Development of Aquatic Macrophytes in Shallow Lakes and Ponds

Abstract

The distribution of macrophytes in shallow lakes and ponds is subject to zonation. A typical zonation of the littoral of Scandinavian lakes under oligotrophic conditions include, from the lake surface to the lowest part of the littoral, helophytes, nymphaeids, elodeids and isoetids. With increasing pollution and eutrophication of lakes leading to increased turbidity and reduced transparency, first to disappear are the isoetids followed by the elodeids. At the same time, i.e. with increasing nutrient levels, the quantity of emergent and floating-leaved plants increases. Further increases in nutrient levels result in system instability, excessive development of chlorococcal algae, blue-greens or filamentous algae, extreme values of oxygen concentration and high pH, oxygen depletion at the bottom, and, in extreme situations, even to the release of free ammonia – the conditions which may lead to fish kills as experienced in fish ponds of Bohemia.