Original paper

Water quality and algal growth potential of watercourses draining agricultural and forested catchments in eastern Croatia (Middle Danube Basin)

Peršić, Vesna; Kočić, Aleksandra; Horvatić, Janja

Abstract

The water quality of watercourses in eastern Croatia was examined in terms of the influence of land use and sampling time in the agricultural and forested catchments. Based on small nitrogen to phosphorus ratios (N/P) and the overall high phosphorus concentrations, nitrogen was expected to limit primary production in the spring sampling. The results indicate that N/P ratio was not a reliable indicator of nutrient limitation since ambient concentrations were sufficient to preclude nutrient limitation. The study, therefore, examined nutrient enrichment experiments and found that watercourses of the rural and agricultural catchment (the Biđ-Bosut) are severely damaged or at high risk of eutrophication and their nutrient contents are far above prescribed concentrations. Only moderate signs of distortion resulting from anthropogenic activities were observed in watercourses draining the forested catchment (the river Spačva basin) while some watercourses draining the agricultural watershed in the Danube-Drava catchment showed nutrient deficiency (primarily nitrogen).

Keywords

agricultureflowing watersphosphorusn/p rationutrient enrichment experimenttrophic conditions