The Hauraki Gulf is at breaking point. Relentless fishing, for more than a century, has slowly dismantled the ecosystem. Here's what we're left with.
Parasites don’t get great publicity—they tend to drink blood or make their home inside intestines—but there’s a lot to value in this vast and varied group of organisms. In the journal Biological Conservation, an international group of scientists, including Allen Heath from AgResearch in New Zealand, describe their importance and present a plan to conserve them. Parasites are animals which spend at least part of their lives feeding on or making their home inside living hosts. This freeloading approach to life is so popular that perhaps 40 per cent of all species may be parasitic, and parasitism may have evolved independently at least 200 times. Parasites are incredibly diverse, too—one study estimates parasitic worms number as many as 300,000 species, substantially more than the 70,000-odd vertebrate species that host them. Their presence isn’t necessarily negative for their host. Some parasites can regulate their host’s immune system, while others store heavy metals that might otherwise prove poisonous. Around four per cent of known parasites infect humans, often to our detriment. The report suggests that parasites could be biomedical resources that help humans. We have already used leeches medicinally for many years, and some researchers are investigating helminths (worms) as a therapy for some autoimmune conditions. In New Zealand, geographic isolation has led to a proliferation of endemic parasite species. The tuatara has its own resident tick species; the hihi is home to a unique coccidian, a microscopic single-celled parasite that dwells in the intestine. But we still have lots to learn and discover about the parasites that dwell in the nooks and crannies of Aotearoa. Otago Museum is amassing parasites as part of a collection that already contains thousands of specimens. “Because the museum attends to many strandings of marine fauna across the South Island, they end up collecting lots of rare parasites that you wouldn’t find otherwise,” says parasitologist Anusha Beer, who recounted finding a three-metre-long intestinal worm while dissecting a stranded sunfish. Such collections enable research into the fascinating lifecycles and myriad strategies devised by parasites. They may also become a compendium of disappearing biodiversity, says Beer: “It’s thought that about half of all parasites will become extinct without ever being discovered.”
Larvae of different sunfish species all look alike: tiny, spiky balls with googly eyes, just two millimetres across. Eventually, they’ll grow into colossal fish several metres long, but at this early life stage, they’re impossible to tell apart based on their appearance. In fact, even the hefty, round adults have been challenging to classify. It wasn’t until 2017 that the different species were untangled by Marianne Nyegaard, who identified three: the ocean sunfish (Mola mola), the bump-head sunfish (Mola alexandrini) and the hoodwinker sunfish (Mola tecta). With the adults sorted, Nyegaard, now a research associate at Auckland Museum, was keen to unravel the next Mola mystery: which baby is which? Genetics could provide the answer, but sunfish babies are hard to come by. “In the last 100 years, there have been 32 larvae collected from all of Australia,” says Nyegaard, “and none from New Zealand.” Larvae held in museum collections are tricky to study: museum specimens are typically preserved in formalin, which destroys DNA. Nyegaard’s lucky break came when Te Papa fish expert Andrew Stewart called her from an Australian research vessel, Investigator, while surveying off the New South Wales coast. They had scooped up three Mola larvae. Two had already been fixed in formalin, but a third had been frozen in a bulk collection of samples. In January 2020, the Mola baby was retrieved from the miscellaneous specimens and sent to the Australian Museum in Sydney. Kerryn Parkinson from the museum’s ichthyology team painstakingly removed a single eyeball, and genomics specialist Andrew King sequenced and matched its DNA to a database. This larva was Mola alexandrini, the bump-head sunfish. Identifying the larva is just one more step towards uncovering the secret lives of sunfish. We still don’t know where, when or how they reproduce—or why we find so few larvae, given the ability of female sunfish to produce hundreds of millions of eggs. For now, Nyegaard is using micro-CT scanning to look at the 32 Australian larvae in exquisite detail, investigating their anatomical development. “Understanding how long it takes the larvae to grow from ‘Pokémon’ to ‘huge mum or dad’ will be extremely valuable.”
As winters get warmer, bumblebees are emerging from hibernation earlier. They urgently need sustenance, but many of the plants they rely on haven’t yet flowered. So they force them to. Consuelo De Moraes, a chemical ecologist at the Swiss Federal Institute of Technology in Zurich, noticed bumblebees chewing distinctive holes in plant leaves. At first, she thought they were taking leaf material back their nest. But it turns out that by inflicting such damage, bumblebees can prompt flowers to bloom as much as a month early. Researchers still don’t know exactly how, but the behaviour may help bumblebees cope better with the impacts of climate change.
Adolescence is just as tough on dogs as it is on humans, researchers have found. What’s more, family dynamics can make it tougher still. A team led by Lucy Asher at the Centre for Behaviour and Evolution at Newcastle University found that when dogs hit puberty at around eight months of age, they get rebellious. Asher suspects this is down to the conflict between the dogs’ urge to seek out mates of their own kind, and their attachment to human families. Researchers found that, as with human teens, when that attachment is already weak, puberty in dogs sets in earlier, and triggers more conflict. It’s temporary—and yet, more adolescent dogs are handed in to animal shelters than any other age group.
Elephant seals hunt fish and squid in the total darkness of the deep. Biologists think the seals’ eyes are sensitive to the faint bioluminescent light emitted by their prey, but a new study has found that the hunted have a way of turning that to their advantage. After researchers fitted very fast light sensors to five elephant seals on the Kerguelen Islands in the southern Indian Ocean near Antarctica, they discovered that some fish and squid wait until the seal is almost upon them before dazzling them with very bright bursts of bioluminescence. The scientists also found, however, that one seal had apparently learned how to trick their prey into flashing early—thus giving their position away.
During winter, dozens of seabird species take flight from New Zealand on epic migrations across the planet—and recent advances in tracking technology mean we can now follow them. What we’re learning has upended scientists’ ideas about the lengths animals will go to in order to raise a family.
Do coastal earthquakes affect whales? Until recently, the sum total of scientific knowledge on the subject was one paper describing a single fin whale fleeing after an earthquake off California. But the 7.8-magnitude Kaikōura earthquake provided an unprecedented opportunity for University of Otago marine mammal researcher Marta Guerra to examine how top predators respond to widespread disturbance of their environment. On the night of November 14, 2016, faults ruptured from the mountains to the sea—right into the head of the Kaikōura Canyon, a sperm-whale hotspot. That triggered massive underwater mudslides, which transformed the sea floor and carried away the communities of invertebrates that live in the mud, feeding a rich food web—with sperm whales the apex predators at the top. The University of Otago has been studying Kaikōura’s sperm whales since 1990, and Guerra already had detailed data on whale behaviour. After the earthquake, there were some obvious changes. Whales stopped frequenting the upper canyon—usually a prime foraging spot—and they changed how often they dived. Sperm whales normally spend 45 minutes to an hour diving up to a kilometre into the deep before resting at the surface for ten minutes to catch their breath. After the earthquake, the whales consistently rested for 25 per cent longer. “That maybe doesn’t sound like a lot, but for a sperm whale that time at the surface is very carefully balanced—it’s a trade-off between air at the surface and food at depth,” says Guerra. “It’s a sign that they’re going to more effort while they’re diving.” Guerra thinks the whales were getting used to an unfamiliar landscape, and facing food shortages in the places they were used to hunting. After a year, their behaviour began returning to normal, a sign of the population’s resilience.
A common beehive pest could be redeployed to chew plastic bags instead of honeycombs. Canadian researchers fed plastic bags to wax moth larvae and found that the larvae’s gut bacteria thrived on the new diet. In fact, some bacteria could live exclusively on polyethylene for more than a year. Researchers tried growing the bacteria by themselves on a petri dish, but found the microbes weren’t as effective at breaking down plastic as they were when they lived inside the guts of larvae.
Australia’s critically endangered night parrot may not be very good at seeing in the dark, according to new research from Flinders University. An international group of researchers CT-scanned a night parrot skull, as well as skulls of related bird species, and found that the night parrot had smaller optic nerves and lobes than the others, suggesting it had limited visual processing ability. The parrot’s vision appears to be sensitive but low-resolution, meaning that it struggles to distinguish predators or obstacles in the dark—raising concerns that it may be crashing into fences in its outback home.
Exposure to a common herbicide can alter the minds of fish, researchers at the University of Otago have found. Atrazine, which is frequently used in New Zealand to kill weeds, was found at low levels in about three quarters of 36 streams and rivers sampled by another University of Otago study. Low levels of atrazine in water doesn’t kill animals, according to research. But does the poison affect them in other ways? To find out, master’s student Simon Lamb added atrazine to a tank of male zebrafish, the lab rats of the aquatic world, to a level frequently found in water sources in the United States. Next, Lamb bred the males with female zebrafish from a non-atrazine tank. Then, he rated the parents and their offspring on a variety of behavioural tests. “What most fish do when you put them in a new environment is they’ll settle down to the bottom, and then once they feel comfortable enough, they’ll swim up through the water column to the surface,” says Lamb. By measuring how long it takes a fish to start exploring, behavioural researchers can get an idea of its anxiety levels and appetite for risk. Lamb also recorded how the fish responded to a mirror, which measures aggression. “We use these proxies to understand what sort of behavioural processes are going on.” The zebrafish that had been exposed to the atrazine were less aggressive and had different risk-taking behaviour. The same was true for all their offspring—even though one parent hadn’t been affected by the chemical. This has implications for whether atrazine should be used in New Zealand, says Sheri Johnson, Lamb’s supervisor. (Atrazine was banned in the European Union in 2004 due to high levels in groundwater.) It’s not known how the fishes’ personality changes may affect their lives—will it alter their ability to find a mate, or to survive, or to evade predators? But the zebrafishes’ behaviour is thought to be widely indicative. “If we’re seeing these effects in zebrafish in the lab,” says Johnson, “that means we’re likely to see these same effects in our native fish in our rivers and streams as well.”
A common pesticide appears to make tree wētā sluggish and shy, according to a study by Adele Parli, a master’s student at the University of Otago. Parli looked at the effects of the rat poison brodifacoum on Wellington tree wētā. Baits designed to kill mammals don’t kill invertebrates, according to current research, but it’s not known whether these poisons affect invertebrates in other ways. Parli’s study showed wētā found the brodifacoum baits appealing, and those that ate the baits came out of their refuges more often, and had lower levels of activity, less boldness and less aggression, compared to wētā that didn’t partake. But it’s not clear whether this is due to the brodifacoum itself, or whether these effects are caused by the cereal mix the toxin is contained in. (It could be that the wētā are stuffing themselves with carbs rather than their usual protein and becoming nutrient-deficient.) Without brodifacoum, many more wētā would be killed by rats or stoats. But behavioural ecologist Sheri Johnson suggests trying to repel wētā from eating the baits: “We need to know more about the long-term consequences of the changes in behaviour we observed.”
The ability to change behaviour makes birds less vulnerable to extinction, according to a study of 8641 bird species around the world by researchers at McGill University in Canada. The scientists built a database of more than 3800 published observations of birds incorporating new foods into their diet, or feeding in new ways, then mapped this information against the birds’ risk of extinction, according to the International Union for the Conservation of Nature. They found that the birds’ ability to innovate predicted whether or not they’re in trouble. Examples of innovation included the carnivorous Himalayan griffon, which normally eats carrion, feeding on pine needles in India. Yellow-rumped warblers were observed sheltering inside a heated milking parlour during a cold spell in Canada and eating the dormant flies they found there. Black shags in Auckland timed their foraging trips with the Devonport ferry timetable, diving when a ferry had moored at the wharf in order to use the currents generated in the shallow water to catch confused fish. The authors also found that adaptability only helps birds facing habitat loss—it doesn’t improve prospects for birds that are overhunted or affected by invasive species.
Almost all garden snail shells coil to the right-hand side of their bodies. You’ll probably never see a left-coiled snail in your life—so when a retiree found one in his London garden, he sent it in to the University of Nottingham. Geneticist Angus Davison knew he had a rare snail on his hands—and with it, an opportunity to study asymmetry. He named the snail Jeremy (pictured above, on top of the ‘normal’ snail). So was Jeremy’s left-coiling shell a heritable condition? If Davison could get Jeremy to reproduce, he’d be able to find out. Trouble was, he’d have to find another left-handed snail first. Due to the location of snails’ reproductive organs, Jeremy wouldn’t be able to mate with a right-handed snail. Davison launched a media campaign to find Jeremy a mate. Citizen scientists around Great Britain carefully examined their garden snails. A snail farmer sent in a left-coiling snail, and a snail enthusiast found another. When the two were presented to Jeremy, they mated with each other. (Eventually, one mated with Jeremy.) And Davison got his answer. In paper published in Biology Letters in June, Davison found that lefty snails are the result of a developmental accident. In other words, a left-coiling shell isn’t heritable in the same way that left-handedness is in humans. Jeremy died at the age of two (or thereabouts) but was survived by 56 children. All of them have right-coiling shells.
Dragonflies can’t hear, but they still don’t like noise. When Japanese and American researchers played traffic sounds in areas without roads, and measured the effects on local wildlife—birds, grasshoppers and dragonflies, which sense only vibrations—they found that the sounds reduced the number and diversity of species present. “These results suggest that noise pollution not only affects acoustically oriented animals,” write the researchers, “but that noise may reverberate through biological communities.”
Hundreds of millions of years ago, mantis shrimps evolved technologies we’re still trying to copy.
Can you spot a blackbird in your backyard?
Can you spot a song thrush in your backyard?
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