The Effects of Three Common Pollutants on the Respiration Rate of Tubificid Worms,
an article summary by Brandon Wolberg, BIOL 490 Fall 2014

Witley & Sikora (1970) examined the effects of three different contaminants (lead, nickel, and phenol) on the respiration rate of two types of annelids: Tubifex tubifex, and Limnodrilus hoffmeisteri. These worms are known as “sludge worms” for their ability to survive toxic environments and are good indicator species to gauge when a particular area has become too toxic for organisms to survive in. Specifically, they recorded the respiration rate through the amount of dissolved oxygen the worms consumed in a controlled environment with varying pH levels (6.5-9.5) ,and then again after exposure to different concentrations of the contaminants over the same variance of pH. They collected samples of both species and retained them in a biologically stable Knopps solution before exposing them to the toxins, which were ionized to a water-soluble form. After exposure , which was generally 24 hours with some exceptions to avoid lethality, the worms were put into a reaction flask, and from there calculations on respiration were performed. As expected, lead had a large negative correlation with respiration across all three pH levels tested. Nickel had a puzzling lack of correlation within both pH levels tested (7.5 and 8.5 as anything lower proved fatal to the worms). This may be because nickel takes time to bind and inhibit respiratory enzymes. The phenol toxin showed a positive correlation with respiration at 8.5 and 9.5 (again, anything lower was lethal). The 9.5 pH level had a very sharp slope, indicative of possibly 2 separate mechanisms working in tandem. These toxins are but a small subset of possibilities of the ranges of chemical environments that may be encountered by freshwater organisms, particularly with the added variable of a nearby wastewater treatment facility. More research will need to be done in order to determine safe thresholds for these and other ecologically important organisms in order to impose regulations so that the byproducts of human manufacturing does not affect nearby ecosystems.

Whitley, S.L. & R.A. Sikora. 1970. The effect of three common pollutants on the respiration rate of tubificid worms. Journal (Water Pollution Control Federation) 42 (Research Supplement): R57-R66.