What’s the first thing you think of when someone says the word ‘animal’? Perhaps your initial thoughts were of a lion, or a bear, an eagle, or even a whale. What about invertebrates, like snails and insects? They seldom cross your mind. That’s a shame, as they are fascinating animals?
Land snails are very important to our ecosystems despite the destruction they cause in our gardens. Snails eat a variety of things, like rotten plants and vegetables, wet leaf litter, fungi, sometimes other invertebrates, and believe it or not, soil. Did you know that, besides the common snails you see in your gardens, NZ actually has native snail species? They are endemic to NZ, and like any other decomposing organisms, these snails are essential to maintain various cycles in our environment.
Over the planet, insects and molluscs, combined, outweigh humans by a factor of 17-fold and mammals by 10-fold. So clearly we should not ignore them?
New Zealand’s snail species are often rare and difficult to find. A study, published in PLOS, by a researcher at the Bio-Protection Research Centre and Lincoln University Stéphane Boyer, studied New Zealand native endangered land snails, including Powelliphanta augusta, to gain insights about this rare species.
The Powelliphanta species are critically threatened and information about them is very limited. In order to help maintain the Powelliphanta populations, Stéphane used DNA to help mitigate their possible extinction risk.
What’s known about this rare snail species?
Powelliphanta augusta, also known as the Mount Augustus snail, is a large, air-breathing, carnivorous snail that belongs to the family Rhytididae. They eat other invertebrates and a large proportion of their diet comes from native earthworms and slugs. These snails live for more than 20 years, which is phenomenal for a snail.
Over the past decade, these snails have undergone drastic changes and their population has plummeted, in part because of the coal mining industry on the West Coast of NZ, as well as heavy predation from invasive species. Deforestation, habitat destruction and predation has resulted in this snail becoming rare in their own habitat. Though breeding programs exist to maintain their population, the question still remain whether their own survival is possible without human intervention?
DNA technology (next-generation sequencing) to study the Mount Augustus Snail
Stéphane Boyer used DNA technology to genetically identify species eaten by P. augusta. This was no easy task, as it required DNA analysis of materials found in a snail’s stomach or faeces. Mount Augustus snails are particularly rare and endangered, meaning any method that requires the death of the snail is prohibited. Snail poo was collected to investigate the DNA composition of the snail’s prey.
Stephane’s wanted to use information about the land snail diet to ensure better conservation practices. This allows other Mount Augusta snail reserves to provide supplemental food for the endemic snails with an appropriate diet. This would give the snails the chance to establish and flourish at a faster rate.
On average, 16 different species of exotic and native earthworms were found in each faeces sample. The results also showed that Mount Augustus snails forage randomly through leaf litter and predate on any worms they stumble upon.
It is a revelation to know that P. augusta can predate on a broad range of earthworm species. This gives allows managers to provide the snail with any species of earthworm that is available to them. The generalist diet has important implications for the conservation strategies and management of P. augusta. The restoration of their habitats, the feeding regimes for snails held in captivity, and the choices of new relocation areas are simplified since the earthworm’s can forage on virtually any worm.
Overall, these DNA methods have increased the options for conservation of many other endangered species whose dietary intake remains unknown. DNA technology is progressing way faster that at a snail pace. Which is great news for our New Zealand snails.
Maui Duley is a postgraduate student completing a Master of Science. He wrote this article as part of his assessment for ECOL 608 Research Methods in Ecology.