Coral Reef Challenges in the Cook Islands

Image: SVII-S surveying the coral reef


In between the constant search for Humpback Whales, the team undertook some coral reef surveys on the main island of Rarotonga. The weather forecast indicated very strong swells so the South of the island was not accessible for diving, we focused instead on the North and West side of the island - which according to coral expert Teina Rongo is the most diverse site in terms of fish and coral population. 


As we deployed the SVII-S in Pue Coral Garden, we find a valley of healthy looking porites coral bommies forming a seascape similar to a field of giant mushrooms. Montipora colonies are spotted and other hard corals are looking healthy on the seabed. However, the lack of marine fauna is conspicuous. Further to the West, at the Black Rock Chimney and Diana's Ridge dive sites, Christophe and the SVII-S slalom in a series of canyons where we spot three eagle rays hanging around the corner, which contrast with the low level density of the fish population. There are plenty of swim throughs that make the site interesting, yet the seabed is not as rich in healthy coral as further north.



Natural Challenges in the Cook Islands

Corals are extremely sensitive to very small changes in ocean chemistry. When factors such as acidity and temperature exceed a certain level, the coral becomes stressed and can eventually die. Coral bleaching was first reported in the Cook Islands during and after the 1982-83 El Niño.


Since then, it’s been observed that this phenomenon occurred with each El Niño, particularly in 1997-1998. Scientific evidence has shown that the main stress factor leading to the death of the corals has been high water temperature, associated with El Nino events. Although a fair amount of the corals have recovered, most did not survive. Coral bleaching events were more likely to occur in lagoons, mostly in very shallow water, after being triggered by extreme low tide.


Natural disturbances in the Cook Islands have indeed played major roles in influencing the health of the coral. Crown of Thorns Starfish  - a common coral-eating predator of the reef - have strongly impacted the health of this region with two outbreaks in the last 40 years, which have seriously decimated the reef. But as another outbreak started to emerge this year, it was aborted thanks to the mobilization of the local people who gathered to get rid of the predator. This proved how important it is to raise awareness and how people can make a difference once they know what is going on underwater.



One of the World's Largest Marine Reserves

Local communities have their own traditional systems of protecting the marine biodiversity in the area. However global warming, cyclones, El Nino events, coral bleaching, the outbreak of Crown of Thorns starfish, and the decline in fish life occurring over the last decades have increased the concerns of traditional leaders about the future of their people and the Cook Islands environment.


The territory of the Cook Islands covers 1,065 million square kilometres. 99.9% of this area is ocean; less than 1% of the Cook Islands' territory is land. With the help of local ocean advocates on the islands (like Kevin Iro or Teina Rongo, whom our team had a chance to meet with during the survey), the Cook islands marine park ‘Marae Moana’ will be officially launched in 2015 as one of the largest marine protected areas in the world.


Christophe was invited to introduce the Catlin Seaview Survey to the house of Ariki - the parliamentary body that gathers high chiefs of the Cook Islands. The traditional leaders exposed their concerns over the state of their reef and the decline of fish life. According to them, the population livelihoods and the health of the Cook Islands people are clearly connected to the health of its waters. As most of the islanders have little knowledge of their own reef, the local leaders showed a strong interest in using our 360 degree imagery to expose the health of their reef, educate people, and use these tools to raise more awareness to support local and global action in the marine reserve.



More to Explore and Survey

The Cook Islands marine park includes many remote atolls, high volcanic islands surrounded by stunning coral reefs and endemic fauna. As we pack up the SVII-S equipment and head to the airport after our survey in the Cook Islands, we are aware that there is much more to explore and document in the 15 widespread and unique Cook Islands.