Hey Birds! A cautionary tale of tiny kiwis

Wikimedia/G. D. Rowley, PD-1923
Wikimedia/G. D. Rowley, PD-1923
A sketch of the little spotted kiwi from Rowley, G.D., Ornithological Miscellany, 1875–78. The bird once roamed New Zealand’s isles, but saw population losses in the 1800s due to hunting and the introduction of new predators. Source: Wikimedia Commons/G. D. Rowley, PD-1923.

Most people who visit New Zealand never see a kiwi in the wild. You might catch a glimpse of one in a dimly lit indoor cage, but in the wild the country’s national bird is a rare sight. Just to clarify, I’m talking about the awkward looking bird, not the odd looking fruit. New Zealand has five species of kiwi birds, native inhabitants of the “land of the long white cloud”. Thanks to introduced predators and hunting, four are on the REDD list. On the other hand, the little spotted kiwi (Apteryx owenii) has been a conservation success story. That is, until now.

Even though the little spotted kiwi is extremely rare very rare, it’s the only kiwi bird without “endangered” status. Its success story is an interesting one. Around a century ago, things were looking decidedly not good for the little spotted kiwi. It had disappeared from New Zealand’s north island altogether, and in 1912, conservationists took five remaining birds from the Jackson Bay on the South Island and moved them to a small island 5 kilometers off the North Island’s coast called Kapiti. Whether or not a native population already inhabited the island is still up for debate today, but the birds were spotted there in 1929, well after relocation.

By the 1980s, the original south island population was gone, but the birds on Kapiti were actually doing pretty well. Meanwhile, another population on D’Urville island wasn’t doing so great. Conservationists did the same thing again: moving the last remaining male and female birds on D’Urville to nearby Long Island, along with three birds from Kapiti. Around the same time, individuals from Kapiti and founded populations on some of New Zealand’s other coastal isles.

Island chart of LSK population movements through conservation efforts. Source: HMT/Ramstad et al.
Island chart of LSK population movements through conservation efforts. Source: HMT/Ramstad et al.

Taking the last individuals from a species in danger of becoming extinct  and focusing all of the energy on protecting them — either in a small area of their native range in the wild or in captivity — is a go-to worst-case scenario tactic in conservation. It worked for cheetahs, the mexican wolf, and another of New Zealand’s avian residents, the Takahe. So, the Kapiti island population flourished, exceeding 1600 individuals today. Based on numbers alone, spotted kiwis are doing great.

But, recent study published in Proceedings of the Royal Society B gives conservationists pause. Results suggests that these populations have inbred themselves into a genetic bottleneck — when a population drops, its genetic variation gets slashed. Basically, they lack genetic variety. A new disease could swoop in and easily wipe them out; the same goes for other challenges like sudden changes in climate (something that’s not out of the realm of possibility in the next million years).

“Yes, we have eight populations, and yes, they are all growing in size in terms of number of birds,” Kristina Ramstad, a co-author and a biologist at Victoria University in Wellington, NZ, told Science. “But they are all incredibly low in genetic diversity. … If the right disease comes along, it could wipe all of them out.” Science‘s Traci Watson outlines another species — the bengali tiger — that suffers a similar problem: a companion study in Proceedings of the Royal Society B found that the tigers retain only 7% of their ancestors’ genetic variation.

A map of the four populations of little spotted kiwis sampled in this study. There are four others, making eight existing populations in total. Source: HMT.
A map of the four populations of little spotted kiwis sampled in this study. There are four others, making eight existing populations in total. Source: HMT.

As for the kiwi study, Ramstad and her colleagues compared genetic data at 15 spots in the species’s genome from populations on Kapiti to those on Red Mercury, Tiritiri Matangi, and Long Island. All four populations were almost genetically identical and had telltale signs of genetic bottlenecks in recent years. Mysteriously, Kapiti birds are losing some measure of genetic diversity each year. The other groups are too. In fact, little spotted kiwis have the lowest diversity of all kiwi species. On Long Island, a single mating pair from Kapiti founded the population that persists today, and that the birds from D’Urville haven’t contributed at all to the overall genetic diversity of the species. For whatever reason, they never mated and disappeared.

“We don’t know why [the D’Urville birds didn’t breed],” Ramstad told Scientific American. “We don’t know how long little spotted kiwi live and we don’t know what’s their oldest age of reproduction. It’s still a bit of a guess, they keep outliving the scientists following them. So the birds [from D’Urville Island], could have been too old, or one of them could have been infertile. It could simply be a case that they didn’t fancy each other.”

So, what’s the takeaway message here: should conservations be doing something differently? or is the game just stacked against them? Keeping up connections between surviving populations — so that they mate and pop out genetically diverse kids — seems to be as important as making sure populations in protected areas have the best shot at survival. The sentiment seems to be that things are just a heck of a lot more complicated than originally thought. And, that’s no reason to throw in the towel. New Zealand’s Department of Conservation plans to relocate Kapiti birds (which have the most genetic diversity of the bunch) to smaller islands to boost their DNA. “Don’t keep all of your kiwis on one island” remains the best tactic at the moment.

For more info, check out Science and Scientific American‘s excellent pieces on the study: here and here.

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Bloomin’ jellies on the rise?

Seacology
Seacology
Chain or salp jellies bloom off the coast of New Zealand. Source: Seacology.

I should preface this with the fact that my experience with jelly fish is limited. To me, they’re just an occasional nuisance that looks cool at the aquarium. I’ve only been stung once, but I did have to wear a fashionable blue unitard to go snorkeling on the Great Barrier Reef  and avoid the seasonal danger of getting stung by a tiny, (sometimes) lethal box jellyfish.

Jellyfish have been around for millions of years, and jellyfish blooms, in Australia and elsewhere, are just another facet of a healthy ocean environment.  But, blooms are becoming more and more common, and spawning the  In the Sea of Japan, a now almost yearly swarm of the gigantic Nomura’s jellyfish (Nemopilema nomurai) famously capsized a boat. Large blooms disrupt fishing industries and even shutdown nuclear power plants.

Y.Taniguchi, Niu Fisheries Cooperative
RAWR BLOBS ATTACK! An outbreak of giant Nomura jellyfish off the coast of Japan in 2003 made life difficult for local fishermen. Source: Y.Taniguchi, Niu Fisheries Cooperative

Jelly fish blooms are cyclic and seasonal — lots of factors come into play like sun exposure, temperature, nutrient levels, changes in ocean currents, and the balance between predators and prey in the ecosystem. Some scientists think human influence might be the underlying issue. Agricultural runoff can add nutrients to the system, providing more food to the zooplankton that jellies eat.

Fishing can also take competitors — small pelagic fish (fish that live in the water column, near the ocean surface) such as sardines, herrings, and anchovies — out of the ecological equation. Jellies also feed on these fishes’ eggs and larva, and sans regulation, their populations can easily explode and invade new territories. Thus, over-fishing is another suspect that some scientists and conservationists point to, and a recent paper in the Bulletin of Marine Science adds evidence to the pile.

Researchers at France’s Institut de Recherche pour le Développement (IRD) present two contrasting case studies in the Benguela ocean current, which flows north along the southeastern coast of Africa. In the first, just off the coast of Namibia in an area with lax fishing regulations, pelagic fish populations barely have time to recover before fishing stars up again, and jellies are already colonizing the area. If the current trajectory plays out, sardines and the like might one day be absent from the local food chain, with negative implications for the ecosystems other inhabitants. On the other hand, the small fish still dominate the second ecosystem, off the coast of South Africa where strict fishing regulations have been in place for nearly half a century.

These scientists aren’t the first to point to over-fishing as the problem. A 2009 review paper published in Trends in Ecology and Evolution pin-pointed over-fishing, in addition to the effects of climate change and excess nutrients from fertilizers and sewage run-off, as a compelling culprit for jellyfish population growth.

“Mounting evidence suggests that open-ocean ecosystems can flip from being dominated by fish, to being dominated by jellyfish,” Anthony Richardson, a marine ecologist and a co-author, said in a statement at the time. “This would have lasting, ecological, economic, and social consequences. We need to start managing the marine environment in a holistic and precautionary way to prevent more examples of what could be termed a ‘jellyfish joyride’.”

Other researchers suggest that jellyfish are doing the same thing in Antarctica, and out-compete local penguins species.

Though some scientists think global jellyfish populations are booming, others aren’t convinced. The data is iffy (from anecdotes and case studies), and historic jelly population data is even worse. These pesky blobs are ridiculously hard to study, especially when they rival sumo wrestlers in weight. However, one group of marine biologists is tackling the daunting task of crunching jellyfish numbers. Their results published earlier this year in PNAS, say that the evidence for a jellyfish population explosion just isn’t there (…yet). It turns out that jelly fish populations oscillate over a natural 20ish year period. They also detected a small linear uptick since the 1970s, but only further monitoring will tell if that trend is a serious problem or a minor blip.

So, if we are indeed on a ‘jellyfish joyride’, how do we get off? One solution or consequence (depending on how you look at it): eat the jellies. It fact, jellyfish ending up on dinner plates seems to be the go-to example of the hardships we’ll face with over-fishing and other global food-related crisis.

Flickr/Roland Tanglao, CC-Generic
Jellyfish strips with soy sauce and sesame oil… looks a lot like pad thai. Source: Flickr/Roland Tanglao, CC-Generic.

Upon reading this, I could not help, but google, “jellyfish edible”. It turns out that some species are harvested for food. They produce tentacle toxins that are not harmful to humans and/or their bodies are more rigid. Rhopilema esculentum is popular in China, while Cannonball jellies (Stomolophus meleagris) off the US east coast are growing in popularity, as well.

In fact, jellyfish has been a staple of Chinese cuisine (read not Panda Express) for centuries. “Jellyfish masters” (I kid you not, it’s an actual job title) soak jellyfish strips in a salty mix, dry them, and ship them off to restaurants, where chefs rehydrate the strips and serve them raw or cooked. Smithsonian describes “cold shredded jellyfish” purchased at Jackey Cafe in DC’s Chinatown as “wetly crunchy” in a seaweed salad sort of way. Yum?