SEXUAL REPRODUCTION AND LARVAL DEVELOPMENT OF NEREIDIDAE POLYCHAETA PERINEREIS CULTRIFERA ( GRUBE , 1840 )

In recent years the polychaete hatcheries has been developed for the production of healthy aquaculture organisms, since polychaetes is being used as live feed due to its has high nutrients compared to artificial feed. In the present study both male and female species Perinereis cultrifera were identified and successfully cultured under the controlled condition. The result of the present study clearly shows that the embryogenesis process and larval development of Perinereis cultrifera based on their egg embryos cleavages. The developments of setigers and eyes also indicate the lateral larval developments of the larval stages of Perinereis cultrifera. The successfully matured juvenile stage of this species was recorded after 20th day with the development of 16-18 setiger. This present study is the first attempt for culturing the Perinereis cultrifera under the hatchery condition in India. In future this study may helpful for culturing the other polychaete species in a hatchery system. et al., IJSIT, 2017, 6(6), 772-782 P. Murugesan IJSIT (www.ijsit.com), Volume 6, Issue 6, November-December 2017 773 INTRODUCTION Polychaetes tend to form the dominant sediment dwelling fauna of most mud flats, estuaries and sheltered sandy shores and it also play a significant role in ecosystem functioning and services (Baharudin et al., 2014). Polychaetes reproductive and developmental modes are conspicuously variable even among morphologically similar congeneric species (Levin & Bridges, 1995). Polychaete worms, community composition and reproductive ability are highly dependent on salinity and temperature gradients (Pardal et al., 1993). These two physical factors may strongly influence species distributions through their impacts on benthic and pelagic stages. Low salinities cause mortality, lower fecundity, and prevent reproduction to varying degrees (Daunys et al., 2000; Pechenik et al., 2000). Polychaetes are commonly divided into three types of reproductive modes, annual species-large reproductive efforts; the perennial species-low reproductive efforts; multi-annual species-high reproductive efforts (Fauchald, 1983). The majority of larger marine invertebrate species, including A. marina and N. virens reproduce by releasing their eggs and/or sperm into the water column so that fertilization takes place externally. These spawning episodes can be highly seasonal, with offspring production often confined to just 1–2 weeks of the year (Watson et al., 2000; Guest et al., 2005). Biologists have recognized phenomena like epitokous metamorphosis, semelparity, stolonization, lunar periodicity of spawning, swarming and exchange of pheromone signals between sexual partners, fertilization; development of the feeding larval stage, brooding and metamorphosis in polychaetes. The Nereididae polychaetes exhibit a wide range of reproductive modes, including external brooding, viviparity and hermaphrodtism. Most species undergo morphological and physiological modifications when they become sexually mature, suiting many of them for a brief pelagic existence and improving the chances that sexual partners will find each other (Schottler, 1989; Fischer, 1999). This metamorphosis of the immature worm into a special reproductive form is known as epitoky, a process that is particularly well described in the sandworm (Hoeger, 1991; Breton et al., 2003). The current study aims to focus on sexual reproductive and various larval development stages in the nereididae po1ychaete Perinereis cultrifera (Grube, 1840). MATERIALS AND METHODS The present study the sexually matured (12.5 to 15.0 cm in length) P. cultrifera were selected for culturing purpose (Figure 1). The male and female polychaetes were identified based on their body colour. After identification 5 pairs of both male and female P. cultrifera were cultured with the regular water exchange, feeding and close observation for maturation. As this is the crucial step in the polychaete culture, utmost care was taken. After recognizing both male and female sexes were separated from the maturation tank and introduced in to spawning tank with maintenance of filtered sea water with 30 psu salinity and temperature of 27 – 28.5°C. The eggs and larval metamorphosis was photographed using light microscope, photographs and video was made with camera. After fertilization, the larvae were reared through et al., IJSIT, 2017, 6(6), 772-782 P. Murugesan IJSIT (www.ijsit.com), Volume 6, Issue 6, November-December 2017 774 metamorphosis using standard technique for polychaetes (Strathmann, 1987). Larvae were kept in larval rearing tanks at a density of 2 per ml and gently stirred with plexiglas paddles. The larval culture was maintained and cleaned every day with filtered sea water and fed with Chlorella sp. respectively