Variable palatability of coral eggs to a planktivorous fish

Predation by fish is generally assumed to be an important source of mortality of coral propagules. Field observations have confirmed that fish feed within the slicks of gametes that form following the annual mass spawning of corals on the Great Barrier Reef. However, these studies cannot determine which species are being consumed. To test whether the eggs of coral species were equally palatable, the eggs of eight common broadcast spawning scleractinian corals were fed to a planktivorous fish. Pomacentrus moluccensis readily consumed the eggs of five acroporid species and two faviid species, but often rejected the eggs of the agariciid Pachyseris speciosa; only 60% of the P. speciosa eggs were ingested compared with 90% of eggs of the other species. Assay testing for chemical defence showed that P. speciosa eggs were chemically distasteful to P. moluccensis.