Beartrap Canyon to Three Forks

Blacks Ford

This is another long section of river without abrupt transitions. I have 13 samples, from the lower beartrap (12, 13, and 14), Blacks Ford (1, 59, 145, 147, 277 and 279) and I-90 (7, 45, 141, 132). It should be safe to interpolate between Blacks Ford and I-90 as there is little difference. Tubifex occurs throughout this section, but it is more seasonal in its occurrence. Peaked early flow and high summer temperature seem to work together to keep Tubifex numbers down during the summer. This varies from year to year. Ilyodrilus templetoni is more common in the summer and T. tubifex in the winter, but because these species are impossible to separate when immature, detailed field investigation of this phenomenon is not possible. I wouldn't have even noticed except the pattern is repeated at so many sites and it can become quite pure in extreme situations. Right now the field data suggest that when Tubifex mostly disappears in the spring and largely does not return until mid-August, the parasite will not prosper. This may represent the downstream limit to the disease in many rivers.

Aquatic Oligochaete species list

5 JAN 1997 D.L. Gustafson
Back to the Madison River Tubifex Summary
AIM home page
dlg@rivers.oscs.montana.edu