Online Information Systems with Alien Species Occurrence Records in Europe: Coverage, Complementarity and Compatibility

This report assesses the coverage of thirty existing on-line national, regional and global databases from which alien species occurrence records within the territory of the European Union can be retrieved. In addition, it quantifies their degree of complementarity, and as such the added value of an integrated information system. Finally, it includes a qualitative evaluation of the feasibility of combining alien species information from existing databases at EU level. comparative analysis of occurrence data across 30 online databases with alien species records uncovers a high degree of complementarity of information. The most comprehensive resource for country level alien species occurrences in Europe (DAISIE) fails to report about one out of every four species known to be alien to one or more countries within the EU27 + Norway territory. When accessing only a single database, a minimum of 10,000 species by country records stay unaccounted for at European level. distributed and largely independent nature of existing alien species information systems has multiple consequences: (i) In the absence of an overarching data exploration system, it complicates the retrieval of information, and the identification of knowledge gaps; (ii) It allows systems to diverge and as such become less compatible; (iii) It potentially makes inefficient use of existing financial and intellectual resources. efficiency and accuracy of existing databases could be improved if communication between systems was enhanced. Expert knowledge could be shared and harmonization of the information would facilitate the retrieval of information, for example through a common network of interoperable web services. Integrated alien species databases currently report occurrences at country level, with limited value for scientists and managers. A shift towards georeferenced occurrences could be achieved in a cost-effective way by link linking to biodiversity databases and digitized archives of relevant journals.