The taphonomy of sedaDNA, cultural biodiversity and catchment ecological restoration in North West Europe

The restoration or ‘rewilding’ of rivers and catchments, which generally involves manipulating biotic drivers, has traditionally used several palaeoecological techniques including plant macrofossils, microfauna and pollen. However, these have well known limitations due to both taxonomic level and indeterminate source-areas. SedaDNA potentially offers partial answers to both of these limitations as well as expanding the organism groups substantially to animals, fish and invertebrates. But in order to fully utilize this new approach we need to understand the taphonomy of sedaDNA so that biases can be assessed and allowed for in any baseline reconstruction. Taphonomy here includes aspects of transport, preservation and bioturbation in the sedaDNA record. In this paper we resolve the spatial input of sedaDNA into a small lake within a small Boreal-zone catchment and the influence of the methodological approach. The taphonomic biases can theoretically come from spatial factors, such variations in sediment connectivity, local environmental factors such as pollution loading, and longer-term variations in sedimentation and land-use. One of the advantages of sedaDNA is that it can record aspects of taphonomy such as the appearance of bioturbating organisms. Notwithstanding this, with comprehensive taxonomic data that is spatially constrained it becomes possible to investigate biotic interactions as well as construct past food webs and ecological dynamics. In this paper we show how sedaDNA metabarcoding can be used to provide an ecological history of key-stone and functionally critical organisms, from a variety of ecosystems and organism groups. These include upland and lowland pasture systems, aquatic plants, mammals, amphibians and fish all of which are part of culturally mediated ecological systems.

This approach is being rolled-out in a new pan-European project on the Molecular Ecology of Medieval European Landscapes (MEMELAND) which aims to provide a 2 millennia evidence based for biocultural restoration in NW Europe from The Arctic Circle to the Alps. The approach utilized here is highly relevant today as it can provide and evidence-base for environmental policies that seek to restore former catchment conditions, promote resilient ecological dynamics and biodiversity.