Distribution and ecology of the stoneflies (Plecoptera)of Flanders (Belgium)

Abstract

Based on a literature survey and the identifi cation of all available collection material from Flanders, a checklist is presented,distribution maps are plotted and the relationship between the occurrence of the different species and water characteristics isanalysed. Of the sixteen stonefly species that have been recorded, three are now extinct in Flanders (Isogenus nubecula, Taeniopteryxnebulosa and T. schoenemundi), while the remaining species are rare. The occurrence of stoneflies is almost restrictedto small brooks, while observations in larger watercourses are almost lacking. Although a few records may indicate that somelarger watercourses have recently been recolonised, these observations consisted of single specimens and might be due to drift.Most stonefly population are strongly isolated and therefore extremely vulnerable. Small brooks in the Campine region (northeastFlanders), which are characterised by a lower pH and a lower conductivity, contained a different stonefly community than thesmall brooks in the rest of Flanders. Leuctra pseudosignifera, Nemoura marginata and Protonemura intricata are mainly found insmall brooks in the loamy region, Amphinemura standfussi, Isoperla grammatica, Leuctra fusca, L. hippopus, N. avicularis andP. meyeri mainly occur in small Campine brooks, while L. nigra, N. cinerea and Nemurella pictetii can be found in both types.Nemoura dubitans can typically be found in stagnant water fed with freatic water. Sustainable populations of these stonefly speciescan only be achieved when their present habitats are adequately protected and in addition, measures should be taken to connectand enlarge the remaining populations.