Monitoring Ceratomyxa shasta in the Klamath River Basin

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Buck McKenzie
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Monitoring Ceratomyxa shasta in the Klamath River Basin November, 2013 The myxozoan parasite Ceratomyxa shasta infects the intestine of salmonid fish and is responsible for high mortality in juvenile

1 Monitoring Ceratomyxa shasta in the Klamath River Basin November, 2013 The myxozoan parasite Ceratomyxa shasta infects the intestine of salmonid fish and is responsible for high mortality in juvenile salmon in the Klamath River basin. The Bartholomew Lab at Oregon State University has been monitoring the spatial and temporal abundance of the parasite in that basin for over five years using sentinel fish exposures, river water sampling and polychaete sampling. Here we provide an update on our 2013 studies. Index sites There are three sites in the upper Klamath River and six in the lower Klamath River (FIGURE 1). The I5 Fish Trap site replaced Klamathon Bridge this year. FIGURE 1. Klamath River index sites for 2013 with site abbreviations and river kilometers (Rkm). Williamson River (WMR) Rkm 441 Lonesome Duck (WLD) Rkm 14.4 Seiad Valley (KSV) Rkm 207 Kinsman Fish Trap (KMN) Rkm 235 I5 Fish Trap (KI5) Rkm 287 Above Beaver Creek (KBC) Rkm 258 Keno Eddy (KED) Rkm 369 Iron Gate Dam Rkm 306 Tully Creek (KTC) Rkm 62 Orleans (KOR) Rkm 90 Sentinel fish exposures (TABLE 1) Details of exposures conducted in April through July were reported in previous updates, but are included here for reference; September results are updated. Groups of native Chinook and coho salmon and out-of-basin rainbow trout were held for three days at specific index sites in the lower and upper Klamath River mainstem beginning April Following the river exposure, the fishes were transported to the Salmon Disease Lab (SDL), OSU and treated with formalin baths and oxytetracycline medicated food for prevention of external parasites and bacterial infections. Fishes were monitored daily for C. shasta clinical disease signs for two months. Moribund fishes were euthanized and examined microscopically for C. shasta-infection by observing wet mounts 1 P a g e

2 of lower gut material; if no myxospores were observed then samples were collected for PCR. Mortality percentages below represent total loss with C. shasta-infections determined microscopically from five days after the fishes were brought to the laboratory. The PCR tests are completed for microscopically negative gut tissues for the April-July exposure loss but are still in progress for those that died and were negative by microscope in September. For September the percent C. shasta-infection may change slightly following PCR analyses. April 19-22, 2013 exposures: Iron Gate Hatchery (IGH) fall Chinook and the Roaring River Hatchery C. shasta susceptible rainbow were exposed in the Klamath River at two lower mainstem sites, upstream of the Beaver Creek confluence (KBC: 80 of each species) and near Seiad Valley (KSV; 40 of each species). The river water temperatures during exposure ranged from C so all of KSV and half of the KBC fishes were held at 13 C upon return to the laboratory; the remainder were held at 18 C to compare the affect of post-exposure rearing water temperature. At termination, on June 26 after 65 days rearing at the SDL, only one Chinook (2.6%) with a C. shasta eye infection was detected at KBC. No Chinook exposed in the river at KSV died. Rainbow trout exposed at KBC and held at 18 C incurred a 21% loss from C. shasta, and at 13 C, 6.4%. Rainbow trout exposed in the river at KSV had a 25.0% loss. Overall, all groups of fishes from the April exposures experienced low losses from C. shasta infections. May 14-17, 2013 exposures: Exposures this month occurred at six sites including the lower Williamson River (WMR), Keno Eddy (KED), near the I5-bridge below Iron Gate Dam (KI5), near Beaver Creek (KBC), Seiad Valley (KSV) and Orleans (KOR). Rainbow trout and IGH Chinook were held at all sites. IGH coho juveniles were held near KBC and KSV. At KBC, three groups of 50 fish each of Chinook were held in separate live cages to evaluate variation in infection rates among the fish in cages. Upon return to the SDL, half of each of the Chinook groups were placed at either 13 or 18 C (to approximate ambient river temperature) and then monitored for clinical disease signs of C. shasta. The rainbow trout (80 fish) and coho (60 fish) exposed at KBC also were divided in half and held at each temperature. Fish groups from other sites were held at 18 C. The May exposure groups were terminated on July 24, at 68 days post-exposure. No Chinook exposed at WMR, KED, KI5 or KBC died, while 2.9% of KSV fish died post-exposure and 9.8% of KOR. The coho held at 18 C post-exposure were the most severely affected with 25% loss in the KBC group and 30.0% loss in the KSV group. No coho exposed at KBC and held at 13 C post-exposure died. Rainbow trout exposed at WMR died the fastest post-exposure. The loss of rainbow trout at KED was 65%, a level notably higher than in previous years. In the lower river, rainbow trout loss was about 43.6 % at KI5 and greater than 94% at KBC, KSV and KOR. For this exposure, the highest Chinook mortality occurred at the most downriver exposure site (KOR) and in general coho loss was greater than Chinook. June 25-28, 2013 exposures: This month, fishes were placed at seven sites including two locations on the lower Williamson River (Nature Conservancy at the mouth of the river, WMR and Lonesome Duck Resort a few km upriver, WLD). Susceptible rainbow trout and Chinook from IGH were held at six sites but only rainbow trout were exposed at WLD. Coho juveniles from IGH were held only at KBC and KSV. At KBC, as in May, three groups of 50 fish each of Chinook were held in separate live cages to evaluate variation in infection rates among the fish in cages. Upon return to the SDL, half of each of the Chinook groups were placed at either 13 or 18 C and then monitored for C. shasta. Also, the rainbow trout (80 fish) exposed at KBC were divided and held at each temperature. Water temperatures ranged from 12-2 P a g e

3 13 C on the Williamson River to nearly 23 C at KI5. Fish groups were held at 18 C, except for the KBC Chinook and rainbow trout groups which were held at 13 C. The June exposure groups were terminated on August 29 and 30 th (62-63 days post-exposure). By termination, only one Chinook exposed at WMR had died but C.shasta was not detected, either microscopically or by PCR. No Chinook died following exposure at KED. One Chinook from KI5 died and no myxospores were found microscopically (PCR testing on this fish and one from the KBC coho exposure was not possible, thus although no parasite was observed microscopically, we could not confirm that the two fishes were not infected). For the three groups of Chinook exposed at KBC and held at 18 C, overall C. shasta-loss was 5.2% (7.4% in one tank, 8% in the second and 0% in the third tank). No Chinook from KBC held at 13 C post-exposure died. Loss of Chinook at KSV was 12.9% and 2.5% at KOR. Coho exposed at KBC incurred a 28.6% C. shasta loss compared to 44.8% for those exposed at KSV. At six sites, more than 91% of the rainbow trout exposed died; the exception was at KI5 (39.6%). More juvenile coho died than Chinook after the June river exposure, similar to the May exposure. July 16-19, 2013 exposure: Rainbow trout and fall Chinook were exposed at two lower Klamath River mainstem sites, KSV and below the confluence of thetrinity River near Tully Creek (KTC). Four groups of 25 Chinook each and two groups of 40 rainbow trout each were held in separate live cages at KSV. At KTC, 40 Trinity River Hatchery (TRH) and IGH Chinook, 40 rainbow trout and 30 IGH coho were held in live cages. Surface water temperatures at the time fish were placed in the live cages were higher than 23 C. After the 70 hr exposure at KSV, the Chinook in all four cages had died. The rainbow trout were found stressed and some were dead. The temperature logger at KSV recorded maximum temperature during the exposure of 25.9 C. At KTC, a few fish were dead in most groups but the remainder survived. To avoid excessive loss from columnaris disease, all groups from the July exposure were held at 18 C except for one rainbow trout group from KSV which was held at 13 C. The July exposure groups were terminated on September 19 (62 days post-exposure). Even though water temperatures were very high during the river exposure, only 2.9% of the TRH Chinook, 3.1% of the IGH Chinook and 4.3% of the IGH coho exposed near KTC were found to be infected with C. shasta. At KSV, where only rainbow trout survived the exposure, there was 77.8% loss at 18 C and 26.3% at 13 C. At KTC, 60% of the exposed rainbow trout has C. shasta infections. September 20-23, 2013 exposure: Susceptible rainbow trout and IGH Chinook were exposed in the Klamath River at two lower mainstem sites, upstream of the Beaver Creek confluence (KBC: 80 of each species) and near Seiad Valley (KSV; 40 of each species). The river water temperatures during exposure averaged C, therefore all of KSV and half of the KBC fishes were held at 18 C upon return to the laboratory; the remainder were held at 13 C to compare the affect of post-exposure rearing water temperature. The September exposure groups were terminated on November 25 (63 days post-exposure). No loss had occurred in the IGH ChF exposed at KBC or KSV in September. The greatest loss from C. shasta infection in susceptible rainbow trout occurred in those held at 18 C at the SDL after being exposed at KSV (70.7%) followed by KBC at 30%. Rainbow trout exposed at KBC and held at 13 C had 18% loss with C. shasta infections. PCR testing is in progress. 3 P a g e

4 TABLE 1. Percent loss attributable to infection by C. shasta by site and fish species as of November 30, 2013 following a three day river exposure. Fishes are held at ambient Klamath River temperature at the Salmon Disease Laboratory and monitored for disease signs for two months post-exposure; April, May, June, July and September groups have been terminated. Numbers represent total loss from 5 days after the fish were brought to the laboratory and are based on the observation of myxospores in wet mounts and include PCR testing on all microscopically negative fish except those from the September groups. ChF = Fall Chinook, TRH = Trinity River Hatchery. Site Exposure date and fish species April May May June June July ChF ChF Coho ChF Coho TRH ChF July July September ChF Coho ChF WMR 0 0 KED 0 0 KI5 0 0 KBC 13 C KBC 18 C KSV KOR KTC Water sampling (FIGURE 2) Collection continued at only two of the five mainstem sites in November: KBC and KSV. Weekly, 1L river water samples were collected every two hours for 24 hours by an ISCO automatic sampler and pooled. After 24 hours, triplicate 1L samples were manually taken from the combined 12L by the Karuk Tribe and Yurok Tribe biologists and filtered within 24 hours. The concentrated captured material was sent to OSU for molecular analysis (detection of total parasite DNA using qpcr). Waterborne parasite abundance was below 1 spore/l at KBC. The November KSV samples contained considerable particulate matter which, despite additional purification steps, inhibited the qpcr and parasite levels could not be accurately quantified. Abundance at KSV was below 1 spore/l at the end of October and is likely to remain at that low level through the winter. 4 P a g e

5 FIGURE 2. Density of Ceratomyxa shasta in 1L water samples collected at Klamath River mainstem index sites January through November, Each data point is the average Cq of 3 x 1L water samples collected weekly. A lower Cq value indicates more parasite is present. Site abbreviations are explained in Figure 1 above. Polychaete sampling No sampling occurred this month; the next collection will occur in winter ACKNOWLEDGEMENTS This report was prepared by: Sascha Hallett, Rich Holt, Julie Alexander, Gerri Buckles and Jerri Bartholomew. The Karuk and Yurok tribes assisted with water sample collection and filtration. Jamie Graene and Johnny Catena (OSU) assisted with qpcr. California Department of Fish and Game (Keith Pomeroy and crew at the Iron Gate Hatchery) provided Klamath River fall Chinook and coho salmon juveniles for our sentinel studies. Roaring River Hatchery, Oregon Department of Fish and Wildlife, Scio, provided susceptible rainbow trout. We are grateful to land owners who allow us access to conduct the sentinel studies and water sampling: The Nature Conservancy and Lonesome Duck Resort both of Klamath Falls, OR; The Sportsman s Park Club near Keno, OR; Fisher s RV Park at Klamath River, CA; Wally Johnson, Seiad Valley; Sandy Bar Resort, Orleans, CA. This research was funded by the Bureau of Reclamation, Department of the Interior, GSA Contract #GS09T13BHD P a g e

Jerri Bartholomew and Sarah Bjork*

Jerri Bartholomew and Sarah Bjork* 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