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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 820

Terry W. Snell and Guido Persoone; Acute toxicity bioassays using rotifers. II. A freshwater test with Brachionus rubens. Aquatic Toxicology 14:81-92, 1989

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A 24-hr toxicity test for freshwater is described using the rotifer Brachionus rubens hatched from cysts. Hatchings are used in a simple protocol that provides for LC50 calculation and yields highly repeatable results. Hatching is initiated by transferring cysts to warmer temperatures and light. At 25 degrees C, hatching commences after 17 hr and by 25 hr, 40% of cysts have hatched. The average hatching percentage for B. rubens cysts was 53%. A reference test using sodium pentachlorophenate (NaPCP) yielded an LC50 of 0.62 mg/l, with a coeffecient of variation of 9.7%. The no observed effect concentration (NOEC) for NaPCP was 0.28 mg/l. Protocols for range-finding and definitive tests of unknown toxicants are also described. Six compounds were assayed and had the following toxicity rankings: copper > NaPCP > cadmium > SDS > free NH3 > malathion. B. rubens was at least twice as sensitive as Brachionus plicatilis to all toxicants tested except malathion. The precision of the B. rubens acute toxicity test is about 3 times better than that of Daphnia. Like its marine counterpart with B. plicatilis, the B. rubens test for freshwater has a major advantage over current aquatic tests in that it eliminates culturing and maintenance of live stocks. Test animals are obtained from dormant eggs which have a shelf life of at least 1 yr. Moreover, the rotifer test proposed is fast, convenient, sensitive and repreatble, making it a useful new tool for routine assessment of aquatic toxicity of chemicals and effluents.