Rena wreck home to 'real biodiversity' ten years after disaster

Tuesday marks ten years since the grounding of the Rena off the coast of Tauranga, sparking New Zealand’s worst maritime environmental disaster.

The catastrophic impact it had on the Astrolabe Reef and hundreds of kilometres of Bay of Plenty coastline left scientists wondering how the ecosystem would ever recover.

Waikato University Marine Ecologist Dr Phil Ross and his team have been diving the wreck, monitoring the watery grave for almost a decade and are thrilled with the progress. 

"First few years I could not imagine this place ever recovering to being a normal reef, it was totally a scrapyard with all kinds of scrap 4- 5 metres high of flattened containers, of scrap metal, of ingots of wire."

The 236 metre Daina Shipping container ship lies around 40 metres below the surface, an hour off the coast of Tauranga.

The Rena went aground in the dead of night on October 5, 2011 as captain Mauro Balomaga, 44, and navigator Leonil Relon, 37, and their crew attempted a shortcut to get into the Port of Tauranga.

The pair served just half of a seven month jail term for their role in New Zealand's worst maritime environmental disaster. 

It cost the New Zealand taxpayer $47 million dollars, offset by $27.6 million paid by Daina Shipping. The Greek firm also compensated local businesses $12.1million.

The salvage operation is the second most expensive cleanup operation in the world, costing  the Rena's owners and insurers in excess of $650 million. 

A thousand tonnes of oil and sticky waste destroyed beaches, birds and wildlife.

Eighty-eight containers washed overboard, hundreds more spat into the ocean when the wreck broke in half during the January storm of 2012.

Biologist Rex Fairweather who has dived the stern recounts how "big sheets of the side of the vessel were just moving around and scraping the reef and the front section of the boat had been scissoring across the reef."

Dr Ross credits salvors involved in the $650 million cleanup for the underwater revival of algae, anemones, sponges and kelp.

"It was a terrible thing to happen and no one wanted it to happen but ten years later it's looking really really good with more and more of the kelp coming back heaps of fish, black angel fish and pig fish.

Newshub joined him on this ten year anniversary dive and he says "potentially [there are] a few minor changes in the wreck".

He's now done "250-300 dives out here over nine and a half years".

"I think it was probably 2018/2019, it got to the point where you knew it would come back. All of a sudden we had a kelp forest that was knee high and then waist high."

In 2016, the Rena's Greek owners applied for resource consent to abandon the wreck claiming further salvage efforts would damage the reef and be risky for salvors.

A move one Motiti group Ngāi Te Hapū challenged, until three years ago when they lost the appeal.

As part of its conditions Daina Shipping is bound by a $9.2 million bond covering ongoing monitoring.

Anti-fouling paint (TBT) from the ship's hull and copper wiring wedged under the stern are being watched.

Originally from Christchurch's earthquake-damaged buildings, the copper wiring was off to China for recycling, when the Rena went down.

"Some of the algae and invertebrates are not growing there because they can't handle copper but when you go 10-20 metres away it's back to normal. If the wreckage moves and the copper is exposed there is contingency for the salvage to restart and recover that copper" says Dr Ross.

Over time he says the copper will dissolve back into the ocean as the sea has copper in it anyway.

Testing for contaminants shows "almost undetectable levels in the food chain", ten years on it seems the Astrolabe reef is well and truly alive.