Early tests from shipwreck 'promising'

Stacie Lilley and Paul South, from the University of Canterbury, are using this quadrat to survey the effects of the Rena disaster on species. Photo / Alan Gibson

Scientists hope a new ground-breaking study will back beliefs that the Bay of Plenty environment has battled back from the Rena disaster.

Students and academics working under research team Te Mauri Moana this week began a project to gauge how a range of species have fared in the eight months since the Rena ran aground on the Astrolabe Reef off the coast of Tauranga.

The group's leader, Professor Chris Battershill, said early samples were promising.

"Our observations suggest we avoided the worst of the disaster, and much of that is because the salvors managed quite effectively to get most of the oil, if not all of it, that hadn't come ashore. If they hadn't, then we'd be in a very different space right now."

Of the 1712 tonnes of oil on board the Rena when it grounded on October 5, 350 tonnes were believed to have spilled into the ocean in the six days after.

Scientists who tracked the accumulation of the more toxic elements of oil in the tissues of shellfish, such as tuatua and pipi, had since been astonished at how quickly levels returned to normal.

"They showed a rapid accumulation through the worst phase of the oil contamination, which peaked in mid-November, and then we were surprised by the fact those levels came down quite quickly in many of the areas," Professor Battershill said.

"By December, and certainly by early January, much of the levels of oil contamination in the tissue had returned to background levels, to the point they couldn't detect them really."

A dozen key species of kaimoana will specifically be tested for damage to their reproductive ability.

"If the reproductive systems of marine organisms have been affected there might not be any juveniles coming through for the next generation or so, but we don't know if that's the case."

Other research will find whether contaminants have progressed through the marine food chain.

Professor Battershill said recovery had been slower at "hot spots" such as central Papamoa Beach, Maketu and the northeast end of Motiti Island, where oil had resurfaced during storms.

But previous testing of paua at Motiti Island, the area closest to the shipwreck, found levels had returned to normal.

A key area of concern remained the Astrolabe Reef, home to caves, valleys and deep drop-off teeming with marine life. Photographs and samples being collected by salvors would give researchers indications of the effects.

"I guess at this point, it'll look bad - there will be a lot of junk around and debris everywhere, but those reefs are in high-current systems and they are close to adjacent reefs, so if there's any localised disturbance in the short term there will be plenty of larvae in the water column that will come to repopulate it."

Te Mauri Moana, which includes academics and students from University of Waikato, Bay of Plenty Polytechnic, Te Whare Wananga o Awanuiarangi and the University of Canterbury, is one of the largest projects within the Rena Recovery programme that will cost up to $3 million.