Ecological characterization of coral growth anomalies on Porites compressa in Hawai‘i

Bulbous skeletal structures with associated aberrant corallites have been abundant on Porites compressa in Kāne‘ohe Bay, O‘ahu, Hawai‘i, for at least the last 19 years. These growth anomalies (GA) appear in the summer in shallow (<3 m) water on some, but not on all colonies. GA-free branches, collected from colonies with GAs, produced GAs when cultured in outdoor flow-thru aquaria. Normal branches, whose tissues were continuous with those of GAs, grew in length much more slowly than normal branches from the same colony that were not connected with a GA, suggesting that there is a translocation of materials from normal tissue to GAs. Small experimental colonies that were either exposed to, or protected from, UV radiation did not differ in their rate of GA formation. GAs had a lower probability of survival than normal branches. This characteristic, in combination with their effect on the growth of normal branches and other reported deficiencies in the tissues of growth anomalies (e.g., reduced or failed reproduction), suggests that GA-bearing colonies of this species have reduced fitness.