Between 2001 and 2016 the influence of diversified share of arable land in the catchment areas of Lake Długie (5.5% of arable land) and Lake Głębokie (73.5% of arable land) on the biochemical processes in shoreline soils was researched in five-year measurement cycles. The research chiefly encompassed the biochemical processes of conversion of nitrogen and phosphorus compounds (phosphatase, urease and protease activity). Simultaneously, the content of mineral nitrogen and assimilable forms of phosphorus in the shoreline soils of both lakes was investigated. During the observations the enzymatic activity in the Lake Długie shoreline soil was significantly greater than in the soil surrounding the shore of Lake Głębokie. However, the catchments areas of both lakes were characterised by similar changes in the enzymatic activity of shoreline soils. Between 2001 and 2006 the enzymatic activity in the soils under study was similar and exhibited a slight increasing tendency. In the consecutive measurement cycles (2011 and 2016) the activity of the enzymes decreased significantly. It was strictly correlated with the increasing content of nitrogen and phosphorus compounds in the soils surrounding both lakes. The biochemical and chemical indicators under analysis clearly point to rapid eutrophication in the shoreline habitats around Lakes Długie and Głębokie.