Relationship Between Temperature and Ceratomyxa shasta–Induced Mortality In Klamath River Salmonids

Water temperature influences almost every biological and physiological process of salmon, including disease resistance. In the Klamath River (California), current thermal conditions are considered sub-optimal for juvenile salmon. In addition to borderline temperatures, these fish must contend with t...

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Bibliographic Details
Published in:The Journal of parasitology 2012-06, Vol.98 (3), p.520-526
Main Authors: Ray, R. Adam, Holt, Richard A, Bartholomew, Jerri L
Format: Article
Language:English
Subjects:
Analysis of Variance
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Biological and medical sciences
California
Ceratomyxa shasta
Fish Diseases - mortality
Fish Diseases - parasitology
Fresh water ecosystems
Freshwater fishes
FUNCTIONAL MORPHOLOGY
Fundamental and applied biological sciences. Psychology
General aspects
General aspects and techniques. Study of several systematic groups. Models
Genotypes
Infections
Invertebrates
Mortality
Myxozoa - pathogenicity
Oncorhynchus kisutch
Oncorhynchus kisutch - parasitology
Oncorhynchus tshawytscha
Parasite hosts
Parasites
Parasitic Diseases, Animal - mortality
Parasitic Diseases, Animal - parasitology
Pathogens
Physiology
River water
Rivers
Salmon
Salmon - parasitology
Specific Pathogen-Free Organisms
Synecology
Temperature
Water temperature
Young animals
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Summary:Water temperature influences almost every biological and physiological process of salmon, including disease resistance. In the Klamath River (California), current thermal conditions are considered sub-optimal for juvenile salmon. In addition to borderline temperatures, these fish must contend with the myxozoan parasite Ceratomyxa shasta, a significant cause of juvenile salmonid mortality in this system. This paper presents 2 studies, conducted from 2007 to 2010, that examine thermal effects on C. shasta–induced mortality in native Klamath River Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon. In each study, fish were exposed to C. shasta in the Klamath River for 72 hr and then reared in the laboratory under temperature-controlled conditions. The first study analyzed data collected from a multi-year monitoring project to asses the influence of elevated temperatures on parasite-induced mortality during the spring/summer migration period. The second study compared disease progression in both species at 4 temperatures (13, 15, 18, and 21 C) representative of spring/summer migration conditions. Both studies demonstrated that elevated water temperatures consistently resulted in higher mortality and faster mean days to death. However, analysis of data from the multi-year monitoring showed that the magnitude of this effect varied among years and was more closely associated with parasite density than with temperature. Also, there was a difference in the timing of peak mortality between species; Chinook incurred high mortalities in 2008 and 2009, whereas coho was greatest in 2007 and 2008. As neither temperature nor parasite density can be easily manipulated, management strategies should focus on disrupting the overlap of this parasite and its obligate hosts to improve emigration success and survival of juvenile salmon in the Klamath River.
ISSN:0022-3395
1937-2345
DOI:10.1645/JP-GE-2737.1