Response of biological productivity to North Atlantic marine front migration during the Holocene

• Main Authors: Harning, David J, Jennings, Anne E, Koseoglu, Denizcan, Belt, Simon T, Geirsdottir, Aslaug, Sepulveda, Julio
• Format: Text
• Language: English
• Published: Copernicus GmbH 2021
• Subjects: envir; geo; Arctic; Greenland; East Greenland; east greenland current; Foraminifera*; Iceland; North Atlantic
• Online Access: https://doi.org/10.5194/cp-2020-119; https://archimer.ifremer.fr/doc/00651/76326/77305.pdf; https://archimer.ifremer.fr/doc/00651/76326/77306.pdf; https://archimer.ifremer.fr/doc/00651/76326/81983.pdf; https://archimer.ifremer.fr/doc/00651/76326/81984.pdf; https://archimer.ifremer.fr/doc/00651/76326/

Marine fronts delineate the boundary between distinct water masses and, through the advection of nutrients, are important facilitators of regional productivity and biodiversity. As the modern climate continues to change the migration frontal zones is evident, but a lack of information about their status prior to instrumental records hinders future projections. Here, we combine data from lipid biomarkers (archaeal isoprenoid glycerol dibiphytanyl glycerol tetraethers and algal highly branched isoprenoids) with planktic and benthic foraminifera assemblage to detail the biological response of the marine Arctic and Polar Front migrations on the North Iceland Shelf (NIS) over the last 8 ka. This multi-proxy approach enables us to quantify the thermal structure relating to Arctic and Polar Front migration, and test how this influences the corresponding changes in local pelagic productivity. Our data show that following an interval of Atlantic Water influence, the Arctic Front and its associated high pelagic productivity stabilized on the NIS at ~ 6.1 ka BP. Following a subsequent trend of regional cooling, Polar Water from the East Greenland Current and the associated Polar Front spread onto the NIS by ~ 3.8 ka BP, greatly diminishing local algal productivity. Within the last century, the Arctic and Polar Fronts have moved back to their current positions relative to the NIS and helped stimulate the productivity that partially supports Iceland's economy. Our Holocene records from the NIS provide important analogues for how the current frontal configuration and the productivity that it supports may change as global temperatures continue to rise.