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

• Published in: Diseases of aquatic organisms Vol. 49; no. 1; pp. 51 - 60
• Main Authors: ALLEN, M. Brady, BERGERSEN, Eric P
• Format: Journal Article
• Language: English
• Published: Oldendorf Inter-Research 24.04.2002
• Subjects: Age Factors; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Aquaculture; Biological and medical sciences; Colorado - epidemiology; Eukaryota - isolation & purification; Fish Diseases - epidemiology; Fish Diseases - parasitology; Fresh Water - parasitology; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Oligochaeta - parasitology; Population Density; Prevalence; Protozoan Infections, Animal - epidemiology; Protozoan Infections, Animal - parasitology; Species Specificity; Synecology; Trout - parasitology; United States; North America; Colorado; America; Host parasite relation; Prevalence; Spatial variation; Oligochaeta; Freshwater environment; Species diversity; Seasonal variation; Pisces; Stream; Salmonidae; Community structure; Protozoa; Tubifex tubifex; Farming animal; Parasite; Zoopathogen; Oncorhynchus mykiss; Annelida; Cnidosporidia; Vertebrata; Salmo trutta; Animal community; Population dynamics; Intermediate host; Invertebrata; Population density
• ISSN: 0177-5103; 1616-1580
• DOI: 10.3354/dao049051

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, high-gradient streams.