Vegetation changes over the last centuries in the Lower Lake Constance region reconstructed from sediment‐core environmental DNA

Abstract

Many European lake ecosystems, including their respective catchment areas, underwent anthropogenic environmental changes over the last centuries. This has resulted in changes in the aquatic and terrestrial vegetation, but historical records on the composition of the past vegetation on centennial scale are scarce. In this study, we examined changes in the terrestrial and aquatic plant communities in and around Lower Lake Constance using metabarcoding of sedimentary DNA (sedDNA) of three cores from different sub‐basins covering the past, up to 300 years. We successfully identified an average of c. 3000 sequence variants (molecular operational taxonomic units ‐ MOTUs) and obtained a taxonomically annotated dataset of 127 species, 104 genera, and 72 families. We could detect major changes in the terrestrial and aquatic vegetation of the Lower Lake Constance region by examining the cores. For example, alpha diversity decreased in the last c. 100 years, and this decrease was more pronounced in the terrestrial than in the aquatic plant community. Unlike the terrestrial plant community, the current aquatic plant‐community composition partially resembles the community from before the 20th‐century eutrophication phase of the lake. In addition to changes that can be attributed to anthropogenic impacts, we also captured the effect of DNA sedimentation on the terrestrial DNA diversity representation in sediments during periods of extensive flooding and potentially as a consequence of extremely cold winters. With sedDNA from Lower Lake Constance, we provide a new local dataset to investigate and extend the historical changes of different shoreline habitats and to identify characteristic and invasive plant species. Such highly resolved datasets spanning the past centuries can provide detailed information on human environmental history in densely populated regions that have undergone severe changes in the recent past.

Environmental DNA of aquatic macrophytes: The potential for reconstructing past and present vegetation and environments

“…12,900 calibrated years before the present [cal BP]), nearly all taxa appeared at once, highlighting their capacity to immigrate rapidly once suitable environmental conditions are established. Ibrahim et al (2022) detected the presence of the alien Canadian waterweed Elodea canadensis in sed aDNA over the last centuries, and Anglès d'Auriac et al (2019) tracked it from water samples over a narrow spatial scale. To date, no study has addressed evolutionary questions for macrophytes with sed aDNA, but examples on other plant taxa have showcased this potential.…”

“…Focusing on this group in sed aDNA could support a temporal reconstruction of water quality and trophic status, for instance where human‐induced eutrophication is a major stake. If multiple sedimentation basins are encountered, a spatial approach could even be added, as showcased by Ibrahim et al (2022) with the overall vegetation in Lake Constance. Pollen remains a widely used proxy for comparison to plant sed aDNA, but no comparison has focused on aquatic taxa that, in general, have more locally dispersed pollen (by water or insects) but poorer taxonomic resolution than the P6 loop (Sønstebø et al, 2010).…”

Environmental DNA of aquatic macrophytes: the potential for reconstructing past and present vegetation and environments

“…12,900 cal BP) nearly all taxa appeared at once, highlighting their capacity to immigrate rapidly once suitable environmental conditions are established. Ibrahim et al (2022) detected the presence of the alien Canadian waterweed Elodea canadensis in sed aDNA over the last centuries, and Anglès d’Auriac et al (2019) tracked it from water samples over a narrow spatial scale. To date, no study has addressed evolutionary questions for macrophytes with sed aDNA, but examples on other plant taxa have opened a way.…”

“…Focusing on this group in sed aDNA could support a temporal reconstruction of water quality and trophic status, for instance where human-induced eutrophication is a major stake. If multiple sedimentation basins are encountered, a spatial approach could even be added, as showcased by Ibrahim et al (2022) with the overall vegetation in Lake Constance. Pollen remains a widely used proxy for comparison to plant sed aDNA, but no comparison has focused on aquatic taxa which, in general, have more locally dispersed pollen (by water or insects) but poorer taxonomic resolution than the P6 loop (Sønstebø et al, 2010).…”

Using ancient sedimentary DNA to forecast ecosystem trajectories under climate change

“…Using both blocking oligos increases detection of mammals and also co-amplifies birds, fish, amphibians and worms (figure 1). Additional organisms, such as diatoms, fungi and lichens, can be amplified through the use of dedicated primers [65][66][67], giving a broader spectrum of biodiversity. Having multiple trophic levels allows a more comprehensive tracing of ecosystem dynamics.…”