Journal of Marine Systems最新文献

{"title":"Spatial distributions of acoustic scattering groups during the warm-to-cold transition period in the Senegal coastal ecosystem and their relationships with environmental variables","authors":"Viviane David ,&nbsp;Jérémie Habasque ,&nbsp;Gildas Roudaut ,&nbsp;Louis Marie ,&nbsp;Delphine Thibault ,&nbsp;Anne Lebourges-Dhaussy ,&nbsp;Xavier Capet ,&nbsp;Eric Machu","doi":"10.1016/j.jmarsys.2025.104113","DOIUrl":"10.1016/j.jmarsys.2025.104113","url":null,"abstract":"<div><div>The coastal area of north-west (NW) Africa is a highly productive ecosystem due to the presence of a strong upwelling. This ecosystem supports large populations of small pelagic fish, such as sardinellas, which have significant socio-economic value for local populations. In this study, we analyzed the acoustic data collected during a one-month survey along the Senegalese coast at the beginning of the upwelling season. Hierarchical clusterings were performed to classify the acoustic data from the epipelagic zone (down to 120 m-depth) separately for daytime and nighttime. The analysis identified five echo-groups during the day and six at night. The resulting echo-groups were then compared to stratified midwater trawl samplings to support hypotheses about the organisms responsible for the echoes. Additionally, a remotely operated towed vehicle (called Scanfish) was used to monitor environmental variables down to 100 m depth. Two machine learning models were applied to link the classified echo-groups to the environmental data for both day and night. Each daytime echo group had a corresponding nighttime echo group, with also similar environmental preferences. Fish schools were mainly found in shallow coastal waters while dense sound-scattering layers detected at 38 kHz, likely composed of small fish or fish larvae, were observed in the temperature range of 17°-21 °C for both day and night. The other echo-groups were composed of fluid-like zooplankton or gas-bearing zooplankton. The sixth night echo-group corresponded to migrant organisms and was predominant at night. Overall, the analyses of the abiotic habitats for each echo-group allow us to better understand the organism distributions during the beginning of the NW Africa upwelling season.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104113"},"PeriodicalIF":2.5,"publicationDate":"2025-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144738421","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 Coffin Bay Estuary: Influences from coastal upwelling in the eastern Great Australian Bight","authors":"Jochen Kämpf","doi":"10.1016/j.jmarsys.2025.104112","DOIUrl":"10.1016/j.jmarsys.2025.104112","url":null,"abstract":"<div><div>Using a coupled physical-biological model at different grid resolutions, this work explores the influences from coastal upwelling on the Coffin Bay Estuary in the eastern Great Australian Bight. The Coffin Bay Estuary, which is a negative estuary, consists of a series of interconnected smaller bay. The findings show the main upwelling plume is topographically steered around but does not enter the Coffin Bay Estuary. Instead, the nitrogen load in seawaters near the estuary is derived from secondary circulations and horizontal turbulence. However, due to photosynthetic consumption in the main upwelling zone, dissolved nitrogen levels are reduced to low values (∼0.8 μM) near the estuary and can only support slow phytoplankton growth. While wind-driven currents rapidly flush the outer bay of the estuary, called Coffin Bay, on a timescale of 5 days, this excludes shallower (&lt;20 m) nearshore water that has a turnover time &gt; 40 days. However, it is this shallower water that is connected to the first inner bay of the estuary, Port Douglas Bay, via strong (&gt;1 m/s) tidal flows in the narrow channel. The other inner bays of the estuary have flushing times &gt;100 days and are not influenced by processes on the ambient continental shelf. Hence, the coastal upwelling region in the eastern Great Australian Bight has generally no or only little influence on the nutrient budget in the Coffin Bay Estuary.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104112"},"PeriodicalIF":2.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703529","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":"Seasonal and decadal variations in nutrients and organic carbon in the lower Huanghe River under drastically changing water-sediment regimes","authors":"Xintong Jiang ,&nbsp;Yue Ming ,&nbsp;Mengyu Wang ,&nbsp;Ailin Yao ,&nbsp;Xianye Wang ,&nbsp;Lei Gao","doi":"10.1016/j.jmarsys.2025.104111","DOIUrl":"10.1016/j.jmarsys.2025.104111","url":null,"abstract":"<div><div>The Huanghe (Yellow) River is well known for its sediment-laden river waters, and it is also a typical large river deeply imprinted by human activities. Surface water samples were collected monthly from March 2019 to October 2022 at the Luokou station in its lower reaches, to elucidate the seasonal variation patterns of POC (particulate organic carbon) in SPM (suspended particulate matter), nutrients, and DOC (dissolved organic carbon) ready to be transported to the sea. The annual water-sediment regulation scheme (WSRS), generally carried out in June and July since 2002 at the Xiaolangdi reservoir, induced pulsed changes in both water discharge and sediment contents downstream that destroyed the natural sediment-water balance, so that the chemical parameters of sediments (POC (%), POC/PN (particulate nitrogen), δ¹³C in POC, and δ¹⁵N in PN) at the lower reaches did not show clear seasonal variation patterns anymore. At the same time, however, concentrations of NO₃⁻, SiO₃²⁻, NO₂⁻, and DOC still maintained apparent seasonal variations. Concentrations of NO₃⁻, SiO₃²⁻, NH₄⁺, and NO₂⁻ as well as DOC displayed significantly decreasing trends after 2000, which were different from their decadal trends of increasing in the last century. These new trends, owing to the successful implementation of the environmental protection projects, as well as to the prolonged retention times of river waters after the constructions of a large number of reservoirs over the river basin, reflected the profound transformation and evolution of the Huanghe River aquatic ecosystems just occurring recently.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104111"},"PeriodicalIF":2.7,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694313","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":"Comparing in situ and satellite-derived primary production estimates in the Canary Current upwelling region","authors":"Nauzet Hernández-Hernández ,&nbsp;Yeray Santana-Falcón ,&nbsp;María F. Montero ,&nbsp;Mar Benavides ,&nbsp;Antonio Delgado-Huertas ,&nbsp;Xosé A. Álvarez-Salgado ,&nbsp;Peter Land ,&nbsp;Javier Arístegui","doi":"10.1016/j.jmarsys.2025.104109","DOIUrl":"10.1016/j.jmarsys.2025.104109","url":null,"abstract":"<div><div>Satellite-based Net Primary Production (NPP) estimates are arguably the best way to improve our understanding of large-scale ocean productivity and to validate Earth System Models. Despite significant progress over recent decades, satellite-derived NPP estimates still suffer from large uncertainties, primarily due to the limited number of <em>in situ</em> primary production (PP) measurements available for their validation. In addition, the most widely used algorithms lead to different, sometimes even contradictory, results. Along with measurements of chlorophyll <em>a</em> concentration (Chl<em>a</em>) and phytoplankton biomass (C_phyto), here we present <em>in situ</em> measurements of PP using ¹⁴C uptake and ¹³C isotope tracing, as well as O₂ and ¹⁸O₂ evolution inside incubation bottles, across the transition zone from the coastal Canary Eastern Boundary Upwelling System (CanEBUS) to the open ocean waters of the Cape Verde Frontal Zone (17–23°N; 16–26°W). We also calculate assimilation numbers (<span><math><msubsup><mi>P</mi><mi>opt</mi><mi>b</mi></msubsup><mo>)</mo></math></span> and growth rates (μ) from <em>in situ</em> measurements. First, we compared <em>in situ</em> PP estimates measured concurrently using the four abovementioned techniques. We then tested the performance of four widely-used models including the Vertically Generalized Production Model (VGPM) and its variant based on Eppley's description of the growth function (Eppley), the Carbon-based Productivity Model (CbPM), and the Carbon, Absorption and Fluorescence Euphotic-resolving model (CAFE), along with the satellite-derived input variables that feed these algorithms. We found that the Chl<em>a</em>-based VGPM and Eppley models were significantly correlated with <em>in situ</em> estimates, regardless of the satellite source used as input data. As for models based on C_phyto, only the CbPM from the Visible Infrared Imaging Radiometer Suite (VIIRS) data demonstrated performance comparable to that of the Chl<em>a</em>-based models. In all other cases, C_phyto-based models were uncorrelated with <em>in situ</em> PP estimates. Our results indicate that the bias associated with the VGPM and Eppley models is primarily due to the algorithms' inability to accurately assess <span><math><msubsup><mi>P</mi><mi>b</mi><mi>opt</mi></msubsup><mspace></mspace></math></span>. Meanwhile, the retrieval of both satellite-derived C_phyto and μ leads to a poor estimate of NPP by the CbPM. Our findings suggest that enhancing the accuracy of NPP estimates derived from satellite-based models necessitates the refinement of the methodology employed in deriving the input data and their subsequent validation, rather than developing increasingly complex models.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104109"},"PeriodicalIF":2.7,"publicationDate":"2025-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703528","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 velocity in the deep layer of South China Sea revealed by using ECCO product","authors":"Jianing Li ,&nbsp;Qingxuan Yang ,&nbsp;Hui Sun","doi":"10.1016/j.jmarsys.2025.104110","DOIUrl":"10.1016/j.jmarsys.2025.104110","url":null,"abstract":"<div><div>Unlike the well-studied South China Sea (SCS) horizontal circulation, the vertical velocity in the SCS, especially in the deep water, is poorly understood. The vertical velocity connects the horizontal circulations at different depths and plays vital roles in modulating vertical material transport and biochemical processes. Using the ECCO4 product, we investigate the distribution of vertical velocities in the deep SCS, and explore the renewal process of the SCS deep water. The vertical velocities deeper than 2500 m all present similar spatial features: the downwelling originates near the Luzon Strait and spreads to the SCS basin interior, while the upwelling mainly takes place near the continental slope and forms an upwelling ring around the downwelling zone. This pattern becomes more and more significant with depth and is temporally stable. The upwelling near the continental slope is dominantly contributed by its diapycnal component, indicating a strong relation to local mixing. The near-bottom vertical velocity field shows a similar spatial-temporal pattern. This vertical velocity distribution suggests the deep-water overflow from the Luzon Strait is the main driving factor of the SCS deep water recycling. The Pacific deep water first sinks into the deep basin interior to supply the SCS deep water; then, it upwells along the slope and returns to the middle layer to accomplish the SCS deep water renewal. These findings not only improve our understanding of the three-dimensional circulation in the SCS, but also serve as an enlightenment for the uplifting of the deep and bottom waters in the open ocean.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104110"},"PeriodicalIF":2.7,"publicationDate":"2025-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704778","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 the unprecedented coastal marine heatwaves along Fujian and Zhejiang provinces, China","authors":"Yulong Yao ,&nbsp;Yuwei Hu ,&nbsp;Chuanming Hu ,&nbsp;Chunzai Wang ,&nbsp;Wenwen Yu","doi":"10.1016/j.jmarsys.2025.104108","DOIUrl":"10.1016/j.jmarsys.2025.104108","url":null,"abstract":"<div><div>In recent decades, coastal marine heatwaves (MHWs) have intensified due to global warming, causing severe impacts on coastal marine ecosystems. In September and October 2021, significant reductions in seaweed production were observed along the coasts of Fujian (−19.23 %) and Zhejiang (−3.27 %) Provinces in China, which may be related to unprecedented coastal MHWs. This study utilizes three high-resolution satellite sea surface temperature (SST) datasets together with oceanic and atmospheric reanalysis products to examine the characteristics and mechanisms of these MHWs. Our analysis reveals that the record-breaking MHWs occurred primarily from September 21 to October 23, with an average intensity of up to 4 °C and lasting nearly the entire month of October. Mixed layer heat budget assessments indicate that net surface heat flux was the key factor influencing temperature changes (Corr = 0.71, <em>p</em> &lt; 0.01). The positive net surface heat flux in September, driven by increased solar shortwave radiation, resulted from the intensification and westward expansion of the western Pacific subtropical high (WPSH). We emphasize that understanding the mechanisms behind the anomalous WPSH in autumn is vital for mitigating climate risks to seaweed production along the Fujian and Zhejiang coasts in the context of global warming.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104108"},"PeriodicalIF":2.7,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144671343","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":"Exploring upwelling phenology and high-frequency hydrographic variability in the Humboldt Archipelago during winter-spring transition and La Niña conditions","authors":"Victor M. Aguilera ,&nbsp;Linda M. Barranco ,&nbsp;Lucas Glasner ,&nbsp;Matías Pizarro-Koch ,&nbsp;Cristian A. Vargas","doi":"10.1016/j.jmarsys.2025.104105","DOIUrl":"10.1016/j.jmarsys.2025.104105","url":null,"abstract":"<div><div>The upwelling system off Coquimbo in central-northern Chile (29–30°S) provides multiple ecosystem services, including the high biodiversity in the Humboldt Archipelago, which benefits human well-being. The influence of upwelling in the archipelago, along with other high-frequency processes that lead to changes in temporal hydrographic conditions (temperature, pH, and oxygen), may have profound effects on the functioning of this ecosystem. In this study, we explored the upwelling phenology (frequency, magnitude, and duration of upwelling events), together with high-frequency variability analyses (semidiurnal, daily, and synoptic), and the vertical structure of the water column in the archipelago from August to November 2022. This period corresponded to the austral winter-spring transition of 2022, which also marked the end of a prolonged La Niña event, during which four months of continuous surface wind and surface (10 m) and subsurface (30 m) hydrographic measurements were analyzed along with four hydrographic surveys. Upwelling events observed throughout the study period promoted negative hydrographic anomalies in temperature (−1.1 °C), oxygen (−79 μmol kg⁻¹), and pH (−0.18 pH_NBS), sometimes lasting up to a week. The synoptic scale dominated the hydrographic variability during the winter (48 % of the variance), whereas the diurnal component became more significant during the spring (37 % of the variance), likely due to higher solar radiation and wider pH/oxygen cycles. Moderated by phytoplankton biomass, low pH (&lt; 7.8 pH_NBS) and hypoxic conditions (&lt; 60 μmol kg⁻¹) prevailed below 30 m depth in the archipelago throughout the study period. Further studies may address the influence of this environmental variability on biological processes related to the productivity of the Humboldt Archipelago.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104105"},"PeriodicalIF":2.7,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144653214","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":"Spatiotemporal variations in Zhe-Min Coastal Fronts in the East China Sea in winter by deep learning","authors":"Qiang Lian,&nbsp;Xihong Jian,&nbsp;Tengfei Li,&nbsp;Shuwen Zhang,&nbsp;Jin Feng,&nbsp;Zhaoyun Chen","doi":"10.1016/j.jmarsys.2025.104104","DOIUrl":"10.1016/j.jmarsys.2025.104104","url":null,"abstract":"<div><div>Oceanic fronts are crucial for marine ecology and the environment due to their vigorous mixing, high productivity, and abundant fishery resources. In this study, the Zhe-Min Coastal Front (ZMCF) in the East China Sea is identified from remote sensing Sea Surface Temperature (SST) images using a combination of the Belkin O'Reilly Algorithm and a deep learning network, addressing the shortcomings of traditional front gradient algorithms. The Ringed Residual U-Net network excels in detecting the ZMCF, particularly in discontinuous, fragmented, and multi-branch fronts. After detecting the ZMCF areas, the monthly variations in SST gradient, front probability, and offshore distance of the ZMCF are analyzed for winter. An empirical orthogonal function (EOF) method is employed to capture the dominant mode of spatiotemporal variations in the ZMCF probability, demonstrating that the cross-shore movement of the ZMCF is closely related to the magnitude of the northerly wind. Under the conditions of the low phase of the Pacific Decadal Oscillation, the intensified ZMCF is trapped near the coast, driven by strong northerly wind during La Niña years. El Niño events exert the opposite effect.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104104"},"PeriodicalIF":2.7,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144623327","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":"Traits associated with food web structure in lagoon and reef ecosystems","authors":"Ana Luisa Avelino Brito ,&nbsp;Tibor Kalapos ,&nbsp;Ferenc Jordán ,&nbsp;Katalin Patonai","doi":"10.1016/j.jmarsys.2025.104095","DOIUrl":"10.1016/j.jmarsys.2025.104095","url":null,"abstract":"<div><div>The oceans are currently facing multiple anthropogenic threats, such as overexploitation, pollution, habitat destruction, and climate change. To address these challenges, ecological indicators are needed to monitor the impact of human activities and assess the effectiveness of conservation measures. Food web topology captures the entire community structure, providing systems-based indicators of ecological status rather than monitoring single species and their composition. In this study, the association between functional organismic traits and topological indices describing the food web structure was tested by using network analysis in 4 reef and 15 lagoon Ecopath with Ecosim models. We aimed to understand if traits and conservation status can be linked with specific network position of a node. We analyzed 3 traits (diet, fertilization type, substratum), conservation status, and 18 topological indices. The results showed at least two significant associations for each trait. Conservation status, fertilization type, and diet displayed more distinct aggregations, being relevant in explaining food web structure. Conservation status aggregated top predators in a risk position (endangered or vulnerable) and also those with fewer network connections. Fertilization type (external, internal, or asexual) could be considered a good grouping trait. Diet has the highest coverage and revealed expected patterns, which can be very helpful for environmental predictions under disturbances, using the trait-based approach. Substratum is the least useful trait for this approach. The associations of ecological traits and topological indices in lagoon and reef food webs might help in conservation “ecosystem-based” management decision-making and prioritization.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104095"},"PeriodicalIF":2.7,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144653213","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":"Recent decline of sea ice area in the Bohai Sea over the period 2001 to 2023","authors":"Zhikun Lin ,&nbsp;Yu Yan ,&nbsp;Yingjun Xu ,&nbsp;Qingkang Hou ,&nbsp;Jialin Zhang ,&nbsp;Jiayu Ding","doi":"10.1016/j.jmarsys.2025.104089","DOIUrl":"10.1016/j.jmarsys.2025.104089","url":null,"abstract":"<div><div>The Bohai Sea, China's northernmost sea, experiences sea ice during winter that impacts shipping, ports, mariculture, and infrastructure, while also serving as vital habitat for the spotted seal. Monitoring sea ice variability is crucial for both marine economic and ecological sustainability. This study utilizes MODIS satellite images with minimal or no cloud cover and employs a sample-based object-oriented feature extraction method, along with visual interpretation corrections, to construct a daily (though discontinuous) time series of sea ice area in the Bohai Sea from 2001 to 2023. The average sea ice area decreased by 0.15 × 10⁴ km² (16.36 %) from 2001–2010 to 2011–2023. The longer initial freezing period (∼5 weeks) and shorter melting period (∼3 weeks) show an asymmetric unimodal pattern in daily average sea ice area variation. The severe freezing phase lasts nearly 6 weeks, typically reaching its peak in late January or early February. Spatially, sea ice freezing frequency decreases from north to south and nearshore to offshore, with frequencies above 40 % concentrated along the northern and eastern coasts of Liaodong Bay. The overall trend of sea ice freezing frequency per pixel shows a decline in 56.98 % of the entire sea area, with an average rate of −0.16 %. The trend of freezing frequency is declining in Liaodong Bay (−0.25 %) and Bohai Bay (−0.10 %) but slightly increasing in Laizhou Bay (0.02 %). Local climate factors, including air temperature, northward wind, and surface sensible heat flux, play a crucial role in sea ice variation in the Bohai Sea, while the AO (<em>r</em> = −0.71, <em>p</em> &lt; 0.01) and NAO (<em>r</em> = −0.61, <em>p</em> &lt; 0.01) indices serve as important large-scale climatic factors.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"250 ","pages":"Article 104089"},"PeriodicalIF":2.7,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549597","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}