In October 2018, mARS attended the final meeting of the METHANOBASE project (project website: http://maialenbarret.wixsite.com/methanobase). One of the aims of the METHANOBASE project (funded by ERANet-LAC) was to profile microbial communities using amplicon and metagenome sequencing techniques to investigate the relations between microbial diversity and methane emissions in Arctic, Subarctic and Subantarctic ecosystems. This generated a very complex and rich dataset, of which the trends are currently still being analyzed by the METHANOBASE team. During this final meeting, mARS provided support in (meta)data archiving, andwe discussed different approaches on formatting the sequence and environmental data prior to publication on the mARS portal and other linked public data repositories (e.g. ENA for the sequences and GBIF for the metadata).This interesting exercise also made clear the need for event-based formatting of data in which multiple repeated measurements can correspond to one biological sample.