Reproductive biology and energetics of the brooding sea star Anasterias antarctica (Equinodermata: Asteroidea) in the Beagle Channel, Tierra del Fuego, Argentina

FRAYSSE C P; CALCAGNO J; BOY C C; PÉREZ A F; EPHERRA L

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Lugar: Turrialba; Año: 2017 vol. 65 p. 221 - 232

0034-7744

The brooding sea star Anasterias antarctica is distributed from the coast of Patagonia to the northern Peninsula of Antarctica. The females of A. antarctica in the Beagle Channel, brood their eggs for seven months and do not feed during this period. In both sexes gonadal maturation occurs in summer and gametogenesis in winter. The endoparasite Dendrogaster argentinensis (Crustacea: Ascothoracica) has been recorded in several species of the genus Anasterias and has been reported as causing castration. The aim of this study was to expand knowledge on the reproductive biology and energetic of the brooding sea star Anasterias antarctica along its reproductive cycle. A second aim was to study the prevalence presence parasite D. argentinensis on A. antarctica. Four samplings of adults were randomly collected in May, August and October (brooding period: brooding females, non-brooding females, and males) and January (non-brooding period: mature females, non-mature females and males). The gonad (GI) and pyloric caeca index (PCI) were calculated as organ wet weight (g) x 100/total wet weight (g). Each individual was sexed by microscopic examination of the gonads. The prevalence of infection with D. argentinensis was also estimated. Sex ratio, brooding females/non-brooding females and mature females/non-mature females ratios did not differ significantly of 1:1. The male GI reached maximum values in January, when most individuals were sexually mature. During the brooding period, the GI of non-brooding females reached its maximum during October when it was significantly higher than those of brooding females. The PCI was minimum in October and were lower in brooding females than non-brooding females (August and October). During the non-brooding period, mature females had a significantly higher GI than non-mature females. The PCI did not vary between males, mature and non mature females. Prevalence of D. argentinensis in A. antarctica was 11.06% and 28% of them did not presented gonads. Towards the end of the brooding period, non-brooding females showed a higher GI than the brooding females, being explained by proliferation and increase of the oocytes size of the non-brooding females. Mature females showed a raised GI with presence of mature oocytes, while the non-mature females exhibited previtelogenic oocytes. Males showed synchronicity in reproductive condition. The females that have not brooded presented a process of active gametogenesis, reaching the summer with a high GI and becoming mature females. The females that had brooded were probably lacking energy for new gonadal maturation. The pyloric caeca would be performing the role of a reserve organ in the brooding females, decreasing its size during the brooding period. D. argentinensis was recorded in sea stars lacking gonads therefore these infected hosts could have been castrated.