Effects of Fe(3+) on Acute Toxicity and Regeneration of Planarian (Dugesia japonica) at Different Temperatures

OBJECTIVE: To investigate the effects of different concentrations of Fe(3+) on the acute toxicity and regeneration of planarian at different temperatures. METHOD: The planarians were treated with 40 mg/l, 50 mg/l, 60 mg/l, and 70 mg/l Fe(3+) solution and placed in 15°C, 20°C, and 25°C, respectively, to observe the mortality and the poisoning pattern of the planarian. In addition, the planarians were cut into three parts of head, trunk, and tail, then placed in Fe(3+) solution at concentrations of 10 mg/l, 15 mg/l, 20 mg/l, and 30 mg/l, and placed in 15°C, 20°C, and 25°C respectively, and the regeneration rate of the planarian was investigated. RESULTS: At the same temperature, in the concentration of Fe(3+) from 40 mg/l to 70 mg/l, the mortality of the planarian increased with the increasing of the concentration of Fe(3+); at the same concentration and different temperatures, the death speed of the planarian is the fastest at 20°C, the next at 25°C, and the lowest at 15°C, indicating that the toxic effect of Fe(3+) can be accelerated at a suitable temperature of 20°C. At the same temperature, in the low concentration of Fe(3+) from 10 mg/l to 30 mg/l, the regeneration rate of the planarian gradually decreased with the increasing of the concentration of Fe(3+); at the same concentration and different temperature, the regeneration rate of planarian was faster at 20°C and 25°C, but the difference between 20°C and 25°C was small, and the slowest at 15°C, indicating that the low temperature significantly affects the planarian regeneration speed. The study also found the regeneration rates of the head, trunk, and tail of the planarian were different; the head regeneration was the fastest, the trunk was the second, and the tail was the slowest. CONCLUSION: Fe(3+) had obvious toxic effects on the survival and regeneration of planarian; the planarian is sensitive to Fe(3+) and may be used to detect Fe(3+) water pollution; in addition, temperature can affect the toxic effects of Fe(3+) and thus affect the survival and regeneration of the planarian. Therefore, the temperature should be taken into consideration when detecting water Fe(3+) pollution.