Biosilicium (BSi) in Sedimenten Mecklenburger Seen (Deutschland) und das Calciumcarbonat-Biosilicium-Verhältnis als Trophie- und Wasserstandsindikator Biogenic Silica (BSi) in Sediments of the Mecklenburgian Lake District (Germany) and the Calcite-Silica-Relation as Indicator for Trophy and Water Level

The BSi content has been investigated in the surface sediments of lakes of different trophic state in the Mecklenburgian Lake District. The BSi content differs between 1 to 1000 mg BSi/g dry matter. High values were found in deep eutrophic lakes. Litoral sediments and shallow eutrophic lakes have lower contents. BSi content was found to be correlated with lake morphometry, depth, trophic level, sediment composition and especially with calcite. With the CaCO₃/BSi-value, 3 groups of lakes can be characterized:

• CaCO₃/BSi = 0 oligotrophic and dystrophic lakes
• CaCO₃/BSi ≤ 10 mesotrophic and eutrophic deep lakes
• CaCO₃/BSi ≤ 10 eutrophic shallow lakes

The results from the recent sediments have been compared with those from older sediments. Using the CaCO₃/BSi-value, climatic change, trophic state, and sea level can be detected.