Palaeolimnological Niche Characterization with Selected Algae: I. Planktonic Diatoms from a Hardwater Habitat

Abstract

Summary In Ammersee, a subalpine hard-water lake in Bavaria, the relationship of selected planktonic diatoms to nutrient requirements has been studied by means of palaeolimnological methods. The lake underwent both eutrophication and oligotrophication within comparably short periods of time. These water management practices caused drastic changes in the diatom flora. In a 1986 sediment core, the occurrence of planktonic diatoms was simultaneously related to several phosphorus fractions, which were sequentially extracted, and to biogenic silica. This relation was done applying SPEARMAN rank correlation and factor analysis. Factor analysis demonstrated that three groups of diatoms with different nutrient requirements could be identified: i) oligotraphent diatoms with low Si- and P-requirements ( Cyclotella kuetzingiana, Cyclotella cf. comensis, Cyclotella comta ), ii) diatoms with high P- and probably medium P-requirements ( Aulacoseira granulate, Stephanodiscus parvus, St. minutulus ), iii) diatoms with high Si- and probably medium to high Si-requirements ( Diatoma elongatum, Tabellaria fenestrata, Asterionella formosa and Aulacoseira islandica ). By applying palaeolimnological techniques, our results identify the ecological valence of selected diatoms with respect to nutrient requirement and confirm that tradeoffs within phytoplankton algae is a multi- rather than a monodimensional process.