Robert Cowie Publishes Article Describing the Devastation of Island Biodiversity

Devastation of island biodiversity: a land snail perspective

Robert Cowie, along with Philippe Bouchet and Benoît Fontaine of the Muséum national d’Histoire naturelle in Paris, just published (open access) a review of the devastation of endemic island land snail faunas, in the journal Philosophical Transactions of the Royal Society B. Although global in scope, the article placed an emphasis on Hawaii and the islands of the Pacific because this is the region across which the highest numbers of land snail species extinctions have taken place. The story goes back into the Pleistocene and early Holocene when climate change and sea-level fluctuations led to the formation of so-called ‘fossilized’ sand dunes that buried numerous species; some of these can now be seen, for instance, in exposed deposits along the trail to Ka‘ena Point from the Wai‘anae side of O‘ahu.

Unfortunately, far more species – on some islands (such as the Gambier Islands) almost the entire land snail fauna – have gone extinct as a result of human activities. The review takes a chronological perspective in discussing in sequence the devastating effects of these activities, which largely followed the same sequential pattern on islands across the globe, even as the starting point varied widely from thousands to hundreds of years ago.

Deforestation and the indirect impacts of invasive species began with the initial arrival of people and became more intensive as time went by, up to the present day. Direct impacts of invasive species on island land snails are exemplified by rats and deliberately introduced predators such as the rosy wolf snail and the New Guinea flatworm; these have probably been the ultimate cause of extinction following the devastating habitat loss that set the extinction process in motion. Few people eat island land snails (they do in New Caledonia, for instance) but hobbyist shell collectors and use of shells of the most pretty and gaudy species for creation of lei, decoration of hats, and other ornamental uses may have had an impact on snail populations. And finally, climate change, although it has not done so yet, may lead to extinction of island land snail species, especially montane species, as their habitat vanishes with a warming climate.