Alve, E. (1990) Variations in Estuarine Foraminiferal Biofacies with Diminishing Oxygen Conditions in Drammensfjord, SE Norway. In: Paleoecology, Biostratigraphy, Paleoceanography and Taxonomy of Agglutinated Foraminifera. , ed. by Hemleben, Christoph. NATO ASI Series, 327 . Kluwer, Dordrecht, pp. 661-694. DOI 10.1007/978-94-011-3350-0_23.

Text Alve1990DramFj.PDF - Reprinted Version Restricted to Registered users only Download (1MB)

Abstract

Distribution of recent, benthic foraminifera in the silled, partly anoxic Drammensfjord, reflects the prevailing hydrographic conditions, and reveals different intra basin responses to depleted oxygen conditions. The redox cline dips from about 35 m in the northern to about 60 m in the southern part of the fjord. Sediment surface samples are strongly dominated by agglutinated taxa except in the most oxygen depleted areas (O2 <2 ml/1) in middle and southern parts. The water masses are subdivided into three units: 1) Brackish surface layer dominated by Miliammina fusca; 2) Transitional water masses with Astrammina sphaerica, Eggerelloides scabrus, Spiroplectammina biformis, and Ammodiscus? gullmarensis as frequently occurring species; and 3) Oxygen depleted water masses (salinity max. 31.2 ‰) dominated by Stainforthia fusiformis. The thin-shelled S. fusiformis shows adaption to low oxygen (<2 ml/1) conditions and muddy, organic rich substrate as long as salinity exceeds about 30 ‰. Species diversity decreases towards the redox cline, and no foraminifera are found in oxygen depleted areas with salinities less than about 30 ‰

Actions (login required)

View Item