Data from initial evaluation of DNA metabarcoding for processing continuous plankton recorder samples

Plankton were identified using standard microscopic methods and by sequencing a mitochondrial COI marker. Data provided in the Dryad Data entry include the DNA sequences (Illumina MiSeq) recovered, the morphological identifications and the R-code used to analyse these data. The results from our study show that a DNA-based approach increased the number of metazoan species identified and provided high resolution taxonomy of groups problematic in conventional surveys (e.g. larval echinoderms and hydrozoans).

Metabarcoding also generally produced more detections than microscopy, but this sensitivity may make cross-contamination during sampling a problem. In some samples, the prevalence of DNA from larger plankton (such as krill) masked the presence of smaller species. Overall, the genetic data represents a substantial shift in perspective, making direct integration into current long-term time-series challenging.

We discuss a number of hurdles that exist for progressing this powerful DNA metabarcoding approach from the current snapshot studies to the requirements of a long-term monitoring program.