Notes on reproduction in the deep-sea cup coral Balanophyllia malouinensis (Squires 1961) from the Southern Ocean

Abstract

Deep-sea scleractinian cup corals are prominent members of Southern Ocean megabenthic communities, though little is known about their life history. This study used paraffin histology and scanning electron microscopy to characterize the reproduction of the scleractinian coral Balanophyllia malouinensis (Squires, 1961) from Burdwood Bank in the Drake Passage. Samples were taken in April and May via otter trawls, Blake trawls, and dredges on three separate cruises: one on the RV Lawrence M. Gould in 2006, and two on the RV Nathaniel B. Palmer in 2008 and 2011. B. malouinensis is gonochoric with rare hermaphroditism. All four spermatocyst stages were seen simultaneously in males; similarly, most females contained oocytes at varying stages of development, though seasonality or periodicity could not be determined without a wider range of sample dates. Average fecundity was 241 ± 184 oocytes/individual (n = 38) and not correlated to cup size. Maturing larvae were found in the mesenteries and coelenteron of females, indicating B. malouinensis broods its larvae. This study was the first to characterize the reproduction of a deep-sea Balanophyllia species and adds to a small but growing body of work seeking to understand the unique benthic communities of Burdwood Bank.