Gunnar Raddum - Academia.edu (original) (raw)

Papers by Gunnar Raddum

Advances in Limnology, Dec 23, 2009

As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout... more As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout Europe, the response of key organisms in mountain lakes to variations in environmental gradients due to geography and climate, pollution and catchment characteristics in Scotland was examined. Samples were taken from the pelagic (zooplankton, bacteria and chlorophyll a) and littoral (benthic invertebrates and epilithic diatoms) zones. Surface sediment samples were taken for analysis of sub-fossil ...

ABSTRACT A program for monitoring acidification in Norway was developed in 1980. The program incl... more ABSTRACT A program for monitoring acidification in Norway was developed in 1980. The program included water chemistry, fish and invertebrates. The monitoring have been performed in areas with strong as well as low acidification. Information about the status of the fauna is regularly obtained from sites covering both affected and unaffected areas. Tolerance limits for different species have been established and used for the evaluation of changes in acidification since the early eighties. A significant improvement in water chemistry was recorded in accordance with a 45 to 70 % reduction in sulphur deposition. The invertebrate monitoring shows recovery of sensitive species, and watersheds with earlier low damage have probably returned to an unaffected status. In the most acidified areas also significant improvements are noted, especially during the last ten years. However, acidic episodes connected with sea-salt deposition and spring snowmelt are found to confound the recovery process in these naturally low buffered systems.

Water, Air, & Soil Pollution, 1986

Hovvatn, a 1-km2 chronically-acidified lake in southernmost Norway, was treated with 200 tonne of... more Hovvatn, a 1-km2 chronically-acidified lake in southernmost Norway, was treated with 200 tonne of powdered limestone in March 1981. An additional 40 tonne were added to a 0.046 km2 pond (Pollen) draining into Hovvatn. The lakes were stocked with brown trout in June 1981 and in each subsequent year. At ice-out pH rose from 4.4 to 6.3 (Hovvatn) and 7.5

Water, Air, and Soil Pollution, 1989

ABSTRACT The chronically acidic Lake Store Hovvatn and the adjoining pond Pollen in southernmost ... more ABSTRACT The chronically acidic Lake Store Hovvatn and the adjoining pond Pollen in southernmost Norway were limed in March 1981. The two locations were stocked with brown trout (Salmo trutta L.) at low and high densities in Hovvatn and Pollen, respectively. After 6 yr of reacidification, the locations were relimed in July 1987. Growth depression during the reacidification process in spite of low fish densities and superabundance of food was observed in Lake Store Hovvatn. Three months after reliming, a substantial growth response was found in trout from Lake Store Hovvatn; Mean annual length increment was 68% higher than that of the preceding year. In Pollen, reliming had no apparent effect on growth. In both populations reliming caused increased swimming activity measured as an increase in CPUE-values. These results show that the growth response to liming depends on population density and food availability. Moreover, the results indicate that the food conversion rate of the trout is negatively affected in acid waters.

River Research and Applications, 2008

The Aurland watershed has been regulated for hydropower since the establishment of a series of po... more The Aurland watershed has been regulated for hydropower since the establishment of a series of power plants during the period 1970-1983. This resulted in a strong reduction of the flow in the river Vassbygdelvi, the inlet river to lake Vassbygdvatn. In the downstream river Aurland, the flow has varied, but from 2000 the intention has been to simulate pre-regulation winter flow as far as possible. The temperature in the river Vassbygdelvi has increased from about 1500 degree-days per year before regulation to above 2000 degree-days after regulation. In the river Aurland the thermal regime, expressed as degree-days per year, was more or less unchanged, but a small reduction in the summer temperature and a corresponding increase during other periods was observed. The mayfly Ephemerella aurivillii (Bengtsson) was not recorded in Vassbygdelvi prior to regulation, but became abundant in the river after. Full-grown larvae were recorded 1-2 months earlier in the river Vassbygdelvi than in the river Aurland after regulation. E. aurivillii has a 1-year life cycle with imagos present in June-August. Young larvae occurred from June to early September. It is concluded that larvae of E. aurivillii could not complete their life cycle within 1 year before regulation in the river Vassbygdelvi, due to low temperature. The study demonstrates how temperature can regulate the distribution of a species with a strict 1-year life cycle.

Journal of Plankton Research, 1987

Hydrobiologia, 1983

Monthly observations on the bryozoa Fredericella sultana have been carried out in the outlet of a... more Monthly observations on the bryozoa Fredericella sultana have been carried out in the outlet of a humic acid lake for more than two years. The growth of the colonies were rapid during algal bloom and in fall the colonies almost covered the free underside of nearly all stones on the bottom.

Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake ... more Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake faunal communities can therefore be important indicators of long-range airborne pollution, climate change and other human impacts. Information about the trophic structure and species composition of alpine lake ecosystems over space and time should therefore give important insights into environmental change effects. To explore the sensitivity of the faunal communities to environmental variability at local and regional scales we sampled biological and environmental variables from alpine lakes in seven different alpine lake districts in six European mountain regions. The fauna of the lakes was mainly com-:15 Uhr Seite 167 eschweizerbart_xxx posed of oligotrophic/ultraoligotrophic species, predominantly chironomids which made up more than 60% of all individuals. Species accumulation curves were used to explore patterns of species turnover and distribution, and the results indicated strong patterns in species diversity and also environmentallydriven patterns in species distributions among lake districts. We used ordination analyses to explore these patterns in more detail. The results showed that the over-riding patterns in faunal assemblages were found between the lake districts. Lake-water chemistry appeared to be the major driver of the faunal assemblages at this scale, but altitude and geography could also account for significant fractions of the variability. In addition to these broad-scale patterns, repeatable trends in the faunal assemblages could be found in the faunal assemblages within lake districts. At this scale, the strongest compositional trends were found along the altitudinal gradient, but the faunal communities also responded to within-district variability in lake-water chemistry. Lake size or maximum depth did not appear to have any statistically significant effect on the littoral faunal assemblages at either scale.

Hydrobiologia, 1988

In connection with the liming of an acid lake in southern Norway, a series of litter bags was pla... more In connection with the liming of an acid lake in southern Norway, a series of litter bags was placed in a pH-gradient in the limed lake and a nearby unlimed lake. During the experiments, which lasted two years, no significant differences in decomposition rates between the various localities at the same depth were noticed. The chironomid collector Tanytarsus pallidicornis was

Ambio, 2003

There is now overwhelming documentation of large-scale chemical recovery from surface water acidi... more There is now overwhelming documentation of large-scale chemical recovery from surface water acidification in Europe, but to date there has been little documentation of biological recovery. Modelling studies based on current emission reduction plans in Europe indicate that there will be further chemical recovery. The uncertainties in these scenarios mainly relate to the future behavior of nitrogen in the ecosystem and the effects of climate change. Four major climate-related confounding factors that may influence the chemical and biological recovery process are: i) increased frequency and severity of sea-salt episodes; ii) increased frequency and severity of drought; iii) increased turnover of organic carbon; iv) increased mineralization of nitrogen. International cooperative work to abate acidification has so far been very successful, but there is still a long way to go, and many potential setbacks. It is essential that future development of water chemistry and aquatic biota in acidified waterbodies continue to be monitored in relation to further emission reductions of S and N and future effects of climate change.

The first AL:PE project (Acidification of Mountain Lakes: Palaeolimnology and Ecology), now calle... more The first AL:PE project (Acidification of Mountain Lakes: Palaeolimnology and Ecology), now called AL:PE 1, was launched in April 1991, and has had a 2 year working period. The final report is now being prepared. The project involves co-operation between seven institutions in UK, Italy, France and Norway, and covers the scientific topics: lake sediments and diatoms, fish, invertebrates and water chemistry in high mountain lakes in the participating countries. The first results showed interesting similarities of the sites in these different mountain regions of Europe. The similarities were obvious at all levels, water chemistry, palaeolimnology, invertebrates and fish. This reflects a similiar reaction from the biological communities to a specific chemical environment in these altitude areas, and are of high importance for the programme with regard to the analysis of the results and the future modelling work. A summary of the water chemistry results from AL:PE 1 shows the acidification status of the different lakes. The extended project AL:PE 2 involves new subject areas: zooplankton, statistical analysis and modelling, and a geographical extension to sites above or beyond the local tree line in Svalbard (Norway),

Global Change and …, 2005

Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan G... more Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan Grimalt3, Bjoern O. Rosseland4, Bente Wathne4, Jordi Catalan5, Rosario Mosello6, Andrea Lami6, David Livingstone7, Evzen Stuchlik8, Vera Straskrabova9, and ...

Ambio, 2003

A novel method, redundancy analysis (RDA), has been used to examine whether chemical recovery fro... more A novel method, redundancy analysis (RDA), has been used to examine whether chemical recovery from acidification in the western Norwegian Nausta watershed produces detectable recovery within the community structure of the macro-zoobenthos. The RDA results have been compared with measures of recovery based on the changes detected using highly specialized and regionally defined biological acidity indices. We found that the beginning of biological recovery in the Nausta watershed was recognizable during the period 1989-1998. Recovery occurred in the upper reaches and in the tributaries. The multivariate approach proved to complement the acidity indices approach, and much biological information can be gained by their combined use. The RDA method is conservative, i.e. does not overestimate biological recovery, and it is not geographically constrained as are the acidity indices. We also found that seasonal climatic factors strongly influence the benthic community, and may confound the detection of the biological recovery process.

Advances in Global Change Research, 2005

Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan G... more Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan Grimalt3, Bjoern O. Rosseland4, Bente Wathne4, Jordi Catalan5, Rosario Mosello6, Andrea Lami6, David Livingstone7, Evzen Stuchlik8, Vera Straskrabova9, and ...

Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake ... more Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake faunal communities can therefore be important indicators of long-range airborne pollution, climate change and other human impacts. Information about the trophic structure and species composition of alpine lake ecosystems over space and time should therefore give important insights into environmental change effects. To explore the sensitivity of the faunal communities to environmental variability at local and regional scales we sampled biological and environmental variables from alpine lakes in seven different alpine lake districts in six European mountain regions. The fauna of the lakes was mainly com-:15 Uhr Seite 167 eschweizerbart_xxx posed of oligotrophic/ultraoligotrophic species, predominantly chironomids which made up more than 60% of all individuals. Species accumulation curves were used to explore patterns of species turnover and distribution, and the results indicated strong patterns in species diversity and also environmentallydriven patterns in species distributions among lake districts. We used ordination analyses to explore these patterns in more detail. The results showed that the over-riding patterns in faunal assemblages were found between the lake districts. Lake-water chemistry appeared to be the major driver of the faunal assemblages at this scale, but altitude and geography could also account for significant fractions of the variability. In addition to these broad-scale patterns, repeatable trends in the faunal assemblages could be found in the faunal assemblages within lake districts. At this scale, the strongest compositional trends were found along the altitudinal gradient, but the faunal communities also responded to within-district variability in lake-water chemistry. Lake size or maximum depth did not appear to have any statistically significant effect on the littoral faunal assemblages at either scale.

Advances in Limnology, Dec 23, 2009

As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout... more As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout Europe, the response of key organisms in mountain lakes to variations in environmental gradients due to geography and climate, pollution and catchment characteristics in Scotland was examined. Samples were taken from the pelagic (zooplankton, bacteria and chlorophyll a) and littoral (benthic invertebrates and epilithic diatoms) zones. Surface sediment samples were taken for analysis of sub-fossil ...

Water, Air, & Soil Pollution, 1995

The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers a... more The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP-Water) started in 1987. The main aim of the programme is to establish degree and geographical extent of acidification of surface waters and evaluate dose/response relationships to aquatic biota attributable to acidic deposition. The sample frequency in each locality is from a few -to a large number every year. Samples of invertebrates are taken from 108 localities. One time samples as well as regularly seasonal samples over years exist in the database. The acidity score (Raddum index) is determined for the different sites and regions, and compared with the corresponding chemical data. The analysis show a strong relationship between water quality and fauna. Sensitive species/taxa are associated with high ANC and pH, while tolerant species/taxa are associated with low pH and ANC. The diversity of the fauna in less acidified areas varies from region to region depending on the native water quality and the adaptions of the fauna. In areas with strongly oligotrophic water, low in ionic strength, the sensitive fauna tolerate lower ANC and pH than in areas with originally high ionic strength and high pH. The critical load of ANC, 20/~eq/l, developed for the oligotrophic water in Norway, should therefore be increased in watersheds with high ionic strength. In Central Europe the data indicate a critical level of ANC --50/zeq/1.

Water, Air, & Soil Pollution, 1995

The acidified Lake Hovvatn have been limed in 1981, 1987, 1989 and 1991. After the first liming t... more The acidified Lake Hovvatn have been limed in 1981, 1987, 1989 and 1991. After the first liming the lake reacidified close to the prelimed condition. The reliming, which started in 1987, was planned to maintain the pH at a relatively high level for the lake. A detailed monitoring of pH and temperature was performed at depth 0.5, 1, 1,5 and 5 m since spring 1993. Quantitative samples of benthic invertebrates were taken in spring and fall in 1977 and regularly at the same seasons from 1981 at depth 0.5, 2, 5 and 10 m. A reference lake, Lille

Advances in Limnology, Dec 23, 2009

As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout... more As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout Europe, the response of key organisms in mountain lakes to variations in environmental gradients due to geography and climate, pollution and catchment characteristics in Scotland was examined. Samples were taken from the pelagic (zooplankton, bacteria and chlorophyll a) and littoral (benthic invertebrates and epilithic diatoms) zones. Surface sediment samples were taken for analysis of sub-fossil ...

ABSTRACT A program for monitoring acidification in Norway was developed in 1980. The program incl... more ABSTRACT A program for monitoring acidification in Norway was developed in 1980. The program included water chemistry, fish and invertebrates. The monitoring have been performed in areas with strong as well as low acidification. Information about the status of the fauna is regularly obtained from sites covering both affected and unaffected areas. Tolerance limits for different species have been established and used for the evaluation of changes in acidification since the early eighties. A significant improvement in water chemistry was recorded in accordance with a 45 to 70 % reduction in sulphur deposition. The invertebrate monitoring shows recovery of sensitive species, and watersheds with earlier low damage have probably returned to an unaffected status. In the most acidified areas also significant improvements are noted, especially during the last ten years. However, acidic episodes connected with sea-salt deposition and spring snowmelt are found to confound the recovery process in these naturally low buffered systems.

Water, Air, & Soil Pollution, 1986

Hovvatn, a 1-km2 chronically-acidified lake in southernmost Norway, was treated with 200 tonne of... more Hovvatn, a 1-km2 chronically-acidified lake in southernmost Norway, was treated with 200 tonne of powdered limestone in March 1981. An additional 40 tonne were added to a 0.046 km2 pond (Pollen) draining into Hovvatn. The lakes were stocked with brown trout in June 1981 and in each subsequent year. At ice-out pH rose from 4.4 to 6.3 (Hovvatn) and 7.5

Water, Air, and Soil Pollution, 1989

ABSTRACT The chronically acidic Lake Store Hovvatn and the adjoining pond Pollen in southernmost ... more ABSTRACT The chronically acidic Lake Store Hovvatn and the adjoining pond Pollen in southernmost Norway were limed in March 1981. The two locations were stocked with brown trout (Salmo trutta L.) at low and high densities in Hovvatn and Pollen, respectively. After 6 yr of reacidification, the locations were relimed in July 1987. Growth depression during the reacidification process in spite of low fish densities and superabundance of food was observed in Lake Store Hovvatn. Three months after reliming, a substantial growth response was found in trout from Lake Store Hovvatn; Mean annual length increment was 68% higher than that of the preceding year. In Pollen, reliming had no apparent effect on growth. In both populations reliming caused increased swimming activity measured as an increase in CPUE-values. These results show that the growth response to liming depends on population density and food availability. Moreover, the results indicate that the food conversion rate of the trout is negatively affected in acid waters.

River Research and Applications, 2008

The Aurland watershed has been regulated for hydropower since the establishment of a series of po... more The Aurland watershed has been regulated for hydropower since the establishment of a series of power plants during the period 1970-1983. This resulted in a strong reduction of the flow in the river Vassbygdelvi, the inlet river to lake Vassbygdvatn. In the downstream river Aurland, the flow has varied, but from 2000 the intention has been to simulate pre-regulation winter flow as far as possible. The temperature in the river Vassbygdelvi has increased from about 1500 degree-days per year before regulation to above 2000 degree-days after regulation. In the river Aurland the thermal regime, expressed as degree-days per year, was more or less unchanged, but a small reduction in the summer temperature and a corresponding increase during other periods was observed. The mayfly Ephemerella aurivillii (Bengtsson) was not recorded in Vassbygdelvi prior to regulation, but became abundant in the river after. Full-grown larvae were recorded 1-2 months earlier in the river Vassbygdelvi than in the river Aurland after regulation. E. aurivillii has a 1-year life cycle with imagos present in June-August. Young larvae occurred from June to early September. It is concluded that larvae of E. aurivillii could not complete their life cycle within 1 year before regulation in the river Vassbygdelvi, due to low temperature. The study demonstrates how temperature can regulate the distribution of a species with a strict 1-year life cycle.

Journal of Plankton Research, 1987

Hydrobiologia, 1983

Monthly observations on the bryozoa Fredericella sultana have been carried out in the outlet of a... more Monthly observations on the bryozoa Fredericella sultana have been carried out in the outlet of a humic acid lake for more than two years. The growth of the colonies were rapid during algal bloom and in fall the colonies almost covered the free underside of nearly all stones on the bottom.

Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake ... more Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake faunal communities can therefore be important indicators of long-range airborne pollution, climate change and other human impacts. Information about the trophic structure and species composition of alpine lake ecosystems over space and time should therefore give important insights into environmental change effects. To explore the sensitivity of the faunal communities to environmental variability at local and regional scales we sampled biological and environmental variables from alpine lakes in seven different alpine lake districts in six European mountain regions. The fauna of the lakes was mainly com-:15 Uhr Seite 167 eschweizerbart_xxx posed of oligotrophic/ultraoligotrophic species, predominantly chironomids which made up more than 60% of all individuals. Species accumulation curves were used to explore patterns of species turnover and distribution, and the results indicated strong patterns in species diversity and also environmentallydriven patterns in species distributions among lake districts. We used ordination analyses to explore these patterns in more detail. The results showed that the over-riding patterns in faunal assemblages were found between the lake districts. Lake-water chemistry appeared to be the major driver of the faunal assemblages at this scale, but altitude and geography could also account for significant fractions of the variability. In addition to these broad-scale patterns, repeatable trends in the faunal assemblages could be found in the faunal assemblages within lake districts. At this scale, the strongest compositional trends were found along the altitudinal gradient, but the faunal communities also responded to within-district variability in lake-water chemistry. Lake size or maximum depth did not appear to have any statistically significant effect on the littoral faunal assemblages at either scale.

Hydrobiologia, 1988

In connection with the liming of an acid lake in southern Norway, a series of litter bags was pla... more In connection with the liming of an acid lake in southern Norway, a series of litter bags was placed in a pH-gradient in the limed lake and a nearby unlimed lake. During the experiments, which lasted two years, no significant differences in decomposition rates between the various localities at the same depth were noticed. The chironomid collector Tanytarsus pallidicornis was

Ambio, 2003

There is now overwhelming documentation of large-scale chemical recovery from surface water acidi... more There is now overwhelming documentation of large-scale chemical recovery from surface water acidification in Europe, but to date there has been little documentation of biological recovery. Modelling studies based on current emission reduction plans in Europe indicate that there will be further chemical recovery. The uncertainties in these scenarios mainly relate to the future behavior of nitrogen in the ecosystem and the effects of climate change. Four major climate-related confounding factors that may influence the chemical and biological recovery process are: i) increased frequency and severity of sea-salt episodes; ii) increased frequency and severity of drought; iii) increased turnover of organic carbon; iv) increased mineralization of nitrogen. International cooperative work to abate acidification has so far been very successful, but there is still a long way to go, and many potential setbacks. It is essential that future development of water chemistry and aquatic biota in acidified waterbodies continue to be monitored in relation to further emission reductions of S and N and future effects of climate change.

The first AL:PE project (Acidification of Mountain Lakes: Palaeolimnology and Ecology), now calle... more The first AL:PE project (Acidification of Mountain Lakes: Palaeolimnology and Ecology), now called AL:PE 1, was launched in April 1991, and has had a 2 year working period. The final report is now being prepared. The project involves co-operation between seven institutions in UK, Italy, France and Norway, and covers the scientific topics: lake sediments and diatoms, fish, invertebrates and water chemistry in high mountain lakes in the participating countries. The first results showed interesting similarities of the sites in these different mountain regions of Europe. The similarities were obvious at all levels, water chemistry, palaeolimnology, invertebrates and fish. This reflects a similiar reaction from the biological communities to a specific chemical environment in these altitude areas, and are of high importance for the programme with regard to the analysis of the results and the future modelling work. A summary of the water chemistry results from AL:PE 1 shows the acidification status of the different lakes. The extended project AL:PE 2 involves new subject areas: zooplankton, statistical analysis and modelling, and a geographical extension to sites above or beyond the local tree line in Svalbard (Norway),

Global Change and …, 2005

Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan G... more Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan Grimalt3, Bjoern O. Rosseland4, Bente Wathne4, Jordi Catalan5, Rosario Mosello6, Andrea Lami6, David Livingstone7, Evzen Stuchlik8, Vera Straskrabova9, and ...

Ambio, 2003

A novel method, redundancy analysis (RDA), has been used to examine whether chemical recovery fro... more A novel method, redundancy analysis (RDA), has been used to examine whether chemical recovery from acidification in the western Norwegian Nausta watershed produces detectable recovery within the community structure of the macro-zoobenthos. The RDA results have been compared with measures of recovery based on the changes detected using highly specialized and regionally defined biological acidity indices. We found that the beginning of biological recovery in the Nausta watershed was recognizable during the period 1989-1998. Recovery occurred in the upper reaches and in the tributaries. The multivariate approach proved to complement the acidity indices approach, and much biological information can be gained by their combined use. The RDA method is conservative, i.e. does not overestimate biological recovery, and it is not geographically constrained as are the acidity indices. We also found that seasonal climatic factors strongly influence the benthic community, and may confound the detection of the biological recovery process.

Advances in Global Change Research, 2005

Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan G... more Richard W. Battarbee1l, Simon Patrick1, Martin Kernan1, Roland Psenner2, Hansjoerg Thies2, Joan Grimalt3, Bjoern O. Rosseland4, Bente Wathne4, Jordi Catalan5, Rosario Mosello6, Andrea Lami6, David Livingstone7, Evzen Stuchlik8, Vera Straskrabova9, and ...

Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake ... more Invertebrates inhabiting alpine water bodies are sensitive to environmental variability and lake faunal communities can therefore be important indicators of long-range airborne pollution, climate change and other human impacts. Information about the trophic structure and species composition of alpine lake ecosystems over space and time should therefore give important insights into environmental change effects. To explore the sensitivity of the faunal communities to environmental variability at local and regional scales we sampled biological and environmental variables from alpine lakes in seven different alpine lake districts in six European mountain regions. The fauna of the lakes was mainly com-:15 Uhr Seite 167 eschweizerbart_xxx posed of oligotrophic/ultraoligotrophic species, predominantly chironomids which made up more than 60% of all individuals. Species accumulation curves were used to explore patterns of species turnover and distribution, and the results indicated strong patterns in species diversity and also environmentallydriven patterns in species distributions among lake districts. We used ordination analyses to explore these patterns in more detail. The results showed that the over-riding patterns in faunal assemblages were found between the lake districts. Lake-water chemistry appeared to be the major driver of the faunal assemblages at this scale, but altitude and geography could also account for significant fractions of the variability. In addition to these broad-scale patterns, repeatable trends in the faunal assemblages could be found in the faunal assemblages within lake districts. At this scale, the strongest compositional trends were found along the altitudinal gradient, but the faunal communities also responded to within-district variability in lake-water chemistry. Lake size or maximum depth did not appear to have any statistically significant effect on the littoral faunal assemblages at either scale.

Advances in Limnology, Dec 23, 2009

As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout... more As part of a comprehensive evaluation of the status of remote mountain lake ecosystems throughout Europe, the response of key organisms in mountain lakes to variations in environmental gradients due to geography and climate, pollution and catchment characteristics in Scotland was examined. Samples were taken from the pelagic (zooplankton, bacteria and chlorophyll a) and littoral (benthic invertebrates and epilithic diatoms) zones. Surface sediment samples were taken for analysis of sub-fossil ...

Water, Air, & Soil Pollution, 1995

The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers a... more The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP-Water) started in 1987. The main aim of the programme is to establish degree and geographical extent of acidification of surface waters and evaluate dose/response relationships to aquatic biota attributable to acidic deposition. The sample frequency in each locality is from a few -to a large number every year. Samples of invertebrates are taken from 108 localities. One time samples as well as regularly seasonal samples over years exist in the database. The acidity score (Raddum index) is determined for the different sites and regions, and compared with the corresponding chemical data. The analysis show a strong relationship between water quality and fauna. Sensitive species/taxa are associated with high ANC and pH, while tolerant species/taxa are associated with low pH and ANC. The diversity of the fauna in less acidified areas varies from region to region depending on the native water quality and the adaptions of the fauna. In areas with strongly oligotrophic water, low in ionic strength, the sensitive fauna tolerate lower ANC and pH than in areas with originally high ionic strength and high pH. The critical load of ANC, 20/~eq/l, developed for the oligotrophic water in Norway, should therefore be increased in watersheds with high ionic strength. In Central Europe the data indicate a critical level of ANC --50/zeq/1.

Water, Air, & Soil Pollution, 1995

The acidified Lake Hovvatn have been limed in 1981, 1987, 1989 and 1991. After the first liming t... more The acidified Lake Hovvatn have been limed in 1981, 1987, 1989 and 1991. After the first liming the lake reacidified close to the prelimed condition. The reliming, which started in 1987, was planned to maintain the pH at a relatively high level for the lake. A detailed monitoring of pH and temperature was performed at depth 0.5, 1, 1,5 and 5 m since spring 1993. Quantitative samples of benthic invertebrates were taken in spring and fall in 1977 and regularly at the same seasons from 1981 at depth 0.5, 2, 5 and 10 m. A reference lake, Lille