Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos

Stable isotopes of oxygen (δ18O) in seawater reflect the combined influences of ocean circulation and atmospheric moisture balance. However, it is difficult to disentangle disparate ocean and atmosphere influences on modern seawater δ18O values, partly because continuous time series of seawater δ18O...

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Main Authors: Conroy, Jessica L., Murray, Nicole K., Patterson, Gillian S., Schore, Aiden I. G., Ikuru, Ima, Cole, Julia E., Chillagana, David, Echeverria, Fernando
Format: Article in Journal/Newspaper
Language:unknown
Published: PO.DAAC, CA, USA 2023
Subjects:
Galápagos
seawater
salinity
Pacific Equatorial Undercurrent
stable isotope
Geological Sciences
Science
Antarctica Journal
Arctic
Online Access:https://hdl.handle.net/2027.42/175878
https://doi.org/10.1029/2022GL102074
id ftumdeepblue:oai:deepblue.lib.umich.edu:2027.42/175878
record_format openpolar
institution Open Polar
collection University of Michigan: Deep Blue
op_collection_id ftumdeepblue
language unknown
topic Galápagos
seawater
salinity
Pacific Equatorial Undercurrent
stable isotope
Geological Sciences
Science
spellingShingle Galápagos
seawater
salinity
Pacific Equatorial Undercurrent
stable isotope
Geological Sciences
Science
Conroy, Jessica L.
Murray, Nicole K.
Patterson, Gillian S.
Schore, Aiden I. G.
Ikuru, Ima
Cole, Julia E.
Chillagana, David
Echeverria, Fernando
Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos
topic_facet Galápagos
seawater
salinity
Pacific Equatorial Undercurrent
stable isotope
Geological Sciences
Science
description Stable isotopes of oxygen (δ18O) in seawater reflect the combined influences of ocean circulation and atmospheric moisture balance. However, it is difficult to disentangle disparate ocean and atmosphere influences on modern seawater δ18O values, partly because continuous time series of seawater δ18O are rare. Here we present a nearly nine-year, continuous record of seawater δ18O values from the Galápagos. Seawater δ18O values faithfully track sea surface salinity and salinity along the equator at 50 m depth. Zonal current velocity within the Equatorial Undercurrent (EUC), directly west of the Galápagos, is strongly correlated with Galápagos surface seawater δ18O values with a 1-month lag. Reconstructions of Galápagos seawater δ18O values could thus provide a window into past variations in the strength of the EUC, an important influence on large-scale tropical Pacific climate.Plain Language SummaryThe Equatorial Undercurrent (EUC) flows beneath the surface of the equatorial Pacific Ocean from west to east, transporting cold, salty, nutrient rich waters. When this current hits the Galápagos, it rises to the surface. Its high nutrient levels serve as the foundation for the diverse Galápagos ecosystem and its colder temperature helps set up a strong sea surface temperature gradient that is the foundation of the tropical Pacific climate system. Despite its importance, little is known about how this current has varied prior to the short period of instrumental observations, and it remains challenging to reproduce in climate models. Here we show how Galápagos seawater stable isotope values track the strength of the EUC. Our findings open up possibilities to extend the record of the EUC back in time with isotope-based paleoclimate proxies from the Galápagos region.Key PointsGalápagos seawater δ18O values strongly covary with equatorial cold tongue salinity valuesSeawater δ18O values are higher with a stronger Pacific Equatorial Undercurrent west of Galápagos Peer Reviewed ...
format Article in Journal/Newspaper
author Conroy, Jessica L.
Murray, Nicole K.
Patterson, Gillian S.
Schore, Aiden I. G.
Ikuru, Ima
Cole, Julia E.
Chillagana, David
Echeverria, Fernando
author_facet Conroy, Jessica L.
Murray, Nicole K.
Patterson, Gillian S.
Schore, Aiden I. G.
Ikuru, Ima
Cole, Julia E.
Chillagana, David
Echeverria, Fernando
author_sort Conroy, Jessica L.
title Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos
title_short Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos
title_full Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos
title_fullStr Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos
title_full_unstemmed Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos
title_sort equatorial undercurrent influence on surface seawater δ18o values in the galápagos
publisher PO.DAAC, CA, USA
publishDate 2023
url https://hdl.handle.net/2027.42/175878
https://doi.org/10.1029/2022GL102074
genre Antarctica Journal
Arctic
genre_facet Antarctica Journal
Arctic
op_relation Conroy, Jessica L.; Murray, Nicole K.; Patterson, Gillian S.; Schore, Aiden I. G.; Ikuru, Ima; Cole, Julia E.; Chillagana, David; Echeverria, Fernando (2023). "Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos." Geophysical Research Letters 50(4): n/a-n/a.
0094-8276
1944-8007
https://hdl.handle.net/2027.42/175878
doi:10.1029/2022GL102074
Geophysical Research Letters
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Liu, Y., Xie, L., Morrison, J. M., Kamykowski, D., & Sweet, W. V. ( 2014 ). Ocean circulation and water mass characteristics around the Galápagos Archipelago simulated by a multiscale nested ocean circulation model. International Journal of Oceanography, 2014, 1 – 16. https://doi.org/10.1155/2014/198686
Martin, N. J., Conroy, J. L., Noone, D., Cobb, K. M., Konecky, B. L., & Rea, S. ( 2018 ). Seasonal and ENSO influences on the stable isotopic composition of Galápagos precipitation. Journal of Geophysical Research: Atmospheres, 123 ( 1 ), 261 – 275. https://doi.org/10.1002/2017JD027380
McCulloch, M. T., Gagan, M. K., Mortimer, G. E., Chivas, A. R., & Isdale, P. J. ( 1994 ). A high-resolution Sr/Ca and δ 18 O coral record from the great barrier reef, Australia, and the 1982–1983 El Niño. Geochimica et Cosmochimica Acta, 58 ( 12 ), 2747 – 2754. https://doi.org/10.1016/0016-7037(94)90142-2
Melnichenko, D. O. ( 2016 ). IPRC/SOEST Aquarius V4.0 Optimally Interpolated Sea Surface Salinity 7-Day global Dataset. Ver. 4.0. PO.DAAC, CA, USA. https://doi.org/10.5067/AQR40-4U7CS
Palacios, D. M. ( 2004 ). Seasonal patterns of sea-surface temperature and ocean color around the galapagos: Regional and local influences. Deep Sea Research Part II: Topical Studies in Oceanography, 51 ( 1–3 ), 43 – 57. https://doi.org/10.1016/j.dsr2.2003.08.001
Reed, E. V., Thompson, D. M., & Anchukaitis, K. J. ( 2022 ). Coral-based sea surface salinity reconstructions and the role of observational uncertainties in inferred variability and trends. Paleoceanography and Paleoclimatology, 37 ( 6 ), e2021PA004371. https://doi.org/10.1029/2021PA004371
Reyes-Macaya, D., Hoogakker, B., Martinez-Mendez, G., Llanillo, P. J., Grasse, P., Mohtadi, M., et al. ( 2022 ). Isotopic characterization of water masses in the southeast Pacific region: Paleoceanographic implications. Journal of Geophysical Research: Oceans, 127 ( 1 ), e2021JC017525. https://doi.org/10.1029/2021JC017525
Rudnick, D. L., Owens, W. B., Johnston, T. S., Karnauskas, K. B., Jakoboski, J., & Todd, R. E. ( 2021 ). The equatorial current system west of the Galápagos islands during the 2014–16 El Niño as observed by underwater gliders. Journal of Physical Oceanography, 51 ( 1 ), 3 – 17. https://doi.org/10.1175/jpo-d-20-0064.1
Russon, T., Tudhope, A., Hegerl, G., Collins, M., & Tindall, J. ( 2013 ). Inter-annual tropical Pacific climate variability in an isotope-enabled CGCM: Implications for interpreting coral stable oxygen isotope records of ENSO. Climate of the Past, 9 ( 4 ), 1543 – 1557. https://doi.org/10.5194/cp-9-1543-2013
Rustic, G. T., Koutavas, A., Marchitto, T. M., & Linsley, B. K. ( 2015 ). Dynamical excitation of the tropical Pacific ocean and ENSO variability by little ice age cooling. Science, 350 ( 6267 ), 1537 – 1541. https://doi.org/10.1126/science.aac9937
Schlosser, P., Newton, R., Ekwurzel, B., Khatiwala, S., Mortlock, R., & Fairbanks, R. ( 2002 ). Decrease of river runoff in the upper waters of the Eurasian basin, Arctic ocean, between 1991 and 1996: Evidence from δ 18 O data. Geophysical Research Letters, 29 ( 9 ), 3-1 – 3-4. https://doi.org/10.1029/2001gl013135
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Thompson, D. M., Conroy, J. L., Konecky, B. L., Stevenson, S., DeLong, K. L., McKay, N., et al. ( 2022 ). Identifying hydro-sensitive coral delta O-18 records for improved high-resolution temperature and salinity reconstructions. Geophysical Research Letters, 49 ( 9 ), e2021GL096153. https://doi.org/10.1029/2021gl096153
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van Geldern, R., & Barth, J. A. C. ( 2012 ). Optimization of instrument setup and post-run corrections for oxygen and hydrogen stable isotope measurements of water by isotope ratio infrared spectroscopy (IRIS). Limnology and Oceanography: Methods, 10 ( 12 ), 1024 – 1036. https://doi.org/10.4319/lom.2012.10.1024
Walter, R. M., Sayani, H. R., Felis, T., Cobb, K. M., Abram, N. J., Arzey, A. K., et al. ( 2022 ). The CoralHydro2k database: A global, actively curated compilation of coral δ 18 O and Sr/Ca proxy records of tropical ocean hydrology and temperature for the common era. Earth System Science Data Discussions, 1 – 56.
Warrier, R. B., Castro, M. C., & Hall, C. M. ( 2012 ). Recharge and source-water insights from the Galapagos Islands using noble gases and stable isotopes. Water Resources Research, 48 ( 3 ), W03508. https://doi.org/10.1029/2011wr010954
Wellington, G. M., Dunbar, R. B., & Merlen, G. ( 1996 ). Calibration of stable oxygen isotope signatures in Galapagos corals. Paleoceanography, 11 ( 4 ), 467 – 480. https://doi.org/10.1029/96pa01023
Yin, Y., Alves, O., & Oke, P. R. ( 2011 ). An ensemble ocean data assimilation system for seasonal prediction. Monthly Weather Review, 139 ( 3 ), 786 – 808. https://doi.org/10.1175/2010mwr3419.1
Yu, L. S., & Weller, R. A. ( 2007 ). Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005). Bulletin of the American Meteorological Society, 88 ( 4 ), 527 – 539. https://doi.org/10.1175/BAMS-88-4-527
Abe, O., Agata, S., Morimoto, M., Abe, M., Yoshimura, K., Hiyama, T., & Yoshida, N. ( 2009 ). A 6.5-year continuous record of sea surface salinity and seawater isotopic composition at Harbour of Ishigaki Island, southwest Japan. Isotopes in Environmental and Health Studies, 45 ( 3 ), 247 – 258. https://doi.org/10.1080/10256010903083847
Benway, H. M., & Mix, A. C. ( 2004 ). Oxygen isotopes, upper-ocean salinity, and precipitation sources in the eastern tropical Pacific. Earth and Planetary Science Letters, 224 ( 3–4 ), 493 – 507. https://doi.org/10.1016/j.epsl.2004.05.014
Garcia, A. M., Winemiller, K., Hoeinghaus, D., Claudino, M., Bastos, R., Correa, F., et al. ( 2017 ). Hydrologic pulsing promotes spatial connectivity and food web subsidies in a subtropical coastal ecosystem. Marine Ecology Progress Series, 567, 17 – 28. https://doi.org/10.3354/meps12060
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Morimoto, M., Abe, O., Kayanne, H., Kurita, N., Matsumoto, E., & Yoshida, N. ( 2002 ). Salinity records for the 1997-98 El Nino from Western Pacific corals. Geophysical Research Letters, 29 ( 11 ), 1540. https://doi.org/10.1029/2001GL013521
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spelling ftumdeepblue:oai:deepblue.lib.umich.edu:2027.42/175878 2024-04-28T08:03:27+00:00 Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos Conroy, Jessica L. Murray, Nicole K. Patterson, Gillian S. Schore, Aiden I. G. Ikuru, Ima Cole, Julia E. Chillagana, David Echeverria, Fernando 2023-02-28 application/pdf https://hdl.handle.net/2027.42/175878 https://doi.org/10.1029/2022GL102074 unknown PO.DAAC, CA, USA Wiley Periodicals, Inc. Conroy, Jessica L.; Murray, Nicole K.; Patterson, Gillian S.; Schore, Aiden I. G.; Ikuru, Ima; Cole, Julia E.; Chillagana, David; Echeverria, Fernando (2023). "Equatorial Undercurrent Influence on Surface Seawater δ18O Values in the Galápagos." Geophysical Research Letters 50(4): n/a-n/a. 0094-8276 1944-8007 https://hdl.handle.net/2027.42/175878 doi:10.1029/2022GL102074 Geophysical Research Letters Shen, G. T., Cole, J. E., Lea, D. W., Linn, L. J., McConnaughey, T. A., & Fairbanks, R. G. ( 1992 ). Surface ocean variability at Galapagos from 1936–1982: Calibration of geochemical tracers in corals. Paleoceanography, 7 ( 5 ), 563 – 588. https://doi.org/10.1029/92pa01825 Liu, Y., Xie, L., Morrison, J. M., Kamykowski, D., & Sweet, W. V. ( 2014 ). Ocean circulation and water mass characteristics around the Galápagos Archipelago simulated by a multiscale nested ocean circulation model. International Journal of Oceanography, 2014, 1 – 16. https://doi.org/10.1155/2014/198686 Martin, N. J., Conroy, J. L., Noone, D., Cobb, K. M., Konecky, B. L., & Rea, S. ( 2018 ). Seasonal and ENSO influences on the stable isotopic composition of Galápagos precipitation. Journal of Geophysical Research: Atmospheres, 123 ( 1 ), 261 – 275. https://doi.org/10.1002/2017JD027380 McCulloch, M. T., Gagan, M. K., Mortimer, G. E., Chivas, A. R., & Isdale, P. J. ( 1994 ). A high-resolution Sr/Ca and δ 18 O coral record from the great barrier reef, Australia, and the 1982–1983 El Niño. Geochimica et Cosmochimica Acta, 58 ( 12 ), 2747 – 2754. https://doi.org/10.1016/0016-7037(94)90142-2 Melnichenko, D. O. ( 2016 ). IPRC/SOEST Aquarius V4.0 Optimally Interpolated Sea Surface Salinity 7-Day global Dataset. Ver. 4.0. PO.DAAC, CA, USA. https://doi.org/10.5067/AQR40-4U7CS Palacios, D. M. ( 2004 ). Seasonal patterns of sea-surface temperature and ocean color around the galapagos: Regional and local influences. Deep Sea Research Part II: Topical Studies in Oceanography, 51 ( 1–3 ), 43 – 57. https://doi.org/10.1016/j.dsr2.2003.08.001 Reed, E. V., Thompson, D. M., & Anchukaitis, K. J. ( 2022 ). Coral-based sea surface salinity reconstructions and the role of observational uncertainties in inferred variability and trends. Paleoceanography and Paleoclimatology, 37 ( 6 ), e2021PA004371. https://doi.org/10.1029/2021PA004371 Reyes-Macaya, D., Hoogakker, B., Martinez-Mendez, G., Llanillo, P. J., Grasse, P., Mohtadi, M., et al. ( 2022 ). Isotopic characterization of water masses in the southeast Pacific region: Paleoceanographic implications. Journal of Geophysical Research: Oceans, 127 ( 1 ), e2021JC017525. https://doi.org/10.1029/2021JC017525 Rudnick, D. L., Owens, W. B., Johnston, T. S., Karnauskas, K. B., Jakoboski, J., & Todd, R. E. ( 2021 ). The equatorial current system west of the Galápagos islands during the 2014–16 El Niño as observed by underwater gliders. Journal of Physical Oceanography, 51 ( 1 ), 3 – 17. https://doi.org/10.1175/jpo-d-20-0064.1 Russon, T., Tudhope, A., Hegerl, G., Collins, M., & Tindall, J. ( 2013 ). Inter-annual tropical Pacific climate variability in an isotope-enabled CGCM: Implications for interpreting coral stable oxygen isotope records of ENSO. Climate of the Past, 9 ( 4 ), 1543 – 1557. https://doi.org/10.5194/cp-9-1543-2013 Rustic, G. T., Koutavas, A., Marchitto, T. M., & Linsley, B. K. ( 2015 ). Dynamical excitation of the tropical Pacific ocean and ENSO variability by little ice age cooling. Science, 350 ( 6267 ), 1537 – 1541. https://doi.org/10.1126/science.aac9937 Schlosser, P., Newton, R., Ekwurzel, B., Khatiwala, S., Mortlock, R., & Fairbanks, R. ( 2002 ). Decrease of river runoff in the upper waters of the Eurasian basin, Arctic ocean, between 1991 and 1996: Evidence from δ 18 O data. Geophysical Research Letters, 29 ( 9 ), 3-1 – 3-4. https://doi.org/10.1029/2001gl013135 Schmidt, G. A., Bigg, G. R., & Rohling, E. J. ( 1999 ). Global seawater oxygen-18 database. Retrieved from http://data.giss.nasa.gov/o18data/ Stevenson, S., Powell, B. S., Cobb, K. M., Nusbaumer, J., Merrifield, M. A., & Noone, D. ( 2018 ). 20th century seawater δ 18 O Dynamics and implications for coral-based climate reconstruction. Paleoceanography and Paleoclimatology, 33 ( 6 ), 606 – 625. https://doi.org/10.1029/2017PA003304 Thompson, D. M., Conroy, J. L., Konecky, B. L., Stevenson, S., DeLong, K. L., McKay, N., et al. ( 2022 ). Identifying hydro-sensitive coral delta O-18 records for improved high-resolution temperature and salinity reconstructions. Geophysical Research Letters, 49 ( 9 ), e2021GL096153. https://doi.org/10.1029/2021gl096153 Trueman, M., & d’Ozouville, N. ( 2010 ). Characterizing the Galápagos terrestrial climate in the face of global climate change. Galápagos Research, 67, 26 – 37. van Geldern, R., & Barth, J. A. C. ( 2012 ). Optimization of instrument setup and post-run corrections for oxygen and hydrogen stable isotope measurements of water by isotope ratio infrared spectroscopy (IRIS). Limnology and Oceanography: Methods, 10 ( 12 ), 1024 – 1036. https://doi.org/10.4319/lom.2012.10.1024 Walter, R. M., Sayani, H. R., Felis, T., Cobb, K. M., Abram, N. J., Arzey, A. K., et al. ( 2022 ). The CoralHydro2k database: A global, actively curated compilation of coral δ 18 O and Sr/Ca proxy records of tropical ocean hydrology and temperature for the common era. Earth System Science Data Discussions, 1 – 56. Warrier, R. B., Castro, M. C., & Hall, C. M. ( 2012 ). Recharge and source-water insights from the Galapagos Islands using noble gases and stable isotopes. Water Resources Research, 48 ( 3 ), W03508. https://doi.org/10.1029/2011wr010954 Wellington, G. M., Dunbar, R. B., & Merlen, G. ( 1996 ). Calibration of stable oxygen isotope signatures in Galapagos corals. Paleoceanography, 11 ( 4 ), 467 – 480. https://doi.org/10.1029/96pa01023 Yin, Y., Alves, O., & Oke, P. R. ( 2011 ). An ensemble ocean data assimilation system for seasonal prediction. Monthly Weather Review, 139 ( 3 ), 786 – 808. https://doi.org/10.1175/2010mwr3419.1 Yu, L. S., & Weller, R. A. ( 2007 ). Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005). Bulletin of the American Meteorological Society, 88 ( 4 ), 527 – 539. https://doi.org/10.1175/BAMS-88-4-527 Abe, O., Agata, S., Morimoto, M., Abe, M., Yoshimura, K., Hiyama, T., & Yoshida, N. ( 2009 ). A 6.5-year continuous record of sea surface salinity and seawater isotopic composition at Harbour of Ishigaki Island, southwest Japan. Isotopes in Environmental and Health Studies, 45 ( 3 ), 247 – 258. https://doi.org/10.1080/10256010903083847 Benway, H. M., & Mix, A. C. ( 2004 ). Oxygen isotopes, upper-ocean salinity, and precipitation sources in the eastern tropical Pacific. Earth and Planetary Science Letters, 224 ( 3–4 ), 493 – 507. https://doi.org/10.1016/j.epsl.2004.05.014 Garcia, A. M., Winemiller, K., Hoeinghaus, D., Claudino, M., Bastos, R., Correa, F., et al. ( 2017 ). Hydrologic pulsing promotes spatial connectivity and food web subsidies in a subtropical coastal ecosystem. Marine Ecology Progress Series, 567, 17 – 28. https://doi.org/10.3354/meps12060 IAEA/WMO. ( 2022 ). International atomic energy agency/world meteorological organization global network for isotopes in precipitation. The GNIP Database. 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Quarterly Journal of the Royal Meteorological Society, 146 ( 730 ), 1999 – 2049. https://doi.org/10.1002/qj.3803 IndexNoFollow Galápagos seawater salinity Pacific Equatorial Undercurrent stable isotope Geological Sciences Science Article 2023 ftumdeepblue https://doi.org/10.1029/2022GL10207410.5067/AQR40-4U7CS10.1016/j.dsr2.2003.08.00110.1029/2021JC01752510.1029/2021gl09615310.3354/meps1206010.1016/s0304-4203(99)00014-610.1038/s41598-021-86043-210.1175/bams-d-13-00117.110.26022/IEDA/11275010.1002/qj.380310 2024-04-03T14:01:00Z Stable isotopes of oxygen (δ18O) in seawater reflect the combined influences of ocean circulation and atmospheric moisture balance. However, it is difficult to disentangle disparate ocean and atmosphere influences on modern seawater δ18O values, partly because continuous time series of seawater δ18O are rare. Here we present a nearly nine-year, continuous record of seawater δ18O values from the Galápagos. Seawater δ18O values faithfully track sea surface salinity and salinity along the equator at 50 m depth. Zonal current velocity within the Equatorial Undercurrent (EUC), directly west of the Galápagos, is strongly correlated with Galápagos surface seawater δ18O values with a 1-month lag. Reconstructions of Galápagos seawater δ18O values could thus provide a window into past variations in the strength of the EUC, an important influence on large-scale tropical Pacific climate.Plain Language SummaryThe Equatorial Undercurrent (EUC) flows beneath the surface of the equatorial Pacific Ocean from west to east, transporting cold, salty, nutrient rich waters. When this current hits the Galápagos, it rises to the surface. Its high nutrient levels serve as the foundation for the diverse Galápagos ecosystem and its colder temperature helps set up a strong sea surface temperature gradient that is the foundation of the tropical Pacific climate system. Despite its importance, little is known about how this current has varied prior to the short period of instrumental observations, and it remains challenging to reproduce in climate models. Here we show how Galápagos seawater stable isotope values track the strength of the EUC. Our findings open up possibilities to extend the record of the EUC back in time with isotope-based paleoclimate proxies from the Galápagos region.Key PointsGalápagos seawater δ18O values strongly covary with equatorial cold tongue salinity valuesSeawater δ18O values are higher with a stronger Pacific Equatorial Undercurrent west of Galápagos Peer Reviewed ... Article in Journal/Newspaper Antarctica Journal Arctic University of Michigan: Deep Blue

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