Distribution and Habitat Characteristics of Manayunkia Speciosa and Infection Prevalence With the Parasite Ceratomyxa Shasta in the Klamath River, Oregon–california

Abstract

A survey for Manayunkia speciosa, the freshwater polychaete host for the myxozoan parasite Ceratomyxa shasta, was conducted from 2003 to 2005 as part of an integrated study of the epizootiology of ceratomyxosis in Klamath River salmonids. Substrata samples (n = 257) were collected in a variety of habitats from Klamath Lake to the mouth of the Klamath River to document occurrence and relative abundance of the polychaete by habitat type and to estimate the prevalence of C. shasta within selected polychaete populations. Populations of M. specios a were identified throughout the Klamath River within pools (51.6%), eddy-pools (47.0%), and runs (40.0%). Large populations of M. speciosa were consistently found at the inflow to the main-stem reservoirs where densities were correlated with distance from the inflow into the reservoir. Using polymerase chain reaction assay and composite samples, 12 of 71 populations identified were tested for C. shasta, revealing a mean infection prevalence of 0.27%. An area of elevated infection prevalence (4.9 and 8.3%) was identified with 2 populations below a barrier to salmonid migration, which explains the high infectious spore densities demonstrated in concurrent studies and observations of C. shasta-induced mortality in Klamath River fall Chinook salmon (Oncorhynchus tshawytscha).

Distribution and abundance of the salmonid parasite Parvicapsula minibicornis (Myxozoa) in the Klamath River basin (Oregon-California, USA)

“…Polychaetes for determination of Parvicapsula minibicornis infection prevalence were collected as part of the survey for Ceratomyxa shasta infection described by Stocking & Bartholomew (2007). Polychaetes from 7 populations in the UKR and 6 in the LKR were chosen to estimate infection prevalence ( Fig.…”

“…Recent studies have also mapped the distribution of the invertebrate host, Manayunkia speciosa, in the river (Stocking & Bartholomew 2007). However, it is not known if the distribution of P. minibicornis in the KR mirrors either that of C. shasta or its invertebrate host.…”

“…Ceratomyxa shasta is present throughout the mainstem KR to the estuary, but absent in tributaries with the exception of the headwaters to Klamath Lake in the upper basin (Hendrickson et al 1989, Stocking et al 2006. Recent studies have also mapped the distribution of the invertebrate host, Manayunkia speciosa, in the river (Stocking & Bartholomew 2007). However, it is not known if the distribution of P. minibicornis in the KR mirrors either that of C. shasta or its invertebrate host.…”

“…Populations collected 10 to 22 Rkm downriver from Iron Gate dam had the highest infection rate of any LKR population. This is also an area were polychaete population densities are high and where Ceratomyxa shasta infection prevalence was greatest (Stocking & Bartholomew 2007). Given that infected polychaetes may release thousands of actinospores that can survive at least 7 d (Foott et al 2007), we expect these polychaete populations provide a high spore dose to fish throughout much of the unobstructed LKR.…”

“…P. minibicornis infections were rated as diseased (parasite stages and glomerulonephritis present in > 33% of the kidney section), infected (parasites present; (2002). Infections in samples of pooled polychaetes were also determined by this assay, with modifications described by Stocking & Bartholomew (2007). Controls included known infected fish and polychaetes and uninfected fish tissues for the polychaete assay.…”