Supplementary material for a relevance and usability evaluation in a data portal for biodiversity research. Data portal: GFBio (https://www.gfbio.org) Evaluation time: February 2016 (at that time the search index consisted of ~ 2 Mio datasets) Eight domain experts rated the Top25 search results of 16 provided search questions on a 7-point-Likert scale from 0 (irrelevant) to 6 (highly relevant). Afterwards, we asked the users to provide and rate up to two own queries. The users also rated 28 statements in a subsequent usability evaluation on a 5-point Likert scale from 'completely disagree' to 'highly agree'. For some statements, only binary ratings were given.