The effect of transplantation on reproduction in clonal ramets of Goniopora columna on Singapore's coral reefs

Abstract

Summary Ramets of the coral Goniopora columna (Dana, 1846–1849) were excised from five large colonies at one site south of mainland Singapore and transplanted within the same site and depth (2.3 m); to a more disturbed site closer to the mainland at a similar depth (2.2 m); and to greater depth at both sites (8.9 m and 7.6 m, respectively). Ramets were left for one year, then harvested before the predicted spawning periods. Fecundity (average number of oocytes polyp−1), reproductive effort (average oocyte diameter), and polyp tissue diameter were compared among transplanted clonal ramets, control ramets, and parent colonies. Typically, fragmentation in corals results in reductions in reproductive output because energy is diverted into tissue repair, but in this case reproductive effort and fecundity did not change significantly when ramets were transplanted within the same site and depth. Clonal fragments transplanted to the more disturbed site had significantly fewer oocytes, smaller oocytes and smaller polyps after one year suggesting that energy was diverted away from normal functions in response to stressors in the new environment. Ramets transplanted to 7–9 m bleached at both sites after acute periods of reduced irradiance, resulting in high mortality and reproductive failure in surviving ramets.