess their impacts on primary production (PP). Four distinct types of vertical structure of MHWs (shallow, sub‐reversed, sub‐intensified and deep MHWs) are identified. Deep MHWs are the most common, accounting for nearly 50% of events. Shallow and sub‐reversed MHWs are generally short‐lived and confined to the upper ocean, whereas sub‐intensified and deep MHWs persist longer and penetrate deeper. Heat budget analysis indicates that air–sea heat flux primarily drives the formation of shallow, sub‐reversed, and deep MHWs, while vertical processes dominate the maintenance of sub‐intensified MHWs. Distinct MHW structures modify vertical stratification and nutrient transport, producing spatially and vertically heterogeneous PP responses across the mixed layer and the euphotic zone. Over the past two decades, the occurrence area, duration, and total intensity of all four MHW types increased significantly, and associated PP anomalies exhibited a declining trend. This decline is largely attributable to strengthened mixed‐layer stratification and reduced mixed‐layer PP, with subsurface processes contributing little to the long‐term trend.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"35 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Community metabolism generates chemical legacies that alter coral physiology","authors":"Laurel C. Diaz, Keanu Rochette‐Yu Tsuen, Kiran Reed, Craig E. Nelson, Nyssa J. Silbiger","doi":"10.1002/lno.70513","DOIUrl":"https://doi.org/10.1002/lno.70513","url":null,"abstract":"Coral reefs are among the world's most diverse ecosystems and contribute substantially to ocean productivity and the carbon budget. Disturbances are shifting reefs to altered community states, yet how these new communities indirectly alter organismal physiology by modifying the local biogeochemical environment remains largely unknown. We investigated this biogeochemical feedback in a 25‐d mesocosm experiment in Mo'orea, French Polynesia. We exposed the common coral <jats:italic>Porites rus</jats:italic> to the biogeochemical environments generated by three distinct communities representative of recent benthic states in this system: coral‐, macroalgae‐, and crustose coralline algae‐enriched relative to a seawater‐only control. While net community production was similar among communities, net community calcification was lowest in the macroalgae‐enriched state. Across treatments, community metabolism drove changes in the organic and inorganic carbon pool, with net community production increasing both pH and dissolved organic carbon. Using structural equation modeling, we tested how these community‐generated chemical legacies propagated through coral physiology. Elevated pH increased chlorophyll <jats:italic>a</jats:italic> content, which increased endosymbiont density, tissue biomass, gross photosynthesis, and respiration through a series of indirect pathways. Dissolved organic carbon had no detectable effect on downstream corals at 25 d. These results reveal a mechanistic pathway linking disturbance‐driven shifts in benthic communities to coral performance. Altered community metabolism modifies local carbon chemistry, which reshapes symbiont physiology and ultimately influences host metabolic function. By identifying the pathways through which community states engineer their chemical environment, this study provides a framework for predicting coral performance and ecosystem trajectories as reefs transition away from coral‐enriched states.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"51 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elevated B‐vitamins within a temperate estuary: Strong spatiotemporal dynamics and links to microbial plankton communities","authors":"Meriel J. Bittner, Catherine C. Bannon, Elden Rowland, Gregor Luetzenburg, Erin M. Bertrand, Lasse Riemann, Ryan W. Paerl","doi":"10.1002/lno.70508","DOIUrl":"https://doi.org/10.1002/lno.70508","url":null,"abstract":"B‐vitamins are organic cofactors required by prokaryotic and eukaryotic planktonic cells; their availability impacts aquatic microbial communities and associated biogeochemistry. Despite their ecological importance, B‐vitamin dynamics and their relationships to plankton composition in estuaries are unclear, limiting our understanding of estuary biology in general as well as how B‐vitamins are distributed in marine systems. Here, we simultaneously quantified multiple B‐vitamins and their vitamers (vitamin related compounds, e.g., precursors for de novo synthesis) in particulate and dissolved phases. Alongside, we characterized the prokaryotic and eukaryotic microbial communities across freshwater to polyhaline zones of the Neuse River Estuary (NRE), North Carolina, USA from summer to fall. We found notable autochthonous B‐vitamin production in the estuary, and the mid‐estuary emerged as a zone of increased levels of B‐vitamins fueled by algal growth. B‐vitamin and vitamer concentrations were highly dynamic on short time scales (weeks) and we identified two specific dynamic modes. Moderate concentration changes likely driven by production/consumption and sporadic rapid concentration peaks presumably driven by shifts in plankton community composition. We identified vitamin B <jats:sub>1</jats:sub> , B <jats:sub>12</jats:sub> , psB <jats:sub>12</jats:sub> (pseudocobalamin), and B <jats:sub>3</jats:sub> as key explanatory variables for change in prokaryotic and eukaryotic NRE plankton, revealing B‐vitamins as important compounds for resolving variability of plankton communities in estuaries. Our study provides insights into the dynamic concentrations of B‐vitamins and vitamers across zones of estuaries and provides new evidence of B‐vitamin influence upon plankton community composition.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"226 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depth-dependent metabolic stratification identifies the oxic deep chlorophyll maximum as a global biogeochemical hotspot","authors":"Satheeswaran Thangaraj,&nbsp;David A. Hutchins,&nbsp;Jun Sun","doi":"10.1002/lno.70501","DOIUrl":"10.1002/lno.70501","url":null,"abstract":"<p>The deep chlorophyll maximum (DCM) is an important feature of the marine photic zone where carbon fixation, nutrient transformations and particle-associated export can be enhanced, collectively influencing marine productivity, biogeochemical cycling and carbon sequestration. However, how microbial metabolism in this layer differs from that in the overlying surface layer (SL) remains poorly characterized. Using depth-resolved metagenomes from the Western Pacific Ocean, validated against global Tara Oceans datasets, we show that the DCM is strongly stratified metabolically even though its taxonomic composition differs only modestly from the SL, revealing a pronounced decoupling of function from taxonomy. Surface communities were enriched in light-driven carbon fixation pathways that consume 3–3.5 adenosine triphosphate (ATP) per CO₂ fixed, whereas DCM communities were enriched in pathways requiring only 1–2 ATP—the reductive tricarboxylic acid cycle and the dicarboxylate/4-hydroxybutyrate cycle—consistent with an energetic niche axis between light-rich surface and light-limited subsurface waters. Fully oxygenated DCM waters (~ 190 <i>μ</i>mol O₂ L⁻¹) contained gene inventories associated with nitrification, denitrification, and sulfur oxidation, together with methane metabolism–associated genes, potentials conventionally restricted to oxygen-minimum zones. These gene suites were consistently enriched at the DCM across all major ocean basins. Methane assimilation showed the same energetic pattern, with the ATP-expensive serine cycle dominating the SL and the lower-cost ribulose monophosphate route enriched in the DCM. Because warming intensifies stratification and is projected to deepen and sharpen DCM features, the metabolic organization of this layer is likely to become more, not less, important to upper-ocean biogeochemistry.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149022148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyrosome fecal pellet production: Implications for grazing and carbon export","authors":"Grace F. Cawley,&nbsp;Stephanie A. Matthews,&nbsp;Natalia Llopis-Monferrer,&nbsp;Minerva Padilla Villa,&nbsp;Katherine Barbeau,&nbsp;Moira Décima","doi":"10.1002/lno.70506","DOIUrl":"10.1002/lno.70506","url":null,"abstract":"<p>This study quantifies the fecal pellet production and pellet sinking rates of the pyrosome <i>Pyrosoma atlanticum</i> in the Southern California Current across a range of conditions, from the productive nearshore to the oligotrophic offshore. Fecal pellet production rates averaged 1310 ± 76 pellets h⁻¹, resulting in the production of up to 390,380 pellets h⁻¹ m⁻² in locations with high densities of 298 ind. m⁻². Fecal pellet mean size was 354 ± 111 <i>μ</i>m, and sinking rates of fresh pellets averaged 47 ± 38 m d⁻¹, while aged pellets had lower rates averaging 31 ± 28 m d⁻¹. We estimate ingestion rates of 55.5 ± 9.5 mg C m⁻² d⁻¹ in the offshore and 41.1 ± 8.28 mg C m⁻² d⁻¹ in nearshore coastal waters. Based on pellet production rates, colony abundance, carbon content per pellet, and literature values of assimilation efficiencies, we estimate that pyrosomes consume the carbon equivalent of ~ 30% of net primary production in offshore waters and 1–26% in coastal waters. We present novel measurements of biogenic silica in pyrosome fecal pellets, indicating that pyrosomes can directly remove 0.5–4% of the euphotic zone-integrated diatom standing stock, with higher rates in nearshore environments. Direct observation of fecal pellets showed unassimilated diatom chains, confirming direct consumption. Our results suggest that pyrosomes contribute to both carbon and silica export, important processes to constrain for understanding biogeochemistry in the region.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"71 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.70506","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148979614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}