A Voyage into Inner Space

Forest and Bird, Issue 310, 1 November 2003, Page 30

A Voyage into Inner Space

ANDREW STEWART

Marine Biologist

talks with DAVE. HANSFORD

about deep-water dliscoveries north of New Zealand:

Transparent squid, a deep-water species, photographed by Peter Batson whose book Deep New Zealand is previewed on pages 32-33.

cientists aboard the research vessel Tangaroa got their first tantalising glimpse of life on the seamounts and underwater abyssal plain to the north of New Zealand, earlier this year. The deep gave up some secrets, but kept many more. As biologist Andrew Stewart recalls: "We came away knowing how little we know. Andrew Stewart shows me one of the discoveries. It’s a vision from a

watery hell. Little more than a mouth full of murderous fangs and a way of aiming it, but he No cradles it gently, teasing out the black gelatinous features with a practised eye for detail. He’s excited. He thinks he could be on to a new species of deep-sea anglerfish here, but the trouble is, his lab is chock-full of new species and he only has one lifetime to try and identify them all. All about, stainless benchtops groan under ranks of specimen jars. Peering back through the alcohol are some of evolution’s most fantastic expressions. Even without the crazy-mirror distortion of the glass these are bizarre animals, confirmed by the pejorative names on the labels floating inside; spookfishes, snaggletooths, gulpers, slickheads, rattails. This — plus a freezer full of bigger corpses — is some of the bounty

reaped by the National Institute of Water and Atmospheric Research (NIWA) vessel Tangaroa as it towed nets and dredges about the deep in New Zealand’s northern waters in May-June. Supported by Australia’s National Oceans Office and the New Zealand Ministry of Fisheries, the NORFANZ

y i expedition took a first, albeit sketchy, look under the waters of a triangle between Lord Howe and Norfolk Islands and the northwestern tip of New Zealand. They began with the Norfolk Ridge, a spine of submarine scarps and volcanoes stretching between Cape Reinga and New Caledonia. While the scientists aboard had never been there, they had seen the results of earlier French projects to the north which had discovered a wealth of oddities, some of which were relics presumed to have gone extinct tens of millions of years ago. Andrew Stewart, the fishes collections manager at Te Papa, was looking for answers. ‘If you look at charts of the region, you see a series of seamounts running down the Norfolk Ridge, he says. "We know that during

Gondwanan times, the ridge was at one point a coastline, which poses all kinds of questions. For instance, do ancient species still follow a possible migration route along the ridge? Were the seamounts acting as oases? What were the effects of various currents and boundaries that cross at right angles to this feature, that perhaps acted as barriers to these migration movements?’ Four weeks at sea wasn’t enough to solve all the mysteries. ‘It was very tantalising, he says. "We sampled down to 2000 metres, which sounds impressive until you realise that the average depth of the world’s oceans is about 4000 metres. That sort of depth around New Zealand has only been sampled a handful of times. ‘Because of time constraints, we only grabbed a snapshot. It’s like taking a spaceship to a far planet and only having the time to make one pass, with all your cameras and sensors firing, then having to return to earth? For all that, the haul was impressive. Tangaroa’s nets and dredges disgorged around 500 species of fish (some that were readily identifiable, many more that weren't), and some 1300 species of invertebrates. Part of the booty was eight drums of ‘gribble’, or fine, shelly seabed sediment, which Te Papa malacologist Bruce Marshall began sifting for tiny molluscs. During the first 10 hours of work, says Stewart, a new mollusc emerged about every two minutes, eventually topping 600 new species. On first assessment, there are about 34 new fish records for New Zealand, roughly half of which are also likely to be new to the planet. But what is all this good for? Why should we know — or even care — about what burrows through the mud and darkness two kilometres under the sea? Clearly, Andrew Stewart has his own reasons, but he gives the official line: "New Zealand is a signatory to the Rio Convention on Biodiversity which means that we’re obliged to care about the biodiversity within our region. And with that obligation comes the duty to answer the questions: "What is the fauna and flora of New Zealand? What is unique here? How do we care for it?"’ ‘Often the little things get overlooked in the stampede to examine the big things, he says, ‘but the little things are the key to the survival of the big things. Especially in the endless cold night that is life at 2000 metres. ‘In the midwater, animals are born, live and die without ever seeing the sea floor or the sun, floating in a kind of inner space? ‘Although the ocean is the world’s largest habitat, it’s not the most densely populated [ Tangaroa trawled the midwater for hours to

capture a single tray of fish], so fishes such as anglerfishes have huge mouths and elastic stomachs, so they can accommodate any type of prey that comes their way. Useful, when meals could be months apart. In this frigid netherworld, finding sustenance — or a mate — takes on a whole new level of difficulty. In response these creatures have produced, with little more than DNA and the evolutionary millennia, devices that the world’s military have spent billions of dollars devising. Most of the denizens down here are coloured black, or blood red. There is no red light at these depths (it’s the first band of the spectrum to fail in the fading light), so a red-coloured animal is all but invisible to predators. Some hunters, however, have developed eyes that can detect the faintest of silhouettes against the barely perceptible glow from the surface. In defence, some of their prey possess banks of light-emitting organs along their underbellies. They can switch them on to match the exact hue and shade of the faint surrounding light so that their narrow bodies simply blend into the background. Other predators have learnt to ‘see’ in infrared — a normally invisible wavelength. Their hapless prey have no idea they’re being stalked, except for those that have responded by producing their own ‘cloaking devices’ which block infrared emissions. Others have learnt to escape by startling their pursuers with brilliant flashes of bioluminescence. It’s this sheer ingenuity that’s captured

Andrew Stewart: "The incredible diversity of ways in which these fishes successfully answer the demands of life at depth. That’s the wonder of it? It’s said we know more about the dark side of the moon than our own seabed. Stewart points out that the space probe ‘Magellan’ mapped the surface of Venus down to just metres, yet we're familiar with perhaps only 10 per cent of the continental shelf and the abyssal plain beyond. By Andrew Stewart’s reckoning, a stranger to New Zealand science turns up, on average, every two or three weeks; which is why he’s champing at the bit to go back to the deep. He would love to bring one of the world’s few 4000 metre-capable submarines out here for a closer look. ‘Td go back tomorrow. There are other ridges to the north — the Three Kings Ridge, the Kermadec Ridge, then there’s the Puysegur Trench, the Tasman Basin off Fiordland. ‘I want to know what’s down there.