摘要：Isoetids are submersed aquatic plants that thrive in soft water, oligotrophic bodies of water and possess small, stiff rosettes and extensive root systems. These roots absorb carbon dioxide and release oxygen, altering the biogeochemistry of sediment. Eriocaulon aquaticum and Lobelia dortmanna are representative isoetids. While Eleocharis acicularis and Utricularia resupinata do not strictly qualify as isoetids, they are commonly found anchored in or attached to sediment populated with isoetids. In a greenhouse experiment, the four macrophytes were planted in two contrasting sediment types to determine how the different species modify sediment redox potential, carbon dioxide concentration, and porewater pH. Eleocharis acicularis and U. resupinata oxidized both sediment types and acidified the porewater more than or equally as extensively as the isoetids (p < 0.05). Eleocharis acicularis was the only species that significantly reduced porewater carbon dioxide (p < 0.05). In the field study, sediment cores were collected over bare sediment and over each of the four species concurrently with redox and pH measurements. Sediment cores associated with all four aquatic plants had significantly higher redox potentials compared to bare sediment (p < 0.05). However, the redox values measured near E. acicularis and U. resupinata were generally lower than those taken near the isoetids. The field sediment oxidation data may be explained by the significantly lower biomass of U. resupinata and E. acicularis compared to the isoetids in the field study (p < 0.05). These results show that E. acicularis and U. resupinata are capable of isoetid-like sediment oxidation under greenhouse and field conditions.
