title: Depth-dependence and monthly variability of charophyte biomass production: consequences for the precipitation of calcium carbonate in a shallow Chara-lake.
abstract: The month-to-month variability of biomass and CaCO3precipitation by dense charophyte beds was studied in a shallow Chara-lake at two depths, 1 and 3 m. Charophyte dry weights (d.w.), the percentage contribution of calcium carbonate to the dry weight and the precipitation of CaCO3per 1 m2were analysed from May to October 2011. Physical-chemical parameters of water were also measured for the same sample locations. The mean dry weight and calcium carbonate precipitation were significantly higher at 1 m than at 3 m. The highest measured charophyte dry weight (exceeding 2000 g m-2) was noted at 1 m depth in September, and the highest CaCO3content in the d.w. (exceeding 80 % of d.w.) was observed at 3 m depth in August. The highest CaCO3precipitation per 1 m2exceeded 1695 g at 1 m depth in August. Significant differences in photosynthetically active radiation (PAR) were found between 1 and 3 m depths; there were no significant differences between depths for other water properties. At both sampling depths, there were distinct correlations between the d.w., CaCO3content and precipitation and water properties. In addition to PAR, the water temperature and magnesium and calcium ion concentrations were among the most significant determinants of CaCO3content and d.w. The results show that light availability seems to be the major factor in determining charophyte biomass in a typical, undisturbed Chara-lake. The study results are discussed in light of the role of charophyte vegetation in whole ecosystem functioning, with a particular focus on sedimentary processes and the biogeochemical cycle within the littoral zone.
authors.affiliation: Polish-German Research Institute, Collegium Polonicum, Kościuszki 1, 69-100, Słubice, Poland. pukacz@europa-uni.de.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Pukacz
authors.affiliation: Department of Hydrobiology, Faculty of Biology, Adam Mickiewicz University in Poznań, Umultowska 89, 61-614, Poznań, Poland.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Pełechaty
authors.affiliation: Department of Water and Soil Analysis, Faculty of Chemistry, Adam Mickiewicz University in Poznań, Umultowska 89b, 61-614, Poznań, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Frankowski
mesh_terms: D018533:Biomass; D002119:Calcium Carbonate / Q000737:chemistry*; D044784:Chara / Q000502:physiology*; D011232:Chemical Precipitation; D017753:Ecosystem; D060106:Lakes / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D002119:Calcium Carbonate
keywords: Biomass production; Calcium carbonate precipitation; Charophytes; Nutrient cycling; Temporal variability