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Lake Łuknajno, a shallow (max. depth 3 m) and relatively large (630 ha) water body situated in the Great Masurian Lakes system (Poland) is strongly affected by its agricultural watershed. The total volume of drainage waters pumped into the lake in 1993 amounted 2.84 x 106 m3 which is equivalent to 65% of the lake volume. In spring and autumn drainage waters were extremely rich in nitrogen (especially nitrates) and the N:P ratio reached 57 in spring. In summer, drainage waters contained relatively more phosphorus so the N:P ratio decreased to nearly 10. Nutrient concentrations in lake water followed the changes in inflowing waters. High concentrations of nitrates and ammonia were noted in lake water in spring but summer concentrations of these ions were close to zero. Soluble reactive phosphorus varied between 10 and 20 μg P 1–1 throughout the season. A constant outflow of nitrogen to the lower Lake Sniardwy was assumed based on a permanent concentration gradient between waters of these two lakes. Lake Łuknajno is a hard water lake. Co-precipitation of phosphorus with calcium carbonate is likely to occur though no significant P accumulation in bottom sediments was found. Sorption of phosphorus on sediments as measured under experimental conditions has minor effects on P cycling. Bottom sediments composed mainly of calcareous gyttja do not accumulate either organic matter or mineral forms of nutrients.

An analysis of Cladocera has been made on sediments from the three Polish lakes Suszek, Blcdowo, and Skrzetuszewskie. The analysed sediments are gyttja from the Subboreal and Subatlantic periods, during which the lakes were subject variously to eutrophication. The eutrophication process has been analysed from the frequency of Cladocera, particularly the index species, and has been correlated with climatic and settlement changes. It was found that in Suszek lake, in which no significant human activity had taken place (palynologically documented), the eutrophication must have been slow and gradual. On the contrary, in the two remaining lakes, in which the human influence was more intense, the eutrophication process underwent intensive changes and coincided somewhat with settlement fluctuations.

Twelve species of aquatic earthworms have been found in European inland waters where they occupy different environments. Two species live exclusively in the sapropel, that is in the black fetid asphyctic mud, while four species can be found either in the sapropel or in the more oxygenated gyttja. The remaining species prefer this type of soil, but Eisenia spelaea in Italy lives only within submerged litter in mountain streams. The biology of these earthworms is discussed and the possibility of their utilization by man is considered.

In the pond of Lobsigensee (2 ha, on the Swiss Plateau) lithostratigraphic and palynostratigraphic units for the Late-glacial and the Holocene have been described. During the Late-Glacial the sediment types are mainly controlled by climate (the end of clay deposition coincides with the end of the Oldest Dryas, i.e. with reforestation at the beginning of Bölling) or by facies (lake marl in the littoral, gyttja in the profundal during Bölling and Alleröd). During the Holocene the facies and the changes in the trophic status, partly combined with water level changes, seem to determine the types of sediment. Two phases of natural eutrophication are deduced from laminated sections during the Boreal and the early Older Atlantic. Towards the end of the Younger Atlantic an early example of a probably anthropogenic eutrophication is found in the layers contemporaneous with the neolithic settlement of the Cortaillod culture. Since the Roman colonization the amount of erosional input has markedly increased.