Astropecten (Astropectinidae) is one of the most species-rich genus among sea stars and their members are worldwide distributed. A. aranciacus (Linnaeus 1758) is one of the largest sea stars in the Mediterranean Sea, with a body size up to 60 cm in diameter. This species lives on sandy, muddy and detrital bottoms, as well as in seagrass beds, between 1 and 200 meters depth. Sea star monthly samples were obtained in the Maresme coast (northwestern Mediterranean Sea) between May 2011 and September 2012. Histological examination of gonads and seasonal variation analysis of the pyloric caeca and gonadal indexes were performed to study the reproductive cycle. Commonly, coastal temperate sea stars have an inverse relationship between gonad index (GI) and pyloric caeca index (PCI); unexpectedly, this was not observed in A. aranciacus. Gonad development was divided into five stages based on an adaptation of scales used for other asteroid species. A. aranciacus showed a 1:1 sex ratio throughout the whole year and an annual well-defined reproductive cycle, with a high proportion of mature individuals between February and April, coinciding with the spring phytoplankton bloom and lowest sea water temperatures. Both sexes had a synchronous gametogenesis. Spawning likely occurred during April and May, when the GI decreased and post spawning individuals were found in the histological samples. First maturity occurred at a major radius length (distance from the centre of the oral disc to the tip of the longest arm) of 112 mm

15th International Echinoderm Conference, 25-29 may 2015, Playa del Carmen

Peer Reviewed