Final Report pdf file

Abstract

Ceratomyxa shasta is a myxozoan parasite identified as a primary contributor to salmon mortality in the Klamath River. The parasite has a complex life cycle with life stages developing in both a fish and a freshwater polychaete host, Manayunkia speciosa. The ecological requirements of this polychaete influence the severity of infection in fish and an understanding of what contributes to high densities and infection of this host may provide management opportunities to reduce the parasite effects. This study investigated the effects of temperature and de-watering on the survival of the polychaete host in its two primary substrates, Cladophora sp. and a mixture of sand and silt, demonstrating an inverse relationship between temperature and polychaete survival. A small percentage of polychaetes survived 24 h de-watering in both substrates, indicating a higher resilience than expected. A laboratory based flow experiment showed that a higher flow (0.05 m/s) facilitated the greatest polychaete densities, whereas experimentally induced polychaete infection prevalence was higher at the slower flow (0.01 m/s).  Infected rainbow trout at the slower flow rate had a shorter mean day to death, indicating a higher infectious dose than at the high flow. These findings indicate that increased water volumes and decreased fish residence times associated with pulsed flows timed for critical points in the parasite life cycle may decrease C. shasta infection rates in both the fish and polychaete host. 

Field collection of polychaetes from Klamath River	Polychaetes in cladophora
Polychaetes in sand-silt	Filtration system for collection of actinospore stages of C. shasta
Channel tanks for testing flow effects. Outflow is directed into aquaria containing Klamath River Chinook salmon.	View looking down into flow tanks showing inflow at top and rainbow trout held in nets above the outflow
Close-up of rainbow trout held for 24h in tanks	Collecting material from filters for processing by QPCR

Photo credit: Jerri Bartholomew
(Please request permission from bartholj@science.oregonstate.edu for use of pictures)