Desmids (Zygnematophyceae, Streptophyta) community drivers and potential as a monitoring tool in South American peat bogs

Tierra del Fuego Island hosts the largest area of peatlands in the Southern Hemisphere, largely encompassing peat bogs where peat is actively formed and thus acting as carbon sinks. Under a scenario of increasing human pressure, the development of scientific tools for the characterization and monitoring of these systems is highly relevant. Desmids have been used as bioindicators in wetlands on account of their high sensitivity to changes in the environment. Here we identified the main drivers of periphytic and planktonic desmid communities in two Fuegian peat bogs, hosting two types of aquatic environments: clear and vegetated pools. Although peat bogs differed in overall species richness and diversity for both communities, some clear trends were detected regarding their dependence on environmental conditions. Unexpectedly, the taxonomic composition of the periphytic desmids did not depend on the substrate. Instead, their diversity and species richness changed along a minero-ombrotrophic gradient. As for planktonic desmids, their abundance and life strategy jointly changed from few large-sized species to larger numbers of small-sized species along with terrestrialization stage of the pools. We conclude that both desmid communities can be used complementarily to monitor changes over time in the trophic and terrestrialization status of peat bog pools.