Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612
The development of modern glacial climates occurred during the Eocene-Oligocene transition (34 to 35.5 Ma) when a decrease of atmospheric CO2 led to a global temperature fall. The ocean was deeply affected, both in the surface and the deep-sea, suffering a strong reorganization including currents an...
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ftuppsalauniv:oai:DiVA.org:uu-256769 2023-05-15T17:32:33+02:00 Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 Fytoplanktons respons till klimatförändringar under Eocen-Oligocen övergången vid Nordatlanten ODP Site 612 Rivero Cuesta, Lucía 2015 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256769 eng eng Uppsala universitet, Institutionen för geovetenskaper Examensarbete vid Institutionen för geovetenskaper, 1650-6553 328 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256769 info:eu-repo/semantics/openAccess Phytoplankton abundance coccoliths silica Eocene Oligocene Fytoplankton antal coccoliter kisel Eocen Oligocen Fitoplancton abundancia cocolitos sílice Eoceno Oligoceno Student thesis info:eu-repo/semantics/bachelorThesis text 2015 ftuppsalauniv 2023-02-23T21:38:33Z The development of modern glacial climates occurred during the Eocene-Oligocene transition (34 to 35.5 Ma) when a decrease of atmospheric CO2 led to a global temperature fall. The ocean was deeply affected, both in the surface and the deep-sea, suffering a strong reorganization including currents and phytoplankton distribution. Spanning that time, 35 samples from the North Atlantic Ocean Drilling Program Site 612 have been analyzed by counting coccoliths abundance in different size groups (< 4 µm, 4 to 8 µm and > 8 µm) and silica fragments abundance. Absolute coccoliths abundance were estimated with two different methods, the “drop” technique and microbeads calibration. In addition, a fragmentation index was calculated to assess the preservational state of the samples. The results obtained fit in the global picture of a decrease in phytoplankton abundance across theEocene-Oligocene boundary, although coccolith and silica fragments abundances show slight different patterns. Absolute abundances estimates showed a large difference between the “drop” and the microbeads methods. The temperature at which samples are dried seems to affect microbeads distribution, leading to an underestimation at temperatures higher than 60º C. In future work the current dataset will be updated with additional calibration and replicate counts to confirm that the “drop” estimates are the more valid results. As the fragmentation index was fairly constant in all samples, no major differences in nannofossil preservation were inferred. Coccoliths abundance drops are thought to be triggered by global temperature fall, general decrease of atmospheric CO2, changes in oceanic circulation, pulses of nutrients or a combination of those. Under tidsspannet som täcker övergången mellan eocen och oligocen, för ungefär 35.5 till 34 miljoner år sedan, genomgick jordens klimat en stor förändring. Under eocen hade vår planet ett varmare klimat och var i ett så kallat ”greenhouse state”. Mot slutet av denna period och i början av oligocen skiftade ... Bachelor Thesis North Atlantic Uppsala University: Publications (DiVA) |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Phytoplankton abundance coccoliths silica Eocene Oligocene Fytoplankton antal coccoliter kisel Eocen Oligocen Fitoplancton abundancia cocolitos sílice Eoceno Oligoceno |
spellingShingle |
Phytoplankton abundance coccoliths silica Eocene Oligocene Fytoplankton antal coccoliter kisel Eocen Oligocen Fitoplancton abundancia cocolitos sílice Eoceno Oligoceno Rivero Cuesta, Lucía Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 |
topic_facet |
Phytoplankton abundance coccoliths silica Eocene Oligocene Fytoplankton antal coccoliter kisel Eocen Oligocen Fitoplancton abundancia cocolitos sílice Eoceno Oligoceno |
description |
The development of modern glacial climates occurred during the Eocene-Oligocene transition (34 to 35.5 Ma) when a decrease of atmospheric CO2 led to a global temperature fall. The ocean was deeply affected, both in the surface and the deep-sea, suffering a strong reorganization including currents and phytoplankton distribution. Spanning that time, 35 samples from the North Atlantic Ocean Drilling Program Site 612 have been analyzed by counting coccoliths abundance in different size groups (< 4 µm, 4 to 8 µm and > 8 µm) and silica fragments abundance. Absolute coccoliths abundance were estimated with two different methods, the “drop” technique and microbeads calibration. In addition, a fragmentation index was calculated to assess the preservational state of the samples. The results obtained fit in the global picture of a decrease in phytoplankton abundance across theEocene-Oligocene boundary, although coccolith and silica fragments abundances show slight different patterns. Absolute abundances estimates showed a large difference between the “drop” and the microbeads methods. The temperature at which samples are dried seems to affect microbeads distribution, leading to an underestimation at temperatures higher than 60º C. In future work the current dataset will be updated with additional calibration and replicate counts to confirm that the “drop” estimates are the more valid results. As the fragmentation index was fairly constant in all samples, no major differences in nannofossil preservation were inferred. Coccoliths abundance drops are thought to be triggered by global temperature fall, general decrease of atmospheric CO2, changes in oceanic circulation, pulses of nutrients or a combination of those. Under tidsspannet som täcker övergången mellan eocen och oligocen, för ungefär 35.5 till 34 miljoner år sedan, genomgick jordens klimat en stor förändring. Under eocen hade vår planet ett varmare klimat och var i ett så kallat ”greenhouse state”. Mot slutet av denna period och i början av oligocen skiftade ... |
format |
Bachelor Thesis |
author |
Rivero Cuesta, Lucía |
author_facet |
Rivero Cuesta, Lucía |
author_sort |
Rivero Cuesta, Lucía |
title |
Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 |
title_short |
Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 |
title_full |
Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 |
title_fullStr |
Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 |
title_full_unstemmed |
Response of Phytoplankton to Climatic Changes during the Eocene-Oligocene Transition at the North Atlantic ODP Site 612 |
title_sort |
response of phytoplankton to climatic changes during the eocene-oligocene transition at the north atlantic odp site 612 |
publisher |
Uppsala universitet, Institutionen för geovetenskaper |
publishDate |
2015 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256769 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
Examensarbete vid Institutionen för geovetenskaper, 1650-6553 328 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256769 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766130724568563712 |