Christer Lännergren - Academia.edu (original) (raw)
Papers by Christer Lännergren
Oikos, 1974
... September. Gloeo-trichia dominated at the end of July and in the first two weeks of August, w... more ... September. Gloeo-trichia dominated at the end of July and in the first two weeks of August, while Aphanizomenon dominated at the end of September (Fig. 3). The succession in 1970 was different (Granhall and Lundgren 1971). ...
Marine Biology, 1978
From February 24 to April 24, weekly samples were collected at fixed depths at one station in Lin... more From February 24 to April 24, weekly samples were collected at fixed depths at one station in Lind&spollene, a landlocked Norwegian fjord. Adenosine triphosphate (ATP), chlorophyll a, phaeophytin, 14C assimilation, and respiratory activity [electron transport system (ETS) activity] were measured in the net-(>30 bm) and nanoplankton. Netplankton contained on the average 48% of the total chlorophyll a and 56% of the ATP, but contributed only 7% to the total carbon assimilation and 11% to the ETS activity. The assimilation numbers for net-and nanoplankton ranged from 0 to 1.2 and from 1.5 to 13.2, respectively. At the oxygen/hydrogen sulphide interface, high concentrations of ATP, but not of chlorophyll a, were found in the nanoplankton fraction. Netplankton algae grew actively only in the first phase of the bloom, and nanoplankton predominated later, apparently due to low nutrient concentrations. During the bloom, Skeletonema costatum made up the main part of the biomass. The number of cells in the chains decreased throughout the bloom, possibly reflecting the lowered silicate content. It appeared that only nanoplankton were grazed by zooplankton, while netplankton sank to the bottom and represented input to the benthos.
Marine Biology, 1979
Buoyancy of natural populations of marine phytoplankton was studied in a fjord in western Norway ... more Buoyancy of natural populations of marine phytoplankton was studied in a fjord in western Norway during the diatom bloom and in autumn. The study was carried out under approximate in situ conditions by means of an apparatus described in the paper. During the spring bloom, positive buoyancy was observed only once. Sinking rates of individual fractions ranged from O to more than 9 m day-I, and the mean sinking rates of the total chlorophyll content from 0 to at least 2.2 m day-I. The highest rates occurred in the post-bloom period, while sinking appeared negligible from the onset of the bloom up to its culmination. In autumn, the population was dominated by small, flagellated cells. Positive buoyancy, or upward migration, was then observed in two out of three experiments. Materials and Methods Buoyancy was studied in a 2.2 m long, transparent Plexiglas tube (the sedimentation tube), which was filled with sea water collected from about 2 m depth in
Botanica Marina, 1976
In situ primary production, Chlorophyll a, and the quantitative and semiqualitative composition o... more In situ primary production, Chlorophyll a, and the quantitative and semiqualitative composition of phytoplankton were studied from March to November in two basins in a Norwegian land-Iocked fjord, which receives sewage effluent from 400 persons. The seasonal production was 60 to 70 mg C/m 2 , and the annual production was estimated at 90 to 100 mg C/m 2. The occurrence of phytoplankton was similar to what has been reported from unpolluted Norwegian waters, and the Chlorophyll a concentrations were small after the spring bloom. Average assimilation numbers were 5.3 and 5.5. The highest assimüation numbers, 13.9 and 18.0, occurred in July, at the time of the smallest biomass. No correlation was found with temperature, light, or nutrients, and a correlation with the phytoplankton composition is suggested. The two basins were in most respects alike, and it is concluded that the effects of the sewage effluent on primary production was negligible.
Sarsia, 1980
Abstract The study covers the period February to August 1978. The hydrography differed little fro... more Abstract The study covers the period February to August 1978. The hydrography differed little from that of the coastal water in general, possibly with the exception of a more stable surface layer. Salinities at the surface ranged from 27.7‰ to 32.9‰ in the bottom water (250 m) from 34.4 to 34.9‰. The highest temperature was 14.5° C at 0 m in August and the lowest was 4° C at 0 m at the end of March. At 250 m depth the temperature decreased from 7.7° C in February to 6.7° C in July. Oxygen saturation was above 100% during the phytoplankton growth period down to a depth of la-3D m. In the deep water oxygen saturation was 86–88%. Two blooms were recorded, one in March-April and Onein June, both dominated by Skeletonema costatum. The highest cell numbers, 105–1071-1, the highest chlorophyll a concentrations, 2.6–3.3 mg m-3, and the highest carbon assimilation rates, 10–20 mg C m-3h-1 (100 μE m-2sec-1 )-1, were all round during the blooms, At other times cell numbers were low, and chlorophyll a concentrations ...
Sarsia, 1977
Abstract An inexpensive apparatus is decribed by which ten samples for carbon assimilation measur... more Abstract An inexpensive apparatus is decribed by which ten samples for carbon assimilation measurements may be filtered simultaneously and a portion of the filtrate from each collected.
Sarsia, 1980
Abstract Nitrogen fixation in the littoral zone of Lindaspollene, near Bergen, was measured from ... more Abstract Nitrogen fixation in the littoral zone of Lindaspollene, near Bergen, was measured from May to September 1976. Samples consisting of a variety of materials were collected from exposed and protected sites. Occurrence of nitrogen fixing blue-green algae appeared to be independent of salinity in the range 10-30 ‰ but was positively correlated with temperature. No fixation was detected in May. Fixation rates from June-September were very variable, ranging from zero to 23 nmol N2/mg d.w. per 2.5 h, with the highest activities in July-August, in decaying matter at protected sites in association with two species of blue-green algae, Anabaew torulosa and Caloihrix confervicola. The rates were several times higher than those earlier reported in Norway.
Internationale Revue der gesamten Hydrobiologie und Hydrographie, 1978
At two stations in a Norwegian land-locked fjord, one more and one less influenced by freshwater ... more At two stations in a Norwegian land-locked fjord, one more and one less influenced by freshwater run-off, studies were made of the primary production, chlorophyll a concentrations, and the quantity and composition of phytoplankton. Samples were taken for analyses of phosphate, nitrate, and silicate, and temperature and salinity were measured. Two kinds of bio-assays were performed: combinations of phosphate, nitrate, and silicate were added to I, natural water incubated in situ, and II, natural water incubated in the laboratory. Lower salinities and higher concentrations of all nutrients were found at the station most influenced by fresh-water. Although the bio-assays indicated that nitrogen was the main limiting nutrient, the biological parameters showed no consistent differences between the two stations. The similarity is tentatively explained by the growth of nanoplankton algae, partly depending on nutrients other than those analysed.
Ecography, 1983
An investigation covering hydrography, chemistry, vascular and cryptogamic plants, nitrogen fixat... more An investigation covering hydrography, chemistry, vascular and cryptogamic plants, nitrogen fixation, phytoplankton biomass and production, and zooplankton was carried out from April to November 1976 in tarn in W Norway, The volume of the tarn was 18000 m3 and the turnover time about 30 d. Temperature ranged between 3.6 and 23.4°C and pH between 4.8 and 5.5. Nuphar luteum and Carex rostrata were the two dominating vasculars-with biomasses of 117 and 97 g m−2, respectively The biomass of the bryophytes (Sphagnum spp.) was about 510 g m−2 and the production of the order 0.2–2.1 μg (mg d.w.)−1h−1. Nitrogen fixation in association with Sphagnum spp. was estimated at 25 g yr−1 for the whole tarn. Phytoplankton was dominated by diatoms, green algae and chrysophyceans. The chlorophyll a content ranged from 2 to 20 mg m−3 and the carbon assimilation rates from 0.03 to 20 mg C m−3h−1 at 0–4 m depths. Production in the period was of the magnitude 22 g C m−2. The copepod Eudiaptomus gracilis was the most common netzooplankter. Large numbers of rotationrians were found during summer.
Sarsia, 1975
Abstract Phosphate, silicate, nitrite/nitrate, and ammonia were studied in a Norwegian land-locke... more Abstract Phosphate, silicate, nitrite/nitrate, and ammonia were studied in a Norwegian land-locked fjord during 1973. In the surface water the concentrations were similar to what has been found in the North Sea, with the exception of silicate, which occurred in higher concentrations in winter. There were indications of nitrogen and silicate limitation. In the bottom water phosphate, silicate, and ammonia accumulated in the course of the year. The accumulation of phosphate was mainly due to liberation from the sediment. As a result of denitrification the content of inorganic combined nitrogen decreased in the bottom water.
Estuaries and Coasts
Nutrient concentrations in coastal waters are influenced not only by land runoff, point sources, ... more Nutrient concentrations in coastal waters are influenced not only by land runoff, point sources, and water exchange with the sea but are also modified by settlement to and release from sediments. This complicates evaluation of measures to reduce nutrient loads. We used a mass-balance box model to calculate long-term (1968–2015) and seasonal source contributions to phosphorus (P) concentrations and cycling in the stratified Stockholm inner archipelago (IA), Baltic Sea. A drastic reduction of sewage P loads in the early 1970s reduced sewage from the major to a minor P source. Further P load reductions in the 1990s cut the direct contribution from the sewage point sources to the annual mean surface water P concentration from 10 μg l−1 (25%) to < 4 μg l−1 (12%). The largest contributions to the surface water P concentration are now (from 1996) inflowing seawater (37%), freshwater (25%), and P recycling from sediments below 20 m depth (26%). Variations in freshwater flushing give high...
Oikos, 1974
... September. Gloeo-trichia dominated at the end of July and in the first two weeks of August, w... more ... September. Gloeo-trichia dominated at the end of July and in the first two weeks of August, while Aphanizomenon dominated at the end of September (Fig. 3). The succession in 1970 was different (Granhall and Lundgren 1971). ...
Marine Biology, 1978
From February 24 to April 24, weekly samples were collected at fixed depths at one station in Lin... more From February 24 to April 24, weekly samples were collected at fixed depths at one station in Lind&spollene, a landlocked Norwegian fjord. Adenosine triphosphate (ATP), chlorophyll a, phaeophytin, 14C assimilation, and respiratory activity [electron transport system (ETS) activity] were measured in the net-(>30 bm) and nanoplankton. Netplankton contained on the average 48% of the total chlorophyll a and 56% of the ATP, but contributed only 7% to the total carbon assimilation and 11% to the ETS activity. The assimilation numbers for net-and nanoplankton ranged from 0 to 1.2 and from 1.5 to 13.2, respectively. At the oxygen/hydrogen sulphide interface, high concentrations of ATP, but not of chlorophyll a, were found in the nanoplankton fraction. Netplankton algae grew actively only in the first phase of the bloom, and nanoplankton predominated later, apparently due to low nutrient concentrations. During the bloom, Skeletonema costatum made up the main part of the biomass. The number of cells in the chains decreased throughout the bloom, possibly reflecting the lowered silicate content. It appeared that only nanoplankton were grazed by zooplankton, while netplankton sank to the bottom and represented input to the benthos.
Marine Biology, 1979
Buoyancy of natural populations of marine phytoplankton was studied in a fjord in western Norway ... more Buoyancy of natural populations of marine phytoplankton was studied in a fjord in western Norway during the diatom bloom and in autumn. The study was carried out under approximate in situ conditions by means of an apparatus described in the paper. During the spring bloom, positive buoyancy was observed only once. Sinking rates of individual fractions ranged from O to more than 9 m day-I, and the mean sinking rates of the total chlorophyll content from 0 to at least 2.2 m day-I. The highest rates occurred in the post-bloom period, while sinking appeared negligible from the onset of the bloom up to its culmination. In autumn, the population was dominated by small, flagellated cells. Positive buoyancy, or upward migration, was then observed in two out of three experiments. Materials and Methods Buoyancy was studied in a 2.2 m long, transparent Plexiglas tube (the sedimentation tube), which was filled with sea water collected from about 2 m depth in
Botanica Marina, 1976
In situ primary production, Chlorophyll a, and the quantitative and semiqualitative composition o... more In situ primary production, Chlorophyll a, and the quantitative and semiqualitative composition of phytoplankton were studied from March to November in two basins in a Norwegian land-Iocked fjord, which receives sewage effluent from 400 persons. The seasonal production was 60 to 70 mg C/m 2 , and the annual production was estimated at 90 to 100 mg C/m 2. The occurrence of phytoplankton was similar to what has been reported from unpolluted Norwegian waters, and the Chlorophyll a concentrations were small after the spring bloom. Average assimilation numbers were 5.3 and 5.5. The highest assimüation numbers, 13.9 and 18.0, occurred in July, at the time of the smallest biomass. No correlation was found with temperature, light, or nutrients, and a correlation with the phytoplankton composition is suggested. The two basins were in most respects alike, and it is concluded that the effects of the sewage effluent on primary production was negligible.
Sarsia, 1980
Abstract The study covers the period February to August 1978. The hydrography differed little fro... more Abstract The study covers the period February to August 1978. The hydrography differed little from that of the coastal water in general, possibly with the exception of a more stable surface layer. Salinities at the surface ranged from 27.7‰ to 32.9‰ in the bottom water (250 m) from 34.4 to 34.9‰. The highest temperature was 14.5° C at 0 m in August and the lowest was 4° C at 0 m at the end of March. At 250 m depth the temperature decreased from 7.7° C in February to 6.7° C in July. Oxygen saturation was above 100% during the phytoplankton growth period down to a depth of la-3D m. In the deep water oxygen saturation was 86–88%. Two blooms were recorded, one in March-April and Onein June, both dominated by Skeletonema costatum. The highest cell numbers, 105–1071-1, the highest chlorophyll a concentrations, 2.6–3.3 mg m-3, and the highest carbon assimilation rates, 10–20 mg C m-3h-1 (100 μE m-2sec-1 )-1, were all round during the blooms, At other times cell numbers were low, and chlorophyll a concentrations ...
Sarsia, 1977
Abstract An inexpensive apparatus is decribed by which ten samples for carbon assimilation measur... more Abstract An inexpensive apparatus is decribed by which ten samples for carbon assimilation measurements may be filtered simultaneously and a portion of the filtrate from each collected.
Sarsia, 1980
Abstract Nitrogen fixation in the littoral zone of Lindaspollene, near Bergen, was measured from ... more Abstract Nitrogen fixation in the littoral zone of Lindaspollene, near Bergen, was measured from May to September 1976. Samples consisting of a variety of materials were collected from exposed and protected sites. Occurrence of nitrogen fixing blue-green algae appeared to be independent of salinity in the range 10-30 ‰ but was positively correlated with temperature. No fixation was detected in May. Fixation rates from June-September were very variable, ranging from zero to 23 nmol N2/mg d.w. per 2.5 h, with the highest activities in July-August, in decaying matter at protected sites in association with two species of blue-green algae, Anabaew torulosa and Caloihrix confervicola. The rates were several times higher than those earlier reported in Norway.
Internationale Revue der gesamten Hydrobiologie und Hydrographie, 1978
At two stations in a Norwegian land-locked fjord, one more and one less influenced by freshwater ... more At two stations in a Norwegian land-locked fjord, one more and one less influenced by freshwater run-off, studies were made of the primary production, chlorophyll a concentrations, and the quantity and composition of phytoplankton. Samples were taken for analyses of phosphate, nitrate, and silicate, and temperature and salinity were measured. Two kinds of bio-assays were performed: combinations of phosphate, nitrate, and silicate were added to I, natural water incubated in situ, and II, natural water incubated in the laboratory. Lower salinities and higher concentrations of all nutrients were found at the station most influenced by fresh-water. Although the bio-assays indicated that nitrogen was the main limiting nutrient, the biological parameters showed no consistent differences between the two stations. The similarity is tentatively explained by the growth of nanoplankton algae, partly depending on nutrients other than those analysed.
Ecography, 1983
An investigation covering hydrography, chemistry, vascular and cryptogamic plants, nitrogen fixat... more An investigation covering hydrography, chemistry, vascular and cryptogamic plants, nitrogen fixation, phytoplankton biomass and production, and zooplankton was carried out from April to November 1976 in tarn in W Norway, The volume of the tarn was 18000 m3 and the turnover time about 30 d. Temperature ranged between 3.6 and 23.4°C and pH between 4.8 and 5.5. Nuphar luteum and Carex rostrata were the two dominating vasculars-with biomasses of 117 and 97 g m−2, respectively The biomass of the bryophytes (Sphagnum spp.) was about 510 g m−2 and the production of the order 0.2–2.1 μg (mg d.w.)−1h−1. Nitrogen fixation in association with Sphagnum spp. was estimated at 25 g yr−1 for the whole tarn. Phytoplankton was dominated by diatoms, green algae and chrysophyceans. The chlorophyll a content ranged from 2 to 20 mg m−3 and the carbon assimilation rates from 0.03 to 20 mg C m−3h−1 at 0–4 m depths. Production in the period was of the magnitude 22 g C m−2. The copepod Eudiaptomus gracilis was the most common netzooplankter. Large numbers of rotationrians were found during summer.
Sarsia, 1975
Abstract Phosphate, silicate, nitrite/nitrate, and ammonia were studied in a Norwegian land-locke... more Abstract Phosphate, silicate, nitrite/nitrate, and ammonia were studied in a Norwegian land-locked fjord during 1973. In the surface water the concentrations were similar to what has been found in the North Sea, with the exception of silicate, which occurred in higher concentrations in winter. There were indications of nitrogen and silicate limitation. In the bottom water phosphate, silicate, and ammonia accumulated in the course of the year. The accumulation of phosphate was mainly due to liberation from the sediment. As a result of denitrification the content of inorganic combined nitrogen decreased in the bottom water.
Estuaries and Coasts
Nutrient concentrations in coastal waters are influenced not only by land runoff, point sources, ... more Nutrient concentrations in coastal waters are influenced not only by land runoff, point sources, and water exchange with the sea but are also modified by settlement to and release from sediments. This complicates evaluation of measures to reduce nutrient loads. We used a mass-balance box model to calculate long-term (1968–2015) and seasonal source contributions to phosphorus (P) concentrations and cycling in the stratified Stockholm inner archipelago (IA), Baltic Sea. A drastic reduction of sewage P loads in the early 1970s reduced sewage from the major to a minor P source. Further P load reductions in the 1990s cut the direct contribution from the sewage point sources to the annual mean surface water P concentration from 10 μg l−1 (25%) to < 4 μg l−1 (12%). The largest contributions to the surface water P concentration are now (from 1996) inflowing seawater (37%), freshwater (25%), and P recycling from sediments below 20 m depth (26%). Variations in freshwater flushing give high...