Effects of predator exclusion on recruit survivorship in an octocoral (Briareum asbestinum) and a scleractinian coral (Porites astreoides)

Recruits of the Caribbean scleractinian coral Porites astreoides and the octocoral Briareum asbestinum were established on artificial substrata and reared on a reef in cages designed to exclude various classes of organisms known to feed on corals. Post-settlement survivorship of recruits was measured for periods of 2 weeks (B. asbestinum) and 1 month (P. astreoides) on East Turtle Reef in the Florida Keys during May and June 2010. Predator exclusion did not affect survivorship among P. astreoides recruits during the study. Recruits of B. asbestinum experienced lower survivorship in treatments that allowed access by fish compared with fish exclusion treatments. The results indicate that predation may be an important determinant of post-settlement mortality among B. asbestinum recruits, and fishes are the primary contributors to predation-induced mortality. B. asbestinum recruit survivorship differed by an order of magnitude between recruits in the control condition and those in the predator exclusion (0.087 and 0.372, respectively). The findings illustrate the need to consider the effects of interactions early in life on the survival, propagation, and recovery of coral populations.