The Effects of Flow on the Salmon Parasite Ceratomyxa shasta : Establishing Baseline Information For Assessment of Flow Management Alternatives For Mitigating Effects of Myxozoan Pathogens in the Klamath River Jerri Bartholomew and Sarah Bjork*
Klamath River IGD Once the third largest salmon fishery on the Pacific coast Declines in salmon from multiple causes - loss of habitat, dams, fishing pressure and water use In 2006, failure of the Klamath River fishery resulted in closure of commercial fishing in S. Oregon and N. California
Causes of disease in juvenile salmon USFWS surveys of outmigrant juvenile Chinook salmon show severe effects of disease since about 2000 Due to chronic diseases caused by myxozoan parasites 2004 estimates 63% juvenile outmigrating Chinook infected with C. shasta
Ceratomyxa shasta Infects: salmon and trout Target tissue: intestine Causes severe necrotic lesions and often high mortality
Ceratomyxa shasta Life cycle Salmonid host Actinospore Myxospore BARTHOLOMEW ET AL. 1997. J. PARASITOL Polychaete host: Manayunkia speciosa
Klamath River Upper Klamath Lower Klamath IGD IGD Below Iron Gate dam characterized by: High juvenile and adult Chinook salmon infection Numerous polychaete populations High parasite densities Potential target area for flow based parasite control
C. shasta : what we know from the fish host Stocks of fish that migrate through endemic areas have an inherent resistance This resistance is genetic, but we don t know the mechanisms Increased temperature increases parasite development in the fish
C. shasta : what we know from the polychaete host M. speciosa is a tiny (~3mm) freshwater, tube dwelling annelid Primarily lives in two substrates; Cladophora spp and sand silt Actinospores develop in the body wall, rate of development and mode of release are unknown
Objectives The objectives of the study were to determine the effects of: Water temperature (changes in water flow and temperature coincide) and dewatering on the survival of the polychaete host Water temperature on the longevity of the actinospore. Water flow (velocity) on polychaete survival and infection in polychaete and fish hosts.
Polychaete survival: water temperature and de-watering Polychaete collection 5, 12, and 20 C low flow Dry 24 h then 12 C flow Determine polychaete density over time
Results: The effects of temperature on polychaete survival 5 C Relative % polychaete d 100 80 60 40 20 0 12 C 20 C 0 20 40 60 80 Days
Results: The effects of de-watering on polychaete survival 100 90 Sand-Silt Relative % polychaete de 80 70 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 Week
The effects of temperature and de- watering on M. speciosa Polychaete survival in the laboratory was highest at colder temperatures However the polychaete is found at higher temperatures in river Polychaetes can survive a 24 hour low water, no flow event
The effects of temperature on longevity of the actinospore Infected polychaete Treatment 0 3 Days 6 10 12 4 C 12 C 20 C 4 C 12 C 20 C + + + + + + + + + + + intact actinospores - Degrading actinospores
The effects of flow on C. shasta infection dynamics Determine the effect flow on: Polychaete survival Polychaete infection prevalence Infection prevalence and severity in susceptible and resistant fish
Experimental flows based on field observations: Slow flow 0.01 m/s Fast flow 0.05 m/s * Limited by pump volume Stocking and Bartholomew 2007
Experimental Design *modelled after Hallett and Bartholomew 2006 Willamette R. water supplied flows (water ambient temperature). Fast Polychaetes collected seeded Fast control Slow seeded Slow control Aquaria in the out flow for fish exposures. Aquaria Channels with filled with sediment Willamette and R. water only polychaetes as control One tank (3 channels) at each flow, seeded with an infected fish. Non-infected fish added to controls
Assessment: Polychaete survival Density determination Count number of polychaetes present at wks 0, 6, 10, 15, and 22 (end of experiment)
Assessment: Polychaete infection prevalence Polychaetes from density determination were assayed for infection by PCR (pooled prevalence assay)
Assessment: Fish infection Groups of: Susceptible rainbow trout Klamath Chinook salmon (resistant)
Results- Polychaete survival Fast Slow 180 180 160 Fast Seeded 160 Slow Seeded 140 Fast Control 140 Slow Control 120 120 Polychaete den 100 80 Polychaete den 100 80 60 60 40 40 20 20 0 0 5 10 15 20 25 Week 0 0 5 10 15 20 25 Week Polychaete survival highest at 15 wk in fast control group
Results- Polychaete infection prevalence 25 Fast seeded 20 Fast control Slow seeded Slow control % Prevalen 15 10 5 0 0 5 10 15 20 25 Week Peak polychaete infection prevalence Slow seeded 12 wk after addition of myxospores
Results: Fish infection Susceptible Rainbow trout No differences in infection prevalence due to high susceptibility of fish background level of polychaete infection Fish at slow flow died faster than fast flow fish indicating more severe infection % Survival 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Fast Seeded Fast Control Slow Seeded Slow Control Willamette Fast Willamete Slow 0 20 40 60 80 100 Days
Chinook salmon results No Chinook became infected during 1 or 4 wk exposure periods Chinook salmon may be resistant to as many as 8,000 actinospores Spore estimate for slow flow seeded wk 15: 25 worms/subsample x 57.5 = 1438 total worms 1438 worms x prevalence (0.14) = 201 infected worms 201 infected worms x ~200 actinospores/infected worm = 40264 actinospores 40264 actinospores/ 5 fish = 8052 actinospores per fish!
% 100 90 80 70 60 50 40 30 20 10 0 Seasonality of infection and the influence of flow Beaver Creek May 2006 prevalence mortality Rainbow trout Chinook 2006 Beaver Creek June 2006 % 100 90 80 70 60 50 40 30 20 10 0 Rainbow trout prevalence mortality Chinook Avg temp during exposure May - 18C June - 20C
Seasonality of infection and the influence of flow % 100 90 80 70 60 50 40 30 20 10 0 Beaver Creek May 2005 prevalence mortality Rainbow trout Chinook 2005 Beaver Creek June 2005 100 90 % 80 70 60 50 40 30 20 10 0 Rainbow trout prevalence mortality Chinook Infection severity in Chinook salmon may have been mitigated as a result of the high flow event Avg temp during exposure May - 18C June - 18C
The effects of parasite dilution Fish were exposed to 20 actinospores in either 500 ml or 3 L for 2 hours 100 90 80 prevalence mortality 70 60 % 50 40 30 20 10 0 500 ml 3 L
Summary Polychaete survival highest at cooler temperatures and fast flow Actinospores last longer at cool temperature but are present for up to 3 days at 20 C Fast flow had lowest polychaete infection prevalence Rainbow trout exposed in fast flow had a prolonged mean day to death Infection prevalence of sentinel fish exposures in the Klamath River reflect decrease in infection after a high flow event Parasite dilution as would occur with high water volumes resulted in decreased fish infection prevalence
Acknowledgments CFDR OSU Sascha Hallett Don Stevens Harriet Lorz Lindsey Osborn Richard Stocking Rich Holt Carly Todd California Energy Commission PIER Oregon Sea Grant OSU Department of Statistics Jack Giovannini and Doug Lamour