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A Simple Technique Used to Filter and Quantify the Actinospore of Myxobolus cerebralis and Determine Its Seasonal Abundance in the Colorado River
Author(s) -
Thompson Kevin G.,
Nehring R. Barry
Publication year - 2000
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/1548-8667(2000)012<0316:astutf>2.0.co;2
Subject(s) - rainbow trout , biology , hydrology (agriculture) , abundance (ecology) , salmo , fishery , loricariidae , sampling (signal processing) , fish <actinopterygii> , environmental science , ecology , filter (signal processing) , geology , geotechnical engineering , catfish , computer science , computer vision
We used a simple technique for filtering the actinospores of Myxobolus cerebralis from natural waters to observe seasonal periodicity at eight sites in the upper Colorado River drainage. We used a tub lined with 20‐μm‐mesh Pecap screen to concentrate actinospores from 1,900‐L samples and estimate density by microscope count. Identity of the observed actinospores as those of M. cerebralis was confirmed in 86 samples by the use of a polymerase chain reaction test. The 42‐ha Windy Gap Reservoir appeared to be a point source of actinospores; the highest densities observed were consistently from samples taken at sites just below the reservoir. Both densities and the frequency of detection were much lower 26 km below the reservoir. The actinospores first appeared in abundance after the runoff in both years of the study. Actinospore densities tended to be greatest during summer and early fall and lowest during spring. In August 1997, a series of significant flow fluctuations and attendant water temperature swings appeared to alternately inhibit and stimulate the release of actinospores. Populations of rainbow trout Oncorhynchus mykiss continue to suffer recruitment failures throughout the study reach, apparently because of the effects of whirling disease in age‐0 fish. This suggests that the detection of low numbers of actinospores by this technique at some sampling locations may indicate a level of infectivity that is destructive for the susceptible rainbow trout.