Reproductive investment and egg production in consecutive spawnings of Aratus pisonii (Crustacea, Brachyura, Grapsoidea).

Abstract

In the present work the egg number laid in sequential broods of the mangrove crab Aratus pisonii (H. Milne Edwards, 1837) were quantified with the aim to test the hypothesis of minus eggs is laid in consecutive spawnings. Ovigerous females of A. pisonii were collected in a mangrove forest (23 degrees 29'S, 45 degrees 09'W) located in Ubatuba, Sao Paulo State, Brazil from March 2000 to March 2003. In laboratory, these females were categorised in two groups: Group 1, females bearing early-stage eggs and, Group 2, females that accomplished subsequent spawning in laboratory. Both groups of females were analised as number and size of eggs, brood dry weight, individual egg dry weight and reproductive output (ratio of female dry weigh and brood dry weight). Twenty seven females realized a subsequent laid in laboratory. The average time interval between a larval release and the subsequent spawning was of 6.4 +/- 5.6 days. The number of eggs and the reproductive output did not differ between the both group of females. Slight differences were detected in the size and weight of eggs, being that the eggs oviposited in a subsequent spawning were smaller but heavier than that one observed for Group 1 females. The variability of eggs produced by A. pisonli can not be attributed to consecutive spawnings. Perhaps the intrinsic state of females accounts more for those differences in the resource allocation.