Sympetrum depressiusculum (Selys), a southern continental dragonfly depending on artificial habitats in atlantic northwestern Germany (state of Northrhine-Westphalia) (Anisoptera: Libellulidae)

– In the atlantic northwest of central Europe, S. depressiusculum is confined to shallow artificial ponds with a particular aquatic vegetation, clear water, rich food supply (zooplancton, zoobenthos) for the larvae, and – due to drying up during winter – with reduced negative impact by fish. Essentially, water temperature has to rise above the average level typical for this region. Carp breeding ponds offer these conditions, favouring S. depressiusculum outside of its original area. The artficial carp breeding ponds provide invaluable chances for species conservation in this geographical region, furthering the state’s official nature conservation management. Some lead water ponds near the Dutch-Belgian border (in the vicinity of Lommel) seem to provide similar habitat conditions. It is assumed, though still an open question, that S. depressiusculum is relying on the same ecological conditions in fish ponds in more continental areas of central Europe (e.g. the Lausitz district near the Oder; the Frankisches Weihergebiet in the hilly zone of northern Bavaria). This paper should promote the verification of this assumption.