Freshwater ecosystems, though covering less than 1% of Earth’s surface, harbor around
10% of all species. Pressures like pollution, water extraction, and habitat loss can
exhibit complex interactions in their effects on freshwater biodiversity. Understanding
the effects of these pressures on ecosystem services and functions of freshwater systems
is crucial for effective environmental policies, and asks for availability of species
data. We therefore compiled European monitoring data on macroinvertebrates from European,
national, and regional biomonitoring and analysed their representativeness with respect
to river size, land use as well as their suitability to derive biodiversity trends.
The dataset consists of over 2.3 million macroinvertebrate abundance records from
2010 to 2015, spanning 28 European countries. Geographically, data are concentrated
in central Europe and England and are not evenly representative across space or river
types. They vary regarding reporting units, general sampling methods, and taxonomic
levels (mainly species level). These differences hamper European-scale biodiversity
comparisons. The WFD primarily focuses on assessing the “ecological status” of water
bodies, which can be achieved using a menu of methods and many biodiversity research
questions require improvements in harmonization of taxonomic resolutions and in method
standardization to enable accurate transnational comparisons. This study emphasizes
the need for improved European coordination and support in collecting, validating,
exchanging, and sharing freshwater biodiversity data to enable meaningful comparisons
among countries. It also delivers an open-access database that enables analyses of
trends and ecological scenario development, offering further opportunities to enhance
freshwater biodiversity conservation and management.
