Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway
Instrumental records from the Norwegian Sea and the Trondheimsfjord show evidence that changes of bottom water temperature and salinity in the fjord are linked to the salinity and temperature variability of the North Atlantic Current (NAC). Changes in primary productivity and salinity in the surface...
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ftdoajarticles:oai:doaj.org/article:78548afb81c14608990c75d83a0c2f37 2023-05-15T17:25:20+02:00 Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway G. Milzer J. Giraudeau J. Faust J. Knies F. Eynaud C. Rühlemann 2013-07-01T00:00:00Z https://doi.org/10.5194/bg-10-4433-2013 https://doaj.org/article/78548afb81c14608990c75d83a0c2f37 EN eng Copernicus Publications http://www.biogeosciences.net/10/4433/2013/bg-10-4433-2013.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-10-4433-2013 1726-4170 1726-4189 https://doaj.org/article/78548afb81c14608990c75d83a0c2f37 Biogeosciences, Vol 10, Iss 7, Pp 4433-4448 (2013) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2013 ftdoajarticles https://doi.org/10.5194/bg-10-4433-2013 2022-12-31T10:11:09Z Instrumental records from the Norwegian Sea and the Trondheimsfjord show evidence that changes of bottom water temperature and salinity in the fjord are linked to the salinity and temperature variability of the North Atlantic Current (NAC). Changes in primary productivity and salinity in the surface and intermediate water masses in the Trondheimsfjord as well as the fjord sedimentary budget are mainly driven by changes in riverine input. In this study we use 59 surface sediment samples that are evenly distributed in the fjord to examine whether dinocyst assemblages and stable isotope ratios of benthic foraminifera reflect the present-day hydrology and can be used as palaeoceanographic proxies. In general, modern benthic δ 18 O and δ 13 C values decrease from the fjord entrance towards the fjord head with lowest values close to river inlets. This is essentially explained by gradients in the amounts of fresh water and terrigenous organic matter delivered from the hinterland. The distribution of benthic δ 13 C ratios across the fjord is controlled by the origin (terrigenous vs. marine) of organic matter, local topography-induced variability in organic matter flux at the water–sediment interface, and organic matter degradation. The dinocyst assemblages display the variations in hydrography with respect to the prevailing currents, the topography, and the freshwater and nutrient supply from rivers. The strength and depth of the pycnocline in the fjord strongly vary seasonally and thereby affect water mass characteristics as well as nutrient availability, temporally creating local conditions that explain the observed species distribution. Our results prove that dinocyst assemblages and benthic foraminiferal isotopes reliably mirror the complex fjord hydrology and can be used as proxies of Holocene climatic variability. Article in Journal/Newspaper north atlantic current North Atlantic Norwegian Sea Directory of Open Access Journals: DOAJ Articles Norwegian Sea Norway Biogeosciences 10 7 4433 4448 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 G. Milzer J. Giraudeau J. Faust J. Knies F. Eynaud C. Rühlemann Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Instrumental records from the Norwegian Sea and the Trondheimsfjord show evidence that changes of bottom water temperature and salinity in the fjord are linked to the salinity and temperature variability of the North Atlantic Current (NAC). Changes in primary productivity and salinity in the surface and intermediate water masses in the Trondheimsfjord as well as the fjord sedimentary budget are mainly driven by changes in riverine input. In this study we use 59 surface sediment samples that are evenly distributed in the fjord to examine whether dinocyst assemblages and stable isotope ratios of benthic foraminifera reflect the present-day hydrology and can be used as palaeoceanographic proxies. In general, modern benthic δ 18 O and δ 13 C values decrease from the fjord entrance towards the fjord head with lowest values close to river inlets. This is essentially explained by gradients in the amounts of fresh water and terrigenous organic matter delivered from the hinterland. The distribution of benthic δ 13 C ratios across the fjord is controlled by the origin (terrigenous vs. marine) of organic matter, local topography-induced variability in organic matter flux at the water–sediment interface, and organic matter degradation. The dinocyst assemblages display the variations in hydrography with respect to the prevailing currents, the topography, and the freshwater and nutrient supply from rivers. The strength and depth of the pycnocline in the fjord strongly vary seasonally and thereby affect water mass characteristics as well as nutrient availability, temporally creating local conditions that explain the observed species distribution. Our results prove that dinocyst assemblages and benthic foraminiferal isotopes reliably mirror the complex fjord hydrology and can be used as proxies of Holocene climatic variability. |
format |
Article in Journal/Newspaper |
author |
G. Milzer J. Giraudeau J. Faust J. Knies F. Eynaud C. Rühlemann |
author_facet |
G. Milzer J. Giraudeau J. Faust J. Knies F. Eynaud C. Rühlemann |
author_sort |
G. Milzer |
title |
Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway |
title_short |
Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway |
title_full |
Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway |
title_fullStr |
Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway |
title_full_unstemmed |
Spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the Trondheimsfjord, central Norway |
title_sort |
spatial distribution of benthic foraminiferal stable isotopes and dinocyst assemblages in surface sediments of the trondheimsfjord, central norway |
publisher |
Copernicus Publications |
publishDate |
2013 |
url |
https://doi.org/10.5194/bg-10-4433-2013 https://doaj.org/article/78548afb81c14608990c75d83a0c2f37 |
geographic |
Norwegian Sea Norway |
geographic_facet |
Norwegian Sea Norway |
genre |
north atlantic current North Atlantic Norwegian Sea |
genre_facet |
north atlantic current North Atlantic Norwegian Sea |
op_source |
Biogeosciences, Vol 10, Iss 7, Pp 4433-4448 (2013) |
op_relation |
http://www.biogeosciences.net/10/4433/2013/bg-10-4433-2013.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-10-4433-2013 1726-4170 1726-4189 https://doaj.org/article/78548afb81c14608990c75d83a0c2f37 |
op_doi |
https://doi.org/10.5194/bg-10-4433-2013 |
container_title |
Biogeosciences |
container_volume |
10 |
container_issue |
7 |
container_start_page |
4433 |
op_container_end_page |
4448 |
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1766116729650413568 |