Relation of Water Temperature to Infections of Coho Salmon (Oncorhynchus kisutch), Chinook Salmon (O. tshawytscha), and Steelhead Trout (Salmo gairdneri) with Aeromonas salmonicida and A. hydrophila

Abstract

Juvenile steelhead trout (Salmo gairdneri), coho salmon (Oncorhynchus kisutch), and spring chinook salmon (O. tshawytscha) were infected by intraperitoneal or intramuscular injection with Aeromonas salmonicida or A. hydrophila at seven temperatures from 3.9 to 20.5 °C. At 3.9 and 6.7 °C, mortality in fish infected with A. salmonicida varied from 2 to 26% among the three salmonid species. At 20.5 °C 93–100% of these animals died within 2 or 3 days; at 6.7 °C or lower the fish survived for 12–23 days. Growth of A. salmonicida in vitro was influenced by temperature in a manner very similar to its influence on the in vivo infection. Comparable experiments with A. hydrophila gave results much like those with A. salmonicida, though some differences were noted. At a temperature of 20.5 °C percent mortality ranged from 64 to 100%. At 9.4 °C or below no deaths attributed to A. hydrophila occurred. Fatally infected fish died more rapidly at the higher temperatures. Key words: Aeromonas salmonicida, A. hydrophila, water temperature, furunculosis, motile aeromonas septicemia, coho salmon, chinook salmon, steelhead trout

Infection of Lake Whitefish (Coregonus clupeaformis) with motile Aeromonas spp. in the Laurentian Great Lakes

“…The LWF solely infected with motile aeromonads were also most common in the summer. This is in concordance with reports that motile aeromonad infections are most common in warm months of the year (Aoki, 1999;Austin and Austin, 2007) and that some strains are unable to elicit mortalities in experimentally infected fish unless water temperatures exceed 9.4°C (Groberg et al, 1978). Although the epizootiology of motile Aeromonas spp.…”

“…has not been extensively studied, aquatic environments are considered replete with these organisms (Hazen et al, 1978), being found in association with aquatic plants (Trust and Sparrow, 1974), invertebrates (King and Shotts, 1988), fish intestines (Sugita et al, 1995), and on fish eggs (Hansen and Olafsen, 1989). Thus, the presence of these bacteria in the environment does not necessarily equate to presence of disease; rather, disease manifestation and ensuing mortalities appear to be stress-mediated (Bullock et al, 1971) and can be exacerbated by a variety of factors, such as pollutants (Hanson and Grizzle, 1985) and elevated water temperatures (Groberg et al, 1978). As such, the motile aeromonad infections detected in LWF and the concurrent clinical signs consistent with MAS may be a sign that the examined LWF stocks are stressed.…”

Aeromonas salmonicida infected fish transfer disease to healthy fish via water

“…Whilst at lower temperatures (6-8°C in case of our studies) the time between infection and death could be prolonged (5-8 days). The effects of temperature on pathogen multiplication and host defence mechanisms is an important relationship [30].…”

Immunosuppression in progeny of chinook salmon infected with Renibacterium salmoninarum: re-analysis of a brood stock segregation experiment

“…The differences in survivorship observed between the sockeye and coho salmon could as easily be due to differences in average size and developmental stage of the 2 species at the beginning of the experiment as to differences between the species in general, as temperature is only one of a multitude of factors affecting the relationship between infection level and the probability of survivorship. Nearly identical experiments were performed with other bacterial diseases of fish, caused by Flexibacter columnaris, Aeromonas salmonicida and A. hydrophila (Holt et al 1975, Groberg et al 1978. BKD was the only one of these diseases for which higher temperatures (17.8 and 20.5°C) resulted in decreased total mortality.…”