Sympecma fusca and S. paedisca occur in a wide spectrum of habitats within standing waters. However, the knowledge of these species distribution in oxbows is poor in Poland. In this study, new sites of S. fusca and S. paedisca along the Vistula River valley, be- tween Jawiszowice and Otałęż in the Małopolska Region (the Lesser Poland), are presented (Tab. 1, Fig. 1) and the importance of oxbows for the species distribution is discussed. Habi- tat conditions concerning hydrological and physico-chemical (12 parameters) water proper- ties are analysed (Tab. 2) with a focus on nutrient contents (phosphate – PO4 3–, ammonium – NH4 +, and nitrate – NO3 −). A total of 22 UTM 10x10 km squares were investigated and S. fusca was recorded in 17, while S. paedisca in 11 UTM squares (Tab. 1, Fig. 1). In total, 51 and 25 new sites of S. fusca and S. paedisca, respectively, were recorded. The species coexisted at 22 (43%) sites. The reproductive behaviour was observed at 29 sites for S. fusca and at 16 ones for S. paedisca. Both species preferred oxbows that during high water periods were temporarily connected with the river, i.e. those situated inside rather than outside of the levees (Fig. 2). Specifically, 63% sites of S. fusca and 76% sites of S. paedisca were located between the levees of the Vistula River. With respect to hydrochemical conditions, both species occurred in habitats with wide ranges of all measured water parameters and there was no significant difference between their preferences in this matter (Fig. 3). Regarding nutrients, both species were found at concentrations reaching 1,5 mg L–1 PO4 3– and 1,6 mg L–1 NH4 +. Nevertheless, a comparison between inhabited and uninhabited waters revealed preferences of both species to relatively low contents of phosphate and ammonium. With respect to nitrate, S. paedisca occurred at their low concentrations, whereas S. fusca did not show any pattern. We conclude that oxbows, particularly those seasonally flooded due to the river proxi- mity, are important habitats for S. fusca and S. paedisca. Thus, special attention should be paid on biotopes situated in great river valleys in Poland. Although both species tolerate broad ranges of physico-chemical water parameters, oxbows with relatively low nutrient concentrations are preferred.
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