Sture Hansson | Stockholm University (original) (raw)
Papers by Sture Hansson
Fisheries Research, 1999
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ABSTRACT Pages: 320 p.
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C.M. / International Council for the Exploration of the Sea ; 1994/J:16, Ref. H Pages: 9 p. The d... more C.M. / International Council for the Exploration of the Sea ; 1994/J:16, Ref. H Pages: 9 p. The daily food consumption of the young-of-the-year (YOY) decreased from 17% of body weight for small fish in the summer to 1% for larger juveniles in late autumn. Stomach content varied in a daily cycle. The observed daily food consumption was on average 38% (range 9-95%) of an estimated maximum consumption. We describe the relation between food consumption and food availability as functional response type 2 (Holling 1959).
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Zooplankton is an important part of Baltic ecosystem and ecosystem-based management requires prod... more Zooplankton is an important part of Baltic ecosystem and ecosystem-based management requires productivity assessment of the region what involves zooplankton identification and abundance estimation. Acoustics is recognized as a reliable monitoring method. Thus, the ability of understanding of backscattering by zooplankton becomes a priority. It was the main motivation of the paper. The main approach is based on (i) the numerical modeling of acoustic backscattering by the typical representative of Baltic zooplankton, mysids and (ii) comparison of the theoretical results with the measured acoustic data. The Modal Based Deformed Wave Born Approximation (MB-DWBA) model was employed. The readily available biologic data for mysids were used. The sensitivity of the backscattering to acoustic frequency, individual size, width of orientation distribution and acoustic properties of biologic tissue was analyzed. The results of modeling were verified using the measured acoustic and biologic data...
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Marine Biology, 2015
ABSTRACT Zooplankton often migrate vertically to deeper dark water during the day to avoid visual... more ABSTRACT Zooplankton often migrate vertically to deeper dark water during the day to avoid visual predators such as fish, a process which can strengthen benthic-pelagic coupling. In the Gulf of Finland, Baltic Sea, a pronounced hypoxic layer develops when there is an inflow of anoxic bottom water from the Central Baltic Sea, which could be a barrier for vertical migrants. Here, we report an acoustic study of the distributions of crustacean zooplankton (mysid shrimp and the copepod Limnocalanus macrurus), gelatinous zooplankton (Aurelia aurita) and fish. Zooplankton trawl nets were used to ground-truth acoustic data. Vertical profiles of oxygen concentration were taken, and the physiological impact of hypoxia on mysids was investigated using biochemical assays. We hypothesised that the vertical distribution of zooplankton and fish would be significantly affected by vertical heterogeneity of oxygen concentrations because anoxia and hypoxia are known to affect physiology and swimming behaviour. In addition, we hypothesised that mysids present in areas with hypoxia would exhibit a preparatory antioxidant response, protecting them from oxidative damage during migrations. The acoustic data showed peaks of crustacean zooplankton biomass in hypoxic (75 m), whereas fish shoals and A. aurita medusae were found in normoxic (5-6 mL L−1) upper water layers (
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Oecologia, 1990
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Environmental science & technology, Jan 20, 2015
The potential for using stable isotope analysis in risk assessment of environmental contaminants ... more The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on δ(15)N and δ(13)C values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. Using the cladoceran Daphnia magna, two experiments were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative eff...
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ABSTRACT C.M. / International Council for the Exploration of the Sea ; 1989/B:27 Pages: 23 p. We ... more ABSTRACT C.M. / International Council for the Exploration of the Sea ; 1989/B:27 Pages: 23 p. We compared fish abundance, biomass and size distribution estimated from sonar data collected with two single-beam echo sounders (70 and 38 kHz) in a coastal area of the Baltic proper. The acoustic signals were analyzed using analysis of a single fish echoes (70 kHz) and using echo integration interpreted with catches in pelagic trawls (38 kHz). Fish were also collected with vertical gill nets. The two sonar systems gave similar echo integration values along an inter-calibration transect. +
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Hydrobiologia, 1997
Predation by the Baltic Sea mysid Mysis mixta onnewly hatched Artemia sp. and culturedDaphnia mag... more Predation by the Baltic Sea mysid Mysis mixta onnewly hatched Artemia sp. and culturedDaphnia magna was examined in the laboratory. Wedesigned experiments to study the effects onconsumption rate of different experimental conditions:light, container size, diel variation, duration ofadaptation period, starvation and the duration of afeeding experiment.Consumption differed significantly between mysids keptin bright light vs mysids in complete darkness, withabout twice
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Oecologia, 2005
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Marine Ecology Progress Series, 1994
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Marine Ecology Progress Series, 1999
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Marine Ecology Progress Series, 1992
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Marine Ecology Progress Series, 1993
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Marine Biology, 1989
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Marine Biology, 1983
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Fisheries Research, 1999
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ABSTRACT Pages: 320 p.
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C.M. / International Council for the Exploration of the Sea ; 1994/J:16, Ref. H Pages: 9 p. The d... more C.M. / International Council for the Exploration of the Sea ; 1994/J:16, Ref. H Pages: 9 p. The daily food consumption of the young-of-the-year (YOY) decreased from 17% of body weight for small fish in the summer to 1% for larger juveniles in late autumn. Stomach content varied in a daily cycle. The observed daily food consumption was on average 38% (range 9-95%) of an estimated maximum consumption. We describe the relation between food consumption and food availability as functional response type 2 (Holling 1959).
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Zooplankton is an important part of Baltic ecosystem and ecosystem-based management requires prod... more Zooplankton is an important part of Baltic ecosystem and ecosystem-based management requires productivity assessment of the region what involves zooplankton identification and abundance estimation. Acoustics is recognized as a reliable monitoring method. Thus, the ability of understanding of backscattering by zooplankton becomes a priority. It was the main motivation of the paper. The main approach is based on (i) the numerical modeling of acoustic backscattering by the typical representative of Baltic zooplankton, mysids and (ii) comparison of the theoretical results with the measured acoustic data. The Modal Based Deformed Wave Born Approximation (MB-DWBA) model was employed. The readily available biologic data for mysids were used. The sensitivity of the backscattering to acoustic frequency, individual size, width of orientation distribution and acoustic properties of biologic tissue was analyzed. The results of modeling were verified using the measured acoustic and biologic data...
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Marine Biology, 2015
ABSTRACT Zooplankton often migrate vertically to deeper dark water during the day to avoid visual... more ABSTRACT Zooplankton often migrate vertically to deeper dark water during the day to avoid visual predators such as fish, a process which can strengthen benthic-pelagic coupling. In the Gulf of Finland, Baltic Sea, a pronounced hypoxic layer develops when there is an inflow of anoxic bottom water from the Central Baltic Sea, which could be a barrier for vertical migrants. Here, we report an acoustic study of the distributions of crustacean zooplankton (mysid shrimp and the copepod Limnocalanus macrurus), gelatinous zooplankton (Aurelia aurita) and fish. Zooplankton trawl nets were used to ground-truth acoustic data. Vertical profiles of oxygen concentration were taken, and the physiological impact of hypoxia on mysids was investigated using biochemical assays. We hypothesised that the vertical distribution of zooplankton and fish would be significantly affected by vertical heterogeneity of oxygen concentrations because anoxia and hypoxia are known to affect physiology and swimming behaviour. In addition, we hypothesised that mysids present in areas with hypoxia would exhibit a preparatory antioxidant response, protecting them from oxidative damage during migrations. The acoustic data showed peaks of crustacean zooplankton biomass in hypoxic (75 m), whereas fish shoals and A. aurita medusae were found in normoxic (5-6 mL L−1) upper water layers (
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Oecologia, 1990
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Environmental science & technology, Jan 20, 2015
The potential for using stable isotope analysis in risk assessment of environmental contaminants ... more The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on δ(15)N and δ(13)C values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. Using the cladoceran Daphnia magna, two experiments were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative eff...
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ABSTRACT C.M. / International Council for the Exploration of the Sea ; 1989/B:27 Pages: 23 p. We ... more ABSTRACT C.M. / International Council for the Exploration of the Sea ; 1989/B:27 Pages: 23 p. We compared fish abundance, biomass and size distribution estimated from sonar data collected with two single-beam echo sounders (70 and 38 kHz) in a coastal area of the Baltic proper. The acoustic signals were analyzed using analysis of a single fish echoes (70 kHz) and using echo integration interpreted with catches in pelagic trawls (38 kHz). Fish were also collected with vertical gill nets. The two sonar systems gave similar echo integration values along an inter-calibration transect. +
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Bookmarks Related papers MentionsView impact
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Hydrobiologia, 1997
Predation by the Baltic Sea mysid Mysis mixta onnewly hatched Artemia sp. and culturedDaphnia mag... more Predation by the Baltic Sea mysid Mysis mixta onnewly hatched Artemia sp. and culturedDaphnia magna was examined in the laboratory. Wedesigned experiments to study the effects onconsumption rate of different experimental conditions:light, container size, diel variation, duration ofadaptation period, starvation and the duration of afeeding experiment.Consumption differed significantly between mysids keptin bright light vs mysids in complete darkness, withabout twice
Bookmarks Related papers MentionsView impact
Oecologia, 2005
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Marine Ecology Progress Series, 1994
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Marine Ecology Progress Series, 1999
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Marine Ecology Progress Series, 1992
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Marine Ecology Progress Series, 1993
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Marine Biology, 1989
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Marine Biology, 1983
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