Effects of tissue loss, age and size on fecundity in the octocoral Pseudopterogorgia elisabethae

Clonal organisms have complex life histories in which traits such as reproductive maturity and fecundity are affected by colony size. Thus changes in reproduction due to tissue loss have the potential to affect population dynamics even among seemingly healthy populations. At sites in The Bahamas the octocoral Pseudopterogorgia elisabethae, which produces a natural product used by the skin care industry, is harvested by cropping branches from large sexually mature colonies. Cropping decouples colony size and age and provides the opportunity to assess the effects of colony size, age and tissue loss on reproductive output. Tissue samples from P. elisabethae colonies from Cross Harbour, Abaco, The Bahamas were collected prior to spawning in 2009 and fecundity was determined. Approximately half of the colonies had been harvested 4 years earlier. There was no relationship between either age or colony size and reproduction among colonies that were large enough to reproduce. Polyps from female colonies that had previously been cropped produced fewer eggs than those that had not been cropped. In an additional experiment, a group of predominantly male colonies was clipped to a height below the size of first reproduction The clipped colonies were less likely to have reproductive polyps, and the male colonies that were clipped to 10–15 cm height had fewer reproductive polyps and fewer spermaries per reproductive polyp than unclipped controls that were 30 cm in height. Size affected whether a colony is reproductive, but age had no discernible effect in the observations and experiments. Tissue loss reduced per polyp fecundity. The results coupled with previous findings of enhanced branch extension in cropped colonies suggest that a long term reallocation of energy from reproduction to growth occurs among colonies that have lost branches.

► Colony age does not affect polyp fecundity in Pseudopterogorgia elisabethae.
► Size affected whether a colony was reproductive but did not affect fecundity.
► Experimentally induced tissue loss to male colonies reduced spermary production.
► Female colonies harvested 4 years earlier had lower fecundity than uninjured colonies.
► Energy reallocation in injured colonies persists years after the damage has healed.