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Marine biomonitoring with eDNA: can metabarcoding of water samples cut it as a tool for surveying benthic communities?

Citation

Antich, Adrià et al. (2020), Marine biomonitoring with eDNA: can metabarcoding of water samples cut it as a tool for surveying benthic communities?, Dryad, Dataset, https://doi.org/10.5061/dryad.vt4b8gtq2

Abstract

In the marine realm, biomonitoring using eDNA of benthic communities requires destructive direct sampling or the setting-up of settlement structures. Comparatively much less effort is required to sample the water column, which can be accessed remotely. In this study we assess the feasibility of obtaining information from the eukaryotic benthic communities by sampling the adjacent water layer. We studied two different rocky-substrate benthic communities with a technique based on quadrat sampling. We also took replicate water samples at distances from a few centimetres to 20 m from the benthic habitat. Using as marker a fragment of the Cytochrome c oxidase subunit I gene with universal primers, we obtained a total of 3,543 molecular operational taxonomic units (MOTUs) from the samples. The structure obtained in the two environments was markedly different, with Metazoa, Archaeplastida Rhodophyta and Stramenopiles being the most diverse group in benthic samples, and HacrobiaAlveolata, Metazoa and Alveolata Rhizaria in the water. Only 265 MOTUs (7.5%) were shared between benthos and water samples, and of these 180 MOTUs (5.1%) were identified as benthic MOTUs that left their DNA in the water. Most of them were found immediately adjacent to the benthos, and their number decreased and The distribution of these benthic shared MOTUs showed a decrease both in number of MOTUs and in number of reads as we moved apart from the benthic habitat. It was concluded that water eDNA, even in the close vicinity of the benthos, was a poor proxy for the analysis of benthic structure, and that direct sampling methods are required for monitoring these complex benthic communities via metabarcoding.