Progress in Oceanography最新文献

{"title":"C:N stoichiometry and the fate of organic carbon in ecosystems of the northwest Pacific Ocean","authors":"Chuanli Zhang ,&nbsp;Yaoyao Wang ,&nbsp;Rong Bi ,&nbsp;Ulrich Sommer ,&nbsp;Guodong Song ,&nbsp;Zhaohui Chen ,&nbsp;Feng Lin ,&nbsp;Jing Zhang ,&nbsp;Meixun Zhao","doi":"10.1016/j.pocean.2024.103372","DOIUrl":"10.1016/j.pocean.2024.103372","url":null,"abstract":"<div><div>Phytoplankton elemental composition regulates the efficiency of energy and material transfer in the interface between phytoplankton and their consumers. The ratio of particulate organic carbon to particulate organic nitrogen (POC:PON) shows considerable regional deviations from the canonical Redfield ratio in the global surface ocean. However, in certain oceanic regions such as the northwest Pacific Ocean (NWPO) POC:PON distribution and its ecological significance remain uncertain. We investigated surface ocean POC:PON distributions at 66 stations in the NWPO, and quantified the correlations between POC:PON and multiple biotic and abiotic factors including sea surface temperature (SST), nutrient concentrations and multiple lipid biomarkers (fatty acids and sterols), by combining correlation analyses and generalized additive models. POC:PON (range: 3.53–14.18 M ratios; median: 6.89) was overall higher in the (sub)tropical biome than that in the high-latitude biome. In the entire study region, SST, nutrient concentration and lipid-derived phytoplankton community structure explained 41 %, 33 % and 26 % of the variance in POC:PON, respectively, while the respective importance of each factor differed between the (sub)tropical and high-latitude biomes. Furthermore, we calculated the percentage of primary production consumed by herbivores (PPC; 54–156 %), showing a higher mean value (117 %) in the high-latitude biome and a lower one (92 %) in the (sub)tropical biome. The spatial distribution pattern of PPC can be attributed to multiple factors, with PPC correlating negatively with SST and positively with lipid-based indicators of phytoplankton food quality and POC concentrations. The increase in SST may be associated with a reduced nitrogen content, resulting in lower PPC in the (sub)tropical biome. This study highlights the significance of SST and elemental and biochemical composition of phytoplankton in regulating the transfer of organic carbon to herbivores in the NWPO.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103372"},"PeriodicalIF":3.8,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655936","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":"Global characterization of modelled micronekton in biophysically defined provinces","authors":"S. Albernhe ,&nbsp;T. Gorgues ,&nbsp;P. Lehodey ,&nbsp;C. Menkes ,&nbsp;O. Titaud ,&nbsp;S. Magon De La Giclais ,&nbsp;A. Conchon","doi":"10.1016/j.pocean.2024.103370","DOIUrl":"10.1016/j.pocean.2024.103370","url":null,"abstract":"<div><div>Micronekton are the mid-trophic level of the ecosystem and contribute to active carbon export to the deep ocean through diel vertical migrations. Better characterization of micronekton functional groups depending on relationships to environmental variables is useful for the management of marine resources, the conservation of biodiversity and a better understanding of climate change impacts. For this purpose, regionalization of global ocean into homogeneous provinces is an approach that is generating increasing interest. However, published regionalizations efforts (i) derived from environmental forcings, that do not specifically focus on micronekton and (ii) derived from acoustic backscatter, which do not allow direct estimates of micronekton biomass. Here, we propose to fill the gap between biophysical regionalizations and micronekton biomass. We notably defined biophysical biomes using global environmental variables known to affect micronekton: temperature of the epipelagic layer, temperature stratification, and net primary production (NPP). Six biophysical biomes were defined with a clustering method. A characterization of these biophysical biomes with simulated micronekton from the SEAPODYM-LMTL model displayed biome-specific relationships between biomass and the environmental variables used in the clustering (i.e. biomasses mostly structured by NPP and temperature). Biophysical biomes also displayed specific vertical structures suggested by modelled micronekton functional groups ratios. Then, a validation of biophysical biomes’ boundaries was performed to identify potential vertical structure reorganization in acoustic backscattering response from adjacent biomes. The regionalization identified homogeneous areas in terms of acoustic vertical structure, which were also different between adjacent biomes. Finally, a comparison with another biomes’ definition computed from micronekton biomasses suggested that environmental variables can account for only some of the variability of the micronekton structures.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103370"},"PeriodicalIF":3.8,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655938","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":"Heterogeneous Sources, Distribution, and removal processes of dissolved black carbon from East China Sea shelf to open ocean of Northwest Pacific","authors":"Xi Zhang ,&nbsp;Yasong Wang ,&nbsp;Zhiliang Liu ,&nbsp;Bilin Liu ,&nbsp;Weichao Wu ,&nbsp;Liang Liu ,&nbsp;Ding He ,&nbsp;Yunping Xu","doi":"10.1016/j.pocean.2024.103374","DOIUrl":"10.1016/j.pocean.2024.103374","url":null,"abstract":"<div><div>Absract: Dissolved black carbon (DBC) can be transported from land to the ocean, representing a significant slow-cycling component in the global carbon cycle. However, the source, distribution, and degradation of DBC in the ocean are not well understood. In this study, water samples were collected from the East China Sea (ECS) shelf to the Northwest Pacific Ocean. The benzene polycarboxylic acid (BPCA) method and ultraviolet–visible spectroscopy were used to analyze DBC and dissolved organic matter, respectively. The concentration of DBC and the (B6CA + B5CA)/BPCAs ratio in surface water showed a decreasing trend from the ECS inner shelf towards the open ocean. This trend indicates the preferential removal of condensed aromatic compounds by photodegradation, while also implicating dilution by open ocean water as a significant factor contributing to the reduction of DBC concentrations. A significant negative correlation between DBC concentration and salinity was observed in surface water samples (r =  − 0.88; p &lt; 0.01). However, this relationship weakened and disappeared in offshore samples, suggesting a reduced influence of riverine inputs. Furthermore, vertical profiles of water samples (0 – 1000 m) revealed a decrease in DBC concentrations and an increase in the ratio of (B6CA + B5CA)/BPCAs, indicating the preferential photodegradation of condensed aromatic DBC molecules in the euphotic zone and the selective accumulation of these molecules in the ocean interior. The DBC flux into the Northwest Pacific Ocean was estimated to be 1.46 Tg/year with 51.7 to 73.1 % removed through photodegradation, while the remaining DBC was either transported into the deep ocean or biodegraded. Given the important role of photodegradation in regulating the DBC flux in the Northwest Pacific Ocean, we recommend further research into its impact on the refractory carbon cycle in global oceans.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103374"},"PeriodicalIF":3.8,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586786","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":"Ice algae as supplementary food rather than major energy source for the Barents sea zooplankton community","authors":"Doreen Kohlbach ,&nbsp;Haakon Hop ,&nbsp;Anette Wold ,&nbsp;Katrin Schmidt ,&nbsp;Lukas Smik ,&nbsp;Simon T. Belt ,&nbsp;Matthias Woll ,&nbsp;Martin Graeve ,&nbsp;Lucie Goraguer ,&nbsp;Øyvind Foss ,&nbsp;Philipp Assmy","doi":"10.1016/j.pocean.2024.103368","DOIUrl":"10.1016/j.pocean.2024.103368","url":null,"abstract":"<div><div>The Barents Sea is a hotspot for environmental change due to global warming. These changes impact the structure and functioning of the marine ecosystem year-round, and it is therefore important to gain knowledge on trophic relationships and the energy flow from primary producers, <em>i.e.</em>, ice algae (sympagic algae) and phytoplankton (pelagic algae) to consumers over the entire seasonal cycle. By using different lipid components as trophic markers, we provide seasonal coverage of the carbon and food-source composition of five of the most abundant and ecologically important zooplankton taxa inhabiting the Barents Sea: copepods, krill, amphipods, pteropods and chaetognaths. Based on the composition of algal-produced fatty acid (FA) markers, carbon-source composition of the zooplankton species reflected changes in the production and availability of food resources during different periods of the year. For example, relative proportions of the dinoflagellate/<em>Phaeocystis</em> FA marker 18:4(<em>n</em>-3) peaked during summer in <em>Calanus</em> copepods, the amphipod <em>Themisto abyssorum</em> and the chaetognath <em>Pseudosagitta maxima</em>, when the production of this FA reached maximum concentrations in phytoplankton. The composition of carnivory FAs (relative contribution of copepod-associated FAs, ratio 18:1(<em>n</em>-9)/18:1(<em>n</em>-7)) and the ratio of zoo- to phytosterols indicated that most grazers relied more on heterotrophic prey during polar night and spring while switching to a more algae-based diet during the summer. Based on source-specific highly branched isoprenoids (HBIs), sympagic carbon had generally a minor contribution to the nutrition of the zooplankton community, particularly during winter and spring when sympagic HBIs were virtually undetected in the animals. In contrast, sympagic HBI metabolites were detected in krill, amphipods and the pteropod <em>Clione limacina</em> during summer and autumn. The krill <em>Meganyctiphanes norvegica</em> was unique in terms of its HBI composition as the only species containing both sympagic and pelagic HBIs during spring. Our results indicate that the Barents Sea zooplankton community is largely based on pelagic carbon, while sympagic carbon is only supplementing species-specific diets, mostly during the second half of the year. This relatively low trophic dependency on sea-ice algae might be an indication of the resilience of this food web towards ongoing sea-ice decline that causes changes to the timing and availability of sympagic and pelagic carbon and food sources.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103368"},"PeriodicalIF":3.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698137","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":"Pre-molt dispersal and use of marine protected areas by Southern Rockhopper Penguins (Eudyptes chrysocome) at the southernmost oceanic regions of South America","authors":"Samanta Dodino ,&nbsp;Ulises Balza ,&nbsp;Luciana Riccialdelli ,&nbsp;Michael J. Polito ,&nbsp;Klemens Pütz ,&nbsp;Andrea Raya Rey","doi":"10.1016/j.pocean.2024.103369","DOIUrl":"10.1016/j.pocean.2024.103369","url":null,"abstract":"<div><div>Marine Protected Areas (MPAs) are crucial for conserving marine biodiversity, and assessing the effectiveness of boundaries in protecting marine species is essential. In the Southwest Atlantic Ocean, four MPAs have been created. In this study we evaluate the use of these MPAs by Southern Rockhopper Penguins (<em>Eudyptes chrysocome</em>) that nest at Isla de los Estados, Argentina during the pre-molt period in February and March 2020 by combining geolocation sensor data and spatial analysis together with stable isotopes analysis (<em>δ</em>¹³C and <em>δ</em>¹⁵N) to assess their spatial and trophic niches. We recaptured 16 of 25 adults to which loggers had been attached (64 % recapture rate, 6 females and 10 males). Penguins dispersed mainly southward and used the MPAs as corridors towards feeding area such as the Antarctic Polar Frontal Zone (APFZ). We found no evidence of sex-specific spatial and trophic niche partitioning. To develop robust conservation strategies, future studies should span multiple years and enhanced sampling effort to comprehensively explore the pre-molt trophic ecology and at-sea distribution of Southern Rockhopper Penguins.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103369"},"PeriodicalIF":3.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655933","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":"Modelling global mesozooplankton biomass using machine learning","authors":"Kailin Liu ,&nbsp;Zhimeng Xu ,&nbsp;Xin Liu ,&nbsp;Bangqin Huang ,&nbsp;Hongbin Liu ,&nbsp;Bingzhang Chen","doi":"10.1016/j.pocean.2024.103371","DOIUrl":"10.1016/j.pocean.2024.103371","url":null,"abstract":"<div><div>Mesozooplankton are a crucial link between primary producers and higher trophic levels and play a vital role in marine food webs, biological carbon pumps, and sustaining fishery resources. However, the global distribution of mesozooplankton biomass and the relevant controlling mechanisms remain elusive. We compared four machine learning algorithms (Boosted Regression Trees, Random Forest, Artificial Neural Network, and Support Vector Machine) to model the spatiotemporal distributions of global mesozooplankton biomass. These algorithms were trained on a compiled dataset of published mesozooplankton biomass observations with corresponding environmental predictors from contemporaneous satellite observations (temperature, chlorophyll, salinity, and mixed layer depth). We found that Random Forest achieved the best predictive accuracy with <em>R²</em> and <em>RMSE</em> (Root Mean Standard Error) of 0.57 and 0.39, respectively. Also, the global distribution of mesozooplankton biomass predicted by the Random Forest model was more consistent with the observational data than other models. We used the Random Forest model to create a global map of mesozooplankton biomass which serves as a reference for validating process-based ecosystem models. The model outputs confirm that environmental factors, especially surface Chl <em>a</em>, a proxy for prey availability, significantly correlate with the spatiotemporal distribution of mesozooplankton biomass. The scaling relationship between the mesozooplankton biomass and Chl <em>a</em> can be used as an emergent constraint for model validation and development. Moreover, our model predicts that the global total mesozooplankton biomass will decrease by 3% by the end of this century under the “business-as-usual” scenarios, potentially reducing fishery production and carbon sequestration. Our study contributes to predicting global mesozooplankton biomass and provides deep insights into the underlying environmental impacts on the distribution of mesozooplankton biomass.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103371"},"PeriodicalIF":3.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552124","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":"Changes in glacial meltwater system around Amundsen sea Polynya illustrated by radium and oxygen isotopes","authors":"Guanghui Chen ,&nbsp;You Jiang ,&nbsp;Yi Wang ,&nbsp;Jun Zhao ,&nbsp;Yusheng Qiu ,&nbsp;Minfang Zheng ,&nbsp;Mengya Chen ,&nbsp;Jianming Pan ,&nbsp;Min Chen","doi":"10.1016/j.pocean.2024.103367","DOIUrl":"10.1016/j.pocean.2024.103367","url":null,"abstract":"<div><div>The Amundsen Sea Polynya (ASP) is the most biologically productive area around Antarctica due to the input of iron-rich glacial meltwater (GMW). However, the source and path of GMW in the ASP, and how these have changed since the Dotson Ice Shelf (DIS), a primary GMW supplier, began experiencing a cooling period after 2011, remain unclear. This study presents the distribution of GMW in the ASP during the austral summer of 2020. Subsurface GMW proportions were estimated using a composite tracer derived from potential temperature, salinity, and dissolved oxygen, while surface GMW were using ²²⁶Ra and ²²⁸Ra. The results indicate that GMW in the ASP originates from DIS and Pine Island Bay. Surface GMW upwelled from the melting basal cavity of DIS is transported northwestward by katabatic winds, while subsurface GMW is transported northwestward beneath the mixed layer, with the upper portion upwelling to the surface in the ASP center along isopycnals (σ_θ) of 27.40 to 27.45 kg/m³. Depth variations of these isopycnals correlate well with brine inventories released by winter sea ice formation, suggesting that sea ice formation influences seawater σ_θ structures and consequently the transport path of subsurface GMW. Compared to 2011, the GMW content in the ASP in 2020 decreased by nearly half, and the transport routes have also changed. These changes align with the significantly reduced GMW discharge from the DIS after 2012. Our study confirms that the GMW system in the ASP has undergone significant changes following the onset of the cooling period experienced by the DIS.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103367"},"PeriodicalIF":3.8,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552123","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":"Drivers of growth and decay of Sargassum in the Tropical Atlantic: A Lagrangian approach","authors":"Witold Podlejski ,&nbsp;Léo Berline ,&nbsp;Julien Jouanno ,&nbsp;Nicolas Barrier ,&nbsp;Christophe Lett","doi":"10.1016/j.pocean.2024.103364","DOIUrl":"10.1016/j.pocean.2024.103364","url":null,"abstract":"<div><div>The proliferation of <em>Sargassum</em> in the Tropical Atlantic has occurred almost every year since 2011, but a strong variability of biomass is observed among years. Essential knowledge about the drivers of <em>Sargassum</em> growth and decay is still lacking to explain this interannual variability. Benefiting from accurate basin scale <em>Sargassum</em> detections provided by remote sensing, and from physical and biogeochemical ocean simulations, we developed a Lagrangian drift-growth model to simulate <em>Sargassum</em> distribution over the period 2016–2020. The resulting trajectories and biomass time series of <em>Sargassum</em> aggregates were analyzed to highlight the main limiting factors of growth and decay. The nitrogen and phosphorous concentrations are found to be weakly restrictive compared to physical limiting factors, especially the temperature. In particular, the warm waters found off northern Brazil appear to be instrumental in triggering the end of seasonal growth of <em>Sargassum</em>. The timing of the seasonal warming of this region strongly impacts the quantities of <em>Sargassum</em> simulated each year. This suggests that this region should be monitored to anticipate the development of <em>Sargassum</em> and resulting strandings.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103364"},"PeriodicalIF":3.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529428","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":"Long-term variation of the eddy kinetic energy in the Northeastern South China sea","authors":"Baolan Wu ,&nbsp;Jianping Gan","doi":"10.1016/j.pocean.2024.103366","DOIUrl":"10.1016/j.pocean.2024.103366","url":null,"abstract":"<div><div>The seasonal to interannual variability of eddy kinetic energy (EKE) in the Northeastern South China Sea (NE-SCS) has been widely studied and it is recognized that they are strongly related to the state of the Kuroshio pathway in the Luzon Strait. While, due to the lack of long-term observations and high-resolution simulations, the decadal change of EKE in NE-SCS remains unexplored. In this study, we show the EKE trend in the past ∼ 30 years in the NE-SCS by using satellite observation and global HYbrid Coordinate Ocean Model reanalysis with the Navy Coupled Ocean Data Assimilation. It is found that due to the weakening of the Kuroshio in the Luzon Strait since 1990 s, the Kuroshio shows an enhanced looping path in the NE-SCS, inducing stronger EKE in this region. Further analysis confirms that the energy transfer by baroclinic instability is dominant for the increasing of EKE, when the Kuroshio intrudes into the NE-SCS and brings more potential energy inside the circulation. The Kuroshio state along the Luzon Strait is the key for modulating the EKE in the NE-SCS. Furthermore, the long-term weakening of Kuroshio current along the Luzon strait during 1993–2020 is determined by the decreasing of subtropical mode water, corresponding to the positive phase of the Atlantic Multidecadal Oscillation. This study provides insight into the interaction between marginal sea (i.e., the SCS) and the open ocean (i.e., the western Pacific Ocean), finally linking to the global climate change.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103366"},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552122","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":"Stable carbon isotopic composition of particulate organic matter in the Cosmonaut and Cooperation Seas in summer","authors":"Jiawen Kang ,&nbsp;Qiang Hao ,&nbsp;Shunan Cao ,&nbsp;Jun Zhao ,&nbsp;Zifei Yang ,&nbsp;Zhen Tang ,&nbsp;Minfang Zheng ,&nbsp;Yusheng Qiu ,&nbsp;Mengya Chen ,&nbsp;Jianming Pan ,&nbsp;Jianfeng He ,&nbsp;Min Chen","doi":"10.1016/j.pocean.2024.103363","DOIUrl":"10.1016/j.pocean.2024.103363","url":null,"abstract":"<div><div>This study examined particulate organic carbon (POC) and its isotopic composition (δ¹³C_POC) in the Cosmonaut and Cooperation Seas in the Antarctica during the summer of 2019. Our results show that the spatial variation of POC concentration in summer surface water generally mirrors that of δ¹³C_POC, with higher POC and δ¹³C_POC values in the Cosmonaut Sea compared to the Cooperation Sea. The δ¹³C_POC values in both seas were positively correlated with the proportion of Chl-a in smaller particles (&lt; 20 μm). However, the relationship with the proportion of biogenic POC in smaller particles (&lt; 20 μm) differed between the two seas. This discrepancy is attributed to differences in the dominant phytoplankton species. In the Cosmonaut Sea, smaller phytoplankton (nano- and pico-phytoplankton) were dominated by <em>Phaeocystis antarctica</em>, whereas in the Cooperation Sea, they were dominated by pennate diatoms. The δ¹³C_POC in deep waters of both seas increased with depth, reflecting the effects of organic remineralization. The carbon isotope fractionation factors during remineralization, estimated using Rayleigh model, were 1.5 ± 0.2‰ and 1.6 ± 0.2‰ in the Cosmonaut Sea and the Cooperation Sea, respectively. These small isotope effects indicate that the isotope signals of organic matter exported from the upper layer are well preserved in the deep ocean. Additionally, anomalously high δ¹³C_POC values were observed in the bottom water outside the Cape Darnley polynya in the Cooperation Sea, reflecting the input of ice algae-derived organic matter from the shelf during AABW formation. A simple isotopic mass balance estimate suggests that 6–19% of the POC in the AABW of the Cooperation Sea is contributed by ice algae. Our study highlights the complexity of factors affecting δ¹³C_POC in the Southern Ocean, emphasizing the importance of phytoplankton community composition.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"229 ","pages":"Article 103363"},"PeriodicalIF":3.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529426","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}