Including intraspecific diversity of eDNA analyses to develop a new holistic approach for Environmental Status Assessments of the benthic deep-sea

Measuring anthropogenic impacts on marine systems is of significant interest to stakeholders across the globe. Yet, assessing the ecological status of deep-sea habitats, the earth's largest biome, is challenging. Implementing environmental DNA analysis into environmental policy is desired and timely but not yet ready. HaploSEA is evaluating the use of meta-genetic diversity for biological assessments of deep-sea benthic communities. These include four novel approaches: (I) Performing holistic metabarcoding analyses including bacteria and archaea, unicellular eukaryotes, and metazoans to analyze natural spatial and temporal variability of entire communities. (II) Including haplotype diversity as a new parameter to describe ecosystems. (III) Establish a generic protocol to define genetic indicator groups based on their intraspecific diversity. (IV) Including capture by hybridization, a novel method for full gene reconstruction, and designing specific capture probes for biotic indicator groups of cyanobacteria, foraminifera, and nematodes. For analyses, we will benefit from a unique metabarcoding database (eDNAbyss, Ifremer) with global coverage and 1500 samples from all ocean basins, which are standardized, analyzed, and processed for five-gene regions. Using state-of-the-art underwater technology, we will sample in the deep sea along a disturbance gradient to collect samples for analysis via the above novel approaches. Finally, I will evaluate the suggested approaches and outline their future use for meta-genetic environmental assessments. HaploSEA is an interactive and multidisciplinary project combining expertise and facilities at top European institutes in deep-sea marine science (Ifremer, GEOMAR, and MARUM). This setup combines specialists from different fields, technical backgrounds, and taxonomic groups to share different perspectives and novel approaches.