Fluctuating asymmetry: a viable indicator of stress on reef-building corals?

Small, random deviations from perfect syrnmetry.(referred to as fluctuating asymmetry, or FA) are considered to be a result of minor developmental accidents, and have been shown to reflect the developmental stability of an organism and the influence of the environment upon it. FA theory has mostly been applied to bilaterally symmetrical animals and plants, with only a few published studies of radially symmetrical organisms. To test for FA in coral polyps, closeup photographic samples were taken of the scleractinian corals Montastrea annularis (columnar and massive morphs) from three locations around Utila Island, Honduras; and Diploastrea heliopora and Pavia speciosa from three sites around Singapore. Measurements were taken from projected images and analysed for symmetry. Although many scleractinian coral polyps appear to be radially symmetrical, the application of FA methods to the above species revealed that their polyps were antisymmetrical, and therefore not suitable subjects for this technique. The measures of symmetry used were novel and could be applied to other FA studies of radial organisms.