Coral Reef Survey for Aitutaki, Cook Islands, 2008

Natural disturbances such as crown-of-thorns starfish outbreaks and coral bleaching in recent years have played a major role in shaping the reefs of Aitutaki today. Although, anthropogenic disturbances may play a major role as well, this remains difficult to comprehend due to lack of a consistent reef monitoring program on Aitutaki. The purpose of this study is to examine the current state of Aitutaki’s reef as well as re-establish its monitoring program. Based on information provided by this survey, the reefs of Aitutaki may have recovered subsequent to the disturbance in the 1990s, however these were patchy possibly a result of the different environmental regimes experienced at each site. Coral cover range from 34% (at Pacific RC) to 8% (at Pacific RI), and size classes were predominantly in the 8-16 cm class (~8-10 year-old colonies) particularly at the more pristine reefs (Pacific RC and Airport). This suggests that these reefs recruited immediately after the COTS outbreak in the ‘90s. The high cover of crustose coralline algae (CCA) at Atuatane suggests that Aitutaki’s reefs are still in the early stages of recovery. However, high CCA cover can hinder the growth and survival of newly settled corals, which may be the case on Aitutaki. The larger colonies only recorded at Maina in the 64-128 cm class suggested that the location of this site or possibly the establishment as a Marine Protected Area (MPA or raui) may have provided a refuge (in terms of being remote) for corals and other marine life. Anthropogenic disturbances as well as COTS at Maina may be minimal. Low coral cover and high turf algae (TA) noted at Atuatane (I) and Tokai’i as well as small coral colony sizes due to die-backs suggested that these sites are experiencing poor conditions for coral growth and survival. The 2005 National Environment Service survey of Manuae proposed the possibility of Manuae being a source population for Aitutaki based on observed ocean currents at the time. Information obtained from NOAA’S Oceanwatch website on ocean surface currents around these islands also supports this possibility. Assuming that Manuae is a source population for Aitutaki, a decline in marine resources on Manuae may affect the recovery of Aitutaki’s reefs.