Does Spirobranchus giganteus protect host Pontes from predation by Acanthaster planci: predator pressure as a mechanism of coevolution?

Abstract

ABSTRACT A novel mutuahstlc relatlon has been observed between serpulld worms Sp~robranchusy iganteus and masslve coral colon~esof Porites lutea and P lobata In response to Acanthaster plancl predatlon on reefs of the central Great Barner Reef (GBR),A ustraha As fe~rilnga ggregatlons of A planci have caused mass mortality of hard corals In these areas, predator-lnduced selectlnn may be operating as an ecological mechanism In the development of the lnteractlon from the S giganteus cornmensalism Into a facultative mutuallsm For the worms masslve Pontes colonies provide both protect~on and an Ideal locat~on for suspension ieedlng (Strathmann et a1 1984 Sm~th pers comm For the coral colony the worms provlde a refuge for adjacent polyps from predatlon by A planci Such protected polyps ~ n ~ t l arteeg en erahon ensurlng the survlval of the colony As Por~teslu tea and P lobata have long colon~all ves (>500 yr) (Potts et a1 1985) the long term survlval of lnd~vldual colonies 1s an Important factor In thelr hfe hlstory strategies and m malntaln~ ngth e observed broad dlstrlbutlon of slze classes of these specles (Potts et a1 1985 Cameron & Endean 1985) In rela tlon to continued predahon by A planci this mutualism may be an important buffer actlng to preserve reef com