Where, when, and how FAIR do data from aquatic mesocosm experiments get published?

We analyzed 192 publications from two EU projects focused on aquatic mesocosm facilities for a) the number of data publications in a repository on its own and the number of data publications associated with a scientific paper, b) the time lag between mesocosm experiments and data or paper publication, and c) adherence of scientific papers to FAIR principles of data publication. More data sets were published alongside scientific papers (103) than in a data repository alone (17). The time lag between experimental end to paper publication (34.9 months) was not significantly different from the time lag between experimental end to data publication (36.7 months). Regarding FAIR principles, 32.6% of papers achieved the highest scores (7 or 8), emphasizing a high data transparency relative to other disciplines. To improve data publications, we recommend increased support (especially for interoperability) for and recognition of researchers, as well as increased efforts by journals, repositories, and funders.