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

ADRIANA C. EXCOFFON; MARÍA L. NAVELLA; FABIÁN H. ACUÑA; AGUSTÍN GARESE

ZOOLOGICAL STUDIES

ACAD SINICA INST ZOOLOGY

Lugar: Taipei, Taiwan; Año: 2011 vol. 50 p. 434 - 442

1021-5506

The octocoral Tripalea clavaria is a gonochoristic species distributed in the Southwest Atlantic from Rio de Janeiro to Magellan Strait restricted to waters below 20º C. Female colonies are significantly more abundant than males, and they are present throughout the year. The male fertile colonies are found only during December to June, because the spermatogenic cycle is shorter than oogenesis, as is characteristic of other octocorals. Fertilization is probably internal, taking place within polyps of the female colonies from March to May. T. clavaria were found during April-June. The size range of larvae was 554-1980 µm and four planulae was the highest number per polyp. The high number of large oocytes per polyp implies that this species allocates most of it energetic resources for sexual reproduction. Concerning with the variability of volume of oocytes per polyp, the lowest value of T. clavaria was 1.35 x 10 5 mm3 and the highest 0.17 mm3. Although the reproductive biology of T. clavaria is similar to other gorgonian octocorals, it presents exceptional features. Despite being small and unbranched colonies, this species has a low size at first reproduction (2.7 cm) and is highly fecund, producing high number of large oocytes compared to other octocorals. Such reproductive traits could explain its successful recruitment on the limited available substrate of the studied rocky outcrops, often characterized by high current flow and turbulence.