Oocyte production, fecundity and size at onset of reproduction of Tripalea clavaria (Cnidaria, Octocorallia, Anthothelidae) in the Southwest Atlantic

EXCOFFON A. C., M. L. NAVELLA, F. H. ACUÑA AND A. GARESE

ZOOLOGICAL STUDIES

ACAD SINICA INST ZOOLOGY

Año: 2011 vol. 50 p. 434 - 442

1021-5506

Oocyte production,fecundity, and size at the onset of reproduction of Tripalea clavaria (Cnidaria, Octocorallia, Anthothelidae) in thesouthwestern Atlantic. Zoological Studies 50(4): 434-442. The octocoral Tripalea clavaria is a gonochoristicspecies distributed in the southwestern Atlantic from Rio de Janeiro to the Magellan Strait and is restricted towaters with temperatures of < 20°C. Female colonies are significantly more abundant than males, and theirgonads are present throughout the entire year. Male fertile colonies were found only in Dec.-June, because thespermatogenic cycle is shorter than oogenesis, as is characteristic of other octocorals. Fertilization is probablyinternal, taking place within polyps of female colonies in Mar.-May. Planulae of T. clavaria were found in Apr.-June. The length of larvae was 554-1980 μm, and a maximum of 4 planulae was observed per polyp. The highnumber of large oocytes per polyp implies that this species allocates most of it energetic resources to sexualreproduction. Regarding the variability of volume of oocytes per polyp, the lowest value was 1.35 × 10-5 mm3,and the highest was 0.17 mm3. Although the reproductive features of T. clavaria are similar to those of othergorgonian octocorals, it has some exceptional features. Despite having small and unbranched colonies, thisspecies exhibits a small colony size at 1st reproduction (2.7 cm) and is highly fecund, producing high numbersof large oocytes compared to other octocorals. Such reproductive traits could explain its successful recruitmenton the limited available substrate of rocky outcrops, often characterized by strong currents and turbulence.