Reproductive biology of two species of holothurian from the deep-sea order Elasipoda, on the Antarctic continental shelf

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Galley, E.A., Tyler, P.A., Smith, C.R., Clarke, Andrew
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2008
• Subjects: Marine Sciences; Biology and Microbiology; Ecology and Environment; Antarctic; Antarctic Peninsula; The Antarctic; Antarc*
• Online Access: http://nora.nerc.ac.uk/id/eprint/11472/

Antarctic shallow-water and deep-sea echinoderms are known to have seasonal gametogenic cycles linked to seasonal pulses of phytodetritus produced in surface waters. We suggest that phytodetritus reaching the Antarctic continental shelf may persist for longer timescales than in shallow OF deep waters as a result of the low temperatures, low flow velocities, and the relatively short descent. If this food source remains available for extended periods throughout the year, Antarctic continental shelf megabenthos may not entrain seasonal gametogenic periodicity. To explore the reproductive response of the elpidiid holothurians, Protelpidia murrayi and Peniagone vignoni, a seasonal series of samples were taken on the West Antarctic Peninsula (WAP) at depths of 550-600 m between November 1999 and March 2001. Gonad indices were measured, and gonad tissues were analysed using histological and image analysis techniques. Oocyte size-frequency distributions were constructed from measurements of oocyte diameter, and analysed to describe reproductive patterns. Histological analyses of gonads tissue from P. murrayi suggest that gametogenesis is synchronised and seasonal, with spawning occurring between March and June. The onset of vitellogenesis appears to be initiated and synchronised by the arrival of the phytodetritus pulse. While, oocyte size-frequency distributions of P. vignoni suggest that oogenesis is synchronous between individuals, and infer a seasonal variation in gametogenic intensity, with an increase in production of vitellogenic oocytes that may be associated with an increase in food supply. The seasonal series of oocyte size-frequency distributions suggests that spawning commenced during October and November. We propose that both P. murrayi and P. vignoni have opportunistic reproductive patterns. In P. murrayi, the distinct gametogenic response to the summer Antarctic-shelf food pulse may be well adapted to any trophic regime with a pulsed food supply. In contrast P. vignoni produces mature gametes all year ...