Publications

transmission and persistence of ceratonova shasta genotypes in chinook salmon.	ceratonova shasta is a myxozoan parasite of salmon and trout transmitted by waterborne actinospores. based on dna sequence data and host specificity, 4 distinct parasite genotypes are recognized. genotypes i and ii are common in the lower reaches of the klamath river, oregon-california, but only infection by genotype i causes mortality in chinook salmon. we conducted sentinel fish exposures and determined genotype composition in river water during exposure, and in fish gills, intestine, and tank ...	2014	24945751
post-mortem sporulation of ceratomyxa shasta (myxozoa) after death in adult chinook salmon.	ceratomyxa shasta (myxozoa) is a common gastrointestinal pathogen of salmonid fishes in the pacific northwest of the united states. we have been investigating this parasite in adult chinook salmon ( oncorhynchus tshawytscha ) in the willamette river, oregon. in prior work, we observed differences in the pattern of development of c. shasta in adult salmon compared to juvenile salmon. adult salmon consistently had large numbers of prespore stages in many of the fish that survived to spawn in the f ...	2014	24725089
infections by renibacterium salmoninarum and nanophyetus salmincola chapin are associated with reduced growth of juvenile chinook salmon, oncorhynchus tshawytscha (walbaum), in the northeast pacific ocean.	we examined 1454 juvenile chinook salmon, oncorhynchus tshawytscha (walbaum), captured in nearshore waters off the coasts of washington and oregon (usa) from 1999 to 2004 for infection by renibacterium salmoninarum, nanophyetus salmincola chapin and skin metacercariae. the prevalence and intensities for each of these infections were established for both yearling and subyearling chinook salmon. two metrics of salmon growth, weight residuals and plasma levels of insulin-like growth factor-1, were ...	2015	24720546
predicted redistribution of ceratomyxa shasta genotypes with salmonid passage in the deschutes river, oregon.	a series of dams on the deschutes river, oregon, act as migration barriers that segregate the river system into upper and lower basins. proposed fish passage between basins would reunite populations of native potamodromous fish and allow anadromous fish of deschutes river origin access to the upper basin. we assessed the potential redistribution of host-species-specific genotypes (o, i, ii, iii) of the myxozoan parasite ceratomyxa shasta that could occur with fish passage and examined the influe ...	2012	23146111
spatial, temporal and host factors structure the ceratomyxa shasta (myxozoa) population in the klamath river basin.	the myxozoan parasite ceratomyxa shasta is a virulent pathogen of salmonid fish in the klamath river, oregon/california, usa. we previously defined four principal genotypes of the parasite (o, i, ii, iii) based on a trinucleotide repeat (atc)(0-3) in internal transcribed spacer region 1 sequences. genotypes occur in sympatry and show marked host preference: i in chinook salmon (oncorhynchus tschawytscha) and ii in non-native rainbow trout (o. mykiss). in the present study, we sequenced the paras ...	2010	20601174
disparate infection patterns of ceratomyxa shasta (myxozoa) in rainbow trout (oncorhynchus mykiss) and chinook salmon (oncorhynchus tshawytscha) correlate with internal transcribed spacer-1 sequence variation in the parasite.	ceratomyxa shasta is a virulent myxosporean parasite of salmon and trout in the pacific northwest of north america. the parasite is endemic in the klamath river, oregon/california, where a series of dams prevent movement of fish hosts between the upper and lower parts of the basin. ceratomyxa shasta exhibits a range of infection patterns in different fish species above and below the dams. we hypothesised that the variations in infection and disease are indicators that different strains of the pa ...	2010	19895812
genotypes and phylogeographical relationships of infectious hematopoietic necrosis virus in california, usa.	infectious hematopoietic necrosis virus (ihnv) contains 3 major genogroups in north america with discreet geographic ranges designated as upper (u), middle (m), and lower (l). a comprehensive genotyping of 237 ihnv isolates from hatchery and wild salmonids in california revealed 25 different sequence types (a to y) all in the l genogroup; specifically, the genogroup contained 14 sequence types that were unique to individual isolates as well as 11 sequence types representing 2 or more identical i ...	2007	17933395
distribution and habitat characteristics of manayunkia speciosa and infection prevalence with the parasite ceratomyxa shasta in the klamath river, oregon-california.	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 p ...	2007	17436945