Relative growth and reproduction in Achelous spinicarpus (Crustacea: Portunidae) on the south-eastern continental shelf of Brazil

• Published in: Journal of the Marine Biological Association of the United Kingdom 2013-05, Vol.93 (3), p.667-674
• Main Authors: Pardal-Souza, André L., Pinheiro, Marcelo A.A.
• Format: Article
• Language: English
• Subjects: Abdomen; Allometry; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biometrics; Cephalothorax; Continental shelves; Crustacea; Decapoda; Developmental stages; Eggs; Fecundity; Females; Fundamental and applied biological sciences. Psychology; Invertebrates; Marine; Morphology; Portunidae; Regression analysis; Sea water ecosystems; Sexes; Sexual maturity; Spine; Student's t-test; Swimming; Synecology; Tropical environments; Variables
• ISSN: 0025-3154; 1469-7769
• DOI: 10.1017/S0025315412000318

This investigation aimed to study the relative growth, morphological sexual maturity and fecundity of the swimming crab Achelous spinicarpus in a tropical region, on the south-eastern continental shelf of Brazil (25°S). Biometry of all specimens was conducted, including measurements of the cephalothorax, cheliped, abdomen and gonopods. Relative growth was described based on the equation for allometry (y = axb), and size at sexual maturity was determined from inflections in relations involving the cheliped, gonopods (males), and abdomen (females), as dependent variables, related to the cephalothorax width (independent variable). Fecundity was estimated by the gravimetric method. The relations of the length of the chelar propodus and carpal spine to the carapace width without the lateral spines (CW) showed positive allometry in both sexes, with a significant variation in the constant ‘b’ for males between the developmental stages (juvenile and adult) and the size at maturity estimated at 37 mm CW. In females, the abdomen was most appropriate for the estimate of morphological maturity, which occurred at a smaller size (32 mm CW), with a change in the growth pattern between the stages, passing from isometric (juveniles) to positive allometric (adults). The gonopods also showed different growth rates between developmental stages, in synchrony with the variables of the cheliped. Mean fecundity for the species was 53,984 eggs, with a positive correlation between the number of eggs exteriorized and the size of the female; the equations allowed interconversion between these variables, due to the adjustment of the power function (r2 ≥ 86%).