Lake Verevi, Estonia - A Highly Stratified Hypertrophic Lake

The present book summarises investigations on Lake Verevi (surface 12.6 ha, mean depth 3.6 m), located in the Estonian town of Elva, initiated since 1929. The seventeen articles in this issue deal with a wide range of questions, starting with a holistic overview of the ecological status, over assessments of long-term changes in biotic and abiotic conditions and finishing with proposed restoration plans. Abiotic chapters provide calculations on water and mass balance, distribution and fractions of phosphorus in the sediment, optical properties and penetration of radiation in the water column, sedimentation rate during the formation of stratification, and nitrogen circulation characteristics. All of these phenomena explain the special environmental features of this highly stratified lake. Long-term changes, seasonal development, primary production and resource ratios inducing the distribution of species composition of various biota (bacterio-, phyto and zooplankton, macrozoobenthos, fish) are discussed. The most important issues in this book are long-term investigations on a complex ecosystem, the phenomenon of partial meromixis, the description of restoration methods, and the existence of narrow microniches for plankton in the water column.

"This book summarises investigations on Lake Verevi (surface 12.6 ha, mean depth 3.6 m), located in the Estonian town of Elva, initiated since 1929. The seventeen articles deal with a wide range of questions, starting with a holistic overview of the ecological status, over assessments of long-term changes in biotic and abiotic conditions and finishing with proposed restoration plans. Abiotic chapters provide calculations on water and mass balance, distribution and fractions of phosphorus in the sediment, optical properties and penetration of radiation in the water column, sedimentation rate during the formation of stratification, and nitrogen circulation characteristics. All these phenomena explain the special environmental features of this highly stratified lake. Long-term changes, seasonal development, primary production and resource ratios inducing the distribution of species composition of various biota (bacterio-, phyto and zooplankton, periphyton, macrovegetation, macrozoobenthos, fish) are discussed. The most important issues are long-term investigations on a complex ecosystem, the phenomenon of partial meromixis, the description of restoration methods, and the existence of narrow microniches for plankton in the water column. The volume firmly establishes Lake Verevi as a model system of a natural aquatic habitat, experiencing a multitude of anthropogenic pressures, but for which restoration plans aim to provide sustainable management in the future."

General description of partly meromictic hypertrophic Lake Verevi, its ecological status, changes during the past eight decades, and restoration problems.- Water and nutrient mass balance of the partly meromictic temperate Lake Verevi.- Distribution of sediment phosphorus fractions in hypertrophic strongly stratified Lake Verevi.- Optical properties and light climate in Lake Verevi.- Sedimentation rate of seston during the formation of temperature stratification after ice break-up in the partly meromictic Lake Verevi.- Nitrogen dynamics in the steeply stratified, temperate Lake Verevi, Estonia.- The formation and dynamics of deep bacteriochlorophyll maximum in the temperate and partly meromictic Lake Verevi.- Bacterioplankton abundance and activity in a small hypertrophic stratified lake.- Long-term changes and seasonal development of phytoplankton in a strongly stratified, hypertrophic lake.- Primary production of phytoplankton in a strongly stratified temperate lake.- Resource ratios and phytoplankton species composition in a strongly stratified lake.- The composition and density of epiphyton on some macrophyte species in the partly meromictic Lake Verevi.- Vertical distribution of zooplankton in a strongly stratified hypertrophic lake.- Vertical and seasonal dynamics of planktonic ciliates in a strongly stratified hypertrophic lake.- Long- and short-term changes of the macrophyte vegetation in strongly stratified hypertrophic Lake Verevi.- Macrozoobenthos of Lake Verevi.- Diel migration and spatial distribution of fish in a small stratified lake.