THE SEASONAL DYNAMICS OF ORGANIC MATTER REMINERALIZATION BY BACTERIAL CONSORTIA IN THE HEATED KONIN LAKES

In the course of a three-year study, analyses were carried out into primary production and bacterial production, as well as into total and bacterial destruction in the Konin lakes (Poland). Investigations demonstrated a significant correlation between the dynamics of microbiological processes and the seasonal variability of mineral and organic forms of nitrogen and phosphorus. The analysis of the chemical and microbiological composition of the lake waters indicates that in the fall-winter seasons, microbiological regeneration processes of the mineral forms of nutrients predominate in these waters. Under favorable thermal and oxygen conditions, heterotrophic bacteria and numerous chemolithotrophs completely decompose organic matter to the mineral level. This is reflected in the DOC (dissolved fractions of organic carbon) decrease and, simultaneously, in the considerable increase in orthophosphates and nitrates. In the spring season, the high accumulation of nutrient compounds stimulates high primary production. The resulting substantial increase in DOC concentration determines the high productivity of bacteriocenosis, which activates a highly efficient microbiological trophic chain, thus contributing to the rapid decomposition of organic matter. Intensive processes of the microbiological decomposition and biotransformation of organic matter, which are dependent on thermal air currents and on water retention, with the simultaneously effective transfer of organic carbon to the higher trophic levels, are crucial factors that affect the homeostasis of the ecosystem of the Konin lakes