Reproductive biology of the deep-sea octocoral Drifa glomerata in the Northwest Atlantic |
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Authors: | Zhao Sun Jean-François Hamel Evan Edinger Annie Mercier |
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Institution: | (1) Ocean Sciences Centre (OSC), Memorial University, St. John’s, Newfoundland and Labrador, A1C 5S7, Canada;(2) Society for the Exploration and Valuing of the Environment (SEVE), 21 Phils Hill Road, Portugal Cove-St. Philips, Newfoundland and Labrador, A1M 2B7, Canada;(3) Departments of Biology and Geography, Memorial University, St. John’s, Newfoundland and Labrador, A1B 3X9, Canada; |
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Abstract: | The present study examined the mode and timing of reproduction of poorly understood deep-water octocorals and the environmental
factors that may influence their reproductive patterns. Data on reproductive characteristics of the octocoral Drifa glomerata (Alcyonacea: Nephtheidae) collected between 2004 and 2007 at ca. 100–330 m depth off Newfoundland and Labrador (eastern Canada)
were compared among years, months and depth ranges. No male gonad was ever observed during the study. The ratio of fertile
colonies possessing large pinkish polyps with oocytes/planulae was >50% throughout the year. The number of brooded planula
larvae within a single fertile polyp varied between 1 and 10 for a total of approximately 40–3,000 in a whole colony. The
size of oocytes and/or planulae was consistently greater in the polyps than in the branchlets, indicating that the development
pathway of oocytes to planulae is from the branchlets to the polyps. Although larval production seemed to persist year round,
the onset of major planulation events occurred in December–January of two consecutive years, when large mature planulae were
released in correlation with the first increase of photoperiod and maximum temperature at 150 m. A second peak in planulation
between April and early June followed the phytoplankton bloom. Seasonal trends were more apparent in colonies from <200 m,
and the planula index varied among sampling depths and years. Larval release in a live colony under laboratory conditions
occurred between January and June 2008, closely following predictions based on field samples. |
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