WATER QUALITY AND ECOLOGY OF THE IEZER AND BOLĂTĂU LAKES

Marcel MÎNDRESCU, Ionuţ Alexandru CRISTEA, Gabriela FLORESCU
University of Suceava, Suceava, Romania marcel.mindrescu@gmail.com

Abstract

Having been in existence for over 400 years, the natural dammed lakes formed by landslide movements, Iezer and Bolătău, enjoy a high level of biodiversity, far above the average of the nearby land area covered with spruce tree forests. Belonging, from the very beginning of their existence, to a land property of Humor Monastery (1495) in Suceava County, the lakes were, for a while, ponds stocked with fish by the monks of that time. Both lakes hold waters situated in the first two water quality categories, the first for Bolătău, and the second for Iezer respectively. A very good quality of water, together with the slightly alkaline pH, allowed the formation of favourable conditions for salmonids (trout). In 1960 there has been a trout stocking action, with eastern brook trout (Salvelinus fontinalis Mitchell), but nine years later (1969), a new species, less vulnerable to these altitude conditions had to be introduced, the native trout (Salmo trutta fario) respectively. Stocking actions continued in 1979 from the same source, namely Putna Valley, this time with rainbow trout (Salmo gairdneri Richardson). Excessive proliferation of trout, because of the abundance of food, led to the necessity to also introduce specimens of common minnow (Phoxinus Phoxinus), for the purpose of serving as food for salmonids. The high pressure exerted by the fish species was reflected in the development, extinction and variety of microorganisms such as Cladocera. Thus, there are plenty of reasons for the two lacustrine units to become strict protected areas.

Keywords: water quality, ecology, fish, microorganisms, Obcinele Bucovinei