A beneficial association between a polychaete worm and a scleractinian coral?

Abstract

Fig 1 Cyphastrea chalcidicum: a View of part of colony showingSpirobranchus giganteus burrows (arrowed), b close-up of burrow,c same burrow 1 year later. Scale bars=10 mmThe polychaete worm Spirobranchus giganteus(Serpulidae) is abundant in coral reefs, beingembedded in both stony corals and hydrozoans suchas Millepora sp. In a study at Eilat (Gulf of Aqaba,Red Sea), we observed a colony of the faviid coralCyphastrea chalcidicum which was almost com-pletely dead and covered with turf algae, apart fromthree small areas of living coral tissue which sur-rounded S. giganteus tubes (Fig. 1). After 1 year,one area of coral tissue grew rapidly to produce sixconcentric circles of living polyps while the otherareas died. In other examples, involving bleaching inFavia favus and predator damage to the coral colonyof Favia laxa, areas of coral tissue immediatelysurrounding the polychaete again showed no dam-age and the colonies quickly recovered. It is sug-gested that there may be some benefits to be gainedfor the coral from its association with polychaeteworms that live within the coral skeleton. These mayinvolve improved water circulation close to the coralsurface which would decrease susceptibility tobleaching (Nakamura et al. 2003), improved dis-persal of waste products of the coral host, andincreased availability of nutrients from waste mate-rials excreted by the associated fauna (Mokady et al.1998).ReferencesMokady O, Loya Y, Lazar B (1998) Ammonium contribution from boring bivalves to their coral host—a mutualisticsymbiosis? Mar Ecol Prog Ser 169:295–301Nakamura T, Yamasaki H, Van Woesik R (2003) Water flow facilitates recovery from bleaching in the coral Stylophorapistillata. Mar Ecol Prog Ser 256:287–291O. Ben-Tzvi (