Use of sediment CO2 by submersed rooted plants

Research output: Contribution to journalJournal articlepeer-review

Background and Aims: Submersed plants have different strategies to overcome inorganic carbon limitation. It is generally assumed that only small rosette species (isoetids) are able to utilize the high sediment CO2 availability. The present study examined to what extent five species of submersed freshwater plants with different morphology and growth characteristics (Lobelia dortmanna, Lilaeopsis macloviana, Ludwigia repens, Vallisneria americana and Hydrocotyle verticillata) are able to support photosynthesis supplied by uptake of CO2 from the sediment.

Methods: Gross photosynthesis was measured in two-compartment split chambers with low inorganic carbon availability in leaf compartments and variable CO2 availability (0 to >8 mmol L-1) in root compartments. Photosynthetic rates based on root-supplied CO2 were compared with maximum rates obtained at saturating leaf CO2 availability, and 14C experiments were conducted for two species to localize bottlenecks for utilization of sediment CO2.

Key Results: All species except Hydrocotyle were able to use sediment CO2, however, with variable efficiency, and with the isoetid, Lobelia, as clearly the most effective and the elodeid, Ludwigia, as the least efficient. At a water column CO2 concentration in equilibrium with air, Lobelia, Lilaeopsis and Vallisneria covered >75% of their CO2 requirements by sediment uptake, and sediment CO2 contributed substantially to photosynthesis at water CO2 concentrations up to 1000 µmol L-1. For all species except Ludwigia, the shoot to root ratio on an areal basis was the single factor best explaining variability in the importance of sediment CO2. For Ludwigia, diffusion barriers limited uptake or transport from roots to stems and transport from stems to leaves.

Conclusions: Submersed plants other than isoetids can utilize sediment CO2, and small and medium sized elodeids with high root to shoot area in particular may benefit substantially from uptake of sediment CO2 in low alkaline lakes.

Original languageEnglish
JournalAnnals of Botany
Volume103
Issue number7
Pages (from-to)1015-1023
ISSN0305-7364
DOIs
Publication statusPublished - 2009

Bibliographical note

Key words: Submersed rooted plants, CO2 uptake, sediment CO2, Lobelia dortmanna, Lilaeopsis macloviana, Ludwigia repens, Vallisneria americana, Hydrocotyle verticillata

ID: 12075769