What would happen if city suburbs as well as offshore islands enjoyed freedom from introduced predators? Is it possible for New Zealand to eliminate them all—stoats, ferrets, weasels, possums, and three species of rat?
By studying 71 lakes in 33 countries from space, researchers from Stanford University have found that toxic algal blooms in freshwater have been increasing since the 1980s. Using satellite data from the past 30 years, they found blooms were becoming more frequent in 70 per cent of the lakes studied, but that this wasn’t linked to usual causes, such as fertiliser use or rainfall changes. The lakes that had fewer blooms over time, however, had warmed less than other lakes.
After severe coral bleaching—the stress response of coral to higher sea surface temperatures—parrotfish thrive, a new study by the Australian Institute of Marine Science (AIMS) has found. Researchers looked at fish populations on two bleached reef areas—the Great Barrier Reef and the Chagos Archipelago in the Indian Ocean, 8000 kilometres away. Parrotfish populations in damaged reef areas were two to eight times as high as normal, and individual fish about 20 per cent larger. The fish use their beak-like teeth to scrape microorganisms off coral. Study co-author Brett Taylor believes the parrotfish’s presence helps the coral repair process, as their feeding creates large areas of newly barren surfaces. He thinks coral and parrotfish might create a positive feedback loop: the fish nibble away microalgae and cyanobacteria ‘scunge’ from the coral, giving it a better chance to recover. “Parrotfish are a vital link in the reef ecosystem,” says co-author Mark Meekan. “As herbivores, their grazing shapes the structure of reefs through effects on coral growth and suppression of algae that would otherwise proliferate. Because of these important ecological roles, they have been described as ‘ecosystem engineers’ of reef systems.”
When did the Anthropocene, the current geological epoch, actually begin? In research published in Science in August 2019, Australian social scientists say humans have been the main influence on the Earth’s climate and environment since 2000 BCE. “The activities of farmers, pastoralists and hunter-gatherers had significantly changed the planet four millennia ago,” writes co-author Andrea Kay from the University of Queensland. “The long-term cumulative changes that early food producers wrought on Earth are greater than many people realise.”
On Scotland’s remote St Kilda island in the summer of 1840, a group of fishermen found a strange seabird sleeping on a ledge. It was black-and-white, flightless, and enormous. The men took it home to their village and tied it up in a stone hut. For three days the bird complained and tried to bite anyone that came near. Then a wild storm arose. Fearful the bird was a witch, and had sent the tempest to punish them for capturing it, the superstitious villagers stoned it to death. It took an hour to die. In reality, the witch-bird was a great auk—the last one ever documented in the British Isles. Four years later, the last pair in existence was killed in Iceland by hunters looking for museum specimens. The species—sometimes known as the penguin of the north—had ranged across the North Atlantic in the millions. What happened? Was the species in decline before intensive harvesting started in the 1500s—or was human hunting alone enough to drive such a numerous species into oblivion? To find out, genetic researcher Jessica Thomas from the University of Swansea analysed the mitochondrial DNA of 41 long-dead great auks. The data showed the species had enjoyed high genetic diversity and a constant population size for thousands of years, and that great auks from across the North Atlantic were able to meet and breed. The researchers then simulated how much hunting would have been necessary to drive the great auk to extinction within 350 years, and found that an annual harvest of 210,000 birds and fewer than 26,000 eggs would have inevitably led to extinction. Sailors’ journals and other historic reports suggest the actual number of birds killed for their meat, eggs, and feathers is likely to have been far higher. Then the museum trade finished them off. “There are lot of very gruesome sailors’ records in terms of how they used to kill them,” says Thomas. “They would have these huge pits where they would corral the great auks into stone huts and then burn them with the oil from their dead relatives.” The study highlights that “pretty much anything is susceptible to extinction”, says study co-author Michael Knapp from the University of Otago, where Thomas was based for some of her research. “People went to the North Atlantic and it was full of great auks. Nobody would have thought there was any risk.” Some of the great auk’s relatives—the puffin, the murre—are still hunted today, and should be more closely monitored, says Knapp. “Anything we exploit in large numbers we need to be very careful about, even if we think there’s a lot of them.”
Poachers are raiding fragile caves to make a quick buck flogging moa bones to the highest bidder. Is it right?
In 2012, New Zealand Geographic broke the story of a secret meeting of scientists in a lodge on the Central Plateau to evaluate the feasibility of a crazy idea. They concluded it might just work. Less than eight years later, Predator Free 2050—a mission to rid the entire country of rats, possums and mustelids—is gathering steam. But why is this important? Isn’t it enough to leave the birds to their sanctuary islands? One major criticism of the predator-free movement is that it involves too much nostalgia: that the quest for a prelapsarian Aotearoa is an expensive fantasy. We can’t go back to how things were. Change is one of the conditions of life on earth. It’s true that we can’t return to the past, that the living world is always in motion. But something else is also true: that we value what’s unique, that variety is prized over uniformity, that we see a danger in the homogenisation that introduced mammals are bringing to this country. If we leave predators to it, it isn’t only birds that they’ll extinguish, but the trees those species pollinate, the insect communities they sustain. You can’t pull threads out of an ecosystem without the whole thing fraying. The idea of Predator Free 2050 can be simplified in this way: Something is going to die. It will either be possums, mustelids, and three species of rat, or it will be most of New Zealand’s native birds and an unknown number of plants and invertebrates. You have to choose. Inaction is a choice. The Predator Free 2050 goal declares that what evolved on this “last, loneliest, loveliest” land, as Rudyard Kipling called us, is worth keeping, and not in the open-air museums of sanctuary islands, but among us. We want rocky outcrops heaving with white-faced storm petrels, and if hitting rats on the head with a belaying pin is what it takes, that’s what it takes. Predator Free 2050 has already proved itself a galvanising force, mobilising more than the sum of its parts—or budget. It acknowledges that something within our animal nature thrives when our neighbours are tūī and ruru and kererū and tīeke. Sanctuaries aren’t good enough. Something is lost when humans are a monoculture. Sometimes, we just need a bold name for what’s already happening around us: a declaration. Great Barrier’s newfound Dark Sky Sanctuary status—little changed on the island in order to acquire the label—immediately birthed a couple of businesses led by locals who discovered a passion in studying the stars. On an astronomy tour by Good Heavens, I noticed that all that was required for this form of sightseeing were beanbags, telescopes, and thermoses of tea. It was harmless as a picnic. And given that stargazing is better in winter—night falls earlier, the skies are clearer, the galactic core of the Milky Way is straight down the centre—it spreads the load of the seasons, the heavy tread of summer’s tourism. Before that—before the Dark Sky Sanctuary name was bestowed on an island just across the horizon from home—I hadn’t realised that the moon is bright enough to cast sharp-edged shadows. Bright enough to read by. Or how many species go about their lives after dark. Humans think of ourselves as separate from the natural world, but we aren’t. We’re part of it, our bodies perhaps more deaf and blind than those of the animals that surround us, but still attuned to greenery and complexity, to sunrise and the oncoming dusk.
With imagination and dedication, as a Waiheke schoolteacher and his students showed 60 years ago.
Cancer cell clusters are blasting off into outer space, in a research effort that aims to crack one of the final frontiers in cancer biology. Housed in a specially designed biomodule, samples of aggressive ovarian, breast, nose and lung cancer will travel to the International Space Station (ISS). The question at stake: how will the cells behave in microgravity? A malignant tumour consists of cancer cells stuck together that replicate uncontrollably, until a point is reached where the cells begin to break off and invade other parts of the body. This switch between clumping together and spreading isn’t well understood, but researchers reckon the cancer cells have a way to ‘sense’ each other, and that this sense relies on the presence of gravity to function. In a preliminary test in a zero-gravity chamber at the University of Technology Sydney, 80 to 90 per cent of cancer cells were ‘disabled’. Now, the mission to send cancer cells to the ISS aims to replicate this finding—with the hope it could lead to future therapies that trick cancer cells into thinking they’re in outer space. “It would not be a magic bullet, but it could give current treatments like chemotherapy a big enough boost to kill the disease,” said Joshua Chou, the scientist leading the study.
Did you ever get a new Fitbit? Did you then spend the next few weeks compulsively checking your wrist, seeing how ‘good’ you’d been that day? Did you take the dog for an extra walk at 10pm just to watch the device tick over 10,000 steps, and go to bed basking in the glow of your achievement because Fitbit, and science, told you that was the minimum distance humans should walk each day to be healthy and live longer? Then welcome. Come on in. Join the club of those of us who’ve been royally duped by health and wellness marketing. Trouble is, there’s little evidence attached to 10,000 steps being better than any other distance to walk in a day. A study of 16741 women in the United States, with an average age of 72, found that after 7500 steps per day, the benefits appeared to level out, at least in the women studied. Investigators from Brigham and Women’s Hospital in Boston found that regardless of intensity, those who walked about 4400 steps each day lived longer than those who averaged just 2700 a day, but that this drop in mortality rates plateaued at 7500. Meanwhile, an Australian study of 1697 people aged 55-85 found that benefits generally increased per extra 1000 steps gained. So how did 10,000 steps become popular? It may stem from a Japanese pedometer company in the 1960s which felt that the character for 10,000, 万, looked similar to a running figure. Scientists are now looking at the speed of steps, or cadence, as an indicator of health, rather than distance.
Life is constantly in motion around the world, floating across oceans and colonising new shores, as frequently today as it did hundreds of millions of years ago. So what’s arriving along New Zealand’s coastlines?
New Zealand and United States researchers have found a link between slow walking speed at 45 years old and accelerated ageing. Their research, which used data from the long-running Dunedin Multidisciplinary Health and Development Study, also pegged slow walking to declining brain function, and indicators of reduced brain health in early childhood. The authors recommend that a walking-speed test be introduced in regular doctors’ check-ups, since gait proves to be an inexpensive indicator of general health.
Museums have a gender equality problem. Wander the halls of any natural history gallery and chances are, you’ll see more male than female specimens on display. Researchers at London's Natural History Museum analysed 2.5 million records from five prominent museums around the world and found that just 40 per cent of bird specimens are female, while 48 per cent of mammal specimens are female. This slight percentage difference equates to 40,000 more male mammals housed in museums. It’s not just an issue for the stuffed display animals, either—the male bent also afflicts research collections. When it comes to type specimens—the ‘official’ specimen used to scientifically describe a species—the sex ratio drops further, with just 27 per cent of birds and 39 per cent of mammals being female. These ratios have remained unchanged for the last 130 years, except in species with marked sexual dimorphism. This is where males have ostentatious features such as bright colours while females may be more understated in appearance. In such species, the proportion of females in museum collections has decreased. This bias towards males has implications for our understanding of evolution, genetics and ecology. “Natural history collections play a critical role in … answering vital questions for the future of biodiversity,” the study authors wrote. “These results imply that previous studies may be impacted by undetected male bias, and vigilance is required when using specimen data, collecting new specimens and designating types.”
At no other point in human history has the planet been this bright after the sun sets. But artificial lights affect us, and the environment around us, in subtle ways... What happens to us when there’s too much light in the night?
The toutouwai (North Island robin, Petroica longipes) has eyes bigger than its stomach. Weighing about the same as a lightbulb, toutouwai regularly take down large invertebrates including wētā, stick insects and even 30-centimetre-long earthworms. But there’s only so much the tiny toutouwai can devour of these meals. Rather than let that protein go to waste, toutouwai are adept at storing leftovers—a caching behaviour similar to a squirrel hiding nuts for winter. To remember where all these tidbits are stored, toutouwai need a good memory map. Researchers gave 63 wild birds a puzzle with a mealworm treat hidden in one of eight compartments. The puzzle was placed in the toutouwai’s territory several times per day, with the treat always hidden in the same compartment. Toutouwai learned the location of the snack, opening fewer compartments to find the mealworm over time. Following these individuals over the next breeding season, researchers found that males with better memory raised more chicks and fed their offspring larger prey items. But for females, food memory was not linked to reproductive fitness, leading the researchers to speculate that females may have other traits under selection pressure—perhaps related to nest-building.
Climate change could spell the end for emperor penguins by the year 2100—that’s the somber prediction of a new international study. If current warming trends continue, emperor penguins will be marching toward an 86 per cent population decline by the end of the century, at which point, “it is very unlikely for them to bounce back,” says study author Stephanie Jenouvrier, a seabird ecologist from Woods Hole Oceanographic Institution. Emperor penguins, the largest penguin species on Earth, require sea ice of a specific type to survive. It must be fixed to Antarctica’s shoreline, but also extend far enough into the open sea to allow for foraging. Without sea ice, emperor penguins are unable to raise their chicks and numbers plummet. By combining two computer models, researchers mapped future sea ice distribution and modelled how the penguin population would respond to changing ice conditions under three different climate scenarios. If humans limit warming to 1.5ºC, as proposed in the Paris Agreement, sea ice will only decrease by five per cent, leading to a 19 per cent drop in emperor penguin numbers by 2100. Under a 2ºC warming regime, sea ice loss triples and 31 per cent of the population is lost. The worst case—guaranteed extinction—arises if no action is taken and current warming is allowed to continue unabated. “If we don’t hit the Paris Accord emissions goals,” says Michelle La Rue, study co-author from the University of Canterbury, “emperor penguins are in deep trouble.”
The British medal that inspired the New Zealand Cross.
Talman Madsen fell in love with the stars before photography.
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