Sökning: "Perch roach"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden Perch roach.

  1. 1. Population ecology of perch (Perca fluviatilis) in boreal lakes

    Författare :Arne Linløkken; Eva Bergman; Larry Greenberg; Anders Hargeby; Karlstads universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; perch; growth; size; mortality; temperature; acidification; density; roach; competition; Biology; Biologi; Biology; Biologi;

    Sammanfattning : I studied the effects of temperature, pH, competition and predation on Eurasian perch (Perca fluviatilis) in 30 lakes in Norway during 1981-2001. The study lakes were situated in two different areas in southern Norway; four lakes in Aust-Agder county in southernmost Norway were explored during 1981-1984 and 26 lakes in Hedmark county in south-eastern Norway were investigated during 1992-2001. LÄS MER

  3. 2. Paleolimnological reconstructions of fish population changes in acidified lakes

    Författare :Fredrik Palm; Göteborgs universitet; []
    Nyckelord :Acidification; Chaoborus; C. flavicans; C. obscuripes; Cyprinids; Daphnia; Fish loss; Fish community composition; Ephippia; Fragmentation; Mandibles; Perch; Roach; Sediments; 210-Pb chronology;

    Sammanfattning : This thesis deals with the potential of using subfossil Chaoborus spp. and Daphnia spp. remains preserved in lake sediments to reveal past fish community alterations related to progressive acidification. LÄS MER

  4. 3. Biodiversity in Swedish Cyprinid Fish: Insights Into Processes of Divergence

    Författare :Marnie H Demandt; Mats Björklund; Erik Petersson; Brent Emerson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; speciation; hybridization; bottleneck; genetic drift; phylogeny; speciation rates; common bream; white bream; roach; Swedish cyprinid fish; Cyprinidae; Biology; Biologi;

    Sammanfattning : Uncovering and understanding the processes that have led to the biological diversity we observe today are of fundamental interest in biology. Since direct observation of speciation is usually impossible, knowledge about the processes behind species formation can be gathered by studying mutations, natural/sexual selection, and genetic drift. LÄS MER

  5. 4. Habitat selection and indirect interactions in fish communities : mechanisms to explain spatial distribution of perch, roach, and vendace

    Författare :Ulrika Beier; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : To increase the understanding of freshwater lake ecosystems, I have studied the habitat selection of perch (Perca fluviatilis L.), roach (Rutilus rutilus (L.)), and vendace (Coregonus albula (L.)). LÄS MER

  7. 5. Environmental influence on Hg and 137Cs levels in perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) from circumneutral lakes

    Författare :Lars Sonesten; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Hg; 137Cs; fish; PLS; land use; cations; humic substances; circumneutral; Biologi; Biology; Biologi; limnologi; Limnology;

    Sammanfattning : Mercury and radioactive caesium have received immense attention in Sweden during the past decades, as common contaminants in fish. This thesis examines how the Hg and 137Cs levels in fish from 79 circumneutral lakes are affected by various environmental factors. LÄS MER