JM Journal of Micropalaeontology JM J. Micropalaeontol. 2041-4978 GSL Publishing Göttingen, Germany 10.1144/jm.26.1.47 Seasonal dynamics and decadal changes of benthic foraminiferal assemblages in the western Baltic Sea (NW Europe) Schönfeld Joachim 0 Numberger Lea 1 IFM-GEOMAR, Wischhofstrasse 1–3, D-24148 Kiel, Germany (e-mail: ) Institut für Geologie und Paläontologie der Universität Tübingen, Sigwartstrasse 10, D-72076 Tübingen, Germany 01 04 2007 26 1 47 60 Copyright: © 2007 Joachim Schönfeld 2007 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://jm.copernicus.org/articles/26/47/2007/jm-26-47-2007.html The full text article is available as a PDF file from https://jm.copernicus.org/articles/26/47/2007/jm-26-47-2007.pdf

Living benthic foraminiferal assemblages were monitored between January and July 2004 in the Kiel Bight, Baltic Sea. Phytoplankton blooms and the deposition of organic detritus were depicted by fluorometer hydro casts and pigment concentrations in surface sediments. Three depositional pulses of organic matter were identified by high phytoplankton concentrations above the sea floor and elevated pigment concentrations in the surface sediment. The foraminiferal assemblage composition remained rather constant but the population density of <i>Elphidium excavatum clavatum</i> showed a two- to six-fold increase within a few days after organic detritus deposition. The foraminiferal assemblage composition was compared to earlier studies in this area. <i>Elphidium excavatum, Ammotium cassis</i> and <i>E. incertum</i> dominated the living fauna in the 1960s and 1970s. The recent survey revealed a predominance of <i>E. excavatum</i> subspecies (more than 90% of the living assemblage). The average population densities were six times higher than in the 1970s. Data structure and model calculations suggested that <i>E. excavatum clavatum</i> is able to reproduce rapidly, with high offspring numbers at elevated food supply. The diminution of <i>A. cassis</i> has occurred in Kiel Bight during the last ten years and was most likely induced by a period of low deep-water salinities in the early 1990s.

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