0000000000239949
AUTHOR
P. Bagge
Reproductive success of Coregonus species in areas loaded by effluents from paper mills
The annual reproductive success of Coregonus albula and C. lavaretus in some polluted and clean areas of the central parts of L. Paijanne was estimated in 1981–90 on the basis of occurrence of larvae in shore seine and seine net samples after the ice melted. In polluted areas (0-5 km from Kaipola paper mill) larvae of coregonids were found only occasionally. In semipolluted areas (5–15 km from the paper mill) the densities of larvae were usually less than 0.1 ind m-2. In ‘clean’ areas the mean densities of larvae ranged from 0.45 to 5.34 inds m-2. A relatively high reproductive success of vendace was observed in 1984–85, moderate success in 1982–83 and low success in 1986–90. The larvae of …
Comparison of sampling methods for semipelagic animals in two deep basins of Lake Saimaa
The efficiency of different methods for sampling semipelagic animals was compared in the deep basins of Lake Paasivesi and Lake Puruvesi of the complex Lake Saimaa, Finland, during 1990–92. Certain semipelagic animals, such as Mysis relicta, amphipods and larvae of Chaoborus flavicans, are important bioindicators of water and benthic quality. However, owing to their high mobility and vertical migrations they are difficult to sample quantitatively with traditional benthic methods.
Effects of paper mill effluents on the fish fauna of stony shores of Lake Päijänne
The fish fauna of the stony littoral in the central parts of L. Paijanne was studied by electric fishing on four occasions during 1988–1989. Ten fish species and 1681 individuals (14.5 kg) were caught in the 15 fishing sites (4096 m2) which gives a mean density of 0.41 ind. m-2 and biomass of 3.5 g m-2. Effluent from two large paper mills causes a clear zonation of the fish fauna in the area. In the most polluted shores, only burbot and perch occurred regularly and the reproduction of other species was inhibited. In the semipolluted area (5–15 km from the Kaipola paper mill), burbot and stone loach occurred regularly, but owing to low numbers of perch and bullhead the total densities were u…
Pesticide residues in some Baltic animals - a review of selected literature
ABSTRACT During the last few years, considerable efforts have been devoted to the tracing of halogenated hydrocarbons, particularly DDT and PCB, and of mercury in Baltic animals. These investigations have already produced some important generalizations, which may be summarized as follows: (1) The concentrations of halogenated hydrocarbons and mercury in the tissues of Baltic animals are in general higher than those found in the corresponding species on the west coast of Sweden and in the Norwegian waters. (2) The highest levels of DDT compounds seem to occur in the animals of the southern Baltic and the Sound (oresund). (3) The highest contents of methylmercury in the Baltic fish occur in c…
The food and parasites of fish in some deep basins of northern L. Päijänne
The composition of the fish stock, food and ‘macroparasites’ were studied in eleven basins (22–100 m) of Lake Jyvasjarvi and North Paijanne in August–September 1976. The fishing was done by means of a series of nets (meshes 15, 21 and 35 mm) laid on the bottom overnight. No fish were found in the two northernmost basins owing to bad oxygen conditions caused by waste waters. Smelt and burbot were the most abundant fish in the catches in other basins but the vendace was rare. Relict crustaceans and some ‘deep water’ copepods (e.g. Heterocope borealis) played an important role in the food of fish in all basins.