Die Diatomeen der Laptevsee (Arktischer Ozean): Taxonomie, biogeographische Verbreitung und ozeanographische Bedeutung

• Main Author: Cremer, Holger
• Format: Thesis
• Language: German
• Published: 1997
• Subjects: Arctic; Arctic Ocean; Laptev Sea; Antarc*; Antarctica; Arktis*; ice algae; laptev; Sea ice
• Online Access: https://oceanrep.geomar.de/id/eprint/49884/; https://oceanrep.geomar.de/id/eprint/49884/1/Cremer.pdf

Diatom assemblages and their distribution patterns in the Laptev Sea (Arctic Ocean) were studied on the basis of sediment and plankton samples. A total of 345 taxa from 56 genera were identified of which 78 taxa have their biogeographic distribution in polar and subpolar waters exclusively. The most diverse genera are Navicula (72 taxa), Pinnularia (27 taxa). Nit:.schia (21 taxa). Cymbella (20 taxa), Eunotia (20 taxa), Fragilaria (20 taxa), and Achnanthes (16 taxa). However. sediment and plankton assemblages are predominated by few species from the genera Aulacoseira. Chaetoceros. Fossula. Fragilariopsis, Nit::.schia and Thalassiosira. Occurrence and distribution of diatom plankton communities are mainly influenced by three environmental conditions: ( 1) by the sea ice cover from November up to May/June. which favors the predominance of ice algae (Fossula arctica, Fragilariopsis spp.) and sub-ice diatoms (Melosira spp., Thalassiosira spp.) in the sea ice and at the ice edge, (2) by the summerly river water input which leads to reduced salinities in the south-eastern and eastern regions of the Laptev Sea. with freshwater­brackish species (Aulacoseira spp Stephanodiscus spp.) and brackish-marine species (Chaetoceros spp. and Thalassiosira hyperborea) being dominant in the plankton, and (3) by the ice-free summer conditions with marine-neritic species of the genera Chaetoceros, Thalassiosira and Melosira pre­dominating the plankton communities in off-shore shelf waters. A factor analysis of 89 sediment samples with 26 species and species groups results in five factors (diatom sediment assemblages) explaining 87 .8% of the total variance and reflecting the conditions of the plankton communities. These five sediment assemblages are (1) the ice algae assemblage, (2) the Thalassiosira antarctica assemblage, (3) the Chaetoceros assemblage. (.J.) the freshwater diatoms assemblage and (5) the Thalassiosira nordenskioeldii assemblage. Based on the geographic signifi­cance of these five sediment assemblages the Laptev Sea ...