Publication Abstract

The effects of chronic irradiation on the reproductive perfomance of Ophryotrocha diadema (Polychaeta, Dorvilleidae)

J.F. Knowles and L.N. Greenwood

The polychaete Ophryotrocha diadema was exposed to gamma-radiation at dose rates of 0, 1.7, 3.2, 7.7, and 13.7 mGy/h continuously over seven generations. Effects on growth and reproduction were obtained for generations 1, 2, 3 and 7. There was no radiation effect on growth rate or time to first egg laying but reproductive performance was clearly affected in all generations. In generation 1 only the highest dose rate of 13.7 mGy/h caused significant decreases in the numbers of egg sacs, eggs and larvae produced. In generations 2 and 3 there were dose-dependent reductions in egg sacs, eggs and larvae, while in generation 7 significant effects were seen but there was a clear tendency for recovery and it is suggested that this is due to selection of a radioresistant population. The lowest dose rate to produce a significant effect was 3.2 mGy/h which caused a reduction in larvae in generation 2 worms. This dose rate is 1600 times greater than that estimated for worms living in an area of radioactive waste disposal and thus the present results increase confidence that radiation levels in such areas are unlikely to produce permanent damage to similar invertebrates at the population level.

Reference:

J.F. Knowles and L.N. Greenwood, 1994. The effects of chronic irradiation on the reproductive perfomance of Ophryotrocha diadema (Polychaeta, Dorvilleidae). Marine Environmental Research, 38: 207-224.