Production of the myxosporean parasite, Ceratomyxa shasta, in fall-run Chinook salmon carcasses in the Klamath river
Graduation Date
2014
Document Type
Thesis
Program
Other
Program
Thesis (M.S.)--Humboldt State University, Natural Resources: Fisheries, 2014
Committee Chair Name
Gary Hendrickson
Committee Chair Affiliation
HSU Faculty or Staff
Keywords
Chinook salmon, Humboldt State University -- Theses -- Natural Resources, Parasites, Klamath River watershed
Abstract
Three experiments were performed to investigate Ceratomyxa shasta myxospore production by post-spawned Chinook salmon carcasses in the Klamath River watershed. Post-spawned Chinook salmon carcasses presumably infected with C. shasta were placed in flow-through plywood boxes submersed in the main-stem channel of the Klamath River, California. Parasites were molecularly quantified in water samples collected daily from the boxes to determine timing of parasite release into the environment. No parasites were detected in samples at any point in time. Myxospore densities in intestinal contents collected from infected Chinook salmon were monitored through time using phase microscopy to identify timing of myxospore development and proliferation in fish carcasses. No significant changes in parasite density were observed in incubating samples. Myxospore prevalence and abundance was measured in intestinal contents collected from 242 Fall-run, post-spawned Chinook salmon carcasses. Carcasses were sampled in October through December of 2011 from four tributaries of the Klamath River: Salmon River, Shasta River, Scott River and Bogus Creek. The probability of Ceratomyxa shasta myxospore detection in post-spawned Chinook salmon carcasses was estimated by fitting candidate binary logistic regressions to myxospore presence-absence data. Myxospore infection severity in post-spawned Chinook salmon carcasses was estimated by fitting candidate linear regressions to myxospore abundance data collected from spore-bearing carcasses. Candidate models were constructed from varying combinations of five explanatory variables: geographic sampling location, date of sampling, carcass fork length, carcass sex and degree of carcass decomposition at the time of sampling. AICc model selection determined that myxospore prevalence was specific to sampling site and was positively related to level of carcass decomposition. Log-transformed myxospore abundance was positively related to carcass fork length. These relationships in connection with age and site-specific Chinook salmon run size estimates are likely responsible for vast differences in regional myxospore production throughout the Klamath River watershed.
Recommended Citation
Campise, Nick, "Production of the myxosporean parasite, Ceratomyxa shasta, in fall-run Chinook salmon carcasses in the Klamath river" (2014). Cal Poly Humboldt theses and projects. 1461.
https://digitalcommons.humboldt.edu/etd/1461
https://scholarworks.calstate.edu/concern/theses/1v53k066q