engleski

VERTICAL DISTRIBUTION OF PERIPHYTON IN LOTIC AREA OF RIVER KRKA

The aim of this study was to determine rate of periphyton growing over artificial surfaces. Plexy slides were exposed for 30, 60, and 90 days on vertical profile (epilimnion, metalimnion and hypolimnion) of lower, lotic area of River Krka from July to September 1995. Besides qualitative and quantitative composition and abundance of algae on perpendicular (direct water flow) and parallel (upper and lower side) surfaces, some physic-chemical parameters were also researched. During research time 90 different species were observed. The most dominant group, Bacillariophiceae was well represented with species. Cyclotella radiosa (Grun.) Lemmer., Achnanthes affinis Grun., Cocconeis placentula Ehr. and Navicula minima Grun. that were present in all samples. Highest growth potential was observed after 60 days of exposition on upper side of horizontally placed surface in epilimnion. During the same exposition time, the lowest growth potential was noted on perpendicular surface in hypolimnion. Results show significant differences in abundance, number and composition of algae between growth surfaces and depths.

periphyton; artificial surfaces; vertical distribution

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