The fore reefs of Mitiaro are among Dr Teina Rongo’s favourite reefs in the Cook Islands. They have unique formations of a particular species of coral that forms plates stacked on top of each other, descending into the drop-off, found only here and neighbouring Manuae.
So last month, visiting the southern group island to run a climate change assessment workshop, Rongo grabbed his snorkel near the end and headed down to the reef.
While snorkeling, he was troubled to see white patches of corals on the fore reef and concluded that the parasitic starfish taramea had finally made its way to Mitiaro – as he had long feared might happen.
Freediving down, he confirmed the presence of taramea at depths of 15 to 25 metres around the harbour on the leeward side of the island.
He didn’t waste time.
He emerged from the water to warn the Mitiaro community that the taramea was concentrated on the north-west side of the island, and that removing them was urgent to reduce the chance of the starfish spreading – especially because their spawning months between October and December were approaching.
The concern was that the taramea were at depths not easily accessible to the Mitiaro community, where freediving is the only option on island to utilize for their removal.
So last week Rongo, the chairman of local environmental group Kōrero o te ‘Ōrau, returned to Mitiaro with Johnny and Ioana Beasley of Akau Film, to get underway with a taramea eradication project.
Taramea, more commonly known as Crown of Thorns starfish, primarily feed on coral. They have have caused the decimation of coral reefs in the Cook Islands since the early 1970s and again in the mid-1990s into the early 2000s.
Today, reefs on Rarotonga and Aitutaki are still recovering from the last taramea outbreak.
Rarotonga reefs are growing back now, perversely sparking fears that the starfish will return again to feed on the plankton of the nutrient-rich waters.
On Aitutaki last month, tourists Erika and Guenter Schmelz wrote to Cook Islands News about about their concerns at the numbers of the starfish in waters outside their holiday house, Amuri Sands Bungalows.
“This year in our first eight days we brought out almost 60 of these coral predator starfish from outside of our house,” they said. “We hope that the problem will be recognised before all corals are dead.”
Aitutaki fisheries and marine officer Richard Story says that he investigates occasional concerns, but the problem on that island is not at the outbreak levels they say in 1997/98 and 2007.
“We had a call from Pacific Resorts to go out and have a look last month,” he says. “We found about six in quite a big area I so it’s not too serious. It’s not a crisis. When you get three or four in a square metre, that’s when it’s a problem.”
In 2014, Rongo had proposed in a report that reef disturbances including taramea outbreaks seem to occur in a southeastward direction for the islands in the southern Cook Islands, with Aitutaki as the source of the problems.
Around Mitiaro now, the levels are more worrying. “Finding the taramea in Mitiaro was not a surprise for me, considering the outbreak that occurred on Aitutaki between 2009 and 2013,” reflects Rongo, now.
Upon returning to Rarotonga last month, Rongo and his environmental group worked to quickly assemble a team to assist the Mitiaro community in removing the taramea. Then last week, they flew back over to Mitiaro.
“We are extremely grateful to Air Rarotonga for coming onboard to get our team of three back to Mitiaro to carry out this work, along with our partner Nia Tero who have been very supportive of Kōrero o te ‘Ōrau’s programmes,” says Rongo.
“Thanks also to the Ministry of Marine Resources who provided their officer on Mitiaro to assist. Meitaki ma’ata to the Mitiaro Fishing Association who provided the use of their boat, and the Mayor and Island Government for their support.”
The team were able to remove most of the taramea at the harbour, through free diving over two days.
“From my experience in the Cook Islands, taramea outbreaks tend to occur on the leeward side of islands moving in a counterclockwise direction.
“If Mitiaro’s reefs are decimated by a taramea outbreak, there is no guarantee that it will recover considering the impacts of climate change such as coral bleaching, coral disease, and ocean acidification.
“What is also worrisome is the presence of coral disease here on Mitiaro – the same disease I spotted in Manuae in 2014.”
The team used their time on Mitiaro to bring awareness about taramea and the uniqueness of the reefs to the community, especially in the school. Senior students were given the opportunity to join the team over the reef to observe how the taramea were removed.
Rongo says: “I love Mitiaro’s reefs and am happy to do what I can to protect them.”