Evidence of Relationships between Tubifex Habitat and Myxobolus Cerebralis Across A Mountian Watershed

Abstract

We tested the hypothesis that the proportions of age-0 salmonids infected by Myxobolus cerebralis, the causative agent of whirling disease, and histologic evidence of whirling disease in stream reaches across a watershed are related to measures of suitable habitat for Tubifex tubifex, the oligochaete host for M. cerebral is. We assumed habitat quality for T. tubifex increased with the amount of fine sediment, aquatic macrophytcs, or low-gradient mesohabitat, i.e., pools and glides, and decrease with increasing channel slope in stream reaches. The highest rates of infection and tissue damage were observed among age-0 salmonids sampled from a cluster of spring streams in the upstream portion of the valley with low channel slopes or modifications to enhance deep-pool cover for adult salmonids, side channels of the main stem river with large amounts of sediment deposition, and mountain streams downstream from beaver (Castor canadensis) ponds with accumulations of fine sediment.