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Toxicity to other aquatic organisms

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An abstract is available in the public literature on a study exposing tadpoles (Rana temporaria) to nominal concentrations of MTBE in the range 100 to 10,000 mg/l. 

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Tadpoles (Rana temporaria) were exposed to nominal concentrations of MTBE in the range 100 to 10,000 mg/l. The 48-h LC50 under these conditions was 2500 mg/l, with concentrations of up to 2000 mg/l without any lethal effect. Exposure to lower levels (100 mg/l) led to a marked weight increase of tadpoles and frogs that had undergone metamorphosis. At this concentration, metamorphosis was stimulated, occurring two days earlier than in controls.

The normal time from hatching to metamorphosis of Rana temporaria is commonly 30-45 days (Loman, 1999), but may show even more plasticity, e.g., 20-60 days, temperature being the most important variable (Merilä et al., 2000).

 

Although any deviation from the normal is usually considered adverse, this is not so in this case. Larvae tend to concentrate into large schools in shallow water where their density sometimes reaches 100 individuals per liter. Crowding effect is typical for such tadpole aggregations, and the sizes of metamorphosed juveniles are variable. Larger juveniles usually metamorphosed first. These have higher survival rates during their first over-wintering, which emphasizes an advantage of early metamorphosis.