Sökning: "mayflies"

Visar resultat 1 - 5 av 6 avhandlingar innehållade ordet mayflies.

  1. 1. The function of seasonal habitat shifts in two congeneric mayflies in a boreal river

    Författare :Olle Söderström; Umeå universitet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; Habitat utilization; diel activity; orientation; predation; life-history; temperature; food quality; mayflies; Parameletus chelifer; Parameletus minor;

    Sammanfattning : Unregulated North Swedish rivers show large seasonal variations in their physical characteristics. During winter the whole littoral zone freezes solid, and in spring the water flow increases rapidly and the same areas become flooded. The two mayflies Parameletus chelifer and P. minor are common in the North Swedish river Vindelälven. LÄS MER

  3. 2. Vattenfysikalisk-kemiska och bottenfaunaförhållanden i ett norrländskt vattendrag påverkat av utsläpp från sulfidmalmbrytning och anrikning

    Författare :Bertil Brånin; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Mining; metals; pollution; stream; physicochemical; invertebrates and diversity index;

    Sammanfattning : Gruvbrytnings- och anrikningsverksamheten av komplexa zink-och kopparsulfidmalmer orsakar på flera håll i Västerbottens län vattenföroreningsproblem. För att studera effekterna av utsläppen i recipienten, har undersökningar och utvärderingar gjorts av de fysikalisk-kemiska och biologiska förhållandena i Vormbäcken 1971 - 1975. LÄS MER

  4. 3. Ecology of freshwater mussels in disturbed environments

    Författare :Martin Österling; Larry Greenberg; Björn Arvidsson; David Strayer; Karlstads universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Unionoida; Margaritifera margaritifera; Dreissena; Salmo trutta; habitat degradation; turbidity; sedimentation; recruitment; conservation.; Biology; Biologi; Biology; Biologi;

    Sammanfattning : The number of species extinctions is increasing at an alarming rate. Long-lived freshwater mussels of the order Unionoida, which include a parasitic stage on a host fish, are highly threatened. Habitat degradation by turbidity and sedimentation is thought to be one major reason for their decline. LÄS MER

  5. 4. Visual ecology of insect superposition eyes

    Författare :Pär A Brännström; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Animal physiology; tiger beetle; hawkmoth; mayfly; insect; visual ecology; eye design; vision; compound eye; Djurfysiologi;

    Sammanfattning : In the superposition compound eye each rhabdom (light sensitive unit) receives light through many ommatidial facets, while in the apposition compound eye every rhabdom receives light from a single facet. The superposition design increases photon capture, which is an advantage in dark environments. LÄS MER

  7. 5. Molecular phylogenetics and taxonomic issues in dragonfly systematics (Insecta: Odonata)

    Författare :Rasmus Hovmöller; Thomas Pape; Mari Källersjö; Kjell Arne Johanson; Karl Kjer; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Systematics and phylogenetics; Systematik och fylogeni;

    Sammanfattning : Dragonflies (Odonata) are one of the ancestral groups of extant insects. They represent one of the three most basal branches in the phylogeny of winged insects. The other two groups are the Ephemeroptera, mayflies, and Neoptera, the latter which covers the remaining winged insects. LÄS MER