Probing secrets of unique islands

Geologist and expedition co-leader Hamish Campbell is part of a 22-strong team taking part in the biggest scientific study of the remote Chatham Islands. Picture / Richard Robinson

One at a time, eight scientists were ferried by a small inflatable across to a steep, rocky islet an hour out from the tiny Chatham Island fishing port of Kaingaroa.

At the end of each trip they faced a two-metre wall of kelp at the foot of a steep rock face covered with seals.

On the crest of each wave, the inflatable rose to the top of the kelp wall, just long enough for a scientist to jump out and clamber onto the rock above. Then the inflatable returned to the fishing boat for the next volunteer.

Each climbed gingerly up the 60m outcrop of an ancient volcano known as The Sisters, some using a rope strung up a steep gully, others picking their way along narrow grooves criss-crossing the rock.

Suddenly, reaching the relatively flat top of the islet, they found themselves in the middle of an albatross colony.

Huge white birds occupied the whole upland of the island, sitting on eggs or, in some cases, protecting two-week-old chicks.

The Sisters, and another even steeper islet called the Forty-Fours which the team climbed on to on Thursday, are home to 99.5 per cent of the world's 6500 pairs of northern royal albatrosses. (The other 0.5 per cent, 20 to 30 pairs, migrated from the Chathams to Taiaroa Head near Dunedin in 1919).

The scientists who scaled The Sisters on Saturday are part of a 22-strong team taking part in the biggest scientific study of this remote part of New Zealand, funded by a three-year, $870,000 grant from the Royal Society's Marsden Fund.

It is an unusual mix of geologists and biologists who are aiming to work out how and when the Chatham Islands rose from the sea, and how the islands' unique forms of life got there and evolved.

On The Sisters, team co-leader Dr Hamish Campbell and fellow geologist Chris Adams, both of the Institute of Geological and Nuclear Sciences, collected rock samples indicating that the volcano that formed the islets erupted, just a few million years ago, through limestone laid down on the sea floor about 20 million years ago.

The biologists, led by Dr Steve Trewick of Massey University, found birds, insects and plants which were different from their cousins 850km to the west on mainland New Zealand - but not as different as they might have expected.

Lincoln University botanist David Given said the plants on the Chathams were similar to those on the mainland, but sometimes many times bigger.

"There are two plant genera found nowhere else in the world - a giant forget-me-not, presumably related to the New Zealand ones but with much greater leaves, and the biggest sow thistle in the world, thought to be most closely related to one off the Chilean coast," he said.

This "giantism" showed how organisms adapted to the islands, where there was more sun and fewer animals around to eat them.

But the plants' basic similarity to species in New Zealand and elsewhere suggested that they had migrated to the Chathams more recently than previously thought.

The study, which also includes scientists from Te Papa, Otago University and Australia's James Cook University as well as several private researchers, is now one year into its three-year programme.

It is expected to lead to many scientific papers and possibly a book.