Reproductive ecology of the deep-sea scleractinian coral Fungiacyathus marenzelleri (Vaughan, 1906) in the northeast Atlantic Ocean

The reproductive biology and its seasonality were examined in the deep-water, solitary coral Fungiacyathus marenzelleri from 2,200 in depth in the NE Atlantic, using histological techniques. A total of 186 corals were collected using either an Otter trawl (semi-balloon) or Agassiz trawl from the research vessel RRS Challenger between 1979 and 1991. All individuals were gonochoric, with all 48 mesenteries being fertile. A high fecundity was recorded (2,892 +/- 44.4 oocytes per polyp) with strong size-dependency. This species is a quasi-continuous reproducer with overlapping gametogenesis for both spermacysts and oocytes. No planulae were observed and broadcasting of gametes is inferred, with the large egg size (max. 750-mum diameter) suggesting lecithotrophic development. There is a non-significant trend towards a synchronous spawning event during June/July. Asexual fission was observed, though in low numbers.