Bicarbonate in the water controls global distribution of aquatic plants

A project that started long time ago as a MSc thesis project has now been published as a Report in the prestigious journal, Science.

In the paper, we show that the global distribution of submerged aquatic freshwater plants is mainly controlled by their ability to utilize bicarbonate (HCO3-) a source of inorganic carbon. In lakes with moderate to high concentrations of bicarbonate, the bicarbonate-users are over-represented compared to those species that are able to use only CO2. Surprisingly, this pattern is not present in streams since these are naturally rich in CO2 and thus there is no competitive advantage of using bicarbonate – the latter requires a special set of enzymes that are expensive to produce.

The road to this discovery had been long and winding… First, we had to diagnose a large set of mainly tropical plants for their ability to use bicarbonate. In total, we ended up with more than 125 species based on own diagnoses and also on literature information. Then we constructed a global bicarbonate map and overlaid this with more than 1 million global observations of the 125+ species. See the exciting results in the original publication.

The paper is entitled “Catchment properties and the photosynthetic trait composition of freshwater plant communities” and the DOI No is 10.1126/science.aay5945 – send me an e-mail if you are unable to access the paper.