Alien macrocrustaceans in freshwater ecosystems in the eastern part of Flanders (Belgium)

Biological invasions of freshwater macroinvertebrates are gaining more and more interest because the ecological and economical impact of some of these species is high. Since crustacean taxa appear to be successful groups invading new areas, an inventory of the macrocrustaceans in Flanders was made. At least 22 freshwater macrocrustacean species have been reported from Flemish water bodies. A detailed study of six canals, one small artificial watercourse and one natural river in the eastern part of Flanders revealed that invaders such as Dikerogammarus villosus, Gammarus tigrinus and Chelicorophium curvispinum are already quite common. Especially D. villosus is currently rapidly expanding and has a serious impact on native and other exotic gammarid species. Based on observations in neighbouring countries, several additional species are expected to arrive in the near future. A follow-up of the alien species together with a monitoring scheme to detect new incoming species is valuable to estimate the size of the problem and to be able to closely follow their ecological and economical impact

PCBs still sticking around

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Forested riparian buffers change the taxonomic and functional composition of stream invertebrate communities in agricultural catchments

Riparian zones form the interface between stream and terrestrial ecosystems and play a key role through their vegetation structure in determining stream biodiversity, ecosystem functioning and regulating human impacts, such as warming, nutrient enrichment and sedimentation. We assessed how differing riparian vegetation types influence the structural and functional composition (based on species traits) of stream invertebrate communities in agricultural catchments. We characterized riparian and stream habitat conditions and sampled stream invertebrate communities in 10 independent site pairs, each comprising one “unbuffered” reach lacking woody riparian vegetation and a second downstream reach with a woody riparian buffer. Forested riparian buffers were associated with greater shading, increased gravel content in stream substrates and faster flow velocities. We detected changes in invertebrate taxonomic composition in response to buffer presence, with an increase in sensitive Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa and increases in key invertebrate species traits, including species with preference for gravel substrates and aerial active dispersal as adults. Riparian vegetation independently explained most variation in taxa composition, whereas riparian and instream habitat together explained most variation in functional composition. Our results highlight how changes in stream invertebrate trait distributions may indirectly reflect differences in riparian habitat, with implications for stream health and cross-ecosystem connectivity