Now showing items 41-47 of 47
Host range, symbiotic effectiveness and nodulation competitiveness of some indigenous cowpea bradyrhizobia isolates from the transitional savanna zone of Ghana
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008)
A shortcut method for sexing juvenile European sea bass, Dicentrarchus labrax L.
(Journal article; Tidsskriftartikkel; Peer reviewed, 2005)
The objective of this study was to develop a rapid and effective method of sexing juvenile sea bass with minimum labour and material.To this end, the gonad squash mount technique was applied along with macroscopic techniques for sexing a large number of experimental fish at the age of 215-275 days post fertilization (p.f.). At this age, 90% of the 3894 fish could be unambiguously sexed by ...
Genetic investigation of swimbladder inflation anomalies in the European sea bass, Dicentrarchus labrax L.
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
Although the aetiology of swimbladder inflation anomalies in important aquaculture species such as European sea bass D. labrax is not fully determined, culture conditions are commonly suggested as main contributory factors. Little information is available on whether swimbladder inflation has a genetic basis for its expression too. In this work, 24 full-sibling sea bass families from a 4 dams x 6 ...
Do the fastest sperm within an ejaculate swim faster in subordinate than in dominant males of Arctic char?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2006)
Theoretical models predict that subordinate males should have higher sperm velocity to compensate for their disadvantaged mating role and because they experience sperm competition more frequently than dominant males. Differences in mean velocity between sperm of dominants and subordinates in the predicted direction are also documented for a few species, including the Arctic char, Salvelinus alpinus ...
Feeding ecology of piscivorous brown trout (Salmo trutta L.) in a subarctic watercourse
(Journal article; Tidsskriftartikkel; Peer reviewed, 2004-02)
Feeding ecology of piscivorous brown trout was studied in the Pasvik watercourse, Norway and Russia. The watercourse is heavily regulated for hydroelectric purposes, and 5000 brown trout > 25 cm are stocked annually to compensate the negative impacts of the impoundments. Stocked and wild trout had almost identical diets consisting mainly of vendace Coregonus albula and partly of whitefish Coregonus ...
Long-term responses of zooplankton to invasion by a planktivorous fish in a subarctic watercourse
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008-08-13)
<p>1. Introduced or invading predators may have strong impacts on prey populations of the recipient community mediated by direct and indirect interactions. The long‐term progression of predation effects, covering the invasion and establishment phase of alien predators, however, has rarely been documented.</p> <p>2. This paper documents the impact of an invasive, specialized planktivorous fish ...
On the numerous concepts in invasion biology
(Journal article; Tidsskriftartikkel; Peer reviewed, 2006-01-20)
The study of biological invasions has triggered the production of a diversity of concepts. The terminology has, however, often been applied inconsistently and inaccurately. This article lists and assesses the most commonly used terms and concepts in invasion ecology. In each case the most coherent definition and use is suggested.