engleski

Hydro-technical measures on the streams at the area of the Nature Park Medvednica, Croatia and their impacts on Austropotamobius torrentium populations

Nature Park Medvednica was founded at year 1981 by the Croatian parliament. About 64% of Park area is covered with natural forests which consist of species like beech, fir, sessile oak, maple, hornbeam and alder. Medvednica is abundant with streams and springs which have a distinctly mountain character ; upper flow is steep and lower slanted. Springs on Medvednica generally have smaller capacity, but are numerous (around 50 only at the southern slopes of the mountain) and therefore are included in water supply of city. Streams are endangered by aggressive hydro-technical measures, construction in the neighbourhood, polluted faecal and other waste water, and disposal of bulk waste. Stream fauna is significant since it includes many endangered and endemic taxa, among them the stone crayfish (Austropotamobius torrentinum Schrank 1803) which is one of the four native European crayfish and is protected by law nationally. As abundance of the stone crayfish is depended on stony and pebble shelters at their habitat canalization of the streams is one of the main reasons for a reduction of their distribution in Park. Presence of the stone crayfish in streams of the NP Medvednica was confirmed in at least 12 streams and further monitoring would be carried out this year with the special attention on hydro-technical measures. Moreover, as crayfish are large omnivores and ecosystem engineers changes of their distribution directly affect distribution of species at lower trophic levels and water quality which was confirmed by determination of extended biotic index (EBI) in three reaches of two canalized streams during three years of monitoring. Physico-chemical data at our study sites indicated also water quality This study represents replicated assessments for natural and canalized streams in Croatia.

Austropotamobius torrentium; Medvednica; stream; hydro-technical measures

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