Pub Date : 2024-11-08DOI: 10.1016/j.dsr2.2024.105435
Mohamed Shaltout , Ahmed Eladawy
Amid escalating global marine heat waves, the Arabian Gulf is critical due to its shallow depths, high temperatures, and vulnerability to climate change impacts. This study provides a detailed spatio-temporal analysis of marine heatwave events from 1982 to 2022 across the Arabian Gulf and the adjacent Gulf of Oman. The study delineates regions of heightened vulnerability within these water bodies by comprehensively analyzing seasonal and annual variabilities and trend assessments. Moreover, an exploration of prevailing surface circulation patterns, underpinned by an extensive study of global circulation model outputs, elucidates the oceanographic mechanisms contributing to temperature dynamics. Identifying 25 significant heat wave events, with a focused examination of the six most protracted episodes, is noteworthy among the findings. Strikingly, the analysis reveals that the Gulf of Oman surpasses the Arabian Gulf in heatwave intensity. Looking forward, the investigation extends to future surface water temperature projections up to the close of the current century. The collective results underscore the region's acute susceptibility to the climate change perturbations of climate change, emphasizing the urgency of targeted interventions to mitigate these effects and address concurrent local stressors.
{"title":"Unveiling marine heatwave dynamics in the Persian /Arabian Gulf and the Gulf of Oman: A spatio-temporal analysis and future projections","authors":"Mohamed Shaltout , Ahmed Eladawy","doi":"10.1016/j.dsr2.2024.105435","DOIUrl":"10.1016/j.dsr2.2024.105435","url":null,"abstract":"<div><div>Amid escalating global marine heat waves, the Arabian Gulf is critical due to its shallow depths, high temperatures, and vulnerability to climate change impacts. This study provides a detailed spatio-temporal analysis of marine heatwave events from 1982 to 2022 across the Arabian Gulf and the adjacent Gulf of Oman. The study delineates regions of heightened vulnerability within these water bodies by comprehensively analyzing seasonal and annual variabilities and trend assessments. Moreover, an exploration of prevailing surface circulation patterns, underpinned by an extensive study of global circulation model outputs, elucidates the oceanographic mechanisms contributing to temperature dynamics. Identifying 25 significant heat wave events, with a focused examination of the six most protracted episodes, is noteworthy among the findings. Strikingly, the analysis reveals that the Gulf of Oman surpasses the Arabian Gulf in heatwave intensity. Looking forward, the investigation extends to future surface water temperature projections up to the close of the current century. The collective results underscore the region's acute susceptibility to the climate change perturbations of climate change, emphasizing the urgency of targeted interventions to mitigate these effects and address concurrent local stressors.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105435"},"PeriodicalIF":2.3,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657495","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 : 2024-11-01DOI: 10.1016/j.dsr2.2024.105434
Giovanni Sanna , André Freiwald
Sensitivity of reef-building corals to environmental factors has far-reaching ecosystem implications, especially in the limited number of cold-water coral (CWC) species that form reefs in the deep sea. Understanding CWC responses to large-scale oceanographic variation in their natural habitat can elucidate their sensitivity to global anthropogenic stressors. Here, we use skeletal samples to analyse fine-scale phenotypic variation in the widespread reef-building CWC Desmophyllum pertusum (Lophelia pertusa) in relation to broad physicochemical gradients in different sites across the Atlantic Ocean and Mediterranean Sea. We find evidence, amidst local and regional differentiation, of species-wide growth responses to physicochemical factors, mainly affecting corallite length, width and their ratio (slenderness). Our results suggest that higher temperature and lower oxygen levels negatively affect skeletal linear extension and budding rate of polyps. As also hinted by the reduced corallite length and slenderness in less developed reefs, these widespread responses may lead to a general decline in CWC reef growth rates as a long-term consequence of ocean warming and deoxygenation. Given this relevance, such responses can be used to model reef growth in a changing ocean.
{"title":"Ecophenotypic variation in a cosmopolitan reef-building coral suggests reduced deep-sea reef growth under ocean change","authors":"Giovanni Sanna , André Freiwald","doi":"10.1016/j.dsr2.2024.105434","DOIUrl":"10.1016/j.dsr2.2024.105434","url":null,"abstract":"<div><div>Sensitivity of reef-building corals to environmental factors has far-reaching ecosystem implications, especially in the limited number of cold-water coral (CWC) species that form reefs in the deep sea. Understanding CWC responses to large-scale oceanographic variation in their natural habitat can elucidate their sensitivity to global anthropogenic stressors. Here, we use skeletal samples to analyse fine-scale phenotypic variation in the widespread reef-building CWC <em>Desmophyllum pertusum</em> (<em>Lophelia pertusa</em>) in relation to broad physicochemical gradients in different sites across the Atlantic Ocean and Mediterranean Sea. We find evidence, amidst local and regional differentiation, of species-wide growth responses to physicochemical factors, mainly affecting corallite length, width and their ratio (slenderness). Our results suggest that higher temperature and lower oxygen levels negatively affect skeletal linear extension and budding rate of polyps. As also hinted by the reduced corallite length and slenderness in less developed reefs, these widespread responses may lead to a general decline in CWC reef growth rates as a long-term consequence of ocean warming and deoxygenation. Given this relevance, such responses can be used to model reef growth in a changing ocean.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105434"},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657494","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 : 2024-10-22DOI: 10.1016/j.dsr2.2024.105433
Lidiya N. Vasilenko , Ira B. Tsoy , Tatyana N. Dautova
The taxonomic composition and abundance of siliceous microfossils in sediments is a valuable source of information about environmental changes at the sea surface today and in the geological past. This paper presents the results of a study of siliceous microplankton (radiolaria, diatoms, and silicoflagellates) in the surface calcareous sediments (silty foraminiferal oozes and sands) of the Nintoku, Jingu, Ojin, Koko, and Yuryaku guyots at the southern end of the Emperor Seamount Chain (ESC). Bottom sediments were collected using an underwater remote-operated vehicle (ROV) Comanche-18. The study revealed the taxonomic diversity and relatively high abundance of siliceous microplankton. Radiolarians are represented by 237 taxa (104 taxa from 68 genera of Spumellaria, 120 taxa from 61 genera of Nassellaria, and 13 taxa from 7 genera of Collodaria). Diatoms are represented by 60 species from 29 genera, and silicoflagellates by 5 species from 3 genera. Differences in siliceous microplankton reflect the northern boundary of warm water in the ESC, passing at approximately 38°N, between the Jingu and Ojin guyots, which coincides with the boundary of the Kuroshio Bifurcation Current, confirmed by the corals and the bathyal fauna of brittle stars (Ophiura). The absence of remains of siliceous microplankton in some sediments is probably due to dissolution, and the presence of extinct taxa from older sedimentary rocks and neritic species is due to process of reworking caused by active hydrodynamics on ESC guyots and transport by currents.
{"title":"Siliceous microfossil assemblages in the southern Emperor Seamount Chain sediments and their biogeographical and paleoceanographical implications","authors":"Lidiya N. Vasilenko , Ira B. Tsoy , Tatyana N. Dautova","doi":"10.1016/j.dsr2.2024.105433","DOIUrl":"10.1016/j.dsr2.2024.105433","url":null,"abstract":"<div><div>The taxonomic composition and abundance of siliceous microfossils in sediments is a valuable source of information about environmental changes at the sea surface today and in the geological past. This paper presents the results of a study of siliceous microplankton (radiolaria, diatoms, and silicoflagellates) in the surface calcareous sediments (silty foraminiferal oozes and sands) of the Nintoku, Jingu, Ojin, Koko, and Yuryaku guyots at the southern end of the Emperor Seamount Chain (ESC). Bottom sediments were collected using an underwater remote-operated vehicle (ROV) Comanche-18. The study revealed the taxonomic diversity and relatively high abundance of siliceous microplankton. Radiolarians are represented by 237 taxa (104 taxa from 68 genera of Spumellaria, 120 taxa from 61 genera of Nassellaria, and 13 taxa from 7 genera of Collodaria). Diatoms are represented by 60 species from 29 genera, and silicoflagellates by 5 species from 3 genera. Differences in siliceous microplankton reflect the northern boundary of warm water in the ESC, passing at approximately 38°N, between the Jingu and Ojin guyots, which coincides with the boundary of the Kuroshio Bifurcation Current, confirmed by the corals and the bathyal fauna of brittle stars (<em>Ophiura</em>). The absence of remains of siliceous microplankton in some sediments is probably due to dissolution, and the presence of extinct taxa from older sedimentary rocks and neritic species is due to process of reworking caused by active hydrodynamics on ESC guyots and transport by currents.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105433"},"PeriodicalIF":2.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593800","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 : 2024-10-18DOI: 10.1016/j.dsr2.2024.105430
Andrey V. Adrianov , Anastassya S. Maiorova
Seamounts and oceanic currents play crucial roles in shaping the genetic diversity of species by either acting as barriers or pathways for species dispersal. In the meiofaunal samples collected using ROV facilities at the slope of the Koko Guyot (2172 m) in the southernmost part of the Emperor Seamount Chain in the Northwestern Pacific, we found representatives of three kinorhynch genera, Echinoderes cf. lupherorum Sørensen et al. 2018, Campyloderes cf. vanhoeffeni Zelinka, 1913 and Sphenoderes sp. 1., previously known from other locations in the Pacific. Kinorhynchs were studied and illustrated using light (LM) and scanning electron (SEM) microscopy to prove the species identity and to compare morphological variations with representatives of these species collected from other, very distant localities in the Pacific. We illustrate the pan-oceanic distribution of the collected species with a system of abyssal currents in the Pacific. The probable distribution pattern corresponds with the northward pathway of Antarctic Bottom Water out of the Southern Ocean in the Pacific through the deep-sea area off New Zealand. Echinoderes lupherorum appears to be the first representative of the Echinoderidae with the pan-Pacific distribution. Discussions on the biogeography of Campyloderes cf. vanhoeffeni Zelinka, 1913 and Sphenoderes in the Pacific are also provided.
{"title":"The first Mud Dragons (Kinorhyncha) from the Emperor Seamount Chain (Northwestern Pacific) with notes on their biogeography and distribution patterns in the Pacific Deep-Sea","authors":"Andrey V. Adrianov , Anastassya S. Maiorova","doi":"10.1016/j.dsr2.2024.105430","DOIUrl":"10.1016/j.dsr2.2024.105430","url":null,"abstract":"<div><div>Seamounts and oceanic currents play crucial roles in shaping the genetic diversity of species by either acting as barriers or pathways for species dispersal. In the meiofaunal samples collected using ROV facilities at the slope of the Koko Guyot (2172 m) in the southernmost part of the Emperor Seamount Chain in the Northwestern Pacific, we found representatives of three kinorhynch genera, <em>Echinoderes</em> cf. <em>lupherorum</em> Sørensen et al. 2018, <em>Campyloderes</em> cf. <em>vanhoeffeni</em> Zelinka, 1913 and <em>Sphenoderes</em> sp. 1., previously known from other locations in the Pacific. Kinorhynchs were studied and illustrated using light (LM) and scanning electron (SEM) microscopy to prove the species identity and to compare morphological variations with representatives of these species collected from other, very distant localities in the Pacific. We illustrate the pan-oceanic distribution of the collected species with a system of abyssal currents in the Pacific. The probable distribution pattern corresponds with the northward pathway of Antarctic Bottom Water out of the Southern Ocean in the Pacific through the deep-sea area off New Zealand. <em>Echinoderes lupherorum</em> appears to be the first representative of the Echinoderidae with the pan-Pacific distribution. Discussions on the biogeography of <em>Campyloderes</em> cf. <em>vanhoeffeni</em> Zelinka, 1913 and <em>Sphenoderes</em> in the Pacific are also provided.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105430"},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534936","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 : 2024-10-18DOI: 10.1016/j.dsr2.2024.105432
Valentina V. Kasyan
The horizontal and vertical distributions of zooplankton over the Emperor Seamounts (Koko, Jingu, Nintoku, and Suiko guyots) were analyzed. The zooplankton was represented by four genera of amphipods, seven genera of pteropods, 39 genera of copepods, and larvae of benthic invertebrates and fish. The abundance and biomass of zooplankton increased towards higher latitudes along the series Koko < Jingu < Nintoku < Suiko guyots. The highest index of diversity was recorded over the Koko and Jingu guyots; the highest species richness occurred over the Jingu and Nintoku guyots. Small-sized copepods, appendicularians, chaetognaths, euphausiids, and fish eggs and larvae concentrated in the epipelagic; large copepods and ostracods were concentrated in the mesopelagic. We identified three types of zooplankton assemblages: a Subtropical assemblage between 34°–35°N characterized by tropical/subtropical forms; a Transition assemblage characterized by subtropical, subarctic, and widespread species between 38°–41°N; and a Subarctic assemblage characterized by subarctic and widespread species between 43°–44°N. The spatial distribution of zooplankton was a function of environmental variables such as surface salinity, temperature at 200 m, and, to a certain extent, by surface Chl-a concentrations.
{"title":"Latitudinal variation in zooplankton over the Emperor Seamounts (34°–44° N, 170°–171° E) during the summer of 2019","authors":"Valentina V. Kasyan","doi":"10.1016/j.dsr2.2024.105432","DOIUrl":"10.1016/j.dsr2.2024.105432","url":null,"abstract":"<div><div>The horizontal and vertical distributions of zooplankton over the Emperor Seamounts (Koko, Jingu, Nintoku, and Suiko guyots) were analyzed. The zooplankton was represented by four genera of amphipods, seven genera of pteropods, 39 genera of copepods, and larvae of benthic invertebrates and fish. The abundance and biomass of zooplankton increased towards higher latitudes along the series Koko < Jingu < Nintoku < Suiko guyots. The highest index of diversity was recorded over the Koko and Jingu guyots; the highest species richness occurred over the Jingu and Nintoku guyots. Small-sized copepods, appendicularians, chaetognaths, euphausiids, and fish eggs and larvae concentrated in the epipelagic; large copepods and ostracods were concentrated in the mesopelagic. We identified three types of zooplankton assemblages: a Subtropical assemblage between 34°–35°N characterized by tropical/subtropical forms; a Transition assemblage characterized by subtropical, subarctic, and widespread species between 38°–41°N; and a Subarctic assemblage characterized by subarctic and widespread species between 43°–44°N. The spatial distribution of zooplankton was a function of environmental variables such as surface salinity, temperature at 200 m, and, to a certain extent, by surface Chl-<em>a</em> concentrations.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105432"},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534937","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 : 2024-10-16DOI: 10.1016/j.dsr2.2024.105431
Nikita S. Polonik, Alexey A. Legkodimov
Dissolved methane (CH4) concentrations were measured in the water column at 25 stations along the four sections above Koko and Jingu guyots (the southern part of Emperor Seamount chain). The measured methane concentrations were relatively low (1–6.5 nM). The patterns of CH4 vertical distributions over Koko and Jingu were different. The greatest dissolved methane concentrations (6.5 nM) were found in the near-bottom layer (357 m) above the Koko summit. For Koko guyot, the greatest CH4 content (3.9–6.5 nM) was mainly associated with the subsurface (10–300 m) layer above the summit. However, another methane plume (6 nM) was detected at 1000 m on the western slope of the guyot. We propose that methane maximum was caused by the influence of the Kuroshio Extension or deep eddies. The CH4 distribution over Jingu gyuot was similar to that in open ocean waters. The greatest methane concentrations (3.8–6 nM) were found in the subsurface layers above the summit. Methane exceeded atmospheric equilibrium concentration in the surface (5–52 % supersaturation) layer for both Koko and Jingu. The methane content and supersaturation level in the subsurface layer was at least two times higher than previously measured values for the open ocean. We believe that the high methane and supersaturation level was caused by enhanced methanogenesis in the water column above the seamounts. The estimated methane flux to the atmosphere varied from 1.4 to 16.3 μmol m−2 day−1 for Koko and from 0.5 to 6.5 μmol m−2 day−1 for Jingu, respectively. The average fluxes calculated for Koko (8.37 μmol m−2 day−1) and Jingu (2.8 μmol m−2 day−1) were significantly greater than the average flux for open and coastal oceans. Given the substantial methane atmospheric contributions, the global methane budget should be reconsidered.
{"title":"Methane distribution above the Emperor Seamount chain","authors":"Nikita S. Polonik, Alexey A. Legkodimov","doi":"10.1016/j.dsr2.2024.105431","DOIUrl":"10.1016/j.dsr2.2024.105431","url":null,"abstract":"<div><div>Dissolved methane (CH<sub>4</sub>) concentrations were measured in the water column at 25 stations along the four sections above Koko and Jingu guyots (the southern part of Emperor Seamount chain). The measured methane concentrations were relatively low (1–6.5 nM). The patterns of CH<sub>4</sub> vertical distributions over Koko and Jingu were different. The greatest dissolved methane concentrations (6.5 nM) were found in the near-bottom layer (357 m) above the Koko summit. For Koko guyot, the greatest CH<sub>4</sub> content (3.9–6.5 nM) was mainly associated with the subsurface (10–300 m) layer above the summit. However, another methane plume (6 nM) was detected at 1000 m on the western slope of the guyot. We propose that methane maximum was caused by the influence of the Kuroshio Extension or deep eddies. The CH<sub>4</sub> distribution over Jingu gyuot was similar to that in open ocean waters. The greatest methane concentrations (3.8–6 nM) were found in the subsurface layers above the summit. Methane exceeded atmospheric equilibrium concentration in the surface (5–52 % supersaturation) layer for both Koko and Jingu. The methane content and supersaturation level in the subsurface layer was at least two times higher than previously measured values for the open ocean. We believe that the high methane and supersaturation level was caused by enhanced methanogenesis in the water column above the seamounts. The estimated methane flux to the atmosphere varied from 1.4 to 16.3 μmol m<sup>−2</sup> day<sup>−1</sup> for Koko and from 0.5 to 6.5 μmol m<sup>−2</sup> day<sup>−1</sup> for Jingu, respectively. The average fluxes calculated for Koko (8.37 μmol m<sup>−2</sup> day<sup>−1</sup>) and Jingu (2.8 μmol m<sup>−2</sup> day<sup>−1</sup>) were significantly greater than the average flux for open and coastal oceans. Given the substantial methane atmospheric contributions, the global methane budget should be reconsidered.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105431"},"PeriodicalIF":2.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534938","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}
The Ross Sea has been the site of extensive investigations since the earliest days of polar exploration. The International Geophysical Year of 1957-58 enhanced research activities with the establishment of scientific stations and the collection of oceanographic observations in the area. While many features of its oceanography, ecology, physics, glaciology, geology, and biogeochemistry are known, recent advances provide new insights into its structure and function, as well as into its relationship to global climate. We present a comprehensive review of the advances of understanding the main processes occurring in the area, such as the formation of dense shelf water and the production of Antarctic Bottom Water (AABW), as well as the main drivers (at both large and local scales) of local dynamics and water mass variability. We also summarize the main modeling applications, which are still limited and need to be improved using high-resolution models and, locally, limited-area models to explain processes driven mainly by thermodynamics and water-mass transformations. The Ross Sea forms the most saline AABW due to the activity of two polynyas in the western sector. A salinity gradient occurs on the shelf, with fresh Low Salinity Shelf Waters concentrated in the eastern Ross Sea, which is influenced by the inflow of fresh water from the Amundsen and Bellingshausen Seas. This freshwater inflow was thought to be the cause of a multi-decadal freshening of the High Salinity Shelf Water, precursor to the AABW, although a rebound in salinity in the Ross Sea has been observed since 2014. The increase in salinity has also affected the production of AABW, with the respective rebound occurring almost simultaneously.
{"title":"Ocean-atmosphere-ice processes in the Ross Sea: A review","authors":"Pierpaolo Falco , Giuseppe Aulicino , Pasquale Castagno , Vincenzo Capozzi , Paola de Ruggiero , Angela Garzia , Antonino Ian Ferola , Yuri Cotroneo , Alessio Colella , Giannetta Fusco , Stefano Pierini , Giorgio Budillon , Enrico Zambianchi , Giancarlo Spezie","doi":"10.1016/j.dsr2.2024.105429","DOIUrl":"10.1016/j.dsr2.2024.105429","url":null,"abstract":"<div><div>The Ross Sea has been the site of extensive investigations since the earliest days of polar exploration. The International Geophysical Year of 1957-58 enhanced research activities with the establishment of scientific stations and the collection of oceanographic observations in the area. While many features of its oceanography, ecology, physics, glaciology, geology, and biogeochemistry are known, recent advances provide new insights into its structure and function, as well as into its relationship to global climate. We present a comprehensive review of the advances of understanding the main processes occurring in the area, such as the formation of dense shelf water and the production of Antarctic Bottom Water (AABW), as well as the main drivers (at both large and local scales) of local dynamics and water mass variability. We also summarize the main modeling applications, which are still limited and need to be improved using high-resolution models and, locally, limited-area models to explain processes driven mainly by thermodynamics and water-mass transformations. The Ross Sea forms the most saline AABW due to the activity of two polynyas in the western sector. A salinity gradient occurs on the shelf, with fresh Low Salinity Shelf Waters concentrated in the eastern Ross Sea, which is influenced by the inflow of fresh water from the Amundsen and Bellingshausen Seas. This freshwater inflow was thought to be the cause of a multi-decadal freshening of the High Salinity Shelf Water, precursor to the AABW, although a rebound in salinity in the Ross Sea has been observed since 2014. The increase in salinity has also affected the production of AABW, with the respective rebound occurring almost simultaneously.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105429"},"PeriodicalIF":2.3,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534939","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}
As Antarctic sea ice extent continues to reach record lows, significant efforts have been directed towards understanding the underlying processes and their regional differences within the Southern Ocean. Here, we explore the dynamics of zonal sea ice transport at the eastern gate of the Ross Sea from 1988 to 2023 using GIOMAS-model and ERA5-reanalysis data. Our analysis reveals a modest overall increase in eastward sea ice transport (3.721 ± 0.672 km³/month per decade), with diverging trends in the coastal and open ocean zones. Driven by easterly winds and the Antarctic Slope Current, the predominant westward transport in the coastal region experienced a significant rise during the early 2000s, followed by a steep decline post-2011. Conversely, driven by the Antarctic Circumpolar Current, the strong open-ocean transport exhibited a moderate increase towards the Amundsen Sea until the late 1990s, which was interrupted by a reversal in 2007. The variability of zonal sea ice transport and its underlying conditions (sea ice concentration, thickness, and zonal drift) revealed considerable shifts throughout the different decades and on seasonal scales. During austral winter, approximately half of the zonal sea ice transport variability seems to be driven by large-scale teleconnections, including the Southern Annular Mode, Southern Oscillation Index, Amundsen Sea Low and the Zonal Wave 3 with considerable impacts on the wind stress field. Whereas during summer, the Southern Oscillation Index emerges as the dominant driver, exhibiting a significant positive correlation (r=0.55, p<0.001) that reflects the influence of the El Niño-Southern Oscillation, while other teleconnections play minimal roles. Our study highlights the complex nature of sea ice transport through the eastern gate of the Ross Sea towards the Amundsen Seas, where contrasting climatic conditions are known to occur.
{"title":"Exploring sea ice transport dynamics at the eastern gate of the Ross Sea","authors":"Naomi Krauzig , Daniela Flocco , Stefan Kern , Enrico Zambianchi","doi":"10.1016/j.dsr2.2024.105428","DOIUrl":"10.1016/j.dsr2.2024.105428","url":null,"abstract":"<div><div>As Antarctic sea ice extent continues to reach record lows, significant efforts have been directed towards understanding the underlying processes and their regional differences within the Southern Ocean. Here, we explore the dynamics of zonal sea ice transport at the eastern gate of the Ross Sea from 1988 to 2023 using GIOMAS-model and ERA5-reanalysis data. Our analysis reveals a modest overall increase in eastward sea ice transport (3.721 ± 0.672 km³/month per decade), with diverging trends in the coastal and open ocean zones. Driven by easterly winds and the Antarctic Slope Current, the predominant westward transport in the coastal region experienced a significant rise during the early 2000s, followed by a steep decline post-2011. Conversely, driven by the Antarctic Circumpolar Current, the strong open-ocean transport exhibited a moderate increase towards the Amundsen Sea until the late 1990s, which was interrupted by a reversal in 2007. The variability of zonal sea ice transport and its underlying conditions (sea ice concentration, thickness, and zonal drift) revealed considerable shifts throughout the different decades and on seasonal scales. During austral winter, approximately half of the zonal sea ice transport variability seems to be driven by large-scale teleconnections, including the Southern Annular Mode, Southern Oscillation Index, Amundsen Sea Low and the Zonal Wave 3 with considerable impacts on the wind stress field. Whereas during summer, the Southern Oscillation Index emerges as the dominant driver, exhibiting a significant positive correlation (r=0.55, p<0.001) that reflects the influence of the El Niño-Southern Oscillation, while other teleconnections play minimal roles. Our study highlights the complex nature of sea ice transport through the eastern gate of the Ross Sea towards the Amundsen Seas, where contrasting climatic conditions are known to occur.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"218 ","pages":"Article 105428"},"PeriodicalIF":2.3,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657493","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 : 2024-10-10DOI: 10.1016/j.dsr2.2024.105427
Raleigh R. Hood, Lynnath E. Beckley, V.V.S.S. Sarma, P.N. Vinayachandran
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Pub Date : 2024-09-28DOI: 10.1016/j.dsr2.2024.105425
Sven Nicolai Katzenmeier , Maren Nothof , Hans-Werner Breiner , Tim Fischer , Thorsten Stoeck
Mesoscale eddies which originate in Eastern Boundary Upwelling Systems (EBUS) such as the Canary Current System, entrap nutrient-rich coastal water and travel offshore while aging. We have analyzed the protistan plankton community structures in the deep chlorophyll maximum (DCM), sub-DCM, and oxygen minimum zone (OMZ) of three differently aged cyclonic EBUS eddies off Northwest Africa, as well as of non-eddy affected reference sites, using DNA metabarcoding. Throughout all water depths, we found that the investigated eddies generated local dispersal-driven hotspots of protistan plankton diversity in the naturally oligotrophic subtropical offshore waters off Northwest Africa. Based on the taxonomic composition of protistan plankton communities, these diversity hotspots are likely to play an important role in carbon sequestration and for regional food webs up to top predatory levels. Thereby, the life-span of an eddy emerged as an important criterion, how local offshore protistan plankton diversity is transformed quantitatively and qualitatively: each of the three eddies was characterized by notably distinct protistan plankton communities. This could be linked to the physicochemical water properties (predominantly macronutrients, temperature, and salinity) of the eddies' cores and rings, which experience pronounced changes during the eddies’ westward trajectories. Furthermore, we found evidence that eddy-specific deep-water protistan communities are relatively short-lived compared to the ones in the sunlit DCM. However, our results do not only witness from the importance of fine-scale physical ocean features for regional ecosystem processes, but they also show the complexity of these ocean features and that we are still far from understanding the biological processes and their driving forces in such features.
源自加那利洋流系统等东部边界上升流系统（EBUS）的中尺度漩涡，在老化过程中会捕获富含营养物质的沿岸水并向近海移动。我们利用 DNA 代谢编码技术分析了西北非附近三个不同老化程度的 EBUS 漩涡的深层叶绿素最高区（DCM）、亚 DCM 和最低含氧区（OMZ）以及未受漩涡影响的参照点的原生浮游生物群落结构。我们发现，在西北非近海天然寡营养亚热带近海水域的所有水深范围内，所调查的漩涡都产生了由扩散驱动的局部原生浮游生物多样性热点。根据原生动物浮游生物群落的分类组成，这些多样性热点可能在碳封存和区域食物网（直至顶级掠食性食物网）中发挥重要作用。因此，漩涡的寿命是一个重要标准，它决定了当地近海原生动物浮游生物多样性如何发生质和量的转变：三个漩涡中的每个漩涡都具有明显不同的原生动物浮游生物群落。这可能与漩涡核心和环的物理化学水属性（主要是大量营养物质、温度和盐度）有关，这些属性在漩涡向西移动的过程中经历了明显的变化。此外，我们发现有证据表明，与日照 DCM 中的原生动物群落相比，漩涡特有的深水原生动物群落寿命相对较短。然而，我们的研究结果不仅证明了细尺度物理海洋特征对区域生态系统过程的重要性，还显示了这些海洋特征的复杂性，以及我们对这些特征中的生物过程及其驱动力的了解还远远不够。
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