Acropora gemmifera encrusting form (left); Large colony of Acropora gemmifera with white tumor (growth anomaly) just below center of image (right).
This species first was reported by a group of researchers from the Hawai‘i Division of Aquatic Resources who were using diver propulsion vehicles to survey South Kona on the West Coast of the Island of Hawai‘i. While observing the reef structure, they happened upon a large number of Acropora gemmifera colonies and their identities were later confirmed by genetic testing.
In all, they encountered 75 colonies in a ~50-meter length of reef in water depths varying from 3-10-meters in depth. Interestingly, they encountered various colony morphologies, ranging from small encrusting forms to “large upright digitate colonies…the largest of which was 71 × 68 × 75.5 cm (LWH)” (pictured above – right).
The researchers also attempted to estimate the age of the largest colony based on the growth rate of a similar species: Acropora humilis. Based on its growth rate, they estimate the large colony’s age at about 80 years.