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MONITORING OF A PULSE FLOW EVENT
Researchers from a range of agencies and institutes interested in reducing the impact of the myxozoan parasite Ceratomyxa shasta on Klamath River salmonids united downstream of Iron Gate Dam (IGD) in February 2011 to gather data associated with a high flow event. Water flow from IGD increased Wednesday, February 9, 2011 from below 2000 cfs to over 5000 cfs as part of a manipulated pulse flow event (BOR press release). This is the highest flow since March 2007.
Researchers were informed of the event just days in advance, so Dr. Bartholomew's lab mobilized to coordinate with researchers from U.S. Fish and Wildlife, Watercourse Engineering Inc., and the Yurok Tribe to organize equipment and personnel in a joint effort to monitor and measure the event. Data and samples were collected before, during, and after the pulse flow with the following objectives:
Summary of data on the May pulsed flow event
Bartholomew Lab, Oregon State University
Three sets of data were collected to evaluate whether the pulsed flow event that occurred May 27 had an effect on Ceratomyxa shasta densities and infection risk in fish. Data and summary conclusions on the water sampling and fish exposures are below; analysis of polychaete samples is still in progress.
Water samples were collected daily at Beaver Creek and Seiad Valley index sites, beginning three days prior to the event and ending on May 30. Samples were collected every 2h using automated samplers, and pooled to make a 6h composite sample that was assayed using a C. shasta-specific QPCR. Data was more complete for Seiad Valley (Figure 1 lower graph). At both sites there was a decrease in spores per liter during the first day of the flow, although densities remained greater than 10 spores/L. By the end of the week densities exceeded pre-flow levels at both sites.
Figure 1. Quantitative PCR results also expressed as C. shasta spores/L. Each data point is the average Cq of 3 x 1L water samples. A lower Cq values indicates more parasite is present.
Sentinel exposures of Iron Gate Hatchery Chinook and coho salmon juveniles were conducted just prior to the flow event on May 23-26 (72 hr) at both Beaver Creek and Seiad Valley and then again during the event on May 27-30. Thirty fish of each species were held at each site before and during the event. After the exposures, the fish were transported to the Salmon Disease Laboratory, reared at 18°C water temperature and monitored for C. shasta infections. The same pattern was seen at both Beaver Creek and Seiad Valley, but it differed between Chinook and coho salmon. For Chinook salmon held at both sites, cumulative percent mortality was higher (53%) prior to the pulse than after (40-43.3%). For coho salmon, mortality was lower (66.7-75.9%) before the pulse than after (79.3-80%) (Figure 2).
Figure 2. Cumulative percent mortality in sentinel IGH Chinook and coho salmon held in the Klamath River at Beaver Creek (KBC) and Seiad Valley (KSV) for 3 days either prior to or during the pulsed flow event.
|1. Collect high discharge data to calibrate a 2-D hydraulic model.||2. Determine the effect of the pulse flow on polychaete populations (the invertebrate host of Ceratomyxa shasta which releases the fish-infective stage).||3. Sample river water for parasites to measure suspended Ceratomyxa shasta spores and determine if these were displaced by the pulse event.||4. Document changes in polychaete habitat (substrate composition, physiochemical characteristics).|
The event provided a unique opportunity, but the short lead time limited researchers in the scope, depth, and interpretation of experiments that could be conducted. For a full report covering the experiments conducted by OSU during the pulse flow event click here.