The brine shrimp, Artemia, was used as an experimental
organism to study the effects of ⁶⁰Co gamma irradiation on the reproductive
performance of an animal population. The total reproductive
ability of the brine shrimp was fractionated into various components
and the effects of irradiation on each of these components
was then determined by studies of reproductive behavior in individual
pair matings. In this study, the components identified were the
number of broods produced per pair, the number of nauplii voided
per pair, the number of nauplii voided per brood, the survival of
nauplii to sexual maturity, the number of mature adults produced
per brood, and finally the number of mature adults produced per pair.
All component parameters of total reproductive performance
were shown to be affected by irradiation. However, the number of
broods per pair was shown to be the factor most affected by doses
of 1200 rads or less.
The final parameter, the number of mature adults produced
per pair, is really the measurement of the net reproductive potential
of Artemia. The net reproduction was also examined by making
counts of the total population contained in three liter population cultures,
and contrasted to the results obtained with the pair mating
studies.
It was demonstrated that the population cultures may be maintained
by using only a small part of the reproductive potential exhibited
in the pair matings. Therefore, we find that the results of
pair matings must necessarily be used to assess the amount that the
reproductive potential of Artemia is decreased due to various doses
of irradiation.
It was determined that for Artemia irradiated at the most sensitive
stage, a dose of 2100 rads produced sterility. At less sensitive
stages, more than 3000 rads would be required to produce
sterility.
In a single experiment, Artemia irradiated with 300 rads gave
an indication of a slight enhancement of reproductive ability as compared
to the control animals. In all cases, doses of 600 rads or less
showed little effect on the reproductive ability of this species
