Libellennieuws uit de Biesbosch Goede waterkwaliteit ‘lokt’ waardevolle soorten

Boesveld, A. & J. van der Neut, 2003. News on dragonflies from the Biesbosch: increasing waterquality facilitates settlement of special species. Brachytron 7(1): 3-14. The Biesbosch is a well known freshwater tidal area in the southwestern parts of The Netherlands. Since the building of the Haringvlietdam, between the villages Stellendam and Hellevoetsluis, a considerable part of the tidal movement disappeared. The water quality of the river the Nieuwe Merwede, actually the border between the Brabantse and the Sliedrechtse Biesbosch, has improved and over the last years a revival of waterplants and dragonflies like Calopteryx virgo, C. splendens, Somatochlora metallica, Gomphus vulgatissimus, G. flavipes and Platycnemis pennipes was noticed. On the other hand, clay-digging created attractive circumstances. Arable land was transformed into wetlands with shallow water and became very attractive for species like Crocothemis erythraea, Cordulia aenea, Ischnura pumilio and Sympetrum fonscolombii. In the future man-made holes will be made in the surrounding dykes. In this way the Water Board Authority tries to create more space for high river discharges from the river Rhine and Meuse in the nearby future.