UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Early Polynesians created monumental structures called marae, using coral as a major element in the construction of the ahu. This study will analyze the relative frequency of coral genera found in the ahu of three different royal coastal marae sites on Mo‘orea and evaluate its correspondence to the composition of adjacent coral communities. Volumetric measurements of the ahu and its constituent coral genera composition were calculated. Transects were performed in both the fringing and barrier reefs surrounding the marae sites in order to record size and frequency of the coral genera present there. Some marae site survey results revealed a strong correlation between the usage of coral as a major element of construction in marae, and modern coral genera distribution and abundance in the surrounding fringing reef. The barrier reef environment suffered minimal impact resulting from marae construction. When all coral genera were combined, there was a significant difference in coral composition between marae site reefs and control site reefs. Additionally, coral measurements revealed a positive correlation of increased coral diameter with increased distance from shore. Using coral head size as a proxy for age, the presence of younger coral communities closer to shore may be the long-term result of older, larger corals being collected nearer to shore for use in the constructing of marae.