Previous observations on the reproductive biology and gametogenesis of Branchiomma luctuosum (Polychaeta: Sabellidae) were extended in this study, with a description of larval development and of reproduction at the population level, comparing populations from the Tyrrhenian Sea (Ischia, Naples) and Ionian Sea (Gulf of Taranto). Although B. luctuosum is a simultaneous hermaphrodite, producing both male and female gametes in each fertile segment, present observations seem to preclude self-fertilization. Both gametes were spawned under laboratory conditions, and broadcasting was confirmed by sperm structure, which appears adapted for external fertilization. Larval development revealed the shortest pelagic period known for sabellids of similar size and life history. Oogenesis was prolonged and extraovarian. The Ionian population seemed to have a resting period during which eggs, having already begun vitellogenesis, remained at a diameter of about 30 μm. After this period, rapid growth was observed: the oocytes reached maximum diameter (140 μm) in about 2 months. The spawning period began earlier and lasted longer in the Ionian population, compared to the Tyrrhenian population. This pattern seems to be due to asynchronous vitellogenesis within individuals. Documenting the reproductive features of this species will help us to understand its role as a primary colonizer, since hermaphroditism and a short pelagic phase may produce high population densities starting from only a few individuals.
Reproduction and simultaneous hermaphroditism in Branchiomma luctuosum (Polychaeta, Sabellidae) from the Mediterranean Sea
Licciano M.;Giangrande A.;
2002-01-01
Abstract
Previous observations on the reproductive biology and gametogenesis of Branchiomma luctuosum (Polychaeta: Sabellidae) were extended in this study, with a description of larval development and of reproduction at the population level, comparing populations from the Tyrrhenian Sea (Ischia, Naples) and Ionian Sea (Gulf of Taranto). Although B. luctuosum is a simultaneous hermaphrodite, producing both male and female gametes in each fertile segment, present observations seem to preclude self-fertilization. Both gametes were spawned under laboratory conditions, and broadcasting was confirmed by sperm structure, which appears adapted for external fertilization. Larval development revealed the shortest pelagic period known for sabellids of similar size and life history. Oogenesis was prolonged and extraovarian. The Ionian population seemed to have a resting period during which eggs, having already begun vitellogenesis, remained at a diameter of about 30 μm. After this period, rapid growth was observed: the oocytes reached maximum diameter (140 μm) in about 2 months. The spawning period began earlier and lasted longer in the Ionian population, compared to the Tyrrhenian population. This pattern seems to be due to asynchronous vitellogenesis within individuals. Documenting the reproductive features of this species will help us to understand its role as a primary colonizer, since hermaphroditism and a short pelagic phase may produce high population densities starting from only a few individuals.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
