title: Low concentrations of sodium hypochlorite affect population dynamics in Gyrodactylus salaris (Malmberg, 1957): practical guidelines for the treatment of the Atlantic salmon, Salmo salar L. parasite.
abstract: Atlantic salmon, Salmo salar L. parr (age 1+), infected by the monogenean ectoparasite Gyrodactylus salaris (Malmberg, 1957), were exposed to chlorine (Cl)-enriched water at three different concentrations: Cllow (0-5 μg Cl L(-1) ), Clmedium (18 μg Cl L(-1) ) and Clhigh (50 μg Cl L(-1) ). There was a negative correlation between G. salaris infections and the hypochlorite concentrations added. The parasite infection was eliminated by day 6-8 and day 2-4 in the groups Clmedium and Clhigh , respectively, while inhibition of G. salaris population growth was observed in the Cllow group. An important note to this matter, however, is that the G. salaris specimens observed at day 6 in Clmedium and at day 2 in Clhigh were all considered dead by subjective judgement. No mortality in the salmon parr was observed during the first 8 days of the experiment, demonstrating that Cl has a stronger effect on G. salaris than on the salmonid host. The differences in sensitivity between the parasite and the Atlantic salmon indicate that hypochlorite has a potential use as a parasiticide with a therapeutic margin. The low-dose sensitivity may imply that Cl pollution in urban areas may pose a greater risk towards biodiversity than previously assumed.
authors.affiliation: Norwegian Institute for Water Research, Oslo, Norway.
authors.forename: A G
authors.initials: AG
authors.lastname: Hagen
authors.forename: S
authors.initials: S
authors.lastname: Hytterød
authors.forename: K
authors.initials: K
authors.lastname: Olstad
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000494:pharmacology / Q000627:therapeutic use; D005393:Fish Diseases / Q000188:drug therapy* / Q000401:mortality; D011157:Population Dynamics; D020317:Salmo salar; D012973:Sodium Hypochlorite / Q000494:pharmacology* / Q000627:therapeutic use*; D014200:Trematoda / Q000187:drug effects*; D014201:Trematode Infections / Q000188:drug therapy / Q000401:mortality / Q000662:veterinary*
chemical_list: D000977:Antiparasitic Agents; D012973:Sodium Hypochlorite
keywords: Monogenea; biodiversity; disinfection; parasite; treatment