Ecological quality of freshwater lakes and their management applications in urban territory

Abstract

Freshwater lakes and rivers are habitats of variety of organisms and their populations giving great importance for freshwater ecosystems and providing water resources, food and recreational possibilities for humans. In spite of their fundamental importance to humans, freshwater lakes have been affected by anthropogenic disturbances, which have led to serious negative effects on the structure, functions and quality of these ecosystems. Lake ecosystems are dependent on inflow of water and supply of matter and energy from their catchment area. In studied lakes significant anthropogenic impact in loads of nutrients in their sediments and water was detected. This highlights the well-known problem of freshwaters in the World and in Europe-eutrophication, which can lead to increased productivity of water ecosystems-increased algae blooms, spreading of macrophytes and decreasing of oxygen content in water. Studied lake ecosystems show presence of human impact, not only by physiochemical parameters, but also by changes in biomass production, cyanobacterial algal blooms and overgrowing with macrophytes was observed. In order to improve water quality, appropriate management measures should be applied. We have analysed advantages and disadvantages of such measures as sediment removal, constructing of wetlands, cutting reeds and forming ecotones.

Quality of Lake Ecosystems and its Role in the Spread of Invasive Species

“…3.9 m). As described previously [29] on Balvu Lake water locks which stabilize water regime on studied lakes are installed.…”

“…Lakes have Pleistocene glacial origin, they are inter-connected and outflowing rate is stabilized with non-Environmental and Climate Technologies ____________________________________________________________________________ 2021 / 25 678 regulated water locks. Between both lakes there is small extension of Lake Pērkonu where Žaugupe River and Pelnupe River carries their water, in case of Žaugupe River noticeably higher amounts of nutrients are introduced into the lake [29]. Regulation of hydrological regime of lakes has been done several times and most important effect was in the 60-ies of last century where hydrological regime of Bolupe River was changed which led to decreased water level of studied lakes by 1.5 m. Altogether with physical changes of hydrological regime there is also increased anthropogenic pressure on lakes including release of sewage waters in lakes.…”