The significance of Chara vegetation in the precipitation of lacustrine calcium carbonate

Abstract

A significant portion of calcium carbonate is deposited in lake sediments as a result of biological processes related to the photosynthetic activity of phytoplankton in the pelagic realm and, in addition, macrophytes in the littoral zone. Lake Wigry, one of the largest lakes in Poland (north-east Poland), is characterized by: (i) carbonate sediments with a CaCO 3 content exceeding 80% within the littoral zone; and (ii) large areas of submerged vegetation dominated by charophytes (macroscopic green algae, Characeae family). It is claimed that charophytes are highly effective in utilizing HCO 3 À and forming thick CaCO 3 encrustations. Thus, this study was aimed at evaluating the CaCO 3 production by dense Chara stands overgrowing the lake bottom reaching a depth of 4 m. In late July 2009, the fresh and dry mass of plants, the percentage contribution of calcium carbonate and the production of CaCO 3 per 1 m 2 were investigated along three transects at three depths (1 m, 2 m and 3 m, with each sample area equal to 0Á0625 m 2 ) per transect. The composition and structure of phytoplankton and the physico-chemical properties of the water analysed in both the littoral and pelagic zones served as the environmental background and demonstrated moderately low fertility in the lake. The greatest dry plant mass exceeded 1000 g m À2 and CaCO 3 encrustations constituted from 59% to over 76% of the charophyte dry weight. Thus, the maximum and average values of carbonates precipitated by charophytes were 685Á5 and 438 g m À2 , respectively, which exceeded previously reported results. A correlation of carbonate production with the depth of Chara stands was detected, and intermediate depths offered the most favourable conditions for carbonate precipitation (589 g m À2 on average). As precipitated carbonates are ultimately stored in bottom deposits, the results highlight the significance of charophytes in lacustrine CaCO 3 sedimentation.

The role of charophytes in a Mediterranean pond created for restoration purposes

“…Their N uptake is very efficient, and they remove this nutrient from the water column (Rodrigo and Alonso-Guillén, 2008). Charophytes are also known to affect phosphorus cycling by direct uptake and by deposition of calcium carbonate in the form of encrustations on the tissues, accompanied by coprecipitation of inorganic P (Pelechaty et al, 2013;Puckaz et al, 2013;Kufel et al, 2013). Charophytes from this water spring also precipitated large amounts of calcium carbonate, with an annual mean of 30% (± 15% SD) of the DW for C. hispida and 21± 9% for N. hyalina.…”

Charophyte occurrence in Ceratophyllum demersum stands

“…Thus, for an appropriate management of aquatic ecosystems and protection of rare and endangered species, it seems important to recognize environmental conditions under which charophytes can occur. According to literature, charophytes can occupy two different habitat types in freshwaters (Casanova & Brock, 1999) where they are exposed to varied environmental pressure and play different roles (as summarized in van den Berg et al, 1998;van den Berg, 1999;Kufel & Kufel, 2002;van Donk & van de Bund, 2002;Martin et al, 2003;Apolinarska et al, 2011;Pełechaty et al, 2013).…”

Oxygen stable isotope composition of carbonate encrustations of two modern, widely distributed, morphologically different charophyte species

“…Dense charophyte meadows greatly intensify carbonate precipitation and contribute to the accumulation of marl sediments in lakes (Kufel & Kufel, 2002;Pentecost et al, 2006;Apolinarska et al, 2011;Pełechaty et al, 2013;Pukacz et al, 2016a). This capacity results from photosynthetic removal of CO 2 from dissolved bicarbonates (McConnaughey, 1997) and leads to the precipitation of insoluble CaCO 3 (mostly calcite) in the form of encrustations on the surface of charophyte thalli.…”