Faculté des sciences

Benthic foraminifer assemblages from norwegian cold-Water coral reefs

Spezzaferri, Silvia ; Rüggeberg, Andres ; Stalder, Claudio ; Margreth, Stephan

In: Journal of Foraminiferal Research, 2013, vol. 43, no. 1, p. 21-39

Quantitative investigations on the total (living + dead) benthic foraminiferal assemblages were performed on 32 surface-sediment samples (0–2 cm, .63-mm size fraction) from water depths ranging from 110–600 m (‘‘on-reef’’) to .2000 m (‘‘off-reef’’) in the Oslo Fjord (Skagerrak Basin), the mid-Norwegian slope (Sula, Røst, and Trænadjupet reefs), and the northern coral-reef... Plus

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    Summary
    Quantitative investigations on the total (living + dead) benthic foraminiferal assemblages were performed on 32 surface-sediment samples (0–2 cm, .63-mm size fraction) from water depths ranging from 110–600 m (‘‘on-reef’’) to .2000 m (‘‘off-reef’’) in the Oslo Fjord (Skagerrak Basin), the mid-Norwegian slope (Sula, Røst, and Trænadjupet reefs), and the northern coral-reef areas in Norway (Korallen, Lopphavet, Stjernsundet, and Sveinsgrunnen reefs). Seven other samples were investigated for their living (stained) and dead (unstained) assemblages. Hierarchical cluster analysis allows the recognition of five benthic species groups linked to foraminiferal microhabitats from on- and off-reef environments as follows: I) shallow ‘‘off-reef’’ areas of the Oslo Fjord, II) deep-sea .1800-m water depth, and III) bathyal between 800–1800 m, and ‘‘on-reef’’ areas of IV) the Skagerrak and V) the shelf and upper continental slope of the mid- and nothern Norwegian margin. The benthic foraminiferal fauna associated with the declining coral reefs in the Oslo Fjord suggests that a low amount of labile organic matter and/or nutrients reach the sea floor making the environment unfavorable for coral growth, reconfirming the previous results on direct measurements of the organic matter. This study indicates that foraminifers can be used as a tool for the characterization of cold-water coral-reef environments.