Can popular systems of trophic classification be used for small water bodies?

The aim of the study was to evaluate the trophic conditions of the waters of twelve small ponds based on the analysis of their physical and chemical parameters according to Carlson's Trophic State Index and OECD. Great differentiation in the trophic status of ponds located in different varieties of landscape was observed and ranged from mesotrophic to weak eutrophic conditions in mid-forest ponds and clay-pits, eutrophic conditions in pastoral ponds, and hypertrophic conditions in urban water bodies. Throughout the analysis, a number of limitations in the classification methods of trophic conditions in the examined water bodies were noted. The specific problems were the shallow depth of ponds, which often corresponded with the depth of the Secchi disc transparency, or the complete overgrowing of the pond water column by macrophytes.