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Duration:05:40
Uploaded:2018-11-02
Last sync:2018-11-02 17:10
Hurricane Walaka wiped out a small Hawaiian island, which could be devastating for some endangered animals, and new research says that we might be wrong about the origins of giant tortoises.

Hosted by: Hank Green

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Sources:
Island:
https://www.civilbeat.org/2018/10/this-remote-hawaiian-island-just-vanished/
https://motherboard.vice.com/en_us/article/evw337/hurricane-walaka-caused-remote-east-island-hawaii-to-disappear-sea-level
https://www.nytimes.com/2018/10/25/us/hawaii-east-island-disappears-walaka.html?rref=collection%2Fsectioncollection%2Fscience
https://nationalpost.com/news/world/hurricane-wipes-six-foot-high-east-island-from-the-face-of-the-planet
http://www.westhawaiitoday.com/2018/10/04/hawaii-news/7-researchers-evacuated-from-papahanaumokuakea-as-storm-nears/
https://www.nhc.noaa.gov/aboutsshws.php
http://www.turtles.org/hawgrnd.htm
Tortoises:
https://www.eurekalert.org/pub_releases/2018-10/mh-teh102318.php
https://onlinelibrary.wiley.com/doi/abs/10.1111/cla.12227
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Images:
https://en.wikipedia.org/wiki/File:French_Frigate_Shoals_map.png
https://commons.wikimedia.org/wiki/File:Ffs_map_lrg.png
https://en.wikipedia.org/wiki/File:French_frigateISS004-E-11926.PNG
https://www.eurekalert.org/pub_releases/2018-10/nsfc-nsw100118.php
https://commons.wikimedia.org/wiki/File:Walaka_2018-10-02_0054Z.jpg
https://commons.wikimedia.org/wiki/File:East_Island,_Hawaii_before_and_after_Hurricane_Walaka.jpg
https://flic.kr/p/TExh4u
https://flic.kr/p/HGje3Y
https://flic.kr/p/ptEGa4
https://www.flickr.com/photos/onms/26640823494/
https://www.flickr.com/photos/papahanaumokuakea/14974739203/
https://www.flickr.com/photos/papahanaumokuakea/15595944542/
https://commons.wikimedia.org/wiki/File:Tern_Island.JPG
https://www.flickr.com/photos/dereksimeone/36836034845
https://www.eurekalert.org/pub_releases/2018-10/mh-teh102318.php
https://www.istockphoto.com/photo/galapagos-giant-tortoise-turtle-galapagos-islands-ecuador-gm812444230-131433345
https://i.kinja-img.com/gawker-media/image/upload/bk2rqsluhfpozpkrz0ar.jpg
[ ♪ Intro ].

Unlike much of the rest of Hawaii,. East Island in French Frigate Shoals isn’t much of a tourist hotspot.

Even locals weren’t super familiar with this small, 4.5-hectare strip of sand 890 kilometres north-west of Honolulu. That is, until it disappeared overnight. The island was almost completely submerged underwater when Hurricane Walaka hit the first week of October.

And Hawaiian scientists confirmed it had been washed away on October 23, a disaster which could affect endangered wildlife for years to come. Hurricane Walaka peaked as a Category 5 storm, the highest on the Saffir-Simpson Hurricane Wind Scale, though it had somewhat weakened to a Category 3 storm by the time it hit the Northwestern Hawaiian Islands. Still, anything in its path faced sustained winds of more than 200 kilometers per hour and a storm surge a few meters high, since seawater is being pushed on shore by such strong winds.

Though East Island was the second largest in the area, it maxed out at about 1.8 metres in elevation and its loose sands were held in place by vegetation. It didn’t stand a chance. Thankfully, the seven researchers working at French Frigate Shoals were evacuated before the storm hit.

That doesn’t mean that weren’t any casualties though. The cluster of small islands that comprise French Frigate Shoals are important breeding grounds for Hawaiian monk seals. 16 percent of the population lives there, and before the storm, 30 percent of seal pups were born on East Island specifically. There are around 1400 Hawaiian monk seals left in the entire world so a hit to one of their main breeding grounds could spell disaster for the species.

Conservation biologists say they won’t know the effect of the storm on the population until they do surveys next year, but they’re staying optimistic. It’s likely many of the seals had migrated away from the island before Walaka hit. But the seals weren’t the only ones affected.

East Island is also the nesting ground for more than half of Hawaii’s green sea turtles, a species that’s threatened with extinction. The turtles, too, had moved on since their breeding season ended before the storm passed through, but losing the island is a big deal because lack of suitable nesting sites is one of the major reasons for the turtles’ low numbers in the first place. Conservationists hope they’ll find other places to nest when they return.

And the island was frequented by seabirds, too, including blackfooted and Laysan albatrosses. How the loss of land will affect them remains to be seen. What shocked those familiar with the island isn’t so much that it disappeared but how quickly it happened.

Another island in the same archipelago, called Whale-Skate, eroded away back in the 1990s, but that took several years. Environmental scientists knew East island would eventually succumb to rising sea levels, but thought its disappearance would take decades, not hours. Although we can’t blame climate change directly for the loss of East Island, the increasing severity of storms is a direct consequence of global climate change according to the Intergovernmental Panel on Climate Change.

That’s because warmer waters feed these storms. What happened to East Island is a sobering reminder of just how vulnerable many habitats are, particularly islands. In other island related news, scientists have dispelled a commonly held belief when it comes to tortoise evolution on islands in a paper published in August in the journal Cladistics.

Island gigantism is a theory that explains how small animals that live on islands become massive over time through evolution, either because of the lack of predators or some other ecological quirk of island life. And this appeared to explain the size of tortoises, as most of the giant species, the ones which can be more than one meter across, are now found on the Galapagos islands. But by completely reconstructing the family tree of the tortoise family, Testudinidae, scientists have shown that massive tortoises likely evolved on the mainland and only later spread to nearby islands.

The researchers looked at a total of 72 groups of tortoises from all over the world, both living and extinct, as well as outgroups, groups of animals that aren’t related to ones being investigated. They used descriptions of the tortoises’ physical features, bone fragments, fossils, and mitochondrial and nuclear DNA to figure out how the groups were related to one another. And their new evolutionary tree showed that giant tortoises popped up several times during Earth’s history in mainland Asia, Africa, Europe, North and South America, before dispersing into nearby islands.

It’s not certain why the bigger species ended up offshore, but it could be that their size helped them survive the long swim and especially the lack of food on that journey. Then, during the Pleistocene ice age, the ones on the mainland disappeared, making it look like island gigantism was at play. But it’s not completely case closed for the tortoises.

Biologists still want to understand why giant tortoises evolved on the mainland, and what wiped them out. Climate change and predation from humans may have been to blame, but they’re still looking for evidence for those in the fossil record. But, if there’s one thing that’s clear, it’s that islands are very important, and not just for vacationing.

Thanks for watching this episode of SciShow News! If you want to keep up to date with the latest in science, be sure to check out our weekly news episodes every Friday. And speaking of new things, we’ve recently enabled channel memberships on this channel.

For about $5 a month, you can become a member and get access to some sweet badges and emojis and our members-only posts in the community tab. Our videos, of course, will continue to be available for everybody for free, but if you want to become a supporting member and get those extra goodies, you can do that just by clicking on that little Join button below the video. [ ♪ Outro ].