THE ICHTHYOFAUNA OF THE DYSTROPHIC LAKE SMOLAK (NORTHERN POLAND) IN LIGHT OF SELECTED PHYSICAL AND CHEMICAL WATER CONDITIONS THIRTY YEARS AFTER THE CONCLUSION OF LIMING AND FERTILIZATION
Andrzej Hutorowicz, Andrzej Kapusta, Tadeusz Krzywosz, Joanna Hutorowicz
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. The aim of ichthyofauna studies conducted in Lake Smolak (northern Poland) in the 2002-2004 period was to evaluate species richness, growth rate, and fish assemblage structure in light of environmental conditions. This initially dystrophic lake, which, in the 1950s, was inhabited by only two fish species – perch, Perca fluviatilis L., and pike, Esox lucius L., was subjected to experimental liming and fertilization (to stimulate eutrophication) and stocking in the 1971-1974 period. Currently, the ichthyofauna of the lake is comprised of ten species belonging to four families. The density of the fish in this lake is not high; the most numerous are roach, Rutilus rutilus (L.) and bream, Abramis brama (L.). Roach was characterized by a rapid growth rate, but that of bream was very slow. The environmental parameters of the lake undoubtedly have a negative impact on the ichthyofauna, especially the gradients of and seasonal variation in the physical and chemical parameters of the water as well as the absence of submerged hydrophytes and the limited occurrence of helophytes.
Key words: DYSTROPHIC LAKE, PHYSICAL AND CHEMICAL CONDITIONS, LIMING, MINERAL FERTILIZATION, ICHTHYOFAUNA, GROWTH RATE
Dr hab. Andrzej Hutorowicz, Instytut Rybactwa Śródlądowego, Zakład Hydrobiologii, ul. Oczapowskiego 10, 10-719 Olsztyn, Tel./Fax: +48 89 5241010, +48 89 5240505;