Continental Shelf Research最新文献_第5页

Characterisation of the eddy-driven variability inshore of the Agulhas Current using sea surface temperature observations 利用海面温度观测表征阿古拉斯海流近岸涡旋驱动的变率

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-22 DOI: 10.1016/j.csr.2025.105598

N. Burgher , L. Braby , S. Herbette , JC Hermes , MJ Roberts

Off the east coast of South Africa, coastal waters inshore of the Agulhas Current are largely affected by oceanic mesoscale turbulence, primarily in the form of meanders such as Natal Pulses and Durban Eddies. This study utilises forty years of modern, high-resolution satellite sea surface temperature (SST) data, offering both improved spatial detail and a longer time series than previous products, to characterise these eddies using an automated meander detection algorithm. Notably, automated detection has never before been applied to Durban Eddies, and Natal Pulses have not been analysed using such a high-resolution, long-term SST dataset. The algorithm successfully estimated the daily position of the inshore edge and core of the Agulhas Current and the “first occurrence” of Agulhas waters for the period of the study —the latter defined as the initial emergence of Agulhas Current waters in a filament or plume associated with Natal Pulses. The analysis reveals that the inshore edge of the Agulhas Current is not subject to seasonal variation but is significantly influenced by the presence of Natal Pulses and Durban Eddies. The first occurrence of Agulhas Current waters was only detected during the passage of Natal Pulses. Results indicate increased variability in regions south of 29.8°S, with Natal Pulses showing an increase in size and surface lifespan in the southern region. Conversely, Durban Eddies exhibit a decrease in size and surface lifespan as they propagate southward. Furthermore, seasonal SST anomalies are generally small, with cold events more frequent; Natal Pulses cause higher variability, while Durban Eddies maintain relative stability.

在南非东海岸外，阿古拉斯洋流近岸的沿海水域很大程度上受到海洋中尺度湍流的影响，主要以曲流的形式出现，如纳塔尔脉冲和德班涡流。这项研究利用了四十年的现代高分辨率卫星海面温度（SST）数据，提供了比以前产品更好的空间细节和更长的时间序列，使用自动曲流检测算法来表征这些漩涡。值得注意的是，自动化检测以前从未应用于德班涡旋，而纳塔尔脉冲也没有使用如此高分辨率的长期海温数据集进行分析。该算法成功地估计了阿古拉斯洋流近岸边缘和核心的每日位置，以及研究期间阿古拉斯洋流的“首次出现”——后者被定义为阿古拉斯洋流在与纳塔尔脉冲相关的细丝或羽状物中首次出现。分析表明，阿古拉斯海流的近岸边缘不受季节变化的影响，但受到纳塔尔脉冲和德班涡流的显著影响。阿古拉斯洋流的第一次出现是在纳塔尔脉冲通过期间才发现的。结果表明，29.8°S以南地区的变异性增加，Natal脉冲显示南部地区的大小和表面寿命增加。相反，德班涡旋在向南传播的过程中，其大小和表面寿命都在减少。此外，季节海温异常一般较小，冷事件更频繁；纳塔尔脉冲引起较高的变异性，而德班涡流保持相对稳定。

{"title":"Characterisation of the eddy-driven variability inshore of the Agulhas Current using sea surface temperature observations","authors":"N. Burgher , L. Braby , S. Herbette , JC Hermes , MJ Roberts","doi":"10.1016/j.csr.2025.105598","DOIUrl":"10.1016/j.csr.2025.105598","url":null,"abstract":"<div><div>Off the east coast of South Africa, coastal waters inshore of the Agulhas Current are largely affected by oceanic mesoscale turbulence, primarily in the form of meanders such as Natal Pulses and Durban Eddies. This study utilises forty years of modern, high-resolution satellite sea surface temperature (SST) data, offering both improved spatial detail and a longer time series than previous products, to characterise these eddies using an automated meander detection algorithm. Notably, automated detection has never before been applied to Durban Eddies, and Natal Pulses have not been analysed using such a high-resolution, long-term SST dataset. The algorithm successfully estimated the daily position of the inshore edge and core of the Agulhas Current and the “first occurrence” of Agulhas waters for the period of the study —the latter defined as the initial emergence of Agulhas Current waters in a filament or plume associated with Natal Pulses. The analysis reveals that the inshore edge of the Agulhas Current is not subject to seasonal variation but is significantly influenced by the presence of Natal Pulses and Durban Eddies. The first occurrence of Agulhas Current waters was only detected during the passage of Natal Pulses. Results indicate increased variability in regions south of 29.8°S, with Natal Pulses showing an increase in size and surface lifespan in the southern region. Conversely, Durban Eddies exhibit a decrease in size and surface lifespan as they propagate southward. Furthermore, seasonal SST anomalies are generally small, with cold events more frequent; Natal Pulses cause higher variability, while Durban Eddies maintain relative stability.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105598"},"PeriodicalIF":2.2,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418563","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}

引用次数: 0

Elevated meroplankton abundance in surface slicks during internal wave forcing at three coastal sites in Mexico 在墨西哥三个沿海地点的内波强迫下，浮油表面浮游生物丰度升高

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-22 DOI: 10.1016/j.csr.2025.105599

Lydia B. Ladah , Andrea Lievana Mactavish , María del Refugio Barba López , James J. Leichter , Fabian J. Tapia , Anatoliy Filonov

The supply of meroplanktonic larvae to coastal habitats by physical transport mechanisms is important for the persistence of benthic marine invertebrate populations. Larvae can accumulate in convergent bands that are often visible as smooth surface slicks in areas where surfactants reduce capillary waves. Slicks can form above passing troughs of internal waves, which occur on most coasts during stratified periods. In this study, during periods of strong internal wave forcing under spring tide conditions in three bays along the Mexican coastline, we sampled high-frequency (f ≥ 1 cycle h⁻¹) changes in the abundance of marine meroplankton. Concurrently, we recorded visual observations of surface slicks and measured physical conditions in the water column (i.e., temperature and currents). Surface slicks were observed at all three sites, with over 70% occurring at times theoretically predicted from current flows. The slick periods showed warmer temperatures or lower strain values, suggesting slicks may be associated with warm convergence zones. Chthamaloid cyprids and mussel veligers were the dominant meroplankton found, with their abundance being significantly greater (2–6 times) within slicks at all sites and a significant positive relationship with temperature found at 2 of the 3 sites. These results support the hypothesis that plankton accumulation does occur in visible surface slicks. We propose that the slicks measured in this study were related to internal wave convergence zones, meriting further exploration as important mechanisms of plankton accumulation.

通过物理运输机制向沿海生境提供浮游生物幼虫对底栖海洋无脊椎动物种群的持续存在具有重要意义。幼虫可以聚集在会聚带中，在表面活性剂减少毛细波的区域，通常可以看到光滑的表面。浮油可以在经过的内波槽上方形成，在分层期间，内波槽会出现在大多数海岸。在本研究中，在墨西哥沿海三个海湾的大潮条件下，在强烈的内波强迫期间，我们采样了海洋浮游生物丰度的高频（f≥1周期h−1）变化。同时，我们记录了表面浮油的目视观察，并测量了水柱中的物理条件（即温度和水流）。在所有三个地点都观察到表面浮油，超过70%的浮油发生在理论上预测的水流中。浮油期温度较高或应变值较低，表明浮油可能与暖辐合带有关。Chthamaloid鲷和贻贝鲷是主要的浮游生物，它们的丰度在所有站点的浮油中都显著增加（2 - 6倍），并且在3个站点中有2个站点与温度呈显著正相关。这些结果支持浮游生物聚集确实发生在可见表面浮油的假设。我们认为本研究测量到的浮油与内波辐合带有关，作为浮游生物聚集的重要机制值得进一步探索。

{"title":"Elevated meroplankton abundance in surface slicks during internal wave forcing at three coastal sites in Mexico","authors":"Lydia B. Ladah , Andrea Lievana Mactavish , María del Refugio Barba López , James J. Leichter , Fabian J. Tapia , Anatoliy Filonov","doi":"10.1016/j.csr.2025.105599","DOIUrl":"10.1016/j.csr.2025.105599","url":null,"abstract":"<div><div>The supply of meroplanktonic larvae to coastal habitats by physical transport mechanisms is important for the persistence of benthic marine invertebrate populations. Larvae can accumulate in convergent bands that are often visible as smooth surface slicks in areas where surfactants reduce capillary waves. Slicks can form above passing troughs of internal waves, which occur on most coasts during stratified periods. In this study, during periods of strong internal wave forcing under spring tide conditions in three bays along the Mexican coastline, we sampled high-frequency (f ≥ 1 cycle h<sup>−1</sup>) changes in the abundance of marine meroplankton. Concurrently, we recorded visual observations of surface slicks and measured physical conditions in the water column (i.e., temperature and currents). Surface slicks were observed at all three sites, with over 70% occurring at times theoretically predicted from current flows. The slick periods showed warmer temperatures or lower strain values, suggesting slicks may be associated with warm convergence zones. Chthamaloid cyprids and mussel veligers were the dominant meroplankton found, with their abundance being significantly greater (2–6 times) within slicks at all sites and a significant positive relationship with temperature found at 2 of the 3 sites. These results support the hypothesis that plankton accumulation does occur in visible surface slicks. We propose that the slicks measured in this study were related to internal wave convergence zones, meriting further exploration as important mechanisms of plankton accumulation.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105599"},"PeriodicalIF":2.2,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418561","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}

引用次数: 0

Utilizing community-led citizen science in delineating population structure of an anadromous hilsa shad (Tenualosa ilisha) from Indian coastal shelf 利用社区主导的公民科学，描绘了印度沿海陆架溯河鲑的种群结构

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-21 DOI: 10.1016/j.csr.2025.105595

Kritish De , Arvind Kumar Dwivedi

Community-led citizen science (CCS) involves engaging the public through effective training for low-cost data collection, monitoring, policy development, and the dissemination of scientific information. This research aimed to train local fishers to capture and share images of Indian shad (Tenualosa ilisha) using Smartphones obtained from the coastal shelf of five river mouth systems (RMS) – Narmada, Tapi, Hooghly, Mahanadi, and Godavari. These images were employed to identify T. ilisha specimens and analyze their population structure using geometric morphometric (GM) techniques based on body shape. The GM approach validated the fishers' ability to correctly identify the species with 100 % accuracy. Additionally, variations in the body shape of T. ilisha were noted between the east and west coasts and among RMS on the east coast (Hooghly, Mahanadi, and Godavari), but not among those on the west coast (Narmada and Tapi). The findings of the present study suggest that CCS is promising in effectively contributing to marine and coastal biodiversity monitoring. Nevertheless, challenges such as electricity shortages, poor internet connectivity, limited technological resources, and low voluntary participation in poverty-stricken remote areas may impact CCS programs. These challenges can be addressed through promoting socio-economic development of local communities through remuneration-based CCS and alternative livelihood options. Coordinated efforts among all stakeholders, including environmental managers and policymakers is essential for better utilization of CCS in sustainable marine policies and improving ocean governance.

社区主导的公民科学（CCS）涉及通过低成本数据收集、监测、政策制定和科学信息传播方面的有效培训让公众参与进来。这项研究旨在培训当地渔民使用从五个河口系统（RMS）的海岸架上获得的智能手机捕捉和分享印度鲥鱼（Tenualosa ilisha）的图像，这五个河口系统是纳尔默达、塔皮、胡格利、马哈纳迪和戈达瓦里。利用这些图像对柽柳标本进行鉴定，并利用基于体型的几何形态测量技术对其种群结构进行分析。转基因方法验证了渔民正确识别物种的能力，准确率达到100%。此外，在东西海岸之间以及东海岸的RMS （Hooghly， Mahanadi和Godavari）之间，发现了T. ilisha体型的变化，但在西海岸的RMS （Narmada和Tapi）中没有。本研究的结果表明，CCS有望有效地促进海洋和沿海生物多样性监测。然而，电力短缺、互联网连接不佳、技术资源有限、贫困偏远地区志愿者参与度低等挑战可能会影响CCS项目。这些挑战可以通过以报酬为基础的CCS和替代生计方案促进当地社区的社会经济发展来解决。包括环境管理者和政策制定者在内的所有利益相关者之间的协调努力对于在可持续海洋政策中更好地利用CCS和改善海洋治理至关重要。

{"title":"Utilizing community-led citizen science in delineating population structure of an anadromous hilsa shad (Tenualosa ilisha) from Indian coastal shelf","authors":"Kritish De , Arvind Kumar Dwivedi","doi":"10.1016/j.csr.2025.105595","DOIUrl":"10.1016/j.csr.2025.105595","url":null,"abstract":"<div><div>Community-led citizen science (CCS) involves engaging the public through effective training for low-cost data collection, monitoring, policy development, and the dissemination of scientific information. This research aimed to train local fishers to capture and share images of Indian shad (<em>Tenualosa ilisha</em>) using Smartphones obtained from the coastal shelf of five river mouth systems (RMS) – Narmada, Tapi, Hooghly, Mahanadi, and Godavari. These images were employed to identify <em>T. ilisha</em> specimens and analyze their population structure using geometric morphometric (GM) techniques based on body shape. The GM approach validated the fishers' ability to correctly identify the species with 100 % accuracy. Additionally, variations in the body shape of <em>T. ilisha</em> were noted between the east and west coasts and among RMS on the east coast (Hooghly, Mahanadi, and Godavari), but not among those on the west coast (Narmada and Tapi). The findings of the present study suggest that CCS is promising in effectively contributing to marine and coastal biodiversity monitoring. Nevertheless, challenges such as electricity shortages, poor internet connectivity, limited technological resources, and low voluntary participation in poverty-stricken remote areas may impact CCS programs. These challenges can be addressed through promoting socio-economic development of local communities through remuneration-based CCS and alternative livelihood options. Coordinated efforts among all stakeholders, including environmental managers and policymakers is essential for better utilization of CCS in sustainable marine policies and improving ocean governance.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105595"},"PeriodicalIF":2.2,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364472","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}

引用次数: 0

Impacts of stratified water column on summer phytoplankton community structure and dynamics in the East Sea, Korea 分层水柱对东海夏季浮游植物群落结构和动态的影响

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-20 DOI: 10.1016/j.csr.2025.105592

Bora Lee , Chung Hyeon Lee , Yun-Bae Kim , Chang Hwan Kim , Chan Hong Park , Seung Ho Baek

Summer stratification strongly regulates nutrient availability and phytoplankton productivity in the East Sea. We examined the combined influences of the East Korea Warm Current (EKWC) and stratification intensity on phytoplankton communities in the Ulleung Basin during four consecutive summers (2021–2024). Years of weak EKWC transport (2021, 2023; 0.1–0.3 m s⁻¹) coincided with restricted offshore dispersal of coastal production and lower surface chlorophyll a (Chl. a; mean 0.34 μg L⁻¹). In contrast, strong EKWC years (2022, 2024; 0.5–0.8 m s⁻¹) exhibited enhanced offshore dispersion and higher Chl. a (mean 0.79 μg L⁻¹). Intensified stratification produced sharp vertical gradients in temperature (24–29 °C at 0–30 m vs. 6–13 °C at 50–100 m), salinity (31.8–32.6 vs. 33.9–34.2), and nitrate (≤5 vs. 6–12 μM), and supported the formation of subsurface chlorophyll maxima (SCM) at 13–47 m, where light and residual nutrients intersected. Community composition displayed strong vertical partitioning: pico-phytoplankton dominated nutrient-depleted surface layers (mean 61 % of biomass), while diatoms prevailed in SCM layers (38–70 %). Dinoflagellates, including Katodinium glaucum and Gyrodinium spp., increased under stratified conditions, and cryptophytes became more abundant at depth. Overall, these results demonstrate that EKWC variability controls horizontal transport of phytoplankton biomass, while stratification governs vertical zonation and taxonomic composition. As sea surface warming intensifies summer stratification, these findings provide critical baseline data for ecosystem models predicting future shifts in nutrient cycling, productivity, and food web dynamics in the East Sea.

夏季分层对东海营养物有效性和浮游植物生产力具有重要的调节作用。研究了2021-2024年连续4个夏季，东朝鲜暖流（EKWC）和分层强度对郁陵盆地浮游植物群落的综合影响。弱EKWC输运年份（2021年，2023年；0.1-0.3 m s−1）与沿海植物在近海的有限扩散和较低的地表叶绿素a （Chl）相吻合。一个;平均0.34 μg L−1)。相比之下，强EKWC年份（2022年，2024年；0.5-0.8 m s−1）表现出增强的离岸色散和更高的Chl。a（平均0.79 μg L−1）。强化的分层作用在温度（0-30 m处24-29°C vs. 50-100 m处6-13°C）、盐度（31.8-32.6 vs. 33.9-34.2）和硝酸盐（≤5 vs. 6-12 μM）上产生了明显的垂直梯度，并支持了13-47 m处地表下叶绿素最大值（SCM）的形成，这是光和残留营养物质相交的地方。群落组成表现出较强的垂直分异：微浮游植物在营养枯竭的表层占主导地位（平均占生物量的61%），硅藻在SCM层占主导地位（38 - 70%）。甲藻（包括Katodinium glaucum和Gyrodinium spp）在分层条件下增加，隐生植物在深层变得更加丰富。总体而言，这些结果表明，EKWC变异控制浮游植物生物量的水平运输，而分层控制垂直带和分类组成。随着海面变暖加剧夏季分层，这些发现为预测东海养分循环、生产力和食物网动态的未来变化的生态系统模型提供了关键的基线数据。

{"title":"Impacts of stratified water column on summer phytoplankton community structure and dynamics in the East Sea, Korea","authors":"Bora Lee , Chung Hyeon Lee , Yun-Bae Kim , Chang Hwan Kim , Chan Hong Park , Seung Ho Baek","doi":"10.1016/j.csr.2025.105592","DOIUrl":"10.1016/j.csr.2025.105592","url":null,"abstract":"<div><div>Summer stratification strongly regulates nutrient availability and phytoplankton productivity in the East Sea. We examined the combined influences of the East Korea Warm Current (EKWC) and stratification intensity on phytoplankton communities in the Ulleung Basin during four consecutive summers (2021–2024). Years of weak EKWC transport (2021, 2023; 0.1–0.3 m s<sup>−1</sup>) coincided with restricted offshore dispersal of coastal production and lower surface chlorophyll <em>a</em> (Chl. <em>a</em>; mean 0.34 μg L<sup>−1</sup>). In contrast, strong EKWC years (2022, 2024; 0.5–0.8 m s<sup>−1</sup>) exhibited enhanced offshore dispersion and higher Chl. <em>a</em> (mean 0.79 μg L<sup>−1</sup>). Intensified stratification produced sharp vertical gradients in temperature (24–29 °C at 0–30 m vs. 6–13 °C at 50–100 m), salinity (31.8–32.6 vs. 33.9–34.2), and nitrate (≤5 vs. 6–12 μM), and supported the formation of subsurface chlorophyll maxima (SCM) at 13–47 m, where light and residual nutrients intersected. Community composition displayed strong vertical partitioning: pico-phytoplankton dominated nutrient-depleted surface layers (mean 61 % of biomass), while diatoms prevailed in SCM layers (38–70 %). Dinoflagellates, including <em>Katodinium glaucum</em> and <em>Gyrodinium</em> spp., increased under stratified conditions, and cryptophytes became more abundant at depth. Overall, these results demonstrate that EKWC variability controls horizontal transport of phytoplankton biomass, while stratification governs vertical zonation and taxonomic composition. As sea surface warming intensifies summer stratification, these findings provide critical baseline data for ecosystem models predicting future shifts in nutrient cycling, productivity, and food web dynamics in the East Sea.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105592"},"PeriodicalIF":2.2,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364471","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}

引用次数: 0

Pyritization may archive the influence of Sulfate-AOM and bioturbation activities in marine sulfidic shelf sediments 黄铁矿化可能记录了海洋硫化物陆架沉积物中硫酸盐- aom和生物扰动活动的影响

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-17 DOI: 10.1016/j.csr.2025.105591

Kalyani Sivan , Aninda Mazumdar , Aditya Peketi , A.K. Sudheer , S.P.K. Pillutla , Subhashree Mishra

Organoclastic sulfate reduction and anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SO₄^2--AOM) are key processes regulating organic matter degradation and methane (CH₄) consumption in marine sediments. We analyzed C-S-Fe, Mo, and U geochemistry in a sediment core collected from the shallow, seasonally hypoxic shelf off the West Coast of India (WCI; Eastern Arabian Sea) at 28.5 mbsl to study the past influence of benthic and AOM activity. Porewater profiles showed high hydrogen sulfide (ΣH₂S) concentrations and a shallow sulfate-methane transition zone (SMTZ; 143–303 cmbsf). The molybdenum/Uranium enrichment factor ratio (Mo_EF/U_EF) indicates persistently sulfidic porewaters during sediment deposition, attributed to SO₄^2--AOM. The high-resolution pyrite sulfur isotope (δ³⁴S_CRS) record reveals two sulfidization trends (Trend I and II), characterized by isotopic fluctuations. Depleted δ³⁴S_CRS values may be attributed to early diagenetic Fe-sulfidization under open system conditions at the sediment-water interface involving benthic reworking during normoxia. In contrast, enriched δ³⁴S_CRS values reflect diminished benthic activity under hypoxic conditions and pyrite precipitation from ³⁴S-enriched ΣH₂S diffusing upward from the SMTZ. Furthermore, increasing δ³⁴S_CRS values (Trend II) below 336.5 cm suggest overprinting of early-stage sulfidization by deep burial sulfidization linked to SMTZ deepening. Therefore, the observed δ³⁴S_CRS variability reflects sulfidization resulting from mixing of isotopically distinct pyrite produced under variable benthic activity and vertical CH₄ flux. Although focused on the seasonally hypoxic shelf off WCI, the findings of this study provide broader implications for understanding the coupled influences of bioturbation, CH₄ flux, and redox variability on sulfur cycling and trace-metal enrichment in shelf sediments globally.

有机碎屑硫酸盐还原和甲烷厌氧氧化耦合硫酸盐还原（SO42—AOM）是调节海洋沉积物中有机物降解和甲烷（CH4）消耗的关键过程。我们分析了从印度西海岸（WCI；东阿拉伯海）28.5 mbsl浅层季节性缺氧陆架收集的沉积物岩心中的C-S-Fe， Mo和U的地球化学特征，以研究底栖生物和AOM活动过去的影响。孔隙水剖面显示高硫化氢（ΣH2S）浓度和浅层硫酸盐-甲烷过渡带（SMTZ; 143-303 cmbsf）。钼铀富集因子比（MoEF/UEF）表明沉积物沉积过程中存在持续的硫化物孔隙水，其成因为SO42—AOM。高分辨率黄铁矿硫同位素（δ34SCRS）记录显示了两个趋势（趋势I和趋势II），其特征是同位素波动。δ34SCRS值的下降可能归因于开放体系条件下沉积物-水界面的早期成岩铁硫化作用，其中包括常氧环境下底栖生物的改造。相反，富δ34SCRS值反映了低氧条件下底栖生物活性降低以及富34s ΣH2S从SMTZ向上扩散的黄铁矿沉淀。δ34SCRS值在336.5 cm以下呈上升趋势（趋势II），表明与SMTZ加深有关的深埋硫化作用叠加了早期硫化作用。因此，观测到的δ34SCRS变率反映了在底栖生物活性和垂直CH4通量变化下产生的同位素不同的黄铁矿混合造成的硫化作用。虽然本研究的重点是WCI的季节性缺氧大陆架，但本研究的结果为理解生物扰动、CH4通量和氧化还原变异对全球大陆架沉积物中硫循环和微量金属富集的耦合影响提供了更广泛的意义。

{"title":"Pyritization may archive the influence of Sulfate-AOM and bioturbation activities in marine sulfidic shelf sediments","authors":"Kalyani Sivan , Aninda Mazumdar , Aditya Peketi , A.K. Sudheer , S.P.K. Pillutla , Subhashree Mishra","doi":"10.1016/j.csr.2025.105591","DOIUrl":"10.1016/j.csr.2025.105591","url":null,"abstract":"<div><div>Organoclastic sulfate reduction and anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SO<sub>4</sub><sup>2-</sup>-AOM) are key processes regulating organic matter degradation and methane (CH<sub>4</sub>) consumption in marine sediments. We analyzed C-S-Fe, Mo, and U geochemistry in a sediment core collected from the shallow, seasonally hypoxic shelf off the West Coast of India (WCI; Eastern Arabian Sea) at 28.5 mbsl to study the past influence of benthic and AOM activity. Porewater profiles showed high hydrogen sulfide (ΣH<sub>2</sub>S) concentrations and a shallow sulfate-methane transition zone (SMTZ; 143–303 cmbsf). The molybdenum/Uranium enrichment factor ratio (Mo<sub>EF</sub>/U<sub>EF</sub>) indicates persistently sulfidic porewaters during sediment deposition, attributed to SO<sub>4</sub><sup>2-</sup>-AOM. The high-resolution pyrite sulfur isotope (δ<sup>34</sup>S<sub>CRS</sub>) record reveals two sulfidization trends (Trend I and II), characterized by isotopic fluctuations. Depleted δ<sup>34</sup>S<sub>CRS</sub> values may be attributed to early diagenetic Fe-sulfidization under open system conditions at the sediment-water interface involving benthic reworking during normoxia. In contrast, enriched δ<sup>34</sup>S<sub>CRS</sub> values reflect diminished benthic activity under hypoxic conditions and pyrite precipitation from <sup>34</sup>S-enriched ΣH<sub>2</sub>S diffusing upward from the SMTZ. Furthermore, increasing δ<sup>34</sup>S<sub>CRS</sub> values (Trend II) below 336.5 cm suggest overprinting of early-stage sulfidization by deep burial sulfidization linked to SMTZ deepening. Therefore, the observed δ<sup>34</sup>S<sub>CRS</sub> variability reflects sulfidization resulting from mixing of isotopically distinct pyrite produced under variable benthic activity and vertical CH<sub>4</sub> flux. Although focused on the seasonally hypoxic shelf off WCI, the findings of this study provide broader implications for understanding the coupled influences of bioturbation, CH<sub>4</sub> flux, and redox variability on sulfur cycling and trace-metal enrichment in shelf sediments globally.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105591"},"PeriodicalIF":2.2,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364473","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}

引用次数: 0

Assessing the potential of consumer-grade fish finders to improve coastal habitat mapping in data-poor areas 评估消费级捕鱼器在数据贫乏地区改善沿海生境测绘的潜力

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-11 DOI: 10.1016/j.csr.2025.105590

Pedro T. Gomes , Renato Henriques , Marcos Rubal , Diana Azevedo , Diego Carreira-Flores

Geospatial information is fundamental for understanding marine biodiversity patterns, species distribution, and environmental change. However, traditional methods for obtaining high-resolution bathymetric data are expensive and time-consuming, limiting data availability and creating significant gaps, particularly in coastal zones. This study explores the potential of consumer-grade sonars (fish finders) as cost-effective tools to improve bathymetric maps and support habitat mapping along a coastal area in northern Portugal. We compared bathymetric data collected by consumer-grade devices with publicly available digital elevation models (DEM) from EMODNET and high-resolution, survey-grade multibeam sonar data from the APA COSMO project. Results revealed strong agreement between consumer-grade sonar data and EMODNET DEM, with substantial improvement in local detail and acceptable errors (RMSE and MAE low; Pearson correlation coefficients from 0.957 to 0.963). Comparisons with COSMO DEM also showed good coherence, highlighting a significant increase in detail proportional to sampling density, though still lacking the fine resolution provided by the professional-grade COSMO dataset. Despite inherent limitations in precision and depth range, consumer-grade sonars proved highly valuable, offering practical solutions for low-resource, small-scale projects, environmental monitoring, and ecological habitat mapping. This study supports integrating these affordable devices into marine research workflows, significantly enhancing bathymetric data availability and spatial resolution, especially where detailed professional data are unavailable or economically unfeasible.

地理空间信息是了解海洋生物多样性格局、物种分布和环境变化的基础。然而，获取高分辨率水深数据的传统方法既昂贵又耗时，限制了数据的可用性，并造成了巨大的缺口，特别是在沿海地区。本研究探索了消费级声纳（寻鱼器）作为经济有效的工具的潜力，以改善深度地图和支持沿葡萄牙北部沿海地区的栖息地测绘。我们将消费级设备收集的测深数据与EMODNET的公开数字高程模型（DEM）和APA COSMO项目的高分辨率测量级多波束声纳数据进行了比较。结果显示，消费级声纳数据与EMODNET DEM之间的一致性很强，在局部细节和可接受误差（RMSE和MAE较低；Pearson相关系数从0.957到0.963）方面有很大改善。与COSMO DEM的对比也显示出良好的一致性，显示出与采样密度成正比的细节显著增加，尽管仍然缺乏专业级COSMO数据集提供的精细分辨率。尽管精度和深度范围存在固有的局限性，但消费级声纳被证明是非常有价值的，为低资源、小规模项目、环境监测和生态栖息地测绘提供了实用的解决方案。该研究支持将这些经济实惠的设备集成到海洋研究工作流程中，显著提高了水深数据的可用性和空间分辨率，特别是在没有详细的专业数据或经济上不可行的情况下。

{"title":"Assessing the potential of consumer-grade fish finders to improve coastal habitat mapping in data-poor areas","authors":"Pedro T. Gomes , Renato Henriques , Marcos Rubal , Diana Azevedo , Diego Carreira-Flores","doi":"10.1016/j.csr.2025.105590","DOIUrl":"10.1016/j.csr.2025.105590","url":null,"abstract":"<div><div>Geospatial information is fundamental for understanding marine biodiversity patterns, species distribution, and environmental change. However, traditional methods for obtaining high-resolution bathymetric data are expensive and time-consuming, limiting data availability and creating significant gaps, particularly in coastal zones. This study explores the potential of consumer-grade sonars (fish finders) as cost-effective tools to improve bathymetric maps and support habitat mapping along a coastal area in northern Portugal. We compared bathymetric data collected by consumer-grade devices with publicly available digital elevation models (DEM) from EMODNET and high-resolution, survey-grade multibeam sonar data from the APA COSMO project. Results revealed strong agreement between consumer-grade sonar data and EMODNET DEM, with substantial improvement in local detail and acceptable errors (RMSE and MAE low; Pearson correlation coefficients from 0.957 to 0.963). Comparisons with COSMO DEM also showed good coherence, highlighting a significant increase in detail proportional to sampling density, though still lacking the fine resolution provided by the professional-grade COSMO dataset. Despite inherent limitations in precision and depth range, consumer-grade sonars proved highly valuable, offering practical solutions for low-resource, small-scale projects, environmental monitoring, and ecological habitat mapping. This study supports integrating these affordable devices into marine research workflows, significantly enhancing bathymetric data availability and spatial resolution, especially where detailed professional data are unavailable or economically unfeasible.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105590"},"PeriodicalIF":2.2,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326452","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}

引用次数: 0

Responses of zooplankton (copepods) in the Indian mud bank-upwelling region 印度泥滩上升流区浮游动物（桡足类）的响应

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-10 DOI: 10.1016/j.csr.2025.105576

S. Parthasarathi , R. Jyothibabu , V. Vidhya , L. Jagadeesan , N. Arunpandi , Unnimaya

In 2014 and 2016, the ecology and composition of zooplankton in the Alappuzha mud bank-upwelling area along the southwest (Kerala) coast of India were studied using biweekly sampling from the Pre-Monsoon (PRM) in April to the late Southwest Monsoon (SWM) in September. The zooplankton community was composed of 17 taxa, with copepods accounting for over 70 % of the total abundance. The biomass and abundance increased during both the SWMs of 2014 and 2016, primarily due to an enhancement in phytoplankton caused by nutrient enrichment associated with coastal upwelling. Nonetheless, the 2016 SWM had more suspended sediments and a longer and more severe oxygen deficiency than the 2014 SWM, resulting in lower zooplankton biomass and abundance. Polychaete larvae and gelatinous zooplankton (siphonophores and appendicularians) were also more abundant during the 2016 SWM because of their adaptations to utilise the abundant food while oxygen levels are low. During the PRM, copepods largely consisted of omnivores that effectively used resources in the microbial food web, such as Centropages orsini, C. furcatus, Acartia danae, and A. erythraea. In contrast, the SWM was dominated by copepods such as Temora turbinata, Pseudodiaptomus serricaudatus, and Oithona similis. Due to its ability to survive in low-oxygen settings, O. similis was significantly more prevalent throughout the SWM in both years. Temora turbinata, an indicator species of upwelling, showed higher dominance in the 2016 SWM when oxygen deficiency was more intense and prolonged. Overall, the zooplankton community exhibited the following characteristics: (a) a temporal shift in composition and abundance, (b) dominance of copepods with a preference for the microbial food web during the PRM and hypoxia-adapted ones during the SWM, and (c) a decrease in overall abundance during the 2016 SWM, indicating the negative effects of oxygen deficiency and increased turbidity. Thus, this study establishes a baseline for comparing how zooplankton (copepods) react to different oxygen and turbidity levels in a coastal upwelling mud bank system during alternate SWMs.

2014年和2016年，利用4月季风前（PRM）至9月西南季风后期（SWM）的双周采样，对印度西南（喀拉拉邦）海岸Alappuzha泥滩上升流区浮游动物生态和组成进行了研究。浮游动物群落由17个类群组成，桡足类占总丰度的70%以上。在2014年和2016年的两个SWMs期间，生物量和丰度都有所增加，这主要是由于与沿海上升流相关的营养物富集导致浮游植物的增加。尽管如此，与2014年的SWM相比，2016年SWM的悬浮沉积物更多，缺氧时间更长，缺氧程度更严重，导致浮游动物生物量和丰度降低。在2016年的SWM期间，多毛类幼虫和胶状浮游动物（虹吸管和尾虫）的数量也更多，因为它们适应了在氧气水平较低的情况下利用丰富的食物。在PRM期间，桡足类主要由杂食动物组成，这些杂食动物有效地利用了微生物食物网中的资源，如Centropages orsini、C. furcatus、Acartia danae和A. erythraea。与此相反，SWM以Temora turbinata、Pseudodiaptomus serricaudatus和Oithona similis等桡足类为主。由于其在低氧环境下生存的能力，在这两年中，在整个SWM中，O. similis明显更为普遍。上升流指示种turbinata在2016年SWM中表现出更高的优势度，缺氧程度越高，持续时间越长。总体而言，浮游动物群落表现出以下特征：(a)组成和丰度的时间变化，(b)在PRM期间以微生物食物网为主的桡足类占优势，在SWM期间以低氧适应的桡足类为主，以及(c) 2016年SWM期间总体丰度下降，表明缺氧和浊度增加的负面影响。因此，本研究建立了一个基线，用于比较在交替的SWMs期间，沿海上升流泥滩系统中浮游动物（桡足类）对不同氧气和浊度水平的反应。

{"title":"Responses of zooplankton (copepods) in the Indian mud bank-upwelling region","authors":"S. Parthasarathi , R. Jyothibabu , V. Vidhya , L. Jagadeesan , N. Arunpandi , Unnimaya","doi":"10.1016/j.csr.2025.105576","DOIUrl":"10.1016/j.csr.2025.105576","url":null,"abstract":"<div><div>In 2014 and 2016, the ecology and composition of zooplankton in the Alappuzha mud bank-upwelling area along the southwest (Kerala) coast of India were studied using biweekly sampling from the Pre-Monsoon (PRM) in April to the late Southwest Monsoon (SWM) in September. The zooplankton community was composed of 17 taxa, with copepods accounting for over 70 % of the total abundance. The biomass and abundance increased during both the SWMs of 2014 and 2016, primarily due to an enhancement in phytoplankton caused by nutrient enrichment associated with coastal upwelling. Nonetheless, the 2016 SWM had more suspended sediments and a longer and more severe oxygen deficiency than the 2014 SWM, resulting in lower zooplankton biomass and abundance. Polychaete larvae and gelatinous zooplankton (siphonophores and appendicularians) were also more abundant during the 2016 SWM because of their adaptations to utilise the abundant food while oxygen levels are low. During the PRM, copepods largely consisted of omnivores that effectively used resources in the microbial food web, such as <em>Centropages orsini</em>, <em>C. furcatus</em>, <em>Acartia danae</em>, and <em>A. erythraea</em>. In contrast, the SWM was dominated by copepods such as <em>Temora turbinata</em>, <em>Pseudodiaptomus serricaudatus</em>, and <em>Oithona similis</em>. Due to its ability to survive in low-oxygen settings, <em>O. similis</em> was significantly more prevalent throughout the SWM in both years. <em>Temora turbinata</em>, an indicator species of upwelling, showed higher dominance in the 2016 SWM when oxygen deficiency was more intense and prolonged. Overall, the zooplankton community exhibited the following characteristics: (a) a temporal shift in composition and abundance, (b) dominance of copepods with a preference for the microbial food web during the PRM and hypoxia-adapted ones during the SWM, and (c) a decrease in overall abundance during the 2016 SWM, indicating the negative effects of oxygen deficiency and increased turbidity. Thus, this study establishes a baseline for comparing how zooplankton (copepods) react to different oxygen and turbidity levels in a coastal upwelling mud bank system during alternate SWMs.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105576"},"PeriodicalIF":2.2,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326453","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}

引用次数: 0

Detection and temporal variation of the thermal front system in the Midriff Archipelago Region of the Gulf of California 加利福尼亚湾米德里夫群岛地区热锋系统的探测和时间变化

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-08 DOI: 10.1016/j.csr.2025.105581

Amelia Sánchez-Pérez , Leonardo Tenorio-Fernández , Emmanuel Romero , Jorge Montes-Aréchiga , Laura Sánchez-Velasco

Based on 20 years of remote-sensing sea surface temperature (SST) data (2004–2023), the temporal persistence of thermal fronts in the Midriff Archipelago Region (MAR), was analyzed. Using the Front Probability Index and wavelet analysis, six main areas of thermal front formation were identified, along with their oscillation periods. The potential relationship between wind and the formation of thermal fronts was also examined using squared wavelet coherence analysis. The thermal front system exhibited significant seasonal variations in terms of formation, location, and intensity. Most intense fronts were formed in specific areas near both coasts, particularly during spring and summer. Most of the year, fronts in five of the six front-forming areas studied were oriented parallel to the axis of the Gulf of California, while in the remaining area they were predominantly transverse to the Gulf of California axis, mainly during winter. The primary periods of variation for thermal fronts were identified as annual and semiannual. This seasonal pattern ensures the constant presence of fronts in the MAR, highlighting the complexity and dynamics of the system. The formation of fronts is attributed to the interaction of various favorable conditions. The results revealed a high coherence between winds and SST gradients. Southerly winds, which prevail during spring and summer, enhanced the formation and distribution of thermal fronts in the western region while reducing them in the east, whereas northerly winds, dominant in fall and winter, had the opposite effect, reducing fronts in the west and intensifying them in the east. Consequently, this study provides a robust foundation for understanding the temporal and spatial variability of thermal front formation in the MAR, serving as a basis for future research on their potential and their impacts on local marine ecosystems.

利用2004-2023年20 a海表温度（SST）数据，分析了米德里夫群岛地区（MAR）热锋的时间持续性。利用锋面概率指数和小波分析，确定了热锋形成的6个主要区域及其振荡周期。利用平方小波相干分析分析了风与热锋形成的潜在关系。热锋系统在形成、位置和强度上均表现出明显的季节变化。最强烈的锋面形成于靠近两岸的特定区域，特别是在春季和夏季。在研究的6个锋面形成区中，有5个锋面在一年的大部分时间里平行于加利福尼亚湾轴线，而在其余地区，锋面主要在冬季横向于加利福尼亚湾轴线。热锋的主要变化周期为一年一次和半年一次。这种季节性模式确保了MAR中锋面的持续存在，突出了系统的复杂性和动态性。锋面的形成是各种有利条件相互作用的结果。结果表明，风和海温梯度之间具有高度的一致性。春夏季盛行的南风增强了西部热锋的形成和分布，东部热锋减弱，秋冬季盛行的北风则相反，西部热锋减弱，东部热锋增强。因此，本研究为了解MAR热锋形成的时空变异性提供了坚实的基础，为进一步研究其潜力及其对当地海洋生态系统的影响奠定了基础。

{"title":"Detection and temporal variation of the thermal front system in the Midriff Archipelago Region of the Gulf of California","authors":"Amelia Sánchez-Pérez , Leonardo Tenorio-Fernández , Emmanuel Romero , Jorge Montes-Aréchiga , Laura Sánchez-Velasco","doi":"10.1016/j.csr.2025.105581","DOIUrl":"10.1016/j.csr.2025.105581","url":null,"abstract":"<div><div>Based on 20 years of remote-sensing sea surface temperature (SST) data (2004–2023), the temporal persistence of thermal fronts in the Midriff Archipelago Region (MAR), was analyzed. Using the Front Probability Index and wavelet analysis, six main areas of thermal front formation were identified, along with their oscillation periods. The potential relationship between wind and the formation of thermal fronts was also examined using squared wavelet coherence analysis. The thermal front system exhibited significant seasonal variations in terms of formation, location, and intensity. Most intense fronts were formed in specific areas near both coasts, particularly during spring and summer. Most of the year, fronts in five of the six front-forming areas studied were oriented parallel to the axis of the Gulf of California, while in the remaining area they were predominantly transverse to the Gulf of California axis, mainly during winter. The primary periods of variation for thermal fronts were identified as annual and semiannual. This seasonal pattern ensures the constant presence of fronts in the MAR, highlighting the complexity and dynamics of the system. The formation of fronts is attributed to the interaction of various favorable conditions. The results revealed a high coherence between winds and SST gradients. Southerly winds, which prevail during spring and summer, enhanced the formation and distribution of thermal fronts in the western region while reducing them in the east, whereas northerly winds, dominant in fall and winter, had the opposite effect, reducing fronts in the west and intensifying them in the east. Consequently, this study provides a robust foundation for understanding the temporal and spatial variability of thermal front formation in the MAR, serving as a basis for future research on their potential and their impacts on local marine ecosystems.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105581"},"PeriodicalIF":2.2,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145271310","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}

引用次数: 0

Lithological and geochemical differentiations in an urbanized, shallow marine cold-seep environment. The case of Patras Gulf active pockmark field 城市化、浅海冷渗环境的岩性地球化学分异。以帕特拉斯湾为例

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-08 DOI: 10.1016/j.csr.2025.105583

Spyros Sergiou, Dimitra Ntrouva, Maria Geraga, Dimitris Christodoulou, George Papatheodorou

The Patras Gulf Pockmark Field (PGPF), located in a shallow, tectonically active marine basin in western Greece, offers a unique setting for studying lithological and geochemical variability in an urban-influenced cold-seep environment. Here we examine nine short sediment cores (∼30 cm) collected from both within pockmarks and the surrounding seafloor to assess sediment texture, elemental composition, and anthropogenic impacts. We find that pockmark sediments are finer-grained, better-sorted, less bioclastic, more organic-rich, and higher in trace metals loads compared to the surrounding seafloor. The sedimentary, geochemical, and hydrodynamic processes within the pockmarks follow the pockmark morphology; the larger the pockmark is, the more terrigenous, fine-grained, and metal-enriched the sediment is, and less oxygenation characterizes the bottom waters. Multivariate factor analysis identified five dominant geochemical processes. Factors 1 and 2, prevailing outside the pockmarks, reflect clay–metal sorption processes and the anticorrelation between bioclastic material and fine-grained terrigenous inputs. Within pockmarks, Factor 3 indicates anthropogenic sources of Ag, Hg, and Zn through organic carbon–metal sequestration, especially in the southern sector of PGPF, influenced by Glafkos River discharges. Factor 4 reflects localized contamination by Zr, Ta, and Nb, while Factor 5 captures sulfidic, low-oxygen conditions linked to redox dynamics. Despite documented fluid escape activity, no clear imprints of active seepage were observed in the studied pockmark sediments. These findings emphasize the dual control of geomorphology and anthropogenic forcing on geochemical processes in shallow marine cold-seep environments, with implications for trace metal mobility, sediment trapping efficiency, and environmental monitoring in similar settings.

Patras Gulf Pockmark Field （PGPF）位于希腊西部一个浅层、构造活跃的海相盆地，为研究城市影响的冷渗环境中的岩性和地球化学变化提供了独特的环境。在这里，我们研究了从麻坑和周围海底收集的9个短沉积物岩心（~ 30厘米），以评估沉积物的质地、元素组成和人为影响。我们发现，与周围的海底相比，麻子沉积物颗粒更细，分选更好，生物碎屑更少，有机物含量更高，微量金属含量更高。麻坑内的沉积、地球化学和水动力过程遵循麻坑的形态；麻坑越大，沉积物的陆源性越强，颗粒越细，金属含量越高，底部水体的氧合作用越少。多因素分析确定了5个主要的地球化学过程。因子1和因子2在麻坑外普遍存在，反映了粘土-金属的吸附过程以及生物碎屑物质与细粒陆源输入物之间的反相关性。在麻坑内，因子3表明银、汞和锌的人为来源是通过有机碳金属固存，特别是在PGPF南段，受Glafkos河排放的影响。因子4反映了Zr、Ta和Nb的局部污染，而因子5捕获了与氧化还原动力学相关的硫化物、低氧条件。尽管记录了流体逸出活动，但在研究的麻坑沉积物中没有观察到明显的活动渗流痕迹。这些发现强调了在浅海冷渗环境中，地貌和人为强迫对地球化学过程的双重控制，对类似环境下的微量金属流动性、沉积物捕获效率和环境监测具有重要意义。

{"title":"Lithological and geochemical differentiations in an urbanized, shallow marine cold-seep environment. The case of Patras Gulf active pockmark field","authors":"Spyros Sergiou, Dimitra Ntrouva, Maria Geraga, Dimitris Christodoulou, George Papatheodorou","doi":"10.1016/j.csr.2025.105583","DOIUrl":"10.1016/j.csr.2025.105583","url":null,"abstract":"<div><div>The Patras Gulf Pockmark Field (PGPF), located in a shallow, tectonically active marine basin in western Greece, offers a unique setting for studying lithological and geochemical variability in an urban-influenced cold-seep environment. Here we examine nine short sediment cores (∼30 cm) collected from both within pockmarks and the surrounding seafloor to assess sediment texture, elemental composition, and anthropogenic impacts. We find that pockmark sediments are finer-grained, better-sorted, less bioclastic, more organic-rich, and higher in trace metals loads compared to the surrounding seafloor. The sedimentary, geochemical, and hydrodynamic processes within the pockmarks follow the pockmark morphology; the larger the pockmark is, the more terrigenous, fine-grained, and metal-enriched the sediment is, and less oxygenation characterizes the bottom waters. Multivariate factor analysis identified five dominant geochemical processes. Factors 1 and 2, prevailing outside the pockmarks, reflect clay–metal sorption processes and the anticorrelation between bioclastic material and fine-grained terrigenous inputs. Within pockmarks, Factor 3 indicates anthropogenic sources of Ag, Hg, and Zn through organic carbon–metal sequestration, especially in the southern sector of PGPF, influenced by Glafkos River discharges. Factor 4 reflects localized contamination by Zr, Ta, and Nb, while Factor 5 captures sulfidic, low-oxygen conditions linked to redox dynamics. Despite documented fluid escape activity, no clear imprints of active seepage were observed in the studied pockmark sediments. These findings emphasize the dual control of geomorphology and anthropogenic forcing on geochemical processes in shallow marine cold-seep environments, with implications for trace metal mobility, sediment trapping efficiency, and environmental monitoring in similar settings.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105583"},"PeriodicalIF":2.2,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145247906","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}

引用次数: 0

Anomalously warm conditions decrease microphytoplankton abundance in Alfonso Basin, Southwest Gulf of California 异常温暖的环境减少了加利福尼亚湾西南部阿方索盆地的浮游微植物丰度

IF 2.2 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2025-10-06 DOI: 10.1016/j.csr.2025.105582

Juan David Acevedo-Acosta , Rafael Cervantes-Duarte , Eduardo González-Rodríguez , Jaime Gómez-Gutiérrez

Global warming is significantly impacting coastal ecosystems, modifying the composition and abundance of microphytoplankton species assemblages. This study investigated the effects of prolonged anomalously warm conditions, particularly during El Niño events, on environmental conditions and net primary productivity (NPP) in Alfonso Basin, Southwest Gulf of California. We combined an in situ monthly time series of biogeochemical variables collected from 2022 to 2023 with 2003–2023 monthly satellite-derived data to identify the well-known seasonal pattern with a higher dinoflagellates/diatoms proportion in the summer and autumn and a lower dinoflagellate/diatom proportion in winter and spring. However, it remains unclear how this ratio has shifted under prolonged interannual anomalously warm conditions. Satellite 2003–2023 sea surface temperatures (SST) increased in an inverse relationship with mixed layer depth (MLD) and NPP, particularly from 2014 to 2023, when predominated SST positive anomalies. These changes were associated with decreased northwesterly winds, enhanced water column stratification, and the early influx of tropical seawater mass, all of which were driven by the transition from La Niña to El Niño event that occurred between June and December 2023. This interannual “tropicalization” phenomenon overall decreased microphytoplankton abundance and a shift in community composition increasing dinoflagellate/diatom ratio. We concluded that the interannual and decadal climate variability strongly modulate the dinoflagellate/diatom ratio dynamics. Anomalous warming events, such as those associated with El Niño and marine heat waves drive multi-year hydrological changes in the subtropical Alfonso Basin, resulting in an elevated dinoflagellate/diatom ratio under conditions of anomalous warm temperatures, increased stratification, and prevailing oligotrophic epipelagic conditions.

全球变暖对沿海生态系统产生了重大影响，改变了微型浮游植物物种组合的组成和丰度。本文研究了Alfonso盆地环境条件和净初级生产力（NPP）的长期异常温暖条件的影响，特别是在El Niño事件期间。我们将2022 - 2023年的生物地球化学变量月度时间序列与2003-2023年的月度卫星数据相结合，确定了众所周知的夏季和秋季甲藻/硅藻比例较高，冬季和春季甲藻/硅藻比例较低的季节模式。然而，在长时间的年际异常温暖条件下，这一比例如何变化仍不清楚。卫星2003-2023年海表温度（SST）与混合层深度（MLD）和NPP呈负相关，特别是2014 - 2023年海表温度以正异常为主。这些变化与西北风减少、水柱分层增强和热带海水团早期涌入有关，这些变化都与发生在2023年6 - 12月La Niña到El Niño事件的转变有关。这种年际“热带化”现象总体上降低了浮游微植物的丰度，群落组成的变化增加了鞭毛藻/硅藻的比例。年际和年代际气候变率对鞭毛藻/硅藻比动态具有强烈的调节作用。异常变暖事件（如与El Niño和海洋热浪相关的事件）驱动亚热带Alfonso盆地的多年水文变化，导致在异常温暖的温度条件下甲藻/硅藻比例升高，分层增加，以及普遍的少营养上层环境。

{"title":"Anomalously warm conditions decrease microphytoplankton abundance in Alfonso Basin, Southwest Gulf of California","authors":"Juan David Acevedo-Acosta , Rafael Cervantes-Duarte , Eduardo González-Rodríguez , Jaime Gómez-Gutiérrez","doi":"10.1016/j.csr.2025.105582","DOIUrl":"10.1016/j.csr.2025.105582","url":null,"abstract":"<div><div>Global warming is significantly impacting coastal ecosystems, modifying the composition and abundance of microphytoplankton species assemblages. This study investigated the effects of prolonged anomalously warm conditions, particularly during El Niño events, on environmental conditions and net primary productivity (NPP) in Alfonso Basin, Southwest Gulf of California. We combined an <em>in situ</em> monthly time series of biogeochemical variables collected from 2022 to 2023 with 2003–2023 monthly satellite-derived data to identify the well-known seasonal pattern with a higher dinoflagellates/diatoms proportion in the summer and autumn and a lower dinoflagellate/diatom proportion in winter and spring. However, it remains unclear how this ratio has shifted under prolonged interannual anomalously warm conditions. Satellite 2003–2023 sea surface temperatures (SST) increased in an inverse relationship with mixed layer depth (MLD) and NPP, particularly from 2014 to 2023, when predominated SST positive anomalies. These changes were associated with decreased northwesterly winds, enhanced water column stratification, and the early influx of tropical seawater mass, all of which were driven by the transition from La Niña to El Niño event that occurred between June and December 2023. This interannual “tropicalization” phenomenon overall decreased microphytoplankton abundance and a shift in community composition increasing dinoflagellate/diatom ratio. We concluded that the interannual and decadal climate variability strongly modulate the dinoflagellate/diatom ratio dynamics. Anomalous warming events, such as those associated with El Niño and marine heat waves drive multi-year hydrological changes in the subtropical Alfonso Basin, resulting in an elevated dinoflagellate/diatom ratio under conditions of anomalous warm temperatures, increased stratification, and prevailing oligotrophic epipelagic conditions.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105582"},"PeriodicalIF":2.2,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326451","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}

引用次数: 0