Chlorophyll a and physical-chemical features of small water bodies as indicators of land use in the Wielkopolska region (Western Poland)

The present paper analyzes the impact of differentiated land uses in the catchment area (pastoreo, forest and urban) on changes in phytoplankton biomass of open water in small water bodies located in the central part of the Wielkopolska region (western Poland). Anthropogenic pressure in the pond surroundings ranged from almost negligible in the forested areas to very strong in the urban areas which were subject to the impact of the large city agglomeration. The examination of chlorophyll a and the physical-chemical features of water were carried out over one week in July 2006. The water of the investigated ponds had a characteristically neutral to alkaline pH and moderate mineralization. Urban ponds exhibited the higher chlorophyll concentrations and pH values. Ponds in the pastoral landscape were characterized by high concentrations of phosphorus due to livestock influence. Some ponds in the pastoral area presented also high nitrate concentrations indicating agricultural influence. A specific feature of mid-forest ponds was a relatively lower concentration of phosphate in the water, but they had a high concentration of DOM, both factors were probably responsible for the maintenance of a low biomass of algae.