SUBMERGED VEGETATION DEVELOPMENT IN 2 SHALLOW, EUTROPHIC LAKES

Submerged macrophyte vegetation in two shallow lakes in the Netherland s, Lake Veluwemeer and Lake Wolderwijd, has been affected by eutrophic ation in the late 1960's and 1970's. Recent changes in the vegetation occurred in the period following lake restoration measures. Between 19 87 and 1993, the dominance of Potamogeton pectinatus decreased, while Charophyte 'meadows' expanded over the same time interval. The pattern of change of the dominant macrophyte species might result from change s in the underwater light climate. Seasonally persistent clear water p atches associated with the Chara meadows have been observed in the las t few years. The interaction between submerged macrophyte vegetation s uccession and water transparency in the lakes is discussed.