Macrophyte distribution pattern in the Krka River - the role of habitat quality

Abstract

The Krka River is a lowland karstic watercourse with an extended underground hydrological net. Travertine cascades, blocks and dams in the riverbed influence the river flow and depth, creating a variety of habitats. The watershed landscape is a mosaic of agricultural and natural patches with some urban areas. Macrophyte and habitat survey was made on the whole river length. Macrophyte community consisted of 33 vascular plant species. Among them Ceratophyllum demersum, Myriophyllum spicatum, Potamogeton filiformis, P. natans, P. nodosus and Najas marina were abundant. RDA analysis distributed species and reaches of the river in three distinct groups. The first group comprises survey units from the source to the middle of the river, near the industrial city of Novo Mesto. The second group consists of survey units in the city, and the third group the units located from Novo Mesto. The importance of water flow, which is the highest in the upper part of the river, and the relation between sediment type and species colonizing habitats with lower flow velocities are clearly shown.