Succession of submerged vegetation in a hydrologically reclaimed opencast mine during first 10 years

Abstract

Succession of submerged vegetation was monitored from the early stages for a period of 10 years by Self‐Contained Underwater Breathing Apparatus (SCUBA) divers in Milada Lake. Milada Lake is the result of a flooded surface coal mine, the first large‐scale hydrological recultivation in the Czech Republic. The main focus was on apparent changes in the percentage cover of primary producers (macrophytes and macroalgae) during early successional stages. In total, data on 33 environmental factors (chemical, physical, and biological) were collected and the importance of their impact was statistically analyzed. Besides macrophytes, we also monitored macroalgae that mainly occupied deep areas (down to 12 m) and have been neglected in literature in contrast to macrophytes. Uniquely, the trophic state of the study site decreased in contrast to most water bodies worldwide. Changes in the plant species composition during succession, including replacement of the dominant group of Characeae with Vaucheria sp. (both macroalgae), correlated with a decrease in nitrate concentration, N–NO3. Furthermore, the herbivorous fish biomass and availability of uncovered lake bottom played important roles in the succession of macrophytes and macroalgae. Although some changes in submerged vegetation during succession of a newly created lake are to be expected, the main shifts observed apparently correlated with the studied factors. The conclusions may be useful for the prediction of succession in similarly created lakes in the future.