Dataset search in biodiversity research: Do metadata in data repositories reflect scholarly information needs?

aware that thorough data descriptions are part of a good scientific practice. In order to pre- serve all kind of scientific data, independently of whether it has been used in publications or not, proper metadata descriptions based on appropriate schemata enhance dataset retrieval and thus, increase data reuse and data citation. Data repositories could offer data curation ser- vices to support scholars in describing research data and to encourage them to describe their data thoroughly. We are aware that it would require high efforts to introduce more domain- specific metadata standards at generalist repositories; however, it would improve data descriptions. Challenges to be addressed in the biodiversity research community The importance of metadata for data discovery has already been recognized by the research community. In the FAIR Data Maturity Model [66], a guideline with indicators for the evalua- tion of the FAIR principles [11], all Findability indicators were considered as ‘essential’. The second Findability indicator (F2-01M) [66] refers to the richness of metadata. It says that an evaluation should consider the amount of metadata and its suitability for data discovery. How- ever, we think, it is unsatisfactory to tell scholars to provide ‘rich metadata’ without any further guidance, as it is often not clear what information is relevant for data discovery per research domain. Here, we recommend to extend the indicator, e.g., with additional documents per domain, providing more information about the various metadata standards and important

search categories per research field. Several studies already proposed guidelines for data reposi- tories [67] and scholars [68, 69] to ensure good data management favoring the usage of domain-specific standards. However, our study reveals that large data repositories only partly follow these recommendations. In particular, general data repositories tend to use only general metadata standards. Although guidelines and proper metadata data standards exist, the ques- tion remains why are they so rarely used? Are the recommendations too broad? Are there too many standards or do standards contain too many fields and elements? Do we need improved software tools and methods to facilitate the integration of different metadata in one search index? We think, only further user studies and discussions in the research community may help to find answers on these questions. First results of such discussions towards more fine-grained recommendations for essential metadata fields in specific research domains are the initiative from GBIF [70] and the work of Jurburg et al [71]. Both approaches aim for a better description of sequence data. We think, more in-depth discussions per research field will support data descriptions and metadata crea- tion as relevant search categories are domain dependent. In biodiversity research, a variety of standards are already available. Taxonomic and occurrence data could be comprehensively described with Darwin Core or ABCD. For environmental data descriptions, EML would be a

good choice. EASE is not a standard yet but could also be considered for future environmental data descriptions. In order to properly describe digital geographic data, ISO19115 is the recom- mended standard of the respective research community. Genome data could be thoroughly described using ISA-Tab. Moreover, ISA-Tab is suitable for the description of a diverse set of environmental and biomedical experiments that employ one or a combination of technologies. For more individual metadata description, but using controlled vocabularies and terminolo- gies, CEDAR could be an option. Our findings reveal that biodiversity data should not only be described from a specific research focus but should contain supplementary information. Apart from observed species, environmental information such as habitat or biome, involved biological, physical and chemi- cal processes, analyzed materials, data parameters measured and geographical information should be considered in metadata creation. PLOS ONE Dataset search in biodiversity research PLOS ONE | https://doi.org/10.1371/journal.pone.0246099 March 24, 2021 30 / 36