Print PageThe parasite, Ceratomyxa shasta, may be strongly influenced by population dynamics of its invertebrate host, the polychaete, Manayunkia speciosa. The polychaete host directly influences parasite transmission to salmonids but our understanding of factors that influence parasite transmission is hampered by a lack of understanding of how the polychaete host influences persistence and transmission of C. shasta. The aims of this study were to characterize population dynamics of, and prevalence of C. shasta infection in, the polychaete host in the Klamath River, California. We characterized polychaete density and size and examined relationships between these factors and prevalence of C. shasta infection in the Klamath River downstream from a series of dams where C. shasta has been implicated in the decline of a variety of salmonids. To estimate polychaete densities, we collected monthly substrate samples from pool habitats in six reaches (spanning >250km) of the Klamath River during summer months of 2006. Size and prevalence of C. shasta infection were determined for a subset of polychaetes collected for density.
Results/Conclusions
Polychaete density was influenced by reach but not by month; density was higher in reaches located proximal to dams than reaches located farther downstream. We did not detect relationships between mean polychaete size and reach or month but minimum polychaete size was negatively correlated with density, which suggests polychaete growth may be density dependent. Preliminary data suggest infection prevalence was higher in reaches located proximal to dams than reaches located farther downstream in all months. Given that polychaete density was also higher in these reaches, these results suggest that polychaete density strongly influence parasite dynamics in this system.
