Why does it matter that a snail died in Hawaii?
On New Year’s Day 2019 George, a snail of the Achatinella apexfulva species, died in a laboratory at the University of Hawaii. The death of a snail might seem like a minor incident, but it’s indicative of a much broader problem: the global loss of biodiversity.
The Hawaiian islands make up just 0.2% of the landmass of the United States of America, but they account for over 30% of the listed species of the continent, so the islands are incredibly important in terms of biodiversity — hence why the loss of a snail here is so representative of the decline of biodiversity on a whole. To properly explain the importance of George’s death, let’s start with his story, and that of snails in Hawaii as a whole.
The story of George the snail
To most of us in the Western world, snails are undesirable and slimy pests who eat our plants. But in Hawaii they have immense cultural significance, and many traditional Hawaiian songs contain reference to snails, such as this one called ‘The Promise of the Tree Shells’:
Kāhuli aku, kāhuli mai
Kāhuli lei ‘ula, lei ‘ākōlea
Kōlea, kōlea, ki’i ka wai
Wai ‘ākōlea, wai ākōlea(The shell of a red ornament
Little tree shell, little tree snail
Kōlea bird, Kōlea bird, fetching the water
Water from the ‘ākōlea fern)
There’s also the Hawaiian legend of the O’ahu tree snail which is said to be the ‘voice of the forest’, singing as they travel up and down trees, and the Hawaiian name for these snails is ‘Pupukanioe’ meaning ‘the shell that sounds long’. There’s no evidence that these (or any) snails actually sing, or make any kind of noise at all, but that’s their legend in Hawaii. For instance, another traditional song is ‘Kahuli Aku’, the lyrics of which describe snails which call out to golden plover birds to bring them water.
Generally speaking, snails are culturally significant in Hawaii due to their common presence, with 752 species of snails known to have lived on the islands. Hawaii has a unique ecosystem due to its isolation, being in the middle of the Pacific Ocean 2000 miles away from another piece of land. This meant that many species had no natural predator and so could thrive without threat, and is one reason that the islands were so bio diverse.
This all changed when non-native humans began to come to the islands more regularly for exploration and trade. This led to snails being ‘collected’ by human visitors who weren’t familiar with them, as well as invasive species being brought to the islands accidentally and deliberately (more on this later), which meant that by the early 1900s many of Hawaii’s snail species were extinct.
In the 1980s conservation attempts began, with schemes like the Snail Extinction Prevention Program bringing snails being into laboratories to take part in breeding programs and protect them from predators. In 1997 a group of 10 Achatinella apexfulva were brought to a laboratory at the University of Hawaii, and in the early 2000s George the snail was born.
Shortly after his birth a pathogen breakout in the laboratory killed the rest of his family, and George became the only known Achatinella apexfulva left in Hawaii — hence his name George, after ‘Lonesome George’ the Pinta Island tortoise who is also the last of his kind. George became a bit of a local celebrity, but despite constant attempts scientists were unable to find another snail of his species to breed him with. On New Year’s Day 2019 George passed away, and another of Hawaii’s snail species became extinct.
George’s death isn’t the end of all hope for Hawaii’s biodiversity: the University of Hawaii laboratory still has thousands of native snails in residence, and they’re even beginning to release some of them back into the wild in very remote, secret locations. Plus, a 2mm sample of George’s foot was frozen and sent to San Diego zoo in the hope that some day they’ll be able to clone him to revive the species. But his story does show how human interference in the environment is causing the loss of biodiversity, through the introduction of invasive species as well as through the impacts of climate change.
The impact of invasive species on biodiversity
As previously mentioned, Hawaii’s native species thrived due to a lack of predators on their isolated islands. Before human travel to the islands became the norm, it’s estimated that a new species would reach the islands by air or by sea only every 100,000 years, but this increased massively — both through the accidental introduction of species arriving with humans on their boats, and through the deliberate introduction of some species. Hawaii doesn’t have any native land mammals, but when Polynesians settled there they brought pigs, goats, deer and dogs as domesticated livestock and as offerings to Hawaiian royalty (‘Goats and European hogs were brought in 1778, sheep in 1791 and cattle in 1793 — Hobdy, 1993.) These became destructive through their intensive grazing habits, damaging soil cover and eating native plants.
Another example of the deliberate introduction of an invasive species is the wolfsnail, brought to Hawaii in an attempt to control populations of giant African snail (a species with a very strong shell capable of piercing car tyres, that was brought to Hawaii accidentally). The wolfsnail did not manage to control the giant African snail, and instead ate native species of snail.
The Erythrina gall wasp, on the other hand, was introduced accidentally from East Africa, and is now also found in Asian countries such as Singapore and the Philippines. The wasp has been incredibly harmful to the wiliwili tree, native to Hawaii, as they lay their eggs in the leaves of the tree and interfere with its ability to take in water and sunlight. Wiliwili trees are an important habitat for other species in Hawaii, but they’ve also long been used as windbreaks, planted along the edges of crop fields to protect crops from wind damage. This example makes it clear how important biodiversity is: the downfall of one species also impacts several others.
The impact of climate change on biodiversity
Human-caused climate change is the other reason for an acceleration in biodiversity loss in Hawaii. Rising sea levels, increasing temperatures, and flooding are all changes to the climate that native species are being forced to adapt to, with varying degrees of success. Mosquitoes, for instance are thriving due to the higher temperatures, but in turn they threaten many of Hawaii’s native birds through carrying diseases such as avian malaria.
Climate change is also magnifying the impact of the existing invasive species. Increased rainfall and higher temperatures, for instance, have allowed the wolfsnails to venture into higher altitudes, and into the last refuges of the native snail species.
Why does it matter: what’s the importance of biodiversity?
“Without biodiversity, there is no future for humanity.” Professor David Macdonald, University of Oxford.
As we’ve seen with the example of the wasps which damage wiliwili trees, which then has an impact on crop growth, our Earth functions as part of a complex ecosystem. Scientists don’t know exactly what makes an ecosystem function correctly, and therefore how much loss the system can take before it crumbles entirely. It appears that there are some key species that would have a huge impact if they were lost, but it also seems that the total number of species overall is important. We don’t have a number to stay within because we simply don’t know how many species can be lost before the ecosystem ceases to function, but we do know that by allowing (and increasing through human activity) biodiversity loss, we are playing a risky game with the future of our planet.
Much of it comes down to stability. If we think about the Earth’s ecosystem as a Jenga game, with each species extinction we are removing one block: how many blocks can be taken out before the tower falls down? Plus we know that human activity is also altering our environment in other ways through climate change: increased greenhouse emissions, higher surface temperatures, decreased water quality etc. Think of this like placing the Jenga tower outside in a storm (representing climate change) and then start taking the blocks out (biodiversity) — then you can start to see how human activity is playing a dangerous game with the structure and ecosystem of our planet, and to see why the work of schemes like the Snail Extinction Protection Program at the University of Hawaii is so important.
