A survey of pocilloporid corals and their endosymbiotic dinoflagellate communities in the Austral and Cook Islands of the South Pacific

Study Extent

Austral Islands (French Polynesia) and Cook Islands

Sampling

To determine whether the a genotype of P. damicornis is present across a 2,000-km, unexplored region of the South Pacific Ocean, corals most closely resembling the best described morphologies of P. damicornis (Veron, 2000) were collected at each of 30 reef sites across five islands/atolls of French Polynesia’s Austral Islands and each of 30 reefs from three islands/atolls of the Cook Islands in April and May 2013. In the Austral Islands, Raivavae, Tubuai, Rurutu, Rimatara, and Maria were surveyed over the latter half of April 2013. Herein, only the data from Raivavae, Tubuai, Maria, and, to a lesser extent, Rurutu, are presented; reefs of Rurutu and Rimatara had been devastated by a crown of thorns starfish (COTS) outbreak and so few adult corals were present. Indeed, not a single P. damicornis-like coral was found at Rimatara.

Method steps

1. Corals were typically collected on SCUBA from depths between 10 and 20 m by random swimming, and depth and time of coral collection were determined by a diving computer (Suunto D4). After taking a picture with an Olympus TG-2 underwater camera, small (50-100 mg) biopsies were removed from coral colonies with bone-cutting pliers and placed into sterile, pre-labeled Whirl-Pak® (Nasco) bags. When present, typically 1-3 pocilloporid colonies were sampled at each site, and 123 colonies were sampled across 48 of the 60 sites visited over the 3.5 week-long duration of the cruise. When corals with a P. damicornis-like appearance were not found, P. verrucosa Ellis and Solander or P. meandrina Dana specimens were instead collected; briefly, although the major aim of the study was to sample only colonies resembling P. damicornis, other pocilloporid corals were collected to serve as out-groups in the phylogenetic analyses and to determine whether intra-generic differences in Symbiodinium assemblages could be documented.
2. Immediately upon returning to the small craft vessel after a dive, coral biopsies were minced with bone-cutting pliers or tweezers, immersed in RNALater® (Life Technologies), and stored at -20 or 4°C for several hours. Upon return to the M.Y. Golden Shadow, samples were homogenized in RNALater with mortars and pestles as in Mayfield et al. (2013b). Homogenized tissues + skeleton in RNALater were frozen in an -80°C freezer onboard the ship for several weeks. Then, they were transferred to a -150°C liquid nitrogen dry shipper (Doble 20 model, Chart Biomedical), exported under CITES permit FR1398700102-E (to ABM), and transferred on a commercial airline to a -80°C freezer at Taiwan’s National Museum of Marine Biology and Aquarium (NMMBA), where extractions were later performed.

Austral Islands (French Polynesia) and Cook Islands