Ahtiainen, M. & Huttunen, P. 1999. Long-term effects of forestry managements on water quality and loading in brooks. Boreal Env. Res. 4: 101–114.
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Erkinaro, J., Økland, F., Moen, K. & Niemelä, E. 1999. Return migration of the Atlantic salmon in the Tana River: distribution and exploitation of radiotagged multi-sea-winter salmon. Boreal Env. Res. 4: 115–124.
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Niemelä, E., Julkunen, M. & Erkinaro, J. 1999. Densities of the juvenile Atlantic salmon (Salmo salar L.) in the subarctic Teno River watercourse, northern Finland. Boreal Env. Res. 4: 125–136.
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Lehtonen, H. 1999. Rehabilitation of lakes for fish and fisheries in Europe — a review. Boreal Env. Res. 4: 137–143.
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Hynynen, J., Palomäki, A., Veijola, H., Meriläinen, J. J., Bagge, P., Manninen, P., Ustinov, A. & Bibiceanu, S. 1999. Planktonic and zoobenthic communities in an oligotrophic lake inhabited by an endemic and endangered seal population. Boreal Env. Res. 4: 145–161.
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Kallio-Nyberg, I. & Koljonen, M.-L. 1999. Sea migration patterns in the Atlantic salmon: a comparative study of two stocks and their hybrids. Boreal Env. Res. 4: 163–174.
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Karro, E. 1999. Long-term changes in groundwater chemistry in four coastal water supply plants in southern Finland. Boreal Env. Res. 4: 175–186.
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Vuori, K.-M., Luotonen, H. & Liljaniemi, P. 1999. Benthic macroinvertebrates and aquatic mosses in pristine streams of the Tolvajärvi region, Russian Karelia. Boreal Env. Res. 4: 187–200.
Abstract
Full text (pdf format)
Ahtiainen, M. & Huttunen, P. 1999. Long-term effects of forestry managements on water quality and loading in brooks. Boreal Env. Res. 4: 101–114.
Erkinaro, J., Økland, F., Moen, K. & Niemelä, E. 1999. Return migration of the Atlantic salmon in the Tana River: distribution and exploitation of radiotagged multi-sea-winter salmon. Boreal Env. Res. 4: 115–124.
Niemelä, E., Julkunen, M. & Erkinaro, J. 1999. Densities of the juvenile Atlantic salmon (Salmo salar L.) in the subarctic Teno River watercourse, northern Finland. Boreal Env. Res. 4: 125–136.
Hynynen, J., Palomäki, A., Veijola, H., Meriläinen, J. J., Bagge, P., Manninen, P., Ustinov, A. & Bibiceanu, S. 1999. Planktonic and zoobenthic communities in an oligotrophic lake inhabited by an endemic and endangered seal population. Boreal Env. Res. 4: 145–161.
Kallio-Nyberg, I. & Koljonen, M.-L. 1999 . Sea migration patterns in the Atlantic salmon: a comparative study of two stocks and their hybrids. Boreal Env. Res. 4: 163–174.
Karro, E. 1999. Long-term changes in groundwater chemistry in four coastal water supply plants in southern Finland. Boreal Env. Res. 4: 175–186.
Vuori, K.-M., Luotonen, H. & Liljaniemi, P. 1999. Benthic macroinvertebrates and aquatic mosses in pristine streams of the Tolvajärvi region, Russian Karelia. Boreal Env. Res. 4: 187–200.
The concentration of suspended solids in a meso-eutrophic basin remained unchanged in the years following clear felling (1983–85). The amount of suspended solids increased upon ditching, ploughing and mounting to a mean level of 81.8 mg l–1 in 1986–88, decreased to a level of 7.8 mg l–1 for 1989–91 and 4.5 mg l–1 for 1992–94. Total phosphorus concentration increased four-fold (142 µg l–1) in 1983–85 following clear felling, and remained at three times the reference concentration (95.4 µg l–1) in 1986–88 following ditching and site preparation. Phosphate phosphorus concentration increased more than five-fold after clear felling (97.8 µg l–1) in 1983–85 and was more than two-fold the reference (39.5 µg l–1) following ditching and site preparation in 1986–88. The concentrations of total phosphorus and phosphate phosphorus returned to the level recorded in a natural state by 1989 onwards. Total nitrogen concentrations doubled (965 µg l–1) upon clear felling, and remained the same after ditching and site preparation in 1986–88. Where a protective strip of forest was left between the felling site and the brook, suspended solid did not increase in response to either clear felling or ploughing of the felled area, nor were any changes observed in total phosphorus, phosphate phosphorus or nitrogen componds.The ditching of peatland down to the level of the mineral soil led to an increase in the suspended solid concentration (17.8 mg l–1) by a factor of more than 12 in the first three years (1983–85) and by a factor of more than four (5.7 mg l–1) in the following three years (1986–88) compared with the reference period. Total nitrogen, nitrate and nitrite concentrations of ground water were markedly low all the time the forests remained in their natural state, but began to rise gradually following clear felling. A high increase was recorded as a consequence of ditching and site preparation.
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A total of 174 multi-sea-winter Atlantic salmon (75–115 cm fork length) were radiotagged in the Tanafjord in 1992–1993 and their upstream migration and exploitation in the Tana River (Teno) were studied. Of the tagged fish, 75% and 77% entered the river, and 40% and 69% of them were later recaptured in 1992 and 1993, respectively. The lower 60 km of the river accounted for 36% of the recaptures. Gillnets and weirs took 68% of the fish recaptured in the river in 1992 but only 40% in 1993, the rest being caught by rod and line. Weirs caught more recently entered salmon than gillnets. Rod and line fishery caught smaller fish than gillnets and weirs. There were no differences in the size distributions between the initially tagged salmon, those that entered the river, were recaptured in the river, or the ones survived until spawning. Exploitation rates (nrecaptured fish/nentered the river) were the highest in the upper reaches of the river system.
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Changes in juvenile wild Atlantic salmon densities in the subarctic Teno River watercourse, northern Finland, have been studied and recorded since 1979 at 57 sites representing different biotypes. Densities were very low in the first few years, after which there was substantial variation. The lowest and highest mean densities of fry at a site in the Teno River were 0.2 and 135 fish per 100 m2, respectively; respective values for parr were 0.9 and 50 fish per 100 m2. The lowest and highest values in the Utsjoki, a river in northern Finland, were 0.1 and 136 fish per 100 m2 for fry and 2.3 and 71 fish per 100 m2 for parr. The highest densities of fry and parr ever recorded in the Teno River were 424 and 106 fish per 100 m2, respectively. The annual densities of fry and parr were interdependent only in a few cases. Different densities in some other northern rivers relative to those in the Teno watercourse might reflect the different fishing culture, but also the stocking of juveniles can increase densities, thus, hampering the interpretation. The densities of the juvenile salmon fluctuated within sampling sites and between years, primarily as a result of fluctuations in the spawning stock, which is strongly affected by changes in the in-river fishing effort. Fluctuations in the juvenile salmon densities are obviously not affected by predation as the proportion of other species in the juvenile salmon's habitat is low. Parr densities in the Teno River catchment are on average clearly lower than those found in rivers which lack a diverse net fishery. Several fishing regulations set after the year 1984 have functioned only partly. Juvenile densities have not crashed despite the increased in-river exploitation by rod and reel anglers but densities of the juvenile salmon have not either increased.
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In order to assess the present biological state and to give some guidelines for the planned monitoring of Pihlajavesi, one of the most important habitats for the threatened endemic relict Saimaa ringed seal (Phoca hispida saimensis Nordq.), the main communities of phytoplankton, zooplankton and benthic invertebrates were described using multivariate statistical analyses. The composition of phytoplankton assemblages was mainly determined by the nutrient concentration and the colour of the water so that the phytoplankton community of a clear-water basin differed in this lake from those of the other basins. In contrast there were no such differences in zooplankton assemblages between the basins, but the distinct difference between the pelagic and littoral communities was evident. The water depth and related parameters, such as bottom quality, were the most important factors affecting on zoobenthic assemblages. Species composition changed gradually with increasing depth, the rate of the change being greatest in the littoral area. The following soft bottom communities were distinguished from the lake: vegetated littoral (1–3 m), sublittoral (3–10 m), upper profundal (10–20 m) and deep profundal communities. The deep profundal assemblage in the effluent-loaded basin differed from that in other basins to such an extent that it could be considered to form a distinct community of its own. Special features of the communities resulting from the high transparency of water are discussed.
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The sea migration patterns of the Atlantic salmon in the Baltic Sea was examined in a crossing and transplantation experiments. Two genetically different salmon stocks originating from rivers Neva and Iijoki and their hybrids were released as smolts (6 561, 485 and 993 smolts, respectively) into the estuary of the Kymijoki, in the Gulf of Finland. The spatial and temporal marine distributions of the experimental groups were analysed from tag recovery data received during 31/2 years (42 months) after release. The recovery rate was 6.5%–17.5%. Multi-way contingency analysis showed that the spatial distributions of the stocks differed in the sea. The feeding migration distance of the hybrids was longer than that of the parental Neva stock, and the male line affected the spatial marine distribution of the hybrids more than did the female line. Genetically different parental stocks showed no significant difference in migratory behaviour in this experiment. No differences were recorded in the temporal distributions of the stocks in the sea. The observed differences confirm that the sea migration pattern is a stock-specific, inherited trait. The longer migration pattern of hybrid stocks than that of parental stocks may be due to coadaptive gene combinations that break down in crossing or to a high phenotypic variation in parents within the stocks.
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Monitoring of four glacial outwash aquifers that have been utilised during the last 30 years for municipal water supply of Espoo community, southern Finland, reveals changes in chemical composition of groundwater. A 1.5 to 2.0-fold increase in electrical conductivity and in concentrations of main cations and anions in abstracted groundwater reflect primarily the geological impact of Litorina deposits. Relict seawater trapped in deeper parts of aquifers and leaching of fossil salts from postglacial clay and silt deposits have a marked effect on the chemistry of groundwater.
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As a preliminary stage in characterizing the biodiversity patterns of pristine stream habitats in Russian Karelia, the macroinvertebrate fauna and bryophyte flora were studied in three river systems of the Tolvajärvi area. The pristine watercourses of this area are among the few representative watercourses to be used as reference sites for the studies dealing with the impact of forestry on lotic biodiversity. The benthic fauna and flora of the area were found to include many species considered as endangered, rare or with a northern distribution in Finland. In Canonical Correspondence Analysis, the most important environmental variables affecting the distribution and abundance of the benthic fauna were the abundance of aquatic mosses, the amount of organic matter and woody debris, the size of the drainage area and the concentrations of nutrients and iron in the water. Filter feeding trichopteran and algae feeding chironomid larvae dominated the stable lake outlet habitats with abundant moss vegetation, while small streams with higher nutrient and iron concentrations and large amount of organic matter were dominated by shredding stonefly species of the generas Nemoura, Nemurella and Leuctra.
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