Journal of Marine Systems最新文献

{"title":"Lagrangian dispersion in the Red River plume region, Northeast Vietnam, from drifter observations and modeling","authors":"Alexei Sentchev ,&nbsp;Thinh Nguyen-Duc ,&nbsp;Stefano Berti ,&nbsp;Nadia K. Ayoub ,&nbsp;Vu Duy Vinh","doi":"10.1016/j.jmarsys.2025.104143","DOIUrl":"10.1016/j.jmarsys.2025.104143","url":null,"abstract":"<div><div>The transport and spatial distribution of materials within river plumes and neighboring waters are strongly influenced by the plume morphology and fronts bounding the plume area. Thus, identifying locations of plume fronts and assessing frontal mixing activity is particularly important for understanding the spatial distribution of biogeochemical tracers and the connectivity between source (river mouth) and offshore regions. Statistical properties of horizontal dispersion in the Red River (RR) plume region were obtained from drifter experiments, conducted in the Gulf of Tonkin during summer 2022, and also from realistic numerical modeling. Adopting a Lagrangian perspective, a method is proposed to characterize the RR plume morphology based on the extraction of Lagrangian Coherent Structures (LCS) from the surface flow field using Finite-Size Lyapunov Exponents (FSLE). Maxima of the attracting FSLE field (FSLE ridge lines) enabled us to identify zones of current convergence and shear in the flow, which are essential for characterizing the dynamics associated with plumes and mapping the fronts delimiting them. It became clear that the body of the RR plume is formed by the individual river plumes of the RR deltaic system. FSLE ridge lines allowed identification of the offshore expansion of individual plumes and revealed a variety of forms, semi-circular or hook-like filaments, characterizing the plume shape. The ballistic regime of dispersion was found inside the plume region, with the dominant direction perpendicular to the coastal flow direction revealing anisotropic shear dispersion. It was observed at scales of 0.3 to 3 km (submesoscale range), with a maximum value of 10–13 day⁻¹, as derived from the analysis of the scale dependent relative dispersion of real drifters. In model simulations, the relative dispersion appeared scale independent in the range below 2 km, indicating a significant effect of grid resolution on the model's representation of lateral mixing.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104143"},"PeriodicalIF":2.5,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267061","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":"Zooplankton seasonal variability in Arctic fjord during cold and warm events – taxonomic and trait-based approaches (Kongsfjorden, Svalbard)","authors":"Marta Gluchowska ,&nbsp;Stig Falk-Petersen ,&nbsp;Haakon Hop ,&nbsp;Anna Olszewska ,&nbsp;Wojciech Walkusz ,&nbsp;Slawomir Kwaśniewski","doi":"10.1016/j.jmarsys.2025.104144","DOIUrl":"10.1016/j.jmarsys.2025.104144","url":null,"abstract":"<div><div>Kongsfjorden, located on the west coast of Spitsbergen (79°N), lies at the boundary between Arctic and Atlantic water masses, making it an ideal site for studying the influence of environmental conditions on ecosystem dynamics and offering insights applicable to other Arctic regions. In this study, we describe the seasonal succession and interannual variability of the zooplankton community in Kongsfjorden in quantitative, taxonomic, and ecological terms, as observed during years with contrasting hydrographic conditions. The analysis is based on data collected in 2002, 2006, and 2007—years characterized by pronounced environmental differences, particularly in spring, with notable variation in seawater temperature and salinity. Zooplankton samples were collected from stations within the fjord and on the adjacent shelf using vertically stratified hauls with a Hydro-Bios Multi Plankton Sampler midi (180 μm mesh). Ecologically, the zooplankton community was analyzed using four traits—body size, feeding mode, spawning strategy, and transparency—allowing classification of 115 taxa into ten functional groups. Across all seasons, zooplankton biomass was consistently dominated by non-gelatinous, medium-sized, free-spawning forms. A clear seasonal shift in functional composition was observed, from current feeders in spring to ambush feeders in autumn, reflecting changes in food availability and trophic dynamics. Trait-based patterns proved more stable than taxonomic composition and more effectively captured key aspects of zooplankton functional roles in ecosystem processes, including trophic interactions, carbon export, and pelago–benthic coupling. Although the data reflect conditions from nearly two decades ago, they represent both cold and warm hydrographic states and remain ecologically relevant. Our findings highlight the sensitivity of Arctic zooplankton communities to early-season hydrography and bloom composition, and underscore the value of trait-based approaches for detecting structural shifts and anticipating ecosystem responses under ongoing Arctic Atlantification.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104144"},"PeriodicalIF":2.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267060","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 patterns of marine heatwaves in the Southern Ocean and their role in air-sea interaction","authors":"K. Gurumoorthi,&nbsp;Alvarinho J. Luis","doi":"10.1016/j.jmarsys.2025.104141","DOIUrl":"10.1016/j.jmarsys.2025.104141","url":null,"abstract":"<div><div>Marine heatwaves (MHWs) are extended periods of abnormally warm ocean conditions in which temperature exceeds the 90th percentile threshold limit. While prior studies have mainly focused on regional trends, the Southern Ocean, particularly around Antarctica, has been relatively understudied despite experiencing considerable warming in recent decades. This study investigates MHWs in the Southern Ocean from 1982 to 2022, highlighting significant spatial and temporal variations in their frequency, intensity, and days. MHWs were found to be more frequent (0.4 events per decade) and intense north of 65°S, especially during the summer, with a marked rise in occurrence after 2008, coinciding with anthropogenic climate change and increasing sea surface temperatures (SST). The study also identifies the influence of climate patterns such as El Niño and the Indian Ocean Dipole (IOD) on MHWs intensity and frequency, particularly in the Ross Sea during spring and autumn. We analyzed the atmospheric impacts of significant MHWs in 2013. The 2013 MHW event serves as a key example of extreme subsurface warming, where temperatures reached 6.2 °C at 120 m depth, significantly increasing the region's heat content. This highlights how MHWs can transmit heat vertically, impacting both surface and deep ocean layers. The findings emphasize the complex interactions between ocean dynamics, and atmospheric conditions in determining MHWs patterns in the Southern Ocean, offering crucial insights for predicting the region's future responses to climate change.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104141"},"PeriodicalIF":2.5,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227505","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":"Grain-size and geochemical evidence for sediment transport mechanisms in the northeastern part of the East Siberian Sea and on the adjacent continental slope","authors":"Ekaterina Ovsepyan ,&nbsp;Evgeniia Dorokhova ,&nbsp;Yaroslav Ovsepyan ,&nbsp;Ramiz Aliev ,&nbsp;Young Keun Jin","doi":"10.1016/j.jmarsys.2025.104140","DOIUrl":"10.1016/j.jmarsys.2025.104140","url":null,"abstract":"<div><div>Grain-size analyses, end-member modeling, X-ray fluorescence, and radionuclide activity measurements were conducted on sediment minicores collected from the middle-outer shelf of the East Siberian Sea (ESS) and the upper part of the adjacent continental slope to elucidate the sedimentation mechanisms in this poorly studied region. The grain-size data demonstrate that clayey silt and silt strongly dominate on the ESS shelf and the continental slope. In contrast, sandy silt has a patchy distribution. End-member modeling, applied here for the first time, indicates that sea ice (frazil and anchor ice) rafting, and nepheloid transport are the primary processes responsible for distributing sedimentary material across the ESS. The XRF data confirm the results of previous studies, reporting a predominantly lithogenic origin for ESS deposits. Combined grain size and geochemical records suggests that the shelf break area serves as a depocenter for fine silt particles, likely supplied by nepheloid flow, and represents the most productive area in the northeastern ESS. High sea surface productivity likely results from influence of nutrient-rich Pacific-derived waters, the upwelling of transformed Atlantic-derived waters, or a combination of both. The accumulation of the high amount of fine silt near the shelf break is suggested to be related to relatively calm bottom-water conditions, resulting from the potential interaction of the northward-flowing cross-shelf currents and episodic southward-moving compensatory flows. Wind direction is considered a key factor controlling the intensity of fine-grained material distribution by nepheloid flows and anchor ice across the ESS shelf. Sedimentation rates derived from the radionuclide activity measurements vary from 1.3 mm yr⁻¹ on the outer shelf to 1.0 mm yr⁻¹ on the upper continental slope.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104140"},"PeriodicalIF":2.5,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227507","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":"Evaluation and projection of Arctic sea ice transport through Fram Strait with emphasis on atmospheric multimodal responses","authors":"Zhou Ye ,&nbsp;Yu Zhang ,&nbsp;Wenyun Guo ,&nbsp;Changsheng Chen ,&nbsp;Hailong Guo ,&nbsp;Weizeng Shao ,&nbsp;Deshuai Wang ,&nbsp;Danya Xu ,&nbsp;Yi Zhou","doi":"10.1016/j.jmarsys.2025.104139","DOIUrl":"10.1016/j.jmarsys.2025.104139","url":null,"abstract":"<div><div>This study evaluates the historical (1988–2014) sea ice drift (SID), sea ice concentration (SIC), sea ice thickness (SIT), and associated sea ice volume transport (SIVT) from 12 CMIP6 models in Fram Strait based on multi-source reference datasets. In addition, a global ice-ocean coupled model based on the Finite Volume Community Ocean Model (Global-FVCOM), is included as a comparison. Both the simulated and reference SIVT show significant interannual variability, but inter-model spread exists. Compared to reference data, the CMIP6 models exhibit greater discrepancies than Global-FVCOM. The comprehensive assessment reveals notable performance differences among the models in simulating varying sea ice variables. Ensemble experiments, incorporating models with varying performance in simulating SIVT, demonstrate a decreasing trend in SIVT across all schemes under the SSP2–4.5 and SSP5–8.5 scenarios, with a more pronounced decline in the latter. Compared to the traditional multi-model mean scheme using all models, the scheme selecting six better-performing models through evaluation results of SIVT exhibits lower SIVT values and a slower decline. There are significant differences among the CMIP6 models regarding the dominant factors contributing to future SIVT variations. The largest number of models demonstrates a strong relationship between the dipole anomaly (DA) and sea ice transport, followed by those associated with the Arctic Oscillation (AO), while the fewest models show a significant connection to the Beaufort-Barents Oscillation (BBO). The choice of time period, whether by year or month, considerably influences the identification of dominant modes for sea ice transport.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104139"},"PeriodicalIF":2.5,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267062","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":"Dynamics of Total organic carbon: Partitioning, distribution and controlling processes in the Indian sector of the Southern Ocean during austral summer","authors":"Melena A. Soares,&nbsp;V. Venkataramana,&nbsp;R.K. Mishra,&nbsp;P. Sabu,&nbsp;R.K. Naik,&nbsp;Manish Tiwari,&nbsp;N. Anilkumar,&nbsp;R. Mohan,&nbsp;K. Mahalinganathan","doi":"10.1016/j.jmarsys.2025.104137","DOIUrl":"10.1016/j.jmarsys.2025.104137","url":null,"abstract":"<div><div>The Southern Ocean (SO) is a globally important region connecting the Pacific, Atlantic and Indian Oceans, having extreme seasonal changes and is crucial with regard to the carbon dynamics. Organic carbon plays a vital role in various biogeochemical processes and the carbon biological pump in the ocean. This study discusses the variability of total organic carbon (TOC) and its partitioning into particulate and dissolved fractions across the different fronts of the Indian sector of the Southern Ocean during two austral summers. A considerable interannual variation in the TOC distribution was noted, TOC concentration ranged from 84.4 to 127.8 μM in 2013 and from 76.3 to 121.2 μM in 2015, with considerable interannual variation in the TOC distribution. This study implied that the dominant phytoplankton community substantially contributed to the changes in composition and partitioning of organic carbon in the epipelagic waters and microbial respiration in the mesopelagic waters. Besides, the zooplankton community and its grazing effect influenced the organic carbon dynamics within the water column. Also, a significant correlation of total organic carbon with temperature, apparent oxygen utilisation and dissolved inorganic carbon, suggests the interplay of physical mixing processes like water mass intrusion and eddies. With biochemical responses altering the TOC distribution. Importantly, even small climate changes like warming in the SO can stimulate alterations in hydrographic processes, the food web structure and carbon pathways, impacting the fate of organic carbon in the oceanic ecosystem.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104137"},"PeriodicalIF":2.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227506","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":"Spatial and temporal distribution of Sthenoteuthis oualaniensis in the Northwest Indian Ocean during different life stages of cyclonic eddies","authors":"Fu Yingyue ,&nbsp;Wu Xiaoci ,&nbsp;Jin Pengchao ,&nbsp;Zhang Zhong ,&nbsp;Xing Qinwang ,&nbsp;Yu Wei","doi":"10.1016/j.jmarsys.2025.104138","DOIUrl":"10.1016/j.jmarsys.2025.104138","url":null,"abstract":"<div><div>Mesoscale eddies, particularly cyclonic eddies (CEs), are known to influence the abundance and distribution of purpleback flying squid (<em>Sthenoteuthis oualaniensis</em>) resources in the northwest Indian Ocean. <em>Sthenoteuthis oualaniensis</em> is a short-lived species and is sensitive to environmental changes. The evolution of CEs is accompanied by structural and energetic transformations, exerting varying impacts on the local marine environment. However, the response of <em>S. oualaniensis</em> to these evolving CEs remains unclear. Therefore, this study analyzed the changes in basic eddy characteristics during CEs evolution and the environmental changes (sea surface temperature, chlorophyll-a concentration, and dissolved oxygen concentration at 150 m depth) driven by CEs. Combined with a habitat suitability index (HSI) model, the distribution of <em>S. oualaniensis</em> during the different life stages of CEs was analyzed. The results showed that the CEs experienced three stages: the early stage, the mature stage and the aged stage. At different stages, the parameters of CEs exhibited distinct distribution patterns. As the eddy evolved, the gravity center of <em>S. oualaniensis</em> abundance in latitude and longitude exhibited a movement trajectory similar to the eddy center. The environmental changes driven by this evolution process influenced the distribution of <em>S. oualaniensis</em>, and the maximum suitable habitat area was generated during the CEs mature stage. These results show that the evolution of CEs significantly affects the habitat distribution of <em>S. oualaniensis</em> in the northwest Indian Ocean.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104138"},"PeriodicalIF":2.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118485","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":"Coral bleaching occurrence and its relation to marine heatwave events in the Southwestern waters of South Sulawesi, Indonesia, as part of the Coral Triangle region","authors":"Dian Noor Handiani ,&nbsp;Nining Sari Ningsih ,&nbsp;Erlin Beliyana","doi":"10.1016/j.jmarsys.2025.104136","DOIUrl":"10.1016/j.jmarsys.2025.104136","url":null,"abstract":"<div><div>This study investigates the escalating threat of marine heatwaves (MHWs) to coral reef ecosystems in the southwestern waters of South Sulawesi, Indonesia. Based on four decades of data from 1982 to 2021, our analysis reveals a substantial increase in both the frequency and intensity of MHWs, with particularly severe events occurring in 2010, 2013, 2016, 2019, and 2020. The 2016 MHW was especially devastating, marked by extreme thermal stress and prolonged duration, reaching up to 215 days in the Lesser Sunda Islands. This event closely aligned with widespread Bleaching Alert Level 2 warnings in regions such as Lombok, indicating a high risk of coral mortality. The Coral Reef Health Index (CRHI) proved to be a valuable tool for reef assessment, showing strong positive correlations with coral cover (<em>r</em> = 0.83) and seagrass cover (<em>r</em> = 0.74), along with a strong negative correlation with rubble cover (<em>r</em> = −0.82). These results highlight the crucial role of reef structure and benthic composition in sustaining ecosystem health. In addition, the observed delay between peak MHW conditions and the occurrence of bleaching events emphasizes the need for real-time, high-resolution monitoring systems that integrate multiple observation methods. Our findings underscore the urgency of implementing comprehensive conservation strategies. These should include global actions to reduce ocean warming and targeted local efforts such as protecting reefs with high CRHI values, minimizing local stressors, and enhancing the effectiveness of marine protected areas. Future research should prioritize the integration of long-term field surveys with advanced remote sensing technologies and the inclusion of a wider range of oceanographic variables such as water quality and ocean acidification. Such approaches are essential for generating actionable data that support adaptive management and the sustained conservation of coral reef ecosystems.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104136"},"PeriodicalIF":2.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105739","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":"Rapid decline of nutrients in the subsurface of the East Sea (Japan Sea) over the past 28 years","authors":"Sojin Park ,&nbsp;Guebuem Kim ,&nbsp;SungHyun Nam ,&nbsp;Joon-Soo Lee ,&nbsp;In-Seong Han","doi":"10.1016/j.jmarsys.2025.104135","DOIUrl":"10.1016/j.jmarsys.2025.104135","url":null,"abstract":"<div><div>A previous study suggested that the Northwest Pacific Ocean has experienced an approximately 25 % decline in nutrients in the subsurface (100–850 m), leading to a 50 % decline in the surface (0–100 m) over the past four decades (<span><span>Kim et al., 2022</span></span>). In this study, we observed a comparable 20 % decrease in nutrients in the East/Japan Sea (EJS) subsurface (200–500 m) from 1995 to 2022, despite its limited connection to the Northwest Pacific through shallow sills (&lt;130 m). This subsurface trend appears to contribute to a 70 % decline in nutrients in the mixed layer (0–50 m) of the eastern EJS. In contrast, complex nutrient trends were observed in the western EJS surface (0–200 m), likely influenced by anthropogenic inputs. The significant nutrient decline in the EJS, which may alter its biological production and carbon cycle, provides further evidence of regional climate regime-shift feedbacks occurring in the North Pacific and other major subtropical gyres.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104135"},"PeriodicalIF":2.5,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145049556","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":"Highly variable bottom water oxygen concentration in the shallow Arkona Basin (Baltic Sea)","authors":"Joachim Kuss ,&nbsp;Ulf Gräwe ,&nbsp;Bronwyn Cahill ,&nbsp;Volker Mohrholz ,&nbsp;Michael Naumann ,&nbsp;Robert Mars ,&nbsp;Siegfried Krüger ,&nbsp;Detlef E. Schulz-Bull ,&nbsp;Joanna J. Waniek","doi":"10.1016/j.jmarsys.2025.104134","DOIUrl":"10.1016/j.jmarsys.2025.104134","url":null,"abstract":"<div><div>Shallow western Baltic Sea waters show seasonal low oxygen concentrations in bottom waters from summer into early autumn. A record of hourly oxygen measured from 2012 to 2017 at a platform in the central Arkona Basin ascertained important developments of distinct short-term variability in bottom water oxygen concentration. Analysis of these years indicated that severe hypoxia of 0–2 mg L⁻¹ occurred in July with a duration between 0 and 10 h, in August between 0 and 61 h and in September again between 0 and 10 h. Using 4 mg L⁻¹ as the threshold, the ranking of the respective years from longest to shortest duration in hypoxic events showed 2012 (982 h) as the worst, followed by 2016 (854 h), 2013 (769 h), 2014 (659 h) and 2015 (351 h). The clear improvement in 2015 was caused by a Major Baltic Inflow that ventilated the system. Interpreting the drivers of short term hypoxia from the <em>in situ</em> measurements alone was difficult, as adequately resolved biogeochemical parameters were not measured. However, coincident three dimensional high resolution coupled hydrographic-biogeochemical modelling, reproduced the oxygen concentrations at the platform, and additionally revealed considerable spatial variability in the oxygen distribution in the area and its causes. Microbial degradation of organic matter in bottom waters was found to be the major oxygen consumption process with nitrification also contributing in some years. Recovery from seasonal periods of hypoxia is linked to the break-up of the seasonal thermocline or is caused by lateral transport of differently preformed oxygenated waters. The study demonstrates the utility of combining high resolution in situ observations with coincident biogeochemical modelling, as a powerful, integrated tool for monitoring and understanding drivers of short-term seasonal hypoxia.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104134"},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144933178","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}