Observations on the reproduction of <i>Acropora</i> corals along the Tuticorin coast of the Gulf of Mannar, Southeastern India

Abstract

Pattern of reproduction was studied in <i>Acropora</i> species along Tuticorin coast in the Gulf of Mannar from 2006-2008. Extensive surveys were conducted to monitor reproductive maturity and the timing of spawning. Gametes were observed from January with colonies releasing gametes by the end of March. <i style="">Acropora cytherea </i>showed immature colonies in January (48-79%) and February (56-76%) and mature colonies in March (36-86%). Likewise, the other species of <i style="">Acropora</i> examined showed 50-75% of immature colonies in January and an increase of 10-20% of immature colonies in February, and matured in March. The average percentage of mature colonies in March was as follows, <i style="">A. formosa</i> 47-76%, <i style="">A. valenciennesi</i> 50-81%, <i style="">A. intermedia</i> 50-81%, <i style="">A. nobilis</i> 25-82%, <i style="">A. micropthalma</i> 56-83%, <i style="">A. hemprichi</i> 39-83%, <i style="">A. hyacinthus</i> 33-100%, <i style="">A. corymbosa</i> 59-65%. Spawning was observed in <i style="">A. cytherea</i> on 24 March 2006, 10 days after full moon; 28 March in 2007, 5 days prior to full moon; and 8 March 2008, 1 day after new moon. Approximately 30,000 egg and sperm bundles were observed in 1 litre of water and each bundle had 20-25 eggs in <i style="">A. cytherea</i>. Environmental parameters, especially rise in temperature at the end of March was believed to play lead role in coral spawning.