Charlene Hurst

Research Projects:

Distribution and Density of Ceratomyxa shasta in the Williamson River, Oregon

The Williamson River (WMR, left) is in the upper portion of the Klamath basin and drains into Klamath Lake.  Our monitoring studies over several years have indicated densities of C. shasta near the mouth of the WMR similar to the high densities found in the lower basin. The presence of high densities of the parasite in the WMR is unexpected, as there is no anadromous fish passage into this portion of the river due to a series of dams. The Goal for this part of the project was to determine the distribution and density of C. shasta and identify the factors responsible. This was conducted by selecting 22 representative sites along the river and in the major tributaries, Spring Creek and Sprague River, and collecting water samples. These samples were then processed using qPCR to quantify the number of parasites present at each location. From these results we have identified two areas of high density consistent over two years of sample collection. This summer we will be conducting a study comparing polychaete habitats between the two high density sites to show if polychaete habitat is a factor responsible for the parasite distribution in the WMR.

Study site ~ Williamson River, Oregon	Collection of water samples to determine parasite density
Water samples are filtered, the captured DNA extracted and a DNA test (quantitative PCR) specific for Ceratomyxa shasta performed	Polychaete collection using a modified Hess sampler

Ceratomyxa shasta strain host specificity

Recently, a fellow graduate student in our lab identified four strains of Ceratomyxa shasta in a variety of fish from the Klamath basin. The hypothesis was that each of the strains had different host specificities based upon field data from naturally infected wild and hatchery fish and also our sentinel studies. To test this hypothesis we set up polychaete populations in a controlled laboratory setting and seeded them each with a different strain of the parasite. We then exposed Iron Gate Chinook and coho salmon, redband, rainbow and steelhead trout to each of the different strains. This experiment is still ongoing, but preliminary results indicate that the parasite is host specific. Parasite host specificity is an important trait to consider, especially when planning for the reintroduction of anadromous salmonids into the upper basin. Strains specific for salmon present in the lower basin may be carried into the upper basin or amplified due to the increased number of hosts to the area.

Sampling intestine for PCR to test for the presence of Ceratomyxa shasta DNA	Experimental setup for Ceratomyxa shasta host specificity experiments