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  • 2020-2024  (6)
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  • 1
    Publication Date: 2024-02-02
    Description: The Antarctic Cold Reversal (ACR; 14.7 to 13 ka) phase of the last deglaciation saw a pause in the rise of atmospheric pCO2 and Antarctic temperature, contrasted with warming in the North. Mechanisms associated with interhemispheric heat transfer have been proposed to explain features of this event, but the response of marine biota and the carbon cycle are debated. The Southern Ocean is a key site of deep-water exchange with the atmosphere, hence deglacial changes in nutrient cycling, circulation, and productivity in this region may have global impact. Here we present a new perspective on the sequence of events in the deglacial Southern Ocean, that includes multi-faunal benthic assemblage (foraminifera and cold-water corals) and geochemical data (Ba/Ca, 14C, δ11B) from the Drake Passage. Our records feature anomalies during peak ACR conditions indicative of circulation, biogeochemistry, and regional ecosystem perturbations. Within this cold episode, peak abundances of thick-walled benthic foraminifera and cold-water corals are observed at shallow depths in the sub-Antarctic (~300 m), while coral populations at greater depths and further south diminished. Geochemical data indicate that habitat shifts were associated with enhanced primary productivity in the sub-Antarctic, a more stratified water column, and poorly oxygenated bottom water. These results are consistent with northward migration of primary production in response to Antarctic cooling and widespread biotic turnover across the Southern Ocean. We suggest that expanding sea ice, suppressed ventilation, and shifting centres of upwelling drove changes in planktic and benthic ecology, and were collectively instrumental in halting CO2 rise in the mid-deglaciation.
    Keywords: AGE; Age, uncertainty; Barium/Calcium ratio; Benthic foraminifera; circulation; cold-water corals; Comment; Depth, bathymetric; DH117; DH74; DH75; DR27; DR34; DR35; DR38; DR40; Drake Passage; Dredge; DRG; Elevation of event; Event label; Genus; Latitude of event; Longitude of event; Nathaniel B. Palmer; NBP0805; NBP0805-DR27; NBP0805-DR34; NBP0805-DR35; NBP0805-DR36; NBP0805-DR38; NBP0805-DR40; NBP0805-TB04; NBP1103; NBP1103-DH07; NBP1103-DH11; NBP1103-DH112; NBP1103-DH113; NBP1103-DH117; NBP1103-DH120; NBP1103-DH14; NBP1103-DH15; NBP1103-DH16; NBP1103-DH19; NBP1103-DH74; NBP1103-DH75; pH; productivity; Reference/source; Sample ID; Site; South Pacific Ocean; δ11B, carbonate
    Type: Dataset
    Format: text/tab-separated-values, 1741 data points
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2024-02-02
    Description: The Antarctic Cold Reversal (ACR; 14.7 to 13 ka) phase of the last deglaciation saw a pause in the rise of atmospheric pCO2 and Antarctic temperature, contrasted with warming in the North. Mechanisms associated with interhemispheric heat transfer have been proposed to explain features of this event, but the response of marine biota and the carbon cycle are debated. The Southern Ocean is a key site of deep-water exchange with the atmosphere, hence deglacial changes in nutrient cycling, circulation, and productivity in this region may have global impact. Here we present a new perspective on the sequence of events in the deglacial Southern Ocean, that includes multi-faunal benthic assemblage (foraminifera and cold-water corals) and geochemical data (Ba/Ca, 14C, δ11B) from the Drake Passage. Our records feature anomalies during peak ACR conditions indicative of circulation, biogeochemistry, and regional ecosystem perturbations. Within this cold episode, peak abundances of thick-walled benthic foraminifera and cold-water corals are observed at shallow depths in the sub-Antarctic (~300 m), while coral populations at greater depths and further south diminished. Geochemical data indicate that habitat shifts were associated with enhanced primary productivity in the sub-Antarctic, a more stratified water column, and poorly oxygenated bottom water. These results are consistent with northward migration of primary production in response to Antarctic cooling and widespread biotic turnover across the Southern Ocean. We suggest that expanding sea ice, suppressed ventilation, and shifting centres of upwelling drove changes in planktic and benthic ecology, and were collectively instrumental in halting CO2 rise in the mid-deglaciation.
    Keywords: AGE; Age, error; Benthic foraminifera; circulation; cold-water corals; DH117; DH40; DH43; DH74; DH75; DR23; DR27; DR34; DR35; DR38; DR40; Drake Passage; Dredge; DRG; Elevation of event; Event label; Genus; Latitude of event; Location; Method comment; Nathaniel B. Palmer; NBP0805; NBP0805-DR22; NBP0805-DR23; NBP0805-DR27; NBP0805-DR34; NBP0805-DR35; NBP0805-DR36; NBP0805-DR38; NBP0805-DR39; NBP0805-DR40; NBP0805-TB04; NBP0805-TB04a; NBP1103; NBP1103-DH07; NBP1103-DH09; NBP1103-DH11; NBP1103-DH112; NBP1103-DH113; NBP1103-DH115; NBP1103-DH117; NBP1103-DH120; NBP1103-DH128; NBP1103-DH129; NBP1103-DH134; NBP1103-DH138; NBP1103-DH14; NBP1103-DH140; NBP1103-DH141; NBP1103-DH143; NBP1103-DH15; NBP1103-DH16; NBP1103-DH19; NBP1103-DH22; NBP1103-DH24; NBP1103-DH36; NBP1103-DH37; NBP1103-DH38; NBP1103-DH40; NBP1103-DH43; NBP1103-DH74; NBP1103-DH75; NBP1103-DH87; NBP1103-DH88; NBP1103-DH91; NBP1103-DH95; NBP1103-DH96; NBP1103-DH97; NBP1103-TB01; NBP1103-TB02; NBP1103-TB10; NBP1103-TO104; pH; productivity; Reference/source; Sample ID; Scotia Sea; South Pacific Ocean
    Type: Dataset
    Format: text/tab-separated-values, 8524 data points
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2024-02-02
    Description: The Antarctic Cold Reversal (ACR; 14.7 to 13 ka) phase of the last deglaciation saw a pause in the rise of atmospheric pCO2 and Antarctic temperature, contrasted with warming in the North. Mechanisms associated with interhemispheric heat transfer have been proposed to explain features of this event, but the response of marine biota and the carbon cycle are debated. The Southern Ocean is a key site of deep-water exchange with the atmosphere, hence deglacial changes in nutrient cycling, circulation, and productivity in this region may have global impact. Here we present a new perspective on the sequence of events in the deglacial Southern Ocean, that includes multi-faunal benthic assemblage (foraminifera and cold-water corals) and geochemical data (Ba/Ca, 14C, δ11B) from the Drake Passage. Our records feature anomalies during peak ACR conditions indicative of circulation, biogeochemistry, and regional ecosystem perturbations. Within this cold episode, peak abundances of thick-walled benthic foraminifera and cold-water corals are observed at shallow depths in the sub-Antarctic (~300 m), while coral populations at greater depths and further south diminished. Geochemical data indicate that habitat shifts were associated with enhanced primary productivity in the sub-Antarctic, a more stratified water column, and poorly oxygenated bottom water. These results are consistent with northward migration of primary production in response to Antarctic cooling and widespread biotic turnover across the Southern Ocean. We suggest that expanding sea ice, suppressed ventilation, and shifting centres of upwelling drove changes in planktic and benthic ecology, and were collectively instrumental in halting CO2 rise in the mid-deglaciation.
    Keywords: Alabaminella weddellensis; Angulogerina earlandi; Bolivina spp.; Bulimina aculeata; Bulimina sp.; Calendar age; Cassidulina carinata; Cassidulina crassa; Cibicidoides spp.; Core; DEPTH, sediment/rock; Epistominella exigua; Falkland Plateau, Southern Falkland Plateau (same site as GC526); Fissurina spp.; Foraminifera; Foraminifera, benthic agglutinated; Fursenkoina fusiformis; GC; GC528 CORE_NO 528; Globobulimina sp.; Gravity corer; Hoeglundina elegans; Hoeglundina sp.; James Clark Ross; JR20110128; JR244; JR244-GC528; Lagena spp.; Melonis barleeanus; Melonis spp.; Nonionella auris; Nonionella pulchella; Nonionella spp.; Number of taxa; Nuttallides umbonifera; Oridorsalis sp.; Oridorsalis umbonatus; Pullenia bulloides; Pullenia quinqueloba; Pyrgo spp.; Sphaeroidina bulloides; Total counts; Triloculina spp.; Uvigerina bifurcata; Uvigerina spp.; Wet mass
    Type: Dataset
    Format: text/tab-separated-values, 4995 data points
    Location Call Number Limitation Availability
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  • 4
    Publication Date: 2023-08-08
    Description: Through the Cooperative Study of the Kuroshio and Adjacent Regions (CSK) program during 1965–1979, the capacities of current member states (MSs) of the Sub-Commission for the Western Pacific (WESTPAC) of the Intergovernmental Oceanographic Commission (IOC) were enhanced with regard to regional ocean science and data management. Following the termination of the CSK in 1979, each MS continued the work to advance ocean science. The results of scientific studies of the Kuroshio and its adjacent regions have been published by various experts including many from the MSs of the WESTPAC; however, to-date, there has been no systematic approach to the research of the Kuroshio and its adjacent regions. This review considered the Kuroshio from the regional perspective of experts of the MSs, that is, from the perspectives of MSs, science, and the future prospects. Experts from each MS reviewed past activities and con tributions and reviewed the knowledge gaps in the fields of physical, biological, and biogeochemical science. Many scientific questions remain regarding the path of the Kuroshio from south to north, as well as associated phenomena, including mesoscale eddies and fronts, the important roles of ocean variations in adjacent regions, and the different roles and mechanisms of air–sea interactions in low- and mid-latitude areas. Despite consid erable effort by many biologists, substantial gaps remain in our biological knowledge of the region. The Kuroshio and its adjacent regions comprise one of the areas of the world with high biodiversity; however, there has been insufficient research into what is the cause of this high biodiversity. From a biogeochemical aspect, high resolution spatiotemporal observations will be required to understand interactions with physical processes both in the Kuroshio region and in the marginal seas. It has been highlighted that long-term fixed-location observations will be needed to understand the key mechanisms of biogeochemical processes, particularly in relation to climate change.
    Description: From Decade Action UN24. Explore the strongest ocean current in the Western Pacific: the 2nd Cooperative Study of Kuroshio and Adjacent Regions – from its sciences to human well beings (CSK-2)
    Description: Published
    Description: Refereed
    Keywords: Marginal seas ; CSK ; IOC ; WESTPAC
    Repository Name: AquaDocs
    Type: Journal Contribution
    Format: 35pp.
    Location Call Number Limitation Availability
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  • 5
    Publication Date: 2024-02-07
    Description: Nitric oxide (NO) is an atmospheric pollutant and climate forcer as well as a key intermediary in the marine nitrogen cycle, but the ocean’s NO contribution and production mechanisms remain unclear. Here, high-resolution NO observations were conducted simultaneously in the surface ocean and the lower atmosphere of the Yellow Sea and the East China Sea; moreover, NO production from photolysis and microbial processes was analyzed. The NO sea–air exchange showed uneven distributions (RSD = 349.1%) with an average flux of 5.3 ± 18.5 × 10–17 mol cm–2 s–1. In coastal waters where nitrite photolysis was the predominant source (89.0%), NO concentrations were remarkably higher (84.7%) than the overall average of the study area. The NO from archaeal nitrification accounted for 52.8% of all microbial production (11.0%). We also examined the relationship between gaseous NO and ozone which helped identify sources of atmospheric NO. The sea-to-air flux of NO in coastal waters was narrowed by contaminated air with elevated NO concentrations. These findings indicate that the emissions of NO from coastal waters, mainly controlled by reactive nitrogen inputs, will increase with the reduced terrestrial NO discharge.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
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  • 6
    Publication Date: 2024-02-07
    Description: Subtropical gyres cover 26%-29% of the world's surface ocean and are conventionally regarded as ocean deserts due to their permanent stratification, depleted surface nutrients, and low biological productivity. Despite tremendous advances over the past three decades, particularly through the Hawaii Ocean Time-series and the Bermuda Atlantic Time-series Study, which have revolutionized our understanding of the biogeochemistry in oligotrophic marine ecosystems, the gyres remain understudied. We review current understanding of upper ocean biogeochemistry in the North Pacific Subtropical Gyre, considering other subtropical gyres for comparison. We focus our synthesis on spatial variability, which shows larger than expected dynamic ranges of properties such as nutrient concentrations, rates of N-2 fixation, and biological production. This review provides new insights into how nutrient sources drive community structure and export in upper subtropical gyres. We examine the euphotic zone (EZ) in subtropical gyres as a two-layered vertically structured system: a nutrient-depleted layer above the top of the nutricline in the well-lit upper ocean and a nutrient-replete layer below in the dimly lit waters. These layers vary in nutrient supply and stoichiometries and physical forcing, promoting differences in community structure and food webs, with direct impacts on the magnitude and composition of export production. We evaluate long-term variations in key biogeochemical parameters in both of these EZ layers. Finally, we identify major knowledge gaps and research challenges in these vast and unique systems that offer opportunities for future studies. Key Points Subtropical gyres display larger spatiotemporal dynamics in biogeochemical properties than previously considered An improved two-layer framework is proposed for the study of nutrient-driven and biologically mediated carbon export in the euphotic zone Future research will benefit from high-resolution samplings, improved sensitivity of nutrient analyses, and advanced modeling capabilities
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Limitation Availability
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