Odmiany polimorficzne węglanu wapnia na powierzchni plech Ulva (Chlorophyta) notowanych w wodach słodkich

Abstract

Process of calcification, which is the formation of calcite — a pure calcium carbonate mineral, commonly takes place among both marine and freshwater algae. The available literature referring to inland waters provides a lot of information about calcareous macroalgae, mainly on extensively encrusted species of Chara, called stoneworts. In addition to this group, where CaCO3 may provide 60% of dry weight, also freshwater green alga Ulva is prone to CaCO3 precipitation (up to 50% of dry weight).Freshwater Ulva exhibit an extracellular calcification mode and the deposits form bands on the surface of a thallus. Owing to a large number of calcite crystals the surface is quite coarse. Microscopic observations demonstrated differences in the size and shape of crystals and divided them into two morphology types of CaCO3 microcrystals: calcite rhombohedrons and aragonite needles. The percentage of CaCO3 in the thalli was about 50% of dry weight.