Ref ID : 6099
Hatakeyama Shigehisa; Effects of Chlornitrofen, a Herbicide, on Reproduction of Brachionus urceolaris (Rotatoria) Through Water and Food (Chlorella). Environmental Pollution 70:143-156, 1991
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Chronic effects of chlornitrofen (CNP) on the reproduction of Brachionus urceolaris (Rotatoria) were investigated by exposure of individuals to CNP from the egg stage, which had been attached to the adult. The survivors of 12 neonates, which had been exposed to CNP 100, 70 or 40 µg liter-1 decreased to 50% at the age of ca. 2, 4 and 6 days, respectively, compared to ca. 6.5 days for those exposed to 0, 10 and 20 µg liter-1 CNP. Release of offspring (mostly two individuals per day) started at two days old. At the peak, four days old, a control female produced 8.1+/-0.9 offspring per day compared with 4.5+/-1.3 (mean+/-SD, n=12) at 40 µg liter-1. The cumulative numbers of offspring produced by a female were 25.8+/-1.2, 24.2+/-2.9, 22.3+/-3.6 and 13.6+/-3.1 (mean+/-SD, n=12) at control, 10, 20, and 40 µg liter-1 CNP exposure, respectively. The 50% reproductive impairment concentration was calculated to be 37 µg liter-1. Growth of neonates was barely detectable at 70 µg liter-1, and the rapid increase in the effect of CNP from 40 to 70 µg liter-1 was attributed to an increase in tolerance with growth of the neonates. The effects of CNP on reproduction were also tested by CNP exposure through food (CNP-accumulated Chlorella). The 50% reproductive impairment concentration of CNP in the alga was calculated to be ca. 600 µg g-1 (wet weight) by the same method used to assess the dissolved CNP, although the effect of CNP which may have been released from the alga to the water could not be estimated precisely.