Journal of Marine Systems最新文献

{"title":"A warmer climate and an increased Yellow River runoff weakened the barrier effect of ocean fronts on the transport of terrestrial suspended sediment and nutrients in the Chinese Bohai Sea","authors":"Yan Liu ,&nbsp;Guangtong Yang ,&nbsp;Xiaoyue Fu ,&nbsp;Guanghao Li ,&nbsp;Liangkun Nie ,&nbsp;Buli Cui ,&nbsp;Xiang Yu ,&nbsp;Chao Zhan ,&nbsp;Longsheng Wang","doi":"10.1016/j.jmarsys.2025.104125","DOIUrl":"10.1016/j.jmarsys.2025.104125","url":null,"abstract":"<div><div>The barrier effect of ocean fronts (OFs) was generally acknowledged but rarely quantified. This study aimed to quantify this barrier effect in the Chinese Bohai Sea under climate changes. Firstly, with the help of GOCI-based remotely sensed retrieval and ancillary data products, we verified this barrier effect based on the contrast of contribution rate of different hydrodynamic factors (temperature, salinity, precipitation, runoff and wind speed) on suspended sediment concentration (SSC) and fluorescence line height (FLH). Secondly, sliding window threshold algorithm (SWTA) was used to obtain the areas of OFs, suspended sediment fronts (SSFs), and fluorescence fronts (FFs) from 2011 to 2020. Thirdly, we obtained outer boundaries of OFs based on morphological opening filter, and to generate closed areas involving coastline. At last, SSC and FLH in the whole Bohai Sea were divided into three categories: high-value, transition, and low-value. Percentages of three categories involved in the closed areas were further used to quantify the barrier effect. The results showed that the barrier effect was weakened due to: 1) the area of OFs decreased by 3.17 × 10³ km², while that of FFs increased by 9.67 × 10³ km²; 2) centroid of SSFs moved away from the Yellow River estuary, while that of FFs moved offshore; 3) percentages of transition, and low-value categories of SSC and FLH involved in the closed areas increased (41.45 %, 37.58 %). The warmer SST and the increased Yellow River runoff jointly led to the weakened barrier effect of OFs in the Chinese Bohai sea from 2011 to 2020.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104125"},"PeriodicalIF":2.5,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144921424","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":"Nutrient variability drivers in shallow coastal waters of the Eastern Arabian Sea during winter monsoon with implications for coastal productivity","authors":"Harikrishna Prasad Mamidala,&nbsp;D. Ganguly,&nbsp;R. Purvaja,&nbsp;R.S. Robin,&nbsp;G. Hariharan,&nbsp;Subbareddy Bonthu,&nbsp;R. Ramesh","doi":"10.1016/j.jmarsys.2025.104124","DOIUrl":"10.1016/j.jmarsys.2025.104124","url":null,"abstract":"<div><div>The Eastern Arabian Sea (EAS) exhibits complex nutrient variability driven by seasonal monsoon dynamics and hydrographic processes. This study investigates the spatial distribution of dissolved inorganic nutrients (DIN, DIP, and DSi), hydrographic conditions, and primary productivity in shallow coastal waters of this region during the winter monsoon of 2019. Our findings reveal regional contrasts, with the North-Eastern Arabian Sea (NEAS) experiencing cooler, nutrient-enriched waters due to convective mixing, supporting higher chlorophyll biomass, whereas the South-Eastern Arabian Sea (SEAS) remains warmer with limited nutrient flux. The coexistence of nutrient maxima and temperature minima in the surface coastal waters of north-eastern region further supports the efficient transport of cooler, nutrient-rich waters to the surface. Nutrient stoichiometry indicates nitrogen limitation in the SEAS and silicate-fuelled productivity in the NEAS. Chlorophyll-a (Chl-<em>a</em>) concentrations were significantly higher in the north-eastern region, reflecting enhanced surface productivity. Dissolved inorganic carbon (DIC) and partial pressure of CO₂ (pCO₂) analyses highlight the supersaturated state of CO₂ in this region, likely driven by convective overturning. Principal component analysis underscores the critical role of temperature, salinity, and mixing in shaping nutrient dynamics and carbon flux. These findings emphasize the need for sustained observation to predict the ecosystem's response to climatic variability and anthropogenic influences, making this study a valuable reference for understanding coastal productivity in monsoon-driven systems.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"252 ","pages":"Article 104124"},"PeriodicalIF":2.5,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144926790","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":"Nutritional characteristics reveal the biological instincts of three species of shellfish and provide dietary preferences for consumers","authors":"Quanquan Li ,&nbsp;Jinxia Wu ,&nbsp;Jie Lu ,&nbsp;Yajie Chang ,&nbsp;Liubin Feng ,&nbsp;Guiping Shen ,&nbsp;Jianghua Feng","doi":"10.1016/j.jmarsys.2025.104123","DOIUrl":"10.1016/j.jmarsys.2025.104123","url":null,"abstract":"<div><div>Shellfish is one of the most important global marine food supply. In this study, quantitative nuclear magnetic resonance (q-NMR) technique was applied to analyze and compare the nutritional compositions and flavor profiles of three species of shellfish, abalone, oyster and scallop, and correlation and metabolic pathways analyses were used to reveal the possible mechanisms affecting their biological nature. Our results indicate that oysters demonstrate the highest nutritional values and pleasant umami and sweet flavors. The difference of choline metabolism in abalone reflect the essential difference of abalone as gastropod. As the shellfish with the lowest salinity preference, glycine in oyster is more involved in the metabolism of taurine and hypotaurine. The lack of obvious aggregation in correlation analysis of scallops may be due to the nature of subtidal organisms. Our results can help to better guide consumers and provide new insights into the biological nature and functions of shellfish.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104123"},"PeriodicalIF":2.5,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144906920","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":"Spatio-temporal variability in medusa biomass linked to oceanographic conditions in a productive shelf ecosystem of the Southwestern Atlantic","authors":"L.M. Chiaverano ,&nbsp;L. Sobrero ,&nbsp;C. Dato ,&nbsp;A. Schiariti","doi":"10.1016/j.jmarsys.2025.104122","DOIUrl":"10.1016/j.jmarsys.2025.104122","url":null,"abstract":"<div><div>This study presents the first large-scale, long-term ecological assessment of a large pelagic cnidarian (<em>Aequorea forskalea</em>) within a highly productive and economically significant marine area of the Southwestern Atlantic. Using nearly three decades of summer fishery survey data (1995–2024), we evaluated the spatial and temporal variability of <em>Aequorea</em> biomass and its relationship with oceanographic conditions. Biomass distribution was spatially structured, concentrating in the San Jorge Gulf, a temporally persistent hotspot of biomass. A major shift in biomass occurred in 2011, marking a transition from a high-biomass phase (1995–2010) to a period of low biomass (2011–2024), coinciding with rising bottom temperatures and decreasing salinity in hotspot areas. Given the spatio-temporal overlap with early life stages of key fisheries species (Argentine hake and Patagonian red shrimp), <em>Aequorea</em> may influence recruitment dynamics through predation and competition. These findings underscore the importance of integrating biological and physical data to understand gelatinous zooplankton dynamics. Long-term fisheries surveys are shown to be valuable sources of baseline data, essential for predicting ecosystem responses to environmental change.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104122"},"PeriodicalIF":2.5,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144892007","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":"Nutrient uptake over Koko Seamount, North Pacific","authors":"Yury Zuenko,&nbsp;Anna Kurnosova","doi":"10.1016/j.jmarsys.2025.104121","DOIUrl":"10.1016/j.jmarsys.2025.104121","url":null,"abstract":"<div><div>Water temperature and salinity profiles were measured on April 9–10, 2019 above the summit of Koko Seamount (35^o15’ N 171^o35’ E, with minimal depth of 260 m) and at the slope, with water sampling to measure nutrients concentration, namely dissolved inorganic phosphorus (DIP) and nitrite and nitrate summed as dissolved inorganic nitrogen (DIN). Both DIP and DIN decreased from depth to sea surface proportionally to salinity increasing, with some deviations from this inverse relationship, which were interpreted as the nutrient uptake for the synthesis of new organic matter. These deviations were mostly minor, apparently due to weak density stratification that prevented active phytoplankton growth, but increased up to 0.21 μmol/L for phosphorus and 4.8 μmol/L for nitrogen at 100 m depth above the southern slope and to 0.13 μmol/L and 1.7 μmol/L, respectively, at the summit of seamount. In the first case, the uptake was presumably caused by photosynthesis in the upward flow that transferred nutrient-rich water into the photic layer and simultaneously retained phytoplankton cells in this layer. In the second case, the nutrients were consumed by phytoplankton which were sunk to the lower part of the thick mixed layer but still had sufficient light for photosynthesis at the top of the seamount. The arrangement and characteristics of these productive areas do not contradict to the Taylor column hypothesis that a stream induces an anticyclonic eddy over a seamount with downward flow in the centre and compensating upward flows at the periphery, although such water structure is not observed in the fields of temperature and salinity, possibly because of strong vertical mixing. The N:P ratio in utilized nutrients was inclined to greater nitrogen uptake in the first case and greater phosphorus uptake in the second case, relative to the Redfield ratio. As a result, the DIN:DIP ratio in water decreased above the southern slope and increased above the eastern slope located near the summit, downstream of the Kuroshio Extension. These results approve the thesis on heightened bioproductivity of seamounts and explain one of its possible mechanism.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104121"},"PeriodicalIF":2.5,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903807","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":"Response of estuary ecosystem to El Niño event: A case study in the Yangtze River Estuary","authors":"Wen Wang ,&nbsp;Gan Chen ,&nbsp;Rongrong Zhao ,&nbsp;Chunxia Gao ,&nbsp;Jianhui Wu ,&nbsp;Dongyan Han","doi":"10.1016/j.jmarsys.2025.104120","DOIUrl":"10.1016/j.jmarsys.2025.104120","url":null,"abstract":"<div><div>The knowledge of how the Yangtze River Estuary (YRE) ecosystem responds to and adapts to the El Niño events is limited but cannot be ignored. Based on the fishery survey data in the YRE in 2013, 2015, and 2017, we constructed and compared three Ecopath models representing three different periods: before, during, and after El Niño event. Results showed that the YRE ecosystem underwent significant change after the occurrence of El Niño. Biomass of phytoplankton and zooplankton increased substantially during the El Niño period, while the biomass of most fish groups and shrimp decreased. During the El Niño period, the YRE ecosystem exhibited low mean trophic levels and low energy transfer efficiency; some ecological network measurements (TPP/TR, TPP/TB, FCI) indicated a more fragile and highly disturbed ecosystem. After the EI Niño event, most of these changes recovered to varying degrees, with species in grazing food chain recovering faster than in detrital based food chain. The variations from 2013 to 2017 reflected the complex impact mechanism of EI Niño on the ecosystem, as well as its resilience after climate disturbance. This study enhances our understanding of how estuarine ecosystems respond to climate events, and may serve as a reference for the development of adaptive management strategies under climate change.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104120"},"PeriodicalIF":2.5,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896027","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":"Unveiling the mesophotic South Atlantic reef system (SARS): Mapping, evolution, and implications for Marine Spatial Planning (MSP) in the Western South Atlantic","authors":"João Regis dos Santos Filho ,&nbsp;Gilberto Tavares de Macedo Dias ,&nbsp;Alberto Garcia Figueiredo Jr. ,&nbsp;Juliane Castro Carneiro ,&nbsp;Cleverson Guizan Silva ,&nbsp;Marcelo Sperle Dias ,&nbsp;Alex Cardoso Bastos","doi":"10.1016/j.jmarsys.2025.104119","DOIUrl":"10.1016/j.jmarsys.2025.104119","url":null,"abstract":"<div><div>Despite the global efforts to recognize the seabed, large-scale mesophotic bioconstructions, the western South Atlantic remains outdated. Utilizing the Geographic Information System (GIS) for reprocessing existing datasets, it was possible to bridge this gap and enable the improvement of Marine Spatial Planning (MSP) in poorly mapped areas. This study presents an unprecedented reanalysis of multidisciplinary public datasets, encompassing information on seabed samples, seabed video inspections, interpretations of the collected data, and dating efforts using GIS and statistical approaches. Results revealed a direct correlation between high carbonate content and gravel, and the visual inspection highlighted the presence of mesophotic reefs, confirming the existence of the mesophotic South Atlantic Reef System (SARS). The most prominent bioengineers were crustose calcareous algae (CCA), rhodoliths (coalescent and free-living form), sponges, corals, and Halimeda. There is a direct relationship between reef age, depth and distance to the coast and an inverse relationship between age and latitude. Countries bordering the SARS should incorporate this unique and fragile seabed feature into their MSP governance, helping strike a balance between conservation and economic growth.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104119"},"PeriodicalIF":2.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879872","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":"Prediction of Arctic kelp forest occurrence using Extreme Gradient Boosting","authors":"Klaudia Kosek ,&nbsp;Wojciech Artichowicz ,&nbsp;Piotr Balazy ,&nbsp;Bernabé Moreno ,&nbsp;Maciej Chełchowski ,&nbsp;Piotr Kukliński","doi":"10.1016/j.jmarsys.2025.104118","DOIUrl":"10.1016/j.jmarsys.2025.104118","url":null,"abstract":"<div><div>Kelp forests are one of the most productive marine habitats of the world that provide number of valuable ecosystem services for diverse range of species. Understanding the physicochemical factors influencing kelp forest occurrence is vital for comprehending its ecosystems' dynamics. That seems especially important in Arctic environments which are strongly influenced by climate change. Therefore, a high-Arctic fjord (Isfjorden), was selected as a model system to investigate the influential parameters for kelp forest occurrence using a binary classification model - Extreme Gradient Boosting (XGBoost). For this purpose, a set of physicochemical parameters, including water masses flow velocity, electrical conductivity (EC), pH, oxygen, light intensity and temperature, were measured at various depths and locations within kelp forest sites and areas without them. Analyses have shown the possibility of effectively predicting kelp forest occurrence using machine learning based on the measured values of the physicochemical parameters. Additionally, the feature importance analysis of the developed XGBoost model revealed the significance of each parameter in the kelp forest occurrence prediction. The created model demonstrated exceptional predictive performance, accurately distinguishing between kelp forest-associated and kelp forest-barren sites with an AUC (Area Under the Curve) of 0.999. This study serves as a foundation for further research on kelp ecosystems worldwide, emphasizing the significance of employing mathematical modeling approaches to unravel the factors governing kelp forest distribution and growth.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104118"},"PeriodicalIF":2.5,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860647","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 variability of hydrodynamics, sediment dynamics and morphological features at a non-tidal river delta coast","authors":"Cihan Sahin,&nbsp;H. Anil Ari Guner,&nbsp;Mehmet Ozturk,&nbsp;Yalcin Yuksel,&nbsp;Kerem Guner","doi":"10.1016/j.jmarsys.2025.104116","DOIUrl":"10.1016/j.jmarsys.2025.104116","url":null,"abstract":"<div><div>The evolution of a deltaic coastline is affected by the interaction between the river flow and sediment supply, and the distribution of sediments by waves and tidal currents. The purpose of this study is to investigate the hydro-sedimentary processes in a vulnerable non-tidal river delta coast on a seasonal and decadal timescale. The Sakarya River delta coast locally experiences significant coastal retreat related to the energetic wave climate and anthropogenic factors, e.g., decrease of sediment discharge to the coast due to large volume reservoirs along river stream, construction of coastal structures accelerating coastal erosion, and regular dredging activities. Seasonal variability in hydrodynamics and sediment dynamics was investigated using three shipboard surveys (in February, July, and November 2019) conducted in the vicinity of the Sakarya River region of influence, covering different meteorological and hydrological conditions, and therefore allowing for observations under different forcing conditions. The field observations include vertical profiles of salinity, turbidity and temperature, collection of water and bottom sediment samples, and river cross-sectional measurements. The long-term variability of the coastline was analyzed using satellite images and the LITLINE numerical model based on a one-line theory, which was calibrated using satellite data. The field measurements indicate strong seasonal variability in hydrodynamics and sediment dynamics. In winter, freshwater extends offshore for <span><math><mo>∼</mo></math></span>1.5 km from the river mouth with SSC values exceeding 0.16 g/L. High bottom shear stresses induced by strong currents cause the erosion of the river bed, increasing the river depth. In the low-flow seasons, the impact distance of the river flow decreased to <span><math><mo>∼</mo></math></span>1 km and the amount of sediment carried by the river dropped to one-third of the value in winter. The river’s carrying capacity decreases due to reduced river discharge by 75 to 80% compared to winter; therefore, fine material in suspension settles and depth decreases. The deposition of the sediments supplied by the river and the distribution of sediments by waves from west to east result in the accumulation of sand in the river mouth that leads to a decrease in the width of the river mouth from about 100 m (in February) to 20 m (in November). The LITLINE numerical model that was run between 1980 and 2019 indicates a yearly average accretion of +4.2 m at the west of the river mouth, supporting the field observations. Unlike the field observations and numerical model results, the satellite images indicate significant erosion of around -280 m at the west of the mouth of the Sakarya River between 1980-2015. The results reveal that regular dredging operations conducted at the river mouth play an important role in the erosion at the west of the mouth.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"251 ","pages":"Article 104116"},"PeriodicalIF":2.5,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841447","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 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}