Highly humic lakes are typical for the boreal zone. These unique ecosystems are characterised as relatively undisturbed habitats with brown water, high acidity, low nutrient content and lack of macrophytes. Current lake assessment methods are not appropriate for ecological assessment of highly humic lakes because of their unique properties and differing human pressures acting on these ecosystems. This study proposes a new approach suitable for the ecological status assessment of highly humic lakes impacted by hydrological modifications. Altogether, 52 macroinvertebrate samples from 15 raised bog lakes were used to develop the method. The studied lakes are located in the raised bogs at the central and eastern parts of Latvia. Altered water level was found as the main threat to the humic lake habitats since no other pressures were established. A multimetric index based on macroinvertebrate abundance, littoral and profundal preferences, Coleoptera taxa richness and the Biological Monitoring Working Party (BMWP) Score is suggested as the most suitable tool to assess the ecological quality of the highly humic lakes.

HIGHLIGHTS. A new approach for ecological flow calculations based on fish data and suggestions for a flow regime instead of one single flow value.A better under

Eurylophella karelica is a rare and poorly investigated species of European Ephemeroptera from the family Ephemerellidae. From the 1930s to 1970s, E. karelica has not been reported from historical localities in Karelia, Lithuania and Poland. New localities from Hungary, Slovenia and Lithuania are discovered over the last 2 decades. This article reports first findings of E. karelica in Latvia and Estonia and explains sporadic distribution of this species. Eurylophella karelica is a rare and poorly investigated species of European Ephemeroptera from the family Ephemerellidae. From the 1930s to 1970s, E. karelica has not been reported from historical localities in Karelia, Lithuania and Poland. New localities from Hungary, Slovenia and Lithuania are discovered over the last 2 decades. This article reports first findings of E. karelica in Latvia and Estonia and explains sporadic distribution of this species.