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  • 1.
    Ahlbeck, Ida
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Living in a predation matrix: Studies on fish and their prey in a Baltic Sea coastal area2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis was written within the framework of a biomanipulation project where young-of-the-year (YOY) pikeperch (Sander lucioperca) were stocked to a Baltic Sea bay to improve water quality through a top-down trophic cascade. The aim of my doctorial studies was however focused on a broader ecological question, namely predation (the main driving force in a biomanipulation). Hence, this thesis consists of four papers where we study the interactions between predator and prey using fish and zooplankton and how these interactions can be measured.

    In paper I we evaluated the performance of different diet analysis methods by individual based modelling and found that when having a nutritional gain perspective, mass based methods described diets best. Paper II investigated how the explorative, foraging and anti-predator behaviour of the YOY pikeperch used for stocking were affected by their rearing environment (pond vs. tank rearing). The more complex and varied environment in the semi-natural ponds seemed to promote a more flexible and active behaviour, better equipping young fish for survival in the wild. For paper III we studied the diel vertical migration in the six copepodite stages of the zooplankton Acartia spp. and Eurytemora affinis in relation to fish biomass, phytoplankton abundance and temperature. Both species migrated and in addition showed increased migration range with size within species, indicating evasion from visual predators. Paper IV addressed the movement of littoral Eurasian perch (Perca fluviatilis) via stable isotope signatures (13C and 15N) and body condition. We found clear indications of sedentarity and intra-habitat dietary differences. Interactions between predators and prey are complex and affected by both physiological and environmental characteristics as well as behavioural traits. The results in this thesis suggest that different species and even different life stages pursue different strategies to survive.

  • 2.
    Ahlbeck, Ida
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Hansson, Sture
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Hjerne, Olle
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Evaluating fish diet analysis methods by individual-based modelling2012Ingår i: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 69, nr 7, s. 1184-1201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Knowledge of diet compositions is important in ecological research. There are many methods available and numerous aspects of diet composition. Here we used modelling to evaluate how well different diet analysis methods describe the true diet of fish, expressed in mass percentages. The methods studied were both basic methods (frequency of occurrence, dominance, numeric, mass, points) and composite indices (Index of Relative Importance, Comparative Feeding Index). Analyses were based on both averaged stomach content of individual fish and on pooled content from several fish. Prey preference, prey size, and evacuation rate influenced the performance of the diet analysis methods. The basic methods performed better than composite indices. Mass and points methods produced diet compositions most similar to the true diet and were also most robust, indicating that these methods should be used to describe energetic-nutritional sources of fish.

  • 3.
    Ahlbeck, Ida
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Hansson, Sture
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Hjerne, Olle
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Evaluation of diet analysis methods by individual based modellingIngår i: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533Artikel i tidskrift (Refereegranskat)
  • 4.
    Ahlbeck, Ida
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Hansson, Sture
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Karlöf, Oliver
    Sedentarity in Eurasian perch (Perca fluviatilis) in a coastal Baltic Sea areaIngår i: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633Artikel i tidskrift (Refereegranskat)
  • 5.
    Ahlbeck, Ida
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Holliland, Per B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Rearing environment affect important life skills in pikeperch (Sander lucioperca)2012Ingår i: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 17, nr 3-4, s. 291-304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of rearing environment on the behaviour of young-of-the-year pikeperch (Sander lucioperca) bred at three different production facilities was investigated. Two groups were reared in semi-natural ponds and one group in indoor tanks. Exploratory, foraging and anti-predator behaviours were studied in aquarium experiments. There were no significant differences between pond- and tank-reared fish in reluctance to explore their new environment, but pond-reared fish spent significantly more time in macro-vegetation. Pond-reared fish were significantly faster to start foraging on live prey (Neomysis integer) that they had not encountered before. As compared with tank-reared fish, pond-reared fish were also significantly more active in their anti-predator response. Rearing environment obviously influences the development of important life skills. These differences may impact the success rate when stocking young-of-the-year pikeperch into natural waters.

  • 6.
    Holliland, Per B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Ahlbeck, Ida
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Westlund, Erica
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Hansson, Sture
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Ontogenetic and seasonal changes in diel vertical migration amplitude of the calanoid copepods Eurytemora affinis and Acartia spp. in a coastal area of the northern Baltic Proper2012Ingår i: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 34, nr 4, s. 298-307Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We studied diel vertical migration (DVM) of the six copepodite stages of two of the most abundant crustacean zooplankton in the Baltic Sea, the calanoid copepods Eurytemora affinis and Acartia spp. The study was conducted monthly from May through October in a bay in the northwestern Baltic proper. Fish biomass, phytoplankton abundance and temperature were obtained in conjunction with the zooplankton sampling. Both copepod species performed DVM. With the exception of females, all E. affinis copepodite stages performed migrations of over 10 m with only a slight increase with the copepodite stage. Adult female E. affinis remained at depth with only slight upward movement at night. In Acartia spp., DVM amplitude increased with stage and size, suggesting an ontogenetic shift in behaviour; although they had a less pronounced DVM than E. affinis. Although DVM amplitude increased with size, indicative of visual predation, fish biomass did not correlate with the amplitude of DVM. However, fish were present throughout the study period. We surmise that these ontogenetic shifts in behaviour are due to size increase and therefore visibility to predators and that the difference in DVM between the species may well be a result of physiological differences and reproductive strategy.

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