Factors influencing the distribution of Myxobolus cerebralis, the causative agent of whirling disease, in the Cache la Poudre River, Colorado

Abstract

Oligochaetes, triactinomyxons (TAMs), and age-0 trout were sampled in the upper Cache la Poudre River, Colorado, to determine the distribution of Myxobolus cerebralis during 1997 and 1998. Densities of the intermediate host, the oligochaete Tubifex tubifex, were 3.5 orders of magnitude higher in the M. cerebralis-infected Poudre Rearing Unit (PRU) trout rearing ponds than at any of the river sampling reaches. Oligochaetes, including T. tubifex, were rare in the river (1 oligochaete m -2 ), except in a few stream side alcoves and eddies (50 oligochaete m -2 ). Species composition of oligochaetes in the river reaches was more diverse than in the PRU. Tubifex tubifex constituted 50% or less of the oligochaete community in the river and 98% in the PRU. Infection rates of T. tubifex were 1% in the area above the PRU, 2% in the PRU, and 6% below the PRU. An increased M. cerebralis intensity of infection in age-0 trout below the PRU could not be attributed entirely to the high numbers of TAMs in its effluent (3.7 TAMs l -1 ). Low densities of TAMs ranging from 0 to 0.2 TAMs l -1 were found in the river reaches, yet nearly all of the age-0 trout were infected soon after emergence. This suggests that very few TAMs, as measured by filtration, need be present in the water column to bring about infection in the majority of trout present. This also indicates that the parasite can persist and potentially cause reduced juvenile trout recruitment in cold, oligotrophic, sediment poor, highgradient streams. KEY WORDS: Salmonid whirling disease · Myxobolus cerebralis · Tubifex tubifex · Trout rearing unit Resale or republication not permitted without written consent of the publisherDis Aquat Org 49: [51][52][53][54][55][56][57][58][59][60] 2002 Wildlife, pers. comm.). Rainbow trout populations in at least 370 km of stream have been affected .Myxobolus cerebralis was first described in Germany in 1893 (Hoffman 1990). Though it is believed to be endemic to Europe , it was not detected until rainbow trout, imported from the USA to a German trout rearing facility, displayed classic WD signs (Hoffman 1990). The mechanism of infection remained unknown for almost a century until Markiw & Wolf (1983) found that tubificid worms were a necessary alternate host for the parasite. Antigenic and genetic evidence has since confirmed the relationship between triactinomyxons (TAMs), which are the waterborne, fish-infective stage of the parasite, and the myxospore, which infects Tubifex tubifex (Markiw 1989, Andree et al. 1997. The oligochaete host for M. cerebralis is apparently restricted to T. tubifex; attempts to infect other oligochaete species with M. cerebralis myxospores have been unsuccessful (Wolf et al. 1986, El-Matbouli & Hoffman 1989, Hedrick et al. 1996.Myxobolus cerebralis was first detected in the Cache la Poudre River in 1988 (Nehring 2000). Drastic declines in the number of age-1 wild rainbow trout became evident in the early 1990s at 4 different monitoring stations in a 30 km reach of the river. In 1995, 5 yr after ...

Modeling the Effects of Climate Change on Disease Severity: A Case Study of Ceratonova (syn Ceratomyxa) shasta in the Klamath River

“…The amount of organic material in a stream is positively associated with the occurrence of several invertebrate hosts. For example, abundance of T. tubifex is correlated with high organic material (Allen and Bergersen 2002;Kaeser et al 2006). Similarly, greater abundances of bryozoans occur in rivers with higher nutrient levels (Hartikainen et al 2009) and increased growth and higher intensity of infection with T. bryosalmonae in bryozoans at higher nutrient/food levels (Hartikainen and Okamura 2012).…”

A Review: Gaps in Our Knowledge on Myxozoan Parasites of Fishes

“…It has been recently demonstrated that suscep tibility to M. cerebralis is variable among oligochaete strains and genotypes (Stevens et al, 2001;Beauchamp et al, 2002). Environmental factors (e.g., habitat sub strates, nutritional potentials and dissolved oxygen lev els) influencing the distribution of oligochaetes have been investigated in relation to the severity of myxozoan infections (Allen and Bergersen, 2002;Koprivnikar et al, 2002;Blazer et al, 2003;Liyanage et al, 2003). It is likely that anthropogenic activities in streams and rivers, e.g.…”

The Ecology ofTubifex tubifexin twoMyxobolus cerebralisEnzootic Streams in Pennsylvania

“…Although T. tubifex worms have been found in abundance at organically enriched sites in the West (Allen and Bergersen 2002), the species appears to be common and widely distributed throughout stream systems that have experienced whirling disease epizootics (Zendt and Bergersen 2000). The spread of M. cerebralis across the intermountain West landscape additionally supports the notion that i?…”

“…We suspect that T. tubifx sediment habitat, such as the Cache La Poudre River in Colorado, contain these worms and have experienced whirling disease epizootics (Zendt and Bergersen 2000;Allen and Bergersen 2002). Nonetheless, the availability of fine sediment habitat has been considered a risk factor for M. cerebralis establishment in this region (Schisler and Bergersen 2002).…”