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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 1264

Vancil James Edward; Acute toxicity of (2,4,5-Trichlorophenoxy) Acetic acid to three species of limnetic rotifers (Keratella cochlearis (Gosse), Keratella americana Carlin, and Brachionus angularis Gosse) and associtaed life history information. The University of Tennessee. :1-148, 1975. Doctor of Philosophy.

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Toxicity (lethal effects) of 2,4,5-T to limnetic rotifers was measured. Technical 2,4,5-T and six commercial herbicide formulations containing 2,4,5-T derivatives were each assayed against one or all of the species: Brachionus angularis, Keratella cochleais, and Keratella americana. The 2,4,5-T derivatives were its triethylamine salt, butyl ester, isooctyl ester, and N-oleyl-1,3-propylene-diamine salt. Life history information was also determined. These studies were undertaken to assess the short-term hazard from 2,4,5-T and to obtain baseline information about the duration of life stages and vitality of the rotifers. The data were collected by making observations of the rotifers at close time intervals while they were contained in concavities of transparent flex vinyl titration plates. Group responses to test conditions were monitored. A complex, chemically defined medium was used with the rotifers and the algae they were fed. Brachionus angularis and Keratella americana received Chlorella vulgaris. Keratella cochearis was fed with Cryptomonas ovata palustris. All determinations were carried out under a continuous light regime at 20.0+/-1.0 degrees C. Some toxicity determinations were made with rotifers supplied with algae at controlled levels, but in the majority of determinations the rotifers were not fed unless organic components of the medium afforded some nutrition. Toxicity was estimated as herbicide concentrations in mg/l corresponding to median mortality at standard intervals of 12, 24, 48, 72, and in some cases, 96 hrs. Nearly all of the toxic effects of the levels of herbicides giving determinations for 12 and 24 hrs were expressed by 48 hrs. Toxicity was not directly related to content of 2,4,5-T and other ingredients of the commercial formulations had a toxic effect. Algae given as food influenced toxicity of a triethylamine salt formulation to Brachionus angularis. At a lower algal concentration toxicity was increased. At double the lower amount it was reduced. Median lethal concentrations for 48 hours ranged from over 100 mg/l for a triethylamine salt formulation to 0.11 mg/l for one containing the N-oleyl-1,3-propylene-diamine salt. The species did not display much difference in sensitivity to 2,4,5-T. The sensitivity was rather similar to that reported for fish. Bioassay in the intended receiving waters before use of the more toxic 2,4,5-T forms is recommended as it has been for fish. Mean egg development time was about one day for the three rotifer species. Mean survival with deprivation of algae ranged from about 3 to about 7 days. Mean longevity of rotifers fed with algae ranged from about 6.25 to about 14.5 days. The average number of eggs produced and hatched per female ranged from 2.6 to 7.6. Mean immature period ranged from about 2.5 to about 5 days. Egg development time, generation time, and interval between eggs were more variable than reported in the literature for other species.