Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2025.103414
Ippei Urabe , Kohei Matsuno , Rikuto Sugioka , Ryan Driscoll , Sara Driscoll , Fokje L. Schaafsma , Atsushi Yamaguchi , Ryuichi Matsukura , Hiroko Sasaki , Hiroto Murase
Several large-scale studies have examined the spatial and temporal (seasonal and interannual) variability in macrozooplankton communities in the eastern Indian sector of the Southern Ocean. In this study, variability in these communities was analyzed using samples collected by the RMT8 during the KY1804 survey, conducted between 80° and 150° E during the austral summer of 2018–2019. Furthermore, these findings were compared with those of the BROKE survey conducted in 1996. Using cluster analysis, the macrozooplankton community was divided into six groups. In both surveys, the zooplankton communities varied between the southern and northern stations of the sampling areas, though their distribution patterns differed between the two years. During the KY1804 survey, Thysanoessa macrura was more prevalent in the western region, while Themisto gaudichaudii and chaetognaths were more abundant in the eastern region; Salpa thompsoni dominated in the eastern region during the BROKE survey. Water temperature had the strongest influence on the macrozooplankton community during the KY1804 survey, whereas salinity was the primary influencing factor during the BROKE survey. This difference may largely reflect differences in sampling timing and latitudinal coverage, though a southward shift in the southern boundary of the Antarctic Circumpolar Current between the surveys may also have contributed. Hydrographic changes over the two decades between 1996 and 2019 likely affected the macrozooplankton community in this region, though differences in spatial and temporal survey coverage complicate interpretation of the results.
{"title":"Spatio-temporal changes in the macrozooplankton community in the eastern Indian sector of the Southern Ocean during austral summers: A comparison between 1996 and 2018–2019","authors":"Ippei Urabe , Kohei Matsuno , Rikuto Sugioka , Ryan Driscoll , Sara Driscoll , Fokje L. Schaafsma , Atsushi Yamaguchi , Ryuichi Matsukura , Hiroko Sasaki , Hiroto Murase","doi":"10.1016/j.pocean.2025.103414","DOIUrl":"10.1016/j.pocean.2025.103414","url":null,"abstract":"<div><div>Several large-scale studies have examined the spatial and temporal (seasonal and interannual) variability in macrozooplankton communities in the eastern Indian sector of the Southern Ocean. In this study, variability in these communities was analyzed using samples collected by the RMT8 during the KY1804 survey, conducted between 80° and 150° E during the austral summer of 2018–2019. Furthermore, these findings were compared with those of the BROKE survey conducted in 1996. Using cluster analysis, the macrozooplankton community was divided into six groups. In both surveys, the zooplankton communities varied between the southern and northern stations of the sampling areas, though their distribution patterns differed between the two years. During the KY1804 survey, <em>Thysanoessa macrura</em> was more prevalent in the western region, while <em>Themisto gaudichaudii</em> and chaetognaths were more abundant in the eastern region; <em>Salpa thompsoni</em> dominated in the eastern region during the BROKE survey. Water temperature had the strongest influence on the macrozooplankton community during the KY1804 survey, whereas salinity was the primary influencing factor during the BROKE survey. This difference may largely reflect differences in sampling timing and latitudinal coverage, though a southward shift in the southern boundary of the Antarctic Circumpolar Current between the surveys may also have contributed. Hydrographic changes over the two decades between 1996 and 2019 likely affected the macrozooplankton community in this region, though differences in spatial and temporal survey coverage complicate interpretation of the results.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103414"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141158","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}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2025.103415
Daniel Santana-Toscano, M.Dolores Pérez-Hernández, Cristina Arumí-Planas, Alonso Hernández-Guerra
The western North Atlantic Subtropical Gyre comprises the warm Gulf Stream (GS) and the cold Deep Western Boundary Current (DWBC), which are the main currents of the Atlantic Meridional Overturning Circulation (AMOC). Hydrographic sections conducted at 66°W (A22) and 52°W (A20) in the western North Atlantic Subtropical Gyre (NASG) have sampled these currents in 1997, 2003, 2012, and 2021. Both single- and three-box inverse models are used to compute mass, heat, and freshwater transport to the hydrographic data of 2021 with no significant differences between methodologies. This study reveals a substantial change in the GS mass transport at both 52°W and 66°W in spring 2021 compared to spring 2012 and summer 1997, but no changes compared to fall 2003. Conversely, the DWBC shows no significant modification between spring 2021 and previous cruises. Moreover, the North Brazil Current mass transport, which is sampled by the A20 section, presents the downstream weakening showcased previously. Heat and freshwater fluxes are not significantly different from zero, therefore the water volumes enclosed by the A20 and A22 sections do not reflect a net air-sea flux in 2021. Although the GS exhibits interdecadal variability, the lack of other changes over time in this area suggests a general stability in the environmental and forcing conditions. This study highlights the consistent mass transports of the main AMOC currents in the western NASG, particularly the GS and DWBC, emphasizing their stability and importance in broader climate and oceanographic processes.
{"title":"Estimating the western North Atlantic Subtropical Gyre zonal currents in 2021 through single- and three-box inverse models","authors":"Daniel Santana-Toscano, M.Dolores Pérez-Hernández, Cristina Arumí-Planas, Alonso Hernández-Guerra","doi":"10.1016/j.pocean.2025.103415","DOIUrl":"10.1016/j.pocean.2025.103415","url":null,"abstract":"<div><div>The western North Atlantic Subtropical Gyre comprises the warm Gulf Stream (GS) and the cold Deep Western Boundary Current (DWBC), which are the main currents of the Atlantic Meridional Overturning Circulation (AMOC). Hydrographic sections conducted at 66°W (A22) and 52°W (A20) in the western North Atlantic Subtropical Gyre (NASG) have sampled these currents in 1997, 2003, 2012, and 2021. Both single- and three-box inverse models are used to compute mass, heat, and freshwater transport to the hydrographic data of 2021 with no significant differences between methodologies. This study reveals a substantial change in the GS mass transport at both 52°W and 66°W in spring 2021 compared to spring 2012 and summer 1997, but no changes compared to fall 2003. Conversely, the DWBC shows no significant modification between spring 2021 and previous cruises. Moreover, the North Brazil Current mass transport, which is sampled by the A20 section, presents the downstream weakening showcased previously. Heat and freshwater fluxes are not significantly different from zero, therefore the water volumes enclosed by the A20 and A22 sections do not reflect a net air-sea flux in 2021. Although the GS exhibits interdecadal variability, the lack of other changes over time in this area suggests a general stability in the environmental and forcing conditions. This study highlights the consistent mass transports of the main AMOC currents in the western NASG, particularly the GS and DWBC, emphasizing their stability and importance in broader climate and oceanographic processes.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103415"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2025.103422
V.V.S.S. Sarma , B. Sridevi , T.M. Balakrishnan Nair , Aneesh A. Lotliker , Sanjiba K. Baliarsingh , E.P.R. Rao
Tropical cyclones modify the upper ocean due to significant mixing associated with increased winds that bring CO2 and nutrient-rich subsurface waters to the surface, altering CO2 flux and biological production. In the region where considerable river discharge occurs with strong stratification, it is hypothesized that tropical cyclones may increase the sink of CO2 into the ocean and vice versa in the region of weak stratification. The balance between CO2 removal through the exchange at the air–water interface and biological production on a shorter time scale may vary with the intensity of the cyclone. To examine this, severe cyclone Michaung and very severe cyclone Hudhud was studied to understand the modifications in CO2 fluxes and net primary production (NPP) in the Bay of Bengal. Both these cyclones occurred in the Bay of Bengal during post monsoon season (October to December) and crossed the land on the east coast of India. The barrier layer thickness was > 40 m in the northern and < 10 m in the southern Bay, resulting in spatial variability in the mixing of the upper ocean. High windspeed associated with cyclones may not rupture the stratification in the northern Bay. This led to an increase in a sink of CO2 from the atmosphere in the northern Bay, whereas the sink was decreased in the southern Bay due to an increase in pCO2 levels through mixing with subsurface waters. In the case of severe cyclone Michaung, the decrease in flux of CO2 due to an increase in pCO2 levels in the surface water through mixing was compensated by an increase in CO2 removal through NPP. In contrast, the decrease in CO2 sink due to the very severe cyclone Hudhud was lower than the increase in NPP, resulting in a net sink of CO2 in the Bay of Bengal. This study suggests that tropical cyclones may enhance CO2 sink into the Bay of Bengal. An increase in the number and intensity of tropical cyclones is projected in future due to climate change that may help to achieve net zero emissions in future.
{"title":"Tropical cyclones enhance net CO2 sink in the Bay of Bengal","authors":"V.V.S.S. Sarma , B. Sridevi , T.M. Balakrishnan Nair , Aneesh A. Lotliker , Sanjiba K. Baliarsingh , E.P.R. Rao","doi":"10.1016/j.pocean.2025.103422","DOIUrl":"10.1016/j.pocean.2025.103422","url":null,"abstract":"<div><div>Tropical cyclones modify the upper ocean due to significant mixing associated with increased winds that bring CO<sub>2</sub> and nutrient-rich subsurface waters to the surface, altering CO<sub>2</sub> flux and biological production. In the region where considerable river discharge occurs with strong stratification, it is hypothesized that tropical cyclones may increase the sink of CO<sub>2</sub> into the ocean and vice versa in the region of weak stratification. The balance between CO<sub>2</sub> removal through the exchange at the air–water interface and biological production on a shorter time scale may vary with the intensity of the cyclone. To examine this, severe cyclone <em>Michaung</em> and very severe cyclone <em>Hudhud</em> was studied to understand the modifications in CO<sub>2</sub> fluxes and net primary production (NPP) in the Bay of Bengal. Both these cyclones occurred in the Bay of Bengal during post monsoon season (October to December) and crossed the land on the east coast of India. The barrier layer thickness was > 40 m in the northern and < 10 m in the southern Bay, resulting in spatial variability in the mixing of the upper ocean. High windspeed associated with cyclones may not rupture the stratification in the northern Bay. This led to an increase in a sink of CO<sub>2</sub> from the atmosphere in the northern Bay, whereas the sink was decreased in the southern Bay due to an increase in pCO<sub>2</sub> levels through mixing with subsurface waters. In the case of severe cyclone <em>Michaung</em>, the decrease in flux of CO<sub>2</sub> due to an increase in pCO<sub>2</sub> levels in the surface water through mixing was compensated by an increase in CO<sub>2</sub> removal through NPP. In contrast, the decrease in CO<sub>2</sub> sink due to the very severe cyclone <em>Hudhud</em> was lower than the increase in NPP, resulting in a net sink of CO<sub>2</sub> in the Bay of Bengal. This study suggests that tropical cyclones may enhance CO<sub>2</sub> sink into the Bay of Bengal. An increase in the number and intensity of tropical cyclones is projected in future due to climate change that may help to achieve net zero emissions in future.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103422"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143072465","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}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2024.103407
T.B. Mashifane , L. Braby , M. Pikiso , S. Sunnassee–Taukoor , R.S. Rapolaki , M.N. Ragoasha
The Agulhas Current is the strongest western boundary current (WBC) in the Southern Hemisphere with a significant impact on the global climate. Through the Agulhas leakage, it transports warm, saline waters into the South Atlantic Ocean. In recent years, a warming trend has been highlighted in the Agulhas Current, with possible implications for dissolved oxygen ([O2]) due to the link between warming and reduced solubility – dynamics that remain relatively unknown in the region. To address this knowledge gap, we use the random forest regression algorithm to predict near–surface [O2] from multiple predictors in the Agulhas Current, presenting the first analysis of these dynamics. The Agulhas–RFR algorithm predicts [O2] exceptionally well, with permutation importance from the ensemble indicating that sea surface temperature (SST) is the highest–ranking predictor. Seasonal changes in solubility, wind, and productivity drive [O2] and the [O2] flux in the Agulhas Current. The seasonal [O2] flux to the atmosphere reaches –1.84 mol m−2 yr−1 during the austral winter across the Agulhas Current. A significant decreasing [O2] trend of up to –7 µmol kg−1 yr−1, attributed to warming, is revealed for the period from 2000 to 2023. Strengthening westerlies and cooling contribute to [O2] drawdown towards the Indian Ocean gyre. The Agulhas–RFR algorithm reveals a declining [O2] trend of –2.29 ± 0.61 µmol kg−1 yr−1 across the Agulhas Current for the study period, representing a 1.4% deoxygenation rate, which is slightly higher than global estimates.
阿古拉斯流是南半球最强的西边界流，对全球气候有重要影响。通过阿古拉斯渗漏，它将温暖的咸水输送到南大西洋。近年来，阿古拉斯海流的变暖趋势得到了强调，由于变暖和溶解度降低之间的联系，这可能对溶解氧（[O2]）产生影响，这一动态在该地区仍然相对未知。为了解决这一知识差距，我们使用随机森林回归算法从Agulhas海流的多个预测因子中预测近地表[O2]，首次对这些动态进行了分析。Agulhas-RFR算法对[O2]的预测非常好，集合的排列重要性表明海面温度（SST）是排名最高的预测因子。溶解度、风和生产力的季节性变化驱动了[O2]和阿古拉斯海流中的[O2]通量。在南方冬季，通过阿古拉斯海流进入大气的季节性[O2]通量达到-1.84 mol m−2 yr−1。2000年至2023年期间，由于气候变暖，[O2]的显著减少趋势高达-7µmol kg−1 yr−1。加强的西风带和冷却有助于[O2]向印度洋环流减少。Agulhas - rfr算法显示，在研究期间，Agulhas海流的[O2]下降趋势为-2.29±0.61µmol kg - 1 yr - 1，代表1.4%的脱氧率，略高于全球估计。
{"title":"Machine learning algorithm reveals surface deoxygenation in the Agulhas Current due to warming","authors":"T.B. Mashifane , L. Braby , M. Pikiso , S. Sunnassee–Taukoor , R.S. Rapolaki , M.N. Ragoasha","doi":"10.1016/j.pocean.2024.103407","DOIUrl":"10.1016/j.pocean.2024.103407","url":null,"abstract":"<div><div>The Agulhas Current is the strongest western boundary current (WBC) in the Southern Hemisphere with a significant impact on the global climate. Through the Agulhas leakage, it transports warm, saline waters into the South Atlantic Ocean. In recent years, a warming trend has been highlighted in the Agulhas Current, with possible implications for dissolved oxygen ([O<sub>2</sub>]) due to the link between warming and reduced solubility – dynamics that remain relatively unknown in the region. To address this knowledge gap, we use the random forest regression algorithm to predict near–surface [O<sub>2</sub>] from multiple predictors in the Agulhas Current, presenting the first analysis of these dynamics. The Agulhas–RFR algorithm predicts [O<sub>2</sub>] exceptionally well, with permutation importance from the ensemble indicating that sea surface temperature (SST) is the highest–ranking predictor. Seasonal changes in solubility, wind, and productivity drive [O<sub>2</sub>] and the [O<sub>2</sub>] flux in the Agulhas Current. The seasonal [O<sub>2</sub>] flux to the atmosphere reaches –1.84 mol m<sup>−2</sup> yr<sup>−1</sup> during the austral winter across the Agulhas Current. A significant decreasing [O<sub>2</sub>] trend of up to –7 µmol kg<sup>−1</sup> yr<sup>−1</sup>, attributed to warming, is revealed for the period from 2000 to 2023. Strengthening westerlies and cooling contribute to [O<sub>2</sub>] drawdown towards the Indian Ocean gyre. The Agulhas–RFR algorithm reveals a declining [O<sub>2</sub>] trend of –2.29 ± 0.61 µmol kg<sup>−1</sup> yr<sup>−1</sup> across the Agulhas Current for the study period, representing a 1.4% deoxygenation rate, which is slightly higher than global estimates.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103407"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2025.103416
Bayoumy Mohamed , Nikolaos Skliris
This study investigates sea level changes in the Red Sea over the last 29 years (1993–2021) by analyzing long-term trends and interannual variations in the total sea level anomaly (SLA). The study also explores the role of thermosteric and halosteric changes and interannual variability of total SLA using an empirical orthogonal function (EOF) analysis and their relationship with large-scale climate modes. The results show that the trends of total and steric SLA were higher in the northern Red Sea (NRS) than in the southern Red Sea (SRS), influenced by low-salinity water inflow from the Aden Gulf. The average SLA trend in the Red Sea between 1993 and 2021 was about 4.17 ± 0.14 mm/year. However, an abrupt change was observed in SLA and its components, with accelerating trends in the post-2008 period compared to the pre-2008 period. This increase was mainly due to the thermosteric effect, which was positively enhanced throughout the Red Sea. The halosteric component in the NRS contributed negatively to the overall steric effect. The interannual SLA variability accounts for about 45 % of the total variability and can be partially explained by the influence of the El Nino Southern Oscillation.
{"title":"Recent sea level changes in the Red Sea: Thermosteric and halosteric contributions, and impacts of natural climate variability","authors":"Bayoumy Mohamed , Nikolaos Skliris","doi":"10.1016/j.pocean.2025.103416","DOIUrl":"10.1016/j.pocean.2025.103416","url":null,"abstract":"<div><div>This study investigates sea level changes in the Red Sea over the last 29 years (1993–2021) by analyzing long-term trends and interannual variations in the total sea level anomaly (SLA). The study also explores the role of thermosteric and halosteric changes and interannual variability of total SLA using an empirical orthogonal function (EOF) analysis and their relationship with large-scale climate modes. The results show that the trends of total and steric SLA were higher in the northern Red Sea (NRS) than in the southern Red Sea (SRS), influenced by low-salinity water inflow from the Aden Gulf. The average SLA trend in the Red Sea between 1993 and 2021 was about 4.17 ± 0.14 mm/year. However, an abrupt change was observed in SLA and its components, with accelerating trends in the post-2008 period compared to the pre-2008 period. This increase was mainly due to the thermosteric effect, which was positively enhanced throughout the Red Sea. The halosteric component in the NRS contributed negatively to the overall steric effect. The interannual SLA variability accounts for about 45 % of the total variability and can be partially explained by the influence of the El Nino Southern Oscillation.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103416"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142967795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2025.103418
Yonghe Tian , Xiaolin Bai , Chuanyin Wang , Zhiyu Liu
Understanding tidal energetics is crucial for comprehending complex oceanic processes in the South China Sea (SCS). Tidal energy budget in different parts of the world’s oceans has been widely estimated, but the dissipation pathways of tidal energy in the eddying ocean remain elusive. Based on a well-validated high-resolution numerical simulation, this study provides an updated estimate of tidal energy budget in the SCS with the modulation of realistic background currents and stratification. It reveals that ∼19.72% of barotropic tidal energy input in the Luzon Strait (LS) is converted to baroclinic tides, ∼75.66% of which is transmitted out of the LS and the other ∼24.34% is dissipated locally. Additionally, ∼61.20% of barotropic tidal energy is transmitted into the SCS, and the other ∼19.07% is dissipated locally. Analysis of barotropic tidal energy budget highlights significant work rate of K1 tide-generating force in the SCS, whereas analysis of baroclinic tidal energy budget reveals the impacts of background fields on energy conversion from barotropic to baroclinic tides and energy dissipation of baroclinic tides. The seasonal variability of tidal dynamics and energetics further highlights the modulations by background fields. An exponential decay of baroclinic tidal energy flux with the distance from the generation site is revealed, and the decay scales for K1 (northwestward and southwestward beam of M2) baroclinic tide are estimated as 404 (195 and 127) km. A simple scaling of baroclinic tidal energy flux in the SCS, which may be used to characterize tidal mixing in large-scale ocean and climate models, is thus devised.
{"title":"Tidal energetics in the eddying South China Sea from a high-resolution numerical simulation","authors":"Yonghe Tian , Xiaolin Bai , Chuanyin Wang , Zhiyu Liu","doi":"10.1016/j.pocean.2025.103418","DOIUrl":"10.1016/j.pocean.2025.103418","url":null,"abstract":"<div><div>Understanding tidal energetics is crucial for comprehending complex oceanic processes in the South China Sea (SCS). Tidal energy budget in different parts of the world’s oceans has been widely estimated, but the dissipation pathways of tidal energy in the eddying ocean remain elusive. Based on a well-validated high-resolution numerical simulation, this study provides an updated estimate of tidal energy budget in the SCS with the modulation of realistic background currents and stratification. It reveals that ∼19.72% of barotropic tidal energy input in the Luzon Strait (LS) is converted to baroclinic tides, ∼75.66% of which is transmitted out of the LS and the other ∼24.34% is dissipated locally. Additionally, ∼61.20% of barotropic tidal energy is transmitted into the SCS, and the other ∼19.07% is dissipated locally. Analysis of barotropic tidal energy budget highlights significant work rate of K<sub>1</sub> tide-generating force in the SCS, whereas analysis of baroclinic tidal energy budget reveals the impacts of background fields on energy conversion from barotropic to baroclinic tides and energy dissipation of baroclinic tides. The seasonal variability of tidal dynamics and energetics further highlights the modulations by background fields. An exponential decay of baroclinic tidal energy flux with the distance from the generation site is revealed, and the decay scales for K<sub>1</sub> (northwestward and southwestward beam of M<sub>2</sub>) baroclinic tide are estimated as 404 (195 and 127) km. A simple scaling of baroclinic tidal energy flux in the SCS, which may be used to characterize tidal mixing in large-scale ocean and climate models, is thus devised.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103418"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097962","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}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2025.103420
Luca Russo , Matteo Loschi , Daniele Bellardini , Roberta Congestri , Michael W. Lomas , Simone Libralato , Domenico D’Alelio
{"title":"Corrigendum to “Food web analysis shows an exacerbated dependence of zooplankton on detritus in oligotrophic systems due to ocean warming” [Prog. Oceanogr. 231 (2025) 103389]","authors":"Luca Russo , Matteo Loschi , Daniele Bellardini , Roberta Congestri , Michael W. Lomas , Simone Libralato , Domenico D’Alelio","doi":"10.1016/j.pocean.2025.103420","DOIUrl":"10.1016/j.pocean.2025.103420","url":null,"abstract":"","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103420"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2024.103389
Luca Russo , Matteo Loschi , Daniele Bellardini , Roberta Congestri , Michael W. Lomas , Simone Libralato , Domenico D’Alelio
Ocean warming can affect plankton both directly, through altered metabolic activities, and indirectly, modifying the physical–chemical properties of the water column, with possible effects on ecosystem functioning. To evaluate the combined action of warming-related physiological responses and environmental changes on plankton functioning, we carried out a long-term analysis (from 1994 to 2019) of the Bermuda Atlantic Time-series Study (BATS) dataset where ocean warming and stratification have driven a decrease in the net primary production over the last decade. Using the time series of plankton observations, we assembled 1000 replicates of a food web model for each year. We observed that the total flow of matter through the model remained constant over time, despite the increased oligotrophication, due to global warming, after 2014. In fact, the plankton food web remained robust through re-modulated trophic interactions with an increased detritivory to herbivory ratio of the food web over time. However, it was problematic to re-establish the trophic connections of the food web broken by ocean warming, as remarked by the increased relative internal ascendency. Thanks to trophic plasticity, the reduced zooplankton dependence on herbivory was compensated by a significant increase in the reliance on carnivory and detritivores, highlighting the crucial role of trophic interactions in buffering significant environmental short-term changes.
{"title":"Food web analysis shows an exacerbated dependence of zooplankton on detritus in oligotrophic systems due to ocean warming","authors":"Luca Russo , Matteo Loschi , Daniele Bellardini , Roberta Congestri , Michael W. Lomas , Simone Libralato , Domenico D’Alelio","doi":"10.1016/j.pocean.2024.103389","DOIUrl":"10.1016/j.pocean.2024.103389","url":null,"abstract":"<div><div>Ocean warming can affect plankton both directly, through altered metabolic activities, and indirectly, modifying the physical–chemical properties of the water column, with possible effects on ecosystem functioning. To evaluate the combined action of warming-related physiological responses and environmental changes on plankton functioning, we carried out a long-term analysis (from 1994 to 2019) of the Bermuda Atlantic Time-series Study (BATS) dataset where ocean warming and stratification have driven a decrease in the net primary production over the last decade. Using the time series of plankton observations, we assembled 1000 replicates of a food web model for each year. We observed that the total flow of matter through the model remained constant over time, despite the increased oligotrophication, due to global warming, after 2014. In fact, the plankton food web remained robust through re-modulated trophic interactions with an increased detritivory to herbivory ratio of the food web over time. However, it was problematic to re-establish the trophic connections of the food web broken by ocean warming, as remarked by the increased relative internal ascendency. Thanks to trophic plasticity, the reduced zooplankton dependence on herbivory was compensated by a significant increase in the reliance on carnivory and detritivores, highlighting the crucial role of trophic interactions in buffering significant environmental short-term changes.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103389"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2024.103409
Andrea Corredor-Acosta , Alexander Galán , Gonzalo S. Saldías , Jorge I. Mardones , Johanna Medellín-Mora , Máximo Frangopulos , Takuhei Shiozaki , Naomi Harada , Humberto E. González , José L. Iriarte
Changes in phytoplankton composition and abundance are controlled by multiple factors, including physical forcing and nutrient stoichiometry. This study seeks to assess the interplay between the environmental and biogeochemical conditions in shaping the phytoplankton community structure in open ocean waters off western Patagonia. For this purpose, we used biological, hydrographic, and chemical data measured aboard the R/V Mirai during the austral summer of 2017, combined with remote sensing and reanalysis products. Although no first-order predictive relationships were found between the environmental and biological data, the results showed a latitudinal gradient of the phytoplankton structure, favoring maximum abundances of diatoms (∼10x104 cells L-1) in the northern area (∼43-48°S) characterized by high stratification and freshwater content. The high diatom abundances of Thalassiosira spp., Chaetoceros spp., Pseudo-nitzschia cf. australis and Pseudo-nitzschia cf. pseudodelicatissima taxa in this area results in a nutrient content decreases (nitrate < 9 μmol kg−1, phosphate < 0.9 μmol kg−1, silicic acid < 1.5 μmol kg−1), and low N:Si (<8) and N:P (<10) ratios. Nonetheless, the total dinoflagellates abundance was equal to or higher than those of diatoms (∼10.2x104 cells L-1) throughout most of the sampling region. Specifically, maximum abundances (∼6.3x104 cells L-1) of Karenia spp. were found in the north under the freshwater influence from the Gulf of Penas, where the highest ammonium:nitrate ratio (∼4 to 11.5) was recorded. In contrast, high dinoflagellate abundances of Azadinium spp. were found in the south (∼48-55°S), where an increase of nutrient content (nitrate ∼12μmol kg-1, phosphate ∼1 μmol kg-1, ammonium ∼0.4 μmol kg-1), and high N:Si and N:P ratios (∼35 and ∼12) were observed. This study highlights a major presence of potentially toxic phytoplankton species in the oceanic zone off northern Patagonia under conditions of strong latitudinal and cross-shore gradients in nutrient content and salinity, related to the interplay between oceanic water masses and freshwater input.
{"title":"Oceanic phytoplankton structure off western Patagonia during the austral summer: Implications for harmful algal blooms","authors":"Andrea Corredor-Acosta , Alexander Galán , Gonzalo S. Saldías , Jorge I. Mardones , Johanna Medellín-Mora , Máximo Frangopulos , Takuhei Shiozaki , Naomi Harada , Humberto E. González , José L. Iriarte","doi":"10.1016/j.pocean.2024.103409","DOIUrl":"10.1016/j.pocean.2024.103409","url":null,"abstract":"<div><div>Changes in phytoplankton composition and abundance are controlled by multiple factors, including physical forcing and nutrient stoichiometry. This study seeks to assess the interplay between the environmental and biogeochemical conditions in shaping the phytoplankton community structure in open ocean waters off western Patagonia. For this purpose, we used biological, hydrographic, and chemical data measured aboard the R/V Mirai during the austral summer of 2017, combined with remote sensing and reanalysis products. Although no first-order predictive relationships were found between the environmental and biological data, the results showed a latitudinal gradient of the phytoplankton structure, favoring maximum abundances of diatoms (∼10x10<sup>4</sup> cells L<sup>-1</sup>) in the northern area (∼43-48°S) characterized by high stratification and freshwater content. The high diatom abundances of <em>Thalassiosira</em> spp.<em>, Chaetoceros</em> spp.<em>, Pseudo-nitzschia</em> cf. <em>australis</em> and <em>Pseudo-nitzschia</em> cf. <em>pseudodelicatissima</em> taxa in this area results in a nutrient content decreases (nitrate < 9 μmol kg<sup>−1</sup>, phosphate < 0.9 μmol kg<sup>−1</sup>, silicic acid < 1.5 μmol kg<sup>−1</sup>), and low N:Si (<8) and N:P (<10) ratios. Nonetheless, the total dinoflagellates abundance was equal to or higher than those of diatoms (∼10.2x10<sup>4</sup> cells L<sup>-</sup><sup>1</sup>) throughout most of the sampling region. Specifically, maximum abundances (∼6.3x10<sup>4</sup> cells L<sup>-</sup><sup>1</sup>) of <em>Karenia</em> spp. were found in the north under the freshwater influence from the Gulf of Penas, where the highest ammonium:nitrate ratio (∼4 to 11.5) was recorded. In contrast, high dinoflagellate abundances of <em>Azadinium</em> spp. were found in the south (∼48-55°S), where an increase of nutrient content (nitrate ∼12μmol kg<sup>-</sup><sup>1</sup>, phosphate ∼1 μmol kg<sup>-</sup><sup>1</sup>, ammonium ∼0.4 μmol kg<sup>-</sup><sup>1</sup>), and high N:Si and N:P ratios (∼35 and ∼12) were observed. This study highlights a major presence of potentially toxic phytoplankton species in the oceanic zone off northern Patagonia under conditions of strong latitudinal and cross-shore gradients in nutrient content and salinity, related to the interplay between oceanic water masses and freshwater input.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103409"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142925064","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}
Pub Date : 2025-02-01DOI: 10.1016/j.pocean.2024.103408
Gennady M. Kamenev , Julia D. Sigwart
The genus Axinulus is the richest in species number and quantitative abundance among representatives of the family Thyasiridae, which is found in the abyssal and hadal zones of the deep-sea areas of the northern Pacific Ocean. Many species of the genus form abundant populations and dominate the benthic communities of these deep-sea areas. The study of the material of bivalves collected by the “AleutBio” deep-sea expedition (2022) in the eastern part of the Aleutian Basin (Bering Sea) and in the Aleutian Trench revealed the occurrence of three species of the genus Axinulus, one of which turned out to be new to science, and Axinulus krylovae and Axinulus oliveri were first records for the eastern Pacific. Here, we describe Axinulus pentagonalis sp. nov. found in the Bering Sea and on the oceanic slopes of the Aleutian Islands at depths of 3646–4630 m and present new data on the distribution of A. krylovae and A. oliveri. The main feature distinguishing the new species from other species of Axinulus is the presence of a unique sculpture of the prodissoconch consisting of thin, curved, ramified, and branched folds extending from a short ridge in the middle of the prodissoconch. In addition, the new species differs from most of related species in the presence of a bulbous tip of the foot divided into two parts. We compare the new species with all related species and analyze the geographic and vertical distribution of all species of the genus Axinulus supplemented by new data.
{"title":"Geographical and vertical distribution of Axinulus (Bivalvia: Thyasiridae): New data on distribution in the North Pacific and description of a new species","authors":"Gennady M. Kamenev , Julia D. Sigwart","doi":"10.1016/j.pocean.2024.103408","DOIUrl":"10.1016/j.pocean.2024.103408","url":null,"abstract":"<div><div>The genus <em>Axinulus</em> is the richest in species number and quantitative abundance among representatives of the family Thyasiridae, which is found in the abyssal and hadal zones of the deep-sea areas of the northern Pacific Ocean. Many species of the genus form abundant populations and dominate the benthic communities of these deep-sea areas. The study of the material of bivalves collected by the “AleutBio” deep-sea expedition (2022) in the eastern part of the Aleutian Basin (Bering Sea) and in the Aleutian Trench revealed the occurrence of three species of the genus <em>Axinulus</em>, one of which turned out to be new to science, and <em>Axinulus krylovae</em> and <em>Axinulus oliveri</em> were first records for the eastern Pacific. Here, we describe <em>Axinulus pentagonalis</em> sp. nov. found in the Bering Sea and on the oceanic slopes of the Aleutian Islands at depths of 3646–4630 m and present new data on the distribution of <em>A. krylovae</em> and <em>A. oliveri</em>. The main feature distinguishing the new species from other species of <em>Axinulus</em> is the presence of a unique sculpture of the prodissoconch consisting of thin, curved, ramified, and branched folds extending from a short ridge in the middle of the prodissoconch. In addition, the new species differs from most of related species in the presence of a bulbous tip of the foot divided into two parts. We compare the new species with all related species and analyze the geographic and vertical distribution of all species of the genus <em>Axinulus</em> supplemented by new data.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103408"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097961","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}
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