Benthic foraminiferal evidence of environmental change in the Skagerrak over the past six decades.

Alve, Elisabeth (1996) Benthic foraminiferal evidence of environmental change in the Skagerrak over the past six decades. NGU Bulletin, 430 . pp. 85-93.

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Abstract

High resolution analyses of fossil benthic foraminiferal assemblages have been performed on two short (<40 em) sediment cores from the deep Skagerrak Basin, NE North Sea. 210Pb-datings of replicate cores from the same two stations have made it possible to calculate accumulation rates of both sediments and benthic foraminiferal tests, and the vertical (historical) assemblage distributions are compared with sediment surface assemblages collected in 1937 and 1992/ 93. The core data show that the accumulation rate of agglutinated tests was relatively constant from about 1770 to 1940-1950 and that it has increased about 5-6 times since the late 1960's compared to average pre-1940 values. This increase is due mainly to increased production in the 4 agglutinated species Haplophragmoides bradyi, Eggerelloides medius, Saccammina spp., and Trochamminopsis pusillus, of which the last 2 were present only as accessory species before the 1960's. The 3 calcareous species Pullenia osloensis, Nonionella iridea, and Cassidulina laevigata, which dominated the dead assemblages prior to the early 1970's, all show subsequent reduced accumulation rates. Despite possible errors caused by postmortem destruction of some agglutinated components, their overall preservation seems to be good enough to reflect the rea l faunal conditions over the last couple of centuries. The faunal development, as reflected by the core data, is in good agreement with the conclusions based on the comparative study of surface assemblages collected in 1937 and 1992/93. That is, the benthic foramini feral assemblages in the deep Skagerrak Basin have changed, and according to the core data, these changes have occurred primarily since the early 1970's.

Document Type: Article
Keywords: Benthic foraminifera, environmental change, Skagerrak
Refereed: Yes
Open Access Journal?: No
Publisher: Norges Geologiske Undersøkelse
Projects: Enrichment
Date Deposited: 15 Jun 2016 08:34
Last Modified: 26 Jun 2020 12:05
URI: https://oceanrep.geomar.de/id/eprint/32975

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