  The increasing amount of research data provides the opportunity to link and
integrate data to create novel hypotheses, to repeat experiments or to compare
recent data to data collected at a different time or place. However, recent
studies have shown that retrieving relevant data for data reuse is a
time-consuming task in daily research practice. In this study, we explore what
hampers dataset retrieval in biodiversity research, a field that produces a
large amount of heterogeneous data. We analyze the primary source in dataset
search - metadata - and determine if they reflect scholarly search interests.
We examine if metadata standards provide elements corresponding to search
interests, we inspect if selected data repositories use metadata standards
representing scholarly interests, and we determine how many fields of the
metadata standards used are filled. To determine search interests in
biodiversity research, we gathered 169 questions that researchers aimed to
answer with the help of retrieved data, identified biological entities and
grouped them into 13 categories. Our findings indicate that environments,
materials and chemicals, species, biological and chemical processes, locations,
data parameters and data types are important search interests in biodiversity
research. The comparison with existing metadata standards shows that
domain-specific standards cover search interests quite well, whereas general
standards do not explicitly contain elements that reflect search interests. We
inspect metadata from five large data repositories. Our results confirm that
metadata currently poorly reflect search interests in biodiversity research.
From these findings, we derive recommendations for researchers and data
repositories how to bridge the gap between search interest and metadata
provided.
