Aquatic Invertebrates of Montana

Some Misconceptions about Tubifex tubifex

I believe that the following statements about Tubifex are wrong for the following reasons.

1. Tubifex requires polluted water.

No species requires polluted water, some just tolerate it better than others. In Montana, T. tubifex is frequently abundant in very clean water. It even occurs in spring water that is bottled and sold for human drinking! However, to the extent that pollution decreases the abundance of competitors and predators and encourages bacterial growth, it may favor T. tubifex.

2. Tubifex is ubiquitous.

It is a world wide species, but it most certainly does not occur in every water body, especially in western trout streams. We have many areas without detectable populations of Tubifex. This species does seem to have great powers of dispersal so that it might be expected anywhere that conditions become suitable for it.

3. Mud is the key to T. tubifex density.

It is already perfectly clear that mud is neither required nor sufficient for T. tubifex presence. That is, may have abundant T. tubifex without mud and you may have abundant mud without T. tubifex. I have found T. tubifex in sand, gravel and cobble as well as on boulders and on bare concrete. However, at a site with T. tubifex, most individuals do favor areas with mud if it is present, and in our area excessive sedimentation is a common form of habitat degradation that can favor T. tubifex

4. Dams encourage T. tubifex by reducing flushing flows.

See also "mud is the key" above. Montana has many sites that have complete flushing of fine sediment each year, but the sediment and T. tubifex come back during the summer or fall. The same is true of canals that are frozen solid and/or completely dried each year. These reset mechanisms might have important implications for the disease process, but their effect on T. tubifex density is temporary. Also, many of our dams are sediment traps that release "sediment hungry" water so that the areas immediately below the dams actually have little or no fine sediment present. Yet these are often the areas with the most T. tubifex present. There is no doubt that dams encourage T. tubifex, but it is more likely due to temperature modification and community simplification than to mud accumulation.

5. Tubifex cannot be identified without DNA testing.

These organisms have been routinely identified as whole mounted specimens with ordinary light microscopes for a several decades time now. It just takes practice!

6. Tubifex is a microscopic-sized worm.

By my standards, it is a relatively big animal. Montana specimens frequently exceed 50 mm in length and the anterior end might reach 2 mm in diameter when sexually mature.