0000000000600234
AUTHOR
Are Nylund
No influence of oxygen levels on pathogenesis and virus shedding in Salmonid alphavirus (SAV)-challenged Atlantic salmon (Salmo salar L.)
Abstract Background For more than three decades, diseases caused by salmonid alphaviruses (SAV) have become a major problem of increasing economic importance in the European fish-farming industry. However, experimental infection trials with SAV result in low or no mortality i.e very different from most field outbreaks of pancreas disease (PD). This probably reflects the difficulties in reproducing complex biotic and abiotic field conditions in the laboratory. In this study we looked at the relationship between SAV-infection in salmon and sub-lethal environmental hypoxia as a result of reduced flow-through in tank systems. Results The experiment demonstrated that constant reduced oxygen leve…
Growth and emigration of third-stage larvae of Hysterothylacium aduncum (Nematoda: Anisakidae) in larval herring Clupea harengus
The growth and emigration of Hystherothylacium aduncum in laboratory-reared herring larvae Clupea harengus was studied. Experimental infections of 36-day-old herring larvae resulted in 126 hosts infected with 306 H. aduncum larvae. Regression analyses showed a significant worm emigration from the rectum to the head of the fish, accompanied by an increase in worm body length. The emigration was independent of worm intensity, which suggests an ontogenetic process. Some worms departed from this pattern by moving posteriorly or by penetrating into the muscle, and in 5 cases, the larvae were observed to leave living fish. This individual variation has not been observed in previous studies and mi…
New data on the early development of Hysterothylacium aduncum (Nematoda, Anisakidae).
This note reports on incidental observations of the early development of the third-stage larvae of Hysterothylacium aduncum from gadid fishes. Gravid H. aduncum females were collected from Pollachius virens, Pollachius pollachius. Gadus morhua, and Molva molva in Norwegian waters. The eggs were incubated at 20 per thousand salinity and 5 C. Spontaneous hatching of third-stage larvae was observed 10-25 days after egg deposition. These larvae were long lived and could infect Acartia tonsa copepods, the infections being maintained for up to 34 days. The morphology of the third-stage larvae in the copepods and some traits of the life cycle were similar to those reported in previous studies. How…