The Dynamics of Macrophytes in a Lake in an Agricultural Landscape

Macrophytes are a group of aquatic organisms affected by constant changes. One of the main factors influencing the rate and direction of these changes is the way of basin management. The aim of this study was to determine the effect of changes in the management of a lake catchment area in an agricultural landscape on the qualitative and quantitative structure of macrophytes and assessment of the ecological status of the lake in question. The study was conducted in the years 1996, 1999 and 2011 in Lake Głębokie Uścimowskie. This lake is small (20.8 ha surface) and shallow (about 6 m depth). In the 1990s in Lake Głębokie Uścimowskie from 14 to 15 plant communities occurred, which occupied 2.9 ha of the lake. This represented only 14.1% of the lake. In 2011 there was a slight growth in the number of phytocenoses (16), and significant increase in the area of phytolittoral—5.98 ha. In the 1990s the range of ESMI index values, allowed the lake to be categorized as one with poor ecological status, but already in 2011 after a similar analysis, the lake was ranked in the upper limits of moderate ecological status of lakes. One of the main reasons for the rise in the ecological status of Lake Głębokie Uścimowskie, determined on the basis of the macrophyte index, as well as for the slight decline in trophy, was probably a sewerage system built in 2006 in Głębokie village.