Not all plants are the same: Exploring metabolism and nitrogen fluxes in a benthic community composed of different aquatic plant species

Abstract

Aquatic plants are important primary producers that affect the nutrient cycling in shallow coastal areas. How benthic communities composed of different plant species affect community metabolism and N fluxes is however, poorly understood, and in situ quantification is scarce. To study primary production and water-sediment N fluxes in a benthic community consisting of various aquatic vascular plant species, diel field experiments were conducted in the Baltic Sea. Nine plant species were incubated in situ with bare sediments as control. The aim was to investigate diel community (including vascular plants, epiphytes, infauna, phytoplankton, and phytobenthos) and biomass-specific metabolism and nitrogen fluxes among different plant species within a benthic community and to compare N fluxes between vegetated and bare sediments. The net production differed between different plant species, while the overall respiration was unaffected by the plant species present. There were no discernible differences in inorganic N fluxes between the different plant species within the benthic community and vegetated and bare sediments, whereas DON fluxes differed significantly. These results demonstrate that aquatic plant species have varying effects on ecosystem processes. Inherent differences between plant species add significant complexity to benthic functional diversity and highlight the important role that species-rich vegetated habitats play for ecosystem functioning in shallow coastal areas.