Culturing of stoneworts and submersed angiosperms with phosphate uptake exclusively from an artificial sediment

Abstract

1. We aimed to demonstrate reproducible nutrition and growth of macrophytes in non-axenic laboratory cultures preventing growth of phytoplankton and epiphytes. 2. Macrophyte shoot segments were planted in a mixture of commercial acid-washed silica sand with crystalline tricalcium phosphate, and this artificial sediment was covered with a layer of pure silica sand. The liquid mineral media used did not contain phosphorus but were rich in all other nutrient elements. A CO 2 reservoir provided sustainable CO 2 supply to macrophyte cultures by gas diffusion through a polyethylene membrane. 3. Chara hispida, Chara tomentosa, Chara baltica, Elodea canadensis, Potamogeton pectinatus and Zanichellia palustris could be cultivated for long term without medium exchange and aeration. Microalgae growth was prevented by the absence of phosphate in the water column. Mobilisation of tricalcium phosphate and phosphate uptake by the rhizoids of C. hispida enabled sustainable rapid shoot growth and increased the concentration of inorganic phosphate in the shoot dry weight by five to six times in comparison with plants cultivated on pure silica sand. A significant growth support from tricalcium phosphate was also observed for E. canadensis, but the rate of phosphate uptake by the roots was not sufficient to maintain a storage pool of inorganic phosphate (P i ) in the growing shoots of this plant. 4. Membrane-controlled CO 2 supply from a reservoir and artificial sediments like the one described provide attractive options for the laboratory culture of macrophytes.

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

“…This is an example of how charophytes can outcompete tall-growing angiosperms such as M. spicatum under low phosphorus supply and high water-clarity (Richter and Gross, 2013). Charophytes have been described to have more efficient nutrient uptake systems at low nutrient availability (Bakker et al, 2010;Wuestenberg et al, 2011), allowing them to outcompete angiosperms. N. hyalina occupied small areas in the water spring, primarily within the emergent vegetation in the shallower areas of the spring (Fig.…”

Extending one-dimensional models for deep lakes to simulate the impact of submerged macrophytes on water quality

“…In 231 lakes and ponds in The Netherlands, chlorophyll-a and nutrient concentrations were lower in systems when areal macrophyte coverage exceeded 5% (Portielje and van der Molen, 1999). In general, nutrient competition is supposed to be highest for non-rooted macrophyte species (e.g., Ceratophyllum species, to a certain extend charophytes (Blindow et al, 2014), although their rhizoids are also able to take up sufficient nutrients for growth (Wüstenberg et al, 2011)) which cannot use the sediment nutrient pool, and thus take up nutrients from the water column (Barko et al, 1988(Barko et al, , 1991. In contrast, rooted macrophytes mainly use nutrients from the sediment (Barko et al, 1988) and, depending on a number of factors, can act as a source or a sink for nutrients (Carignan and Kalff, 1980;Pieczynska, 1993).…”

Two-tier vessel for photoautotrophic high-density cultures

“…Here we report on the culture of cyanobacteria in a two-tier vessel enabling CO 2 supply through a membrane while gas exchange with the atmosphere takes place through a separate pathway (Ehwald et al 2015). The culture vessel described in this study is an improvement of the previously described system, which consisted of membrane-coated reservoirs containing the CO 2 buffer (Pörs et al 2010, Wüstenberg et al 2011, Ehwald et al 2014). Here we tested whether bubble-free CO 2 supply across a porous and hydrophobic flat membrane was suitable for culturing the model organi s m s S y n e c h o c y s t i s s p .…”