Deep-sea Research Part Ii-topical Studies in Oceanography最新文献

{"title":"Seasonal Indonesian Throughflow (ITF) across southern Java determines genetic connectivity of Sardinella lemuru (Bleeker, 1835)","authors":"A. Sartimbul ,&nbsp;V.A. Winata ,&nbsp;R.D. Kasitowati ,&nbsp;F. Iranawati ,&nbsp;E. Rohadi ,&nbsp;D. Yona ,&nbsp;U.G. Anjeli ,&nbsp;W.S. Pranowo ,&nbsp;F.M. Lauro","doi":"10.1016/j.dsr2.2023.105295","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105295","url":null,"abstract":"<div><p><em>Sardinella lemuru</em> populations are considered near-threatened in Bali Strait. Despite declining fish stock, documented landings of <em>S. lemuru</em> at the Prigi waters unexpectedly climbed during the 2nd transitional inter-monsoon season of 2019. Here we used a combination of molecular taxonomy and morphometrics-meristics to determine the genetic link between <em>S. lemuru</em> populations in East Java's southern seas (Prigi and Puger) and those in the Philippines. The results of both molecular and morphometric-meristic analyses suggest that extensive genetic mixing between the populations from Prigi and the Philippines is occurring. Most samples clustered with the <em>S. lemuru</em> populations from the Philippines in Clade-1 and Haplogroup A and B implied high genetic connectivity. The inferred patterns of haplotype network and haplogroup relative frequency indicate the dispersal, genetic homogeneity, and absence of geographical barriers between <em>S. lemuru</em> populations were also supported by a seasonal model of ocean circulation: during the southeast monsoon, greater Indonesian Through-Flow and South Java Current, followed by westward currents along Java's south coast. The findings of this study give much-needed evidence that <em>S. lemuru</em><span> populations disperse to a secondary fishing area (in Prigi waters), followed by high plankton abundance in 2019, as a result of ITF<span> and local seasonal circulation. The unique sequences of Puger-2017 and the remainder of Prigi-2017 in Clade-2 with overall moderate genetic distance separated from Clade-1 because the Puger water mass are influenced by the Java Sea and Madura Strait or possibly migrated from their habitats in the western part of Indonesia or the Java Sea.</span></span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105295"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174439","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":"Vertical imbalance in organic carbon budgets is indicative of a missing vertical transfer during a phytoplankton bloom near South Georgia (COMICS)","authors":"S.L.C. Giering ,&nbsp;R. Sanders ,&nbsp;S. Blackbird ,&nbsp;N. Briggs ,&nbsp;F. Carvalho ,&nbsp;H. East ,&nbsp;B. Espinola ,&nbsp;S.A. Henson ,&nbsp;K. Kiriakoulakis ,&nbsp;M.H. Iversen ,&nbsp;R.S. Lampitt ,&nbsp;K. Pabortsava ,&nbsp;C. Pebody ,&nbsp;K. Peel ,&nbsp;C. Preece ,&nbsp;K. Saw ,&nbsp;M. Villa-Alfageme ,&nbsp;G.A. Wolff","doi":"10.1016/j.dsr2.2023.105277","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105277","url":null,"abstract":"<div><p>The biological carbon pump, driven principally by the surface production of sinking organic matter and its subsequent remineralization to carbon dioxide (CO₂) in the deep ocean, maintains atmospheric CO₂ concentrations around 200 ppm lower than they would be if the ocean were abiotic. One important driver of the magnitude of this effect is the depth to which organic matter sinks before it is remineralised, a parameter we have limited confidence in measuring given the difficulty involved in balancing sources and sinks in the ocean's interior. One solution to this imbalance might be a temporal offset in which organic carbon accumulates in the mesopelagic zone (100–1000 m depth) early in the productive season before it is consumed later. Here, we develop a novel accounting method to address non-steady state conditions by estimating fluxes of particulate organic matter into, and accumulation within, distinct vertical layers in the mesopelagic zone using high-resolution spatiotemporal vertical profiles. We apply this approach to a time series of measurements made during the declining phase of a large diatom bloom in a low-circulation region of the Southern Ocean downstream of South Georgia. Our data show that the major export event led to a significant accumulation of organic matter in the upper mesopelagic zone (100–200 m depth) which declined over the following weeks, implying that temporal offsets need to be considered when compiling budgets. However, even when accounting for this accumulation, a mismatch in the vertically resolved organic carbon budget remained, implying that there are likely widespread processes that we do not yet understand that redistribute material vertically within the mesopelagic zone.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105277"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174485","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":"Atmospheric and advective forcing of upwelling on South Africa's central Agulhas Bank","authors":"Lisa Hancke ,&nbsp;David Smeed ,&nbsp;Mike Roberts ,&nbsp;Cristina Russo ,&nbsp;Darren Rayner ,&nbsp;Fatma Jebri","doi":"10.1016/j.dsr2.2023.105293","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105293","url":null,"abstract":"<div><p>Current and temperature structures on South Africa's central Agulhas Bank are described from six months of moored observations and ancillary data collected during the seasonal transition from austral spring to summer (October 2018–March 2019). The occurrence of an intermittend mid-shelf upwelling ridge, associated with increased productivity, is an important part of the shelf's thermal structure. However, the subsurface evolution of this cold ridge has not been documented to date. A mooring array that transected the wide central shelf captured the seasonal increase in stratification that culminated in the formation of a cold ridge in late summer. We show that the cold ridge originates in the wind-driven upwelling zone on the eastern Agulhas Bank and emphasise the importance of oceanic forcing in maintaining the subsurface thermal structure through advective steering of wind-driven coastal upwelling plumes and through dynamic shelf edge upwelling. The main source of the cold basal layer at the mooring transect originated from upwelling further east, but persistent near-seabed temperatures &lt;9 °C on the outer shelf during the encroachment of the Agulhas Current confirm the contribution of shelf edge upwelling, offshore of the mooring transect, to the cold bottom layer on the Agulhas Bank. Of particular interest is the strengthening of the south-westward shelf current, inshore of cyclonic flow in the Agulhas Bight that accelerated the offshore advection of productive coastal water in the shape of the cold ridge. We show the shelf circulation to be highly coherent across and along the shelf. Shelf-wide barotropic pulses were driven by increased zonal wind stress that was in turn associated with variation in coastal sea level. In the light of global climate change, this work highlights the importance of long term in-situ monitoring in understanding ecosystem functioning on the highly dynamic Agulhas Bank.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105293"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174426","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":"Causal relations between the loop current penetration and the inflow/outflow conditions inferred with a rigorous quantitative causality analysis","authors":"Yang Yang ,&nbsp;Guanqi Fu ,&nbsp;X. San Liang ,&nbsp;Robert H. Weisberg ,&nbsp;Yonggang Liu","doi":"10.1016/j.dsr2.2023.105298","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105298","url":null,"abstract":"<div><p>The causal relationship between the Loop Current (LC) penetration into the Gulf of Mexico and the inflow/outflow conditions in the Yucatan Channel and the Straits of Florida is analyzed using a recently developed causality analysis, which is quantitative in nature, and rigorously derived from first principles. Long-term time series from a 23-year high-resolution reanalysis product reveals that the LC penetration is associated with a dipole (tripole) mode of transport (vorticity flux) in both channels. These relationships, though significant from a perspective of correlation, do not necessarily imply causality. By applying the causality analysis, we identify a clear asymmetry of causality, that is, the flow conditions in the Yucatan Channel and the Straits of Florida can both cause the LC penetration. Conversely, the LC path state is less causal to the current variability in the two channels. The spatial causal structures further reveal that the upstream influence from the Yucatan Channel is strong in the main body of the LC as well as its extension area, while the downstream influence from the Straits of Florida is confined within the eastern branch of the LC. The asymmetric causal relations obtained from the data-assimilative reanalysis product are further confirmed in a free-running model simulation forced by three repeated cycles of atmospheric forcing, although the strength of the causality could vary from one simulation cycle to another, due to the intrinsic variability of the LC system.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105298"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174424","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":"Trend of annual and semiannual harmonics of sea surface temperature in the tropical Indian Ocean, 1979–2018","authors":"V.A. Abhishek,&nbsp;V. Vijith,&nbsp;N. Anup","doi":"10.1016/j.dsr2.2023.105292","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105292","url":null,"abstract":"<div><p><span><span><span>In the Indian Ocean (IO), the annual and semiannual oscillations of the </span>sea surface temperature<span> (SST) contribute more than 80% of the total variance. It is known that the SST in the tropical IO has warmed at a rate of 0.15 °C/decade since 1979. However, such an estimate of the decadal trend of the annual and semiannual harmonics of SST remains unknown, despite being a strong component of the SST signal. Here we use a widely accepted data product (TropFlux) to quantify the annual and semiannual harmonics in the tropical IO for the first time. The northern IO has a distinctly strong semiannual cycle (1–1.8 °C), which is showing an amplifying trend (∼ 0.04 °C/decade) since 1979. Furthermore, a damping trend in annual amplitude exists over much of the IO, except along the northwestern Bay of Bengal, the Seychelles-Chagos thermocline ridge, the </span></span>Persian Gulf, and the Indonesian </span>throughflow<span><span><span> region. The estimated damping of the annual amplitude is highest over the Arabian Sea. In contrast, the southern tropical IO has a predominant annual cycle, the amplitude of which has weakened during 1979–2018. In the north IO, net air-sea heat flux and vertical processes show a dominant semiannual harmonic oscillation similar to SST. Additionally, the annual amplitude is influential over southern IO. Horizontal </span>advection contributes significantly along the boundary-current regions and the western equatorial IO. Our analysis of combined annual and semiannual cycles shows significant warming in the tropical IO during October–November and cooling during July–August owing to the amplification of semiannual oscillation. These changes in the SST can influence air-sea interaction processes such as </span>cyclogenesis and monsoon.</span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105292"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174425","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":"Forecasts of marine heatwaves for marine industries: Reducing risk, building resilience and enhancing management responses","authors":"Jason R. Hartog ,&nbsp;Claire M. Spillman ,&nbsp;Grant Smith ,&nbsp;Alistair J. Hobday","doi":"10.1016/j.dsr2.2023.105276","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105276","url":null,"abstract":"<div><p>Ocean use has always been risky because of uncertain and dramatic ocean conditions and modern businesses continue to experience risk due to environmental extremes. A changing physical environment due to anthropogenic climate change and increased frequency of extreme events such as marine heatwaves makes past experience less valuable. This risk can be reduced by utilising seasonal forecasts that provide early warning of climate events several months ahead of time. However, to benefit from a forecast, a marine business will need to be agile to respond to changing information and response options. We define a set of seven attributes that can influence and enhance this management agility; leadership, social expectations, signal strength, system manipulation, regulatory environment, market forces, and value of the operations. The management agility of different marine businesses in fisheries, aquaculture, and tourism can influence their ability to use seasonal forecast information effectively, and potentially modify the usual negative relationship between resilience and the frequency of the stress event, thus reducing the impact of extreme events. Engagement between forecast developers and marine users can also improve responses, while at the same time, improving the agility of businesses can enhance overall resilience to extreme events and lower their risk.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105276"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174440","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":"Interannual variability of red sea overflow water pathways in the Western Arabian Sea in an eddy rich reanalysis","authors":"Viviane V. Menezes","doi":"10.1016/j.dsr2.2023.105289","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105289","url":null,"abstract":"<div><p>The present study investigates the interannual variability of the advective pathways and transit times of the Red Sea Overflow Water (RSOW) in the western Arabian Sea using virtual particles as a proxy indicator for the poorly understood RSOW spreading. The Lagrangian simulations are based on the GLORYS12 eddy-rich reanalysis (1/12°), which assimilates most satellite and in situ observations from 1993 to 2018. Statistical analysis of particle positions reveals the Gulf's mouth is always the main RSOW export route out of the Gulf of Aden. Moreover, there is substantial interannual variability in the three RSOW pathways in the western Arabian Sea, which are consistent with in-situ salinity variability at the RSOW layer. The faster Socotra pathway is strongest for particles released in 1998–1999 and 2012 and almost non-existent for the ones released in 2006–2007. The strongest state of the Socotra pathway co-occurs with some of the most powerful El-Nino/Southern Oscillation and Indian Ocean Dipole events in history. A decadal seesaw stands out between the Northwest pathway, which advects RSOW northward offshore the Arabian Peninsula, and the Southwest pathway, which advects RSOW southward to the Somali Basin along the eastern side of Socotra. While the Northwest pathway strengthened from 1996 to 2011, the Southwest weakened. These changes are associated with interannual variability in the western boundary undercurrents and subsurface eddy kinetic energy. Interestingly, the Northwest pathway trajectories are eddy-dominated, in striking contrast with the Socotra and Southwest pathways, in which western boundary undercurrents are major players. This fact suggests that eddy-induced transport is likely to have a significant role in spreading the RSOW northward. No considerable interannual variability in transit times is detected for any pathway.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105289"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174436","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":"Effects of monsoons and storms on the structuring and diversity of picoeukaryotic microbial communities in a tropical coastal environment","authors":"Maria Anna Michaela De La Cruz ,&nbsp;Brian William Hingpit ,&nbsp;Laure Guillou ,&nbsp;Deo Florence L. Onda","doi":"10.1016/j.dsr2.2023.105294","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105294","url":null,"abstract":"&lt;div&gt;&lt;p&gt;&lt;span&gt;Picoeukaryotes are key components in &lt;/span&gt;marine ecosystems&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt; that play crucial roles in food webs and biogeochemical cycles. Despite their significance, many aspects of their &lt;/span&gt;community ecology and diversity remain understudied. Here, we investigated the taxonomic and functional diversity of picoeukaryotic communities in response to monsoonal patterns and weather disturbances brought about by storms, characterizing tropical coastal regions. To do this, water samples were collected almost weekly or bi-weekly at a single location in a tropical coastal environment covering the late northeast (NE) and southwest (SW) monsoons. We then performed high-throughput &lt;/span&gt;amplicon&lt;span&gt; sequencing of the V4 region of the 18S rRNA gene to generate taxonomic profiles of the communities across time. Clustering based on environmental parameters grouped our samples into months associated with NE monsoon, SW monsoon, and stormy SW monsoon, demonstrating seasonality&lt;span&gt; influenced by monsoons and storms, typically observed in tropical coastal waters. In comparison, clustering based on abundance only grouped the samples into NE and SW monsoon, with most communities during storm period joining the NE monsoon samples. These samples exhibited greater diversity, with smaller taxa such as Syndiniales, Prymnesiophyceae, Picozoa, Cercozoa, Stramenopiles, and Chlorophytes being the most abundant groups present. In contrast, SW monsoon samples have lower diversity but have become generally dominated by large-celled taxa, mostly diatoms. Multivariate and correlation analyses both revealed nitrate as the strongest environmental driver of the picoeukaryotic community structuring. Meanwhile, network analysis grouped the taxa into three modules, more consistent with the clustering based on environmental parameters, implying that although storms may not significantly change the community composition, they may however influence the dominating taxa. Each module was composed of a unique set of co-occurring taxa, highlighting high turnover of picoeukaryotic communities between each season. In addition, our results showed that SW monsoon-associated module had higher interconnectivity than other modules, suggesting that the interactions during this period may be less species-specific, thus, more adaptable than during NE monsoon. However, we observed that extreme fluctuations caused by storms could have possibly allowed for selection of dominant taxa. Shotgun &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;metagenomic&lt;span&gt; sequencing of representative samples from each monsoon period also revealed that differently abundant functional genes, particularly genes associated to nitrogen metabolism&lt;span&gt;&lt;span&gt;, might have also helped in adaptation to the changing nutrient conditions. Our observations provide new insights on the potential trajectory of microbial communities under environmental stresses, which are important in understanding the implications of emerging thr","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105294"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174441","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":"Surface ocean carbon budget in the 2017 south Georgia diatom bloom: Observations and validation of profiling biogeochemical argo floats","authors":"Aimee Coggins ,&nbsp;Andrew J. Watson ,&nbsp;Ute Schuster ,&nbsp;Neill Mackay ,&nbsp;Brian King ,&nbsp;Elaine McDonagh ,&nbsp;Alex J. Poulton","doi":"10.1016/j.dsr2.2023.105275","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105275","url":null,"abstract":"<div><p>Estimates of the partial pressure of CO₂ (<em>p</em>CO₂<span><span><span>) derived from biogeochemical Argo floats have the potential to improve our knowledge of the highly variable and partially observed Southern Ocean </span>carbon sink through sampling at improved temporal and spatial resolution. Here we use the data from six biogeochemical Argo floats to characterise near-surface </span>dissolved inorganic carbon (DIC) concentrations and fluxes at the site of an intense (Chl-a &gt;3 mg m</span>⁻³) mesoscale diatom bloom situated northwest of South Georgia. Concurrently, we provide independent analysis and validation of the methodology used by the Southern Ocean Carbon and Climate Observational and Modelling (SOCCOM) project for deriving surface <em>p</em>CO₂ from float-based pH and oxygen measurements. We compare the float observations with co-located ship data from bottle samples over a month-long period. When compared to data sampled within 24 h and 25 km of each float profile, we find good agreement with a mean offset of −0.005 ± 0.018 (1σ) between float pH and bottle-derived pH. This translates to comparable <em>p</em>CO₂ estimates between ship measurements and floats with a mean difference of 2.6 ± 12.8 (1σ) μatm, providing support for the use of biogeochemical Argo float data to supplement shipboard <em>p</em>CO₂ measurements in the Southern Ocean. Based on float-derived <em>p</em>CO₂ we calculate a sizeable local flux of CO₂ of 24 ± 7 mmol C m⁻² d⁻¹ (over a 27-day period) from the atmosphere into the surface mixed layer, driven by a large air-sea <em>p</em>CO₂<span> gradient and strong but variable winds. Despite the considerable air-sea flux, the local mixed layer carbon budget appears to be dominated by entrainment and detrainment of carbon-rich waters into and out of the mixed layer. However, given the large uncertainties associated with these fluxes and the significant challenges associated with closing the mixed layer budget, further research is required to refine float-based mixed layer DIC fluxes.</span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105275"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174442","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":"Phytoplankton and seston fatty acid dynamics in the northern Bering-Chukchi Sea region","authors":"Jens M. Nielsen ,&nbsp;Louise A. Copeman ,&nbsp;Lisa B. Eisner ,&nbsp;Kelia E. Axler ,&nbsp;Calvin W. Mordy ,&nbsp;Michael W. Lomas","doi":"10.1016/j.dsr2.2022.105247","DOIUrl":"https://doi.org/10.1016/j.dsr2.2022.105247","url":null,"abstract":"<div><p>Arctic and subarctic ecosystems are transitioning due to ocean warming, resulting in conditions that will lead to shifts in phytoplankton<span><span><span><span> communities, their nutritional compositions, and production of fatty acids (FAs). FA biomarkers are useful indicators of changing phytoplankton community composition and provide insight into basal resource quality for higher trophic level consumers such as zooplankton, fish, birds and </span>marine mammals<span>, yet phytoplankton FA information is largely lacking from the Bering and Chukchi Sea regions. Therefore, we analyzed </span></span>suspended particulate matter<span> (seston) FAs, chlorophyll-a (Chl-a) and environmental data<span><span> collected from four surveys in the northern Bering and Chukchi Seas, two during June of 2017 and 2018 and two during August and September 2017 and 2019. Our objectives were to determine 1) whether seston FA composition was correlated with phytoplankton taxonomic composition analyzed using imaging microscope (FlowCAM) techniques, 2) if there were seasonal differences in seston FA concentrations, and 3) how FA concentrations varied with environmental variables. We found significant seasonal differences in seston FA compositions, with diatom biomarkers more prevalent in spring, followed by a community shift to dinoflagellate and small flagellate FA biomarkers in late summer. These results were confirmed by FlowCAM analyses. FA biomarkers were correlated with total and large size-fractioned Chl-a concentrations, nitrogen concentration and temperature. Lastly, we used a model framework to predict availability of the diatom-associated </span>essential FA, </span></span></span>eicosapentaenoic acid (EPA, 20:5n-3). Our analysis provides new information on phytoplankton FA dynamics and the important nutritional role of phytoplankton for higher trophic level consumers in the northern Bering and Chukchi Sea regions.</span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"208 ","pages":"Article 105247"},"PeriodicalIF":3.0,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174544","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}