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

PÉREZ, A.F.; FRAYSSE, C.; BOY, C.C.; EPHERRA, L.; CALCAGNO, J.A.

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Lugar: Turrialba; Año: 2017

0034-7744

Thebrooding sea star Anasterias antarctica is distributed on the coasts ofPatagonia and the north of Antarctic Peninsula. The females of A. antarcticaof Beagle Channel, brood their eggs for seven months and do not feedduring this period. Gonadal maturation occurs in summer and gametogenesis inwinter in both sexes. The endoparasite Dendrogaster argentinensis hasbeen recorded in the Anasterias genus. The aim of this study was toenlarge knowledge on reproductive biology of this brooding sea star and presentan approach to energetic studies. Moreover, it was proposed to study thepresence of the parasite D. argentinensis in A. antarctica.Adults of A. antarctica wererandomly collected. Four samplings were performed, three during the broodingperiod (brooding females, non-brooding females, and males) and one during thenon-brooding period (mature females, non-mature females and males). The indexesof different body components (gonad (GI) and pyloric caeca index (PCI)) werecalculated as organ wet weight (g) x 100/total wet weight (g). Sections ofgonads were examined microscopically and each individual was sexed. Theprevalence of infection with D. argentinensis was calculated.Sex ratio, brooding females/non-brooding femalesand mature females/non-mature females? ratios did not differ significantly of1:1. The male GI reached maximum values in January, when most individuals weresexually mature. During brooding period, the GI of brooding females reached itsmaximum in October whereas GI of non-brooding females increased slightly. Themean PCI was minimum in October and were lower in brooding females thannon-brooding females (August and October). During non-brooding period, maturefemales had a significantly higher GI than non-mature females. The PCI did not vary significantly in males orbetween females during non-brooding period (mature and non-mature females).Prevalence of D. argentinensis in A. antarcticawas 11.06%. All specimens without gonads were parasitized. Towards the end ofthe brooding period, non-brooding females showed a higher GI than the broodingfemales, being explained by proliferation and increase of the oocytes size ofthe non-brooding females. Mature females showed a raised GI with presence ofmature oocytes, while the non-mature females exhibited previtelogenic oocytes.Males? population showed synchronicity in reproductive condition and the GIincreased on January when all males were sexually mature. The females that havenot brooded, presented a process of active gametogenesis reaching the summerwith a high GI and becoming mature females, while the females that have broodedprobably have not energy enough to grant a new gonadal maturation and face anew period of incubation. The pyloric caeca is performing the role of a reserveorgan in the brooding females, decreasing its size during the brooding period. D.argentinensis was recorded in sea stars lacking gonads (100%) thereforethese infected hosts could have been castrated.