Santa Barbara Basin sedaDNA

DNA was extracted from five Santa Barbara Basin sediment samples (up to abou t 11 000 years old) and both a metabarcoding (18S-V9 rRNA, diat-rbcL) and a metagenomic shotgun approach was applied to (i) compare eukaryote, especially diatom, composition, and (ii) assess sequence length and database related biases. The associated publication reports that eukaryote composition differed considerably between shotgun and metabarcoding data, which was related to differences in read lengths (av. 112 and 161 bp, respectively), and overamplification of short reads in metabarcoding data. Diatom composition was influenced by reference bias that was exacerbated in metabarcoding data and characterised by increased representation of Chaetoceros, Thalassiosira and Pseudo-nitzschia. The results are relevant to sedaDNA studies aiming to accurately characterise paleo-ecosystems from either metabarcoding or metagenomic data.