Large pools and fluxes of carbon, calcium and phosphorus in dense charophyte stands in ponds

Bicarbonate and calcium set bounds on photosynthesis degradation processes in calcareous freshwaters. Charophytic algae use bicarbonate photosynthesis, direct variable proportions to assimilate organic carbon precipitate carbonate their surfaces. To evaluate pools of (Corg), (Ccarbonate), phosphorus (P) dense charophyte vegetation, we studied apical basal tissue surface precipitates, as well underlying sediments ten ponds. We also quantified the release calcium, phosphate from shoots dark experiments. found that Corg:Ccarbonate quotient stands averaged 1.19 during spring summer. The formed by dead charophytes 0.97 accordance with some respiratory CO2 without dissolution bicarbonate. molar was close 2.0 sediment pond water. In incubations, subjected released a 2:1; lowered pH (7.0–8.0) increased release. Thus, crust living not inert, hitherto anticipated. Phosphate occurred only, unrelated pH, may have derived decomposition, rather than dissolution. Extensive were associated (200–600 mg m?2) had about 2/3 incorporated alga 1/3 crust. Overall, biogeochemistry carbon, are closely linked Carbonate crusts at night continuously might balance extensive precipitation daytime photosynthesis. substantial P-pool derive P-deprived water, but P-rich sediment. Charophyte still contribute nutrient-poor conditions forming carbonate-rich high P-binding capacity.