Climate change a looming threat for native invertebrates, reports find
New conservation reports have shone a light on just how diverse New Zealands creepy crawlies really are, but their tendency to stay local means many are in grave danger. The Department of Conservation (DOC) has released three Threat Classification System reviews, two covering native leaf-veined slugs and land snails, and one covering native spiders. The reviews, which are carried out by expert panels every five years, analyse the threats facing native species by group. They can then declare just how endangered a species is. READ MORE: * Katipo spiders: another native species in decline * Last call for five-yearly native bird threat level updates * Secluded slug no worry to gardeners One report analysed New Zealands 63 species of leaf-veined slug. It found six species were threatened, 28 were at risk, and 20 were not threatened. Eleven species were data deficient, and 46 were noted as new listings including two that were critically endangered. It also found New Zealands one species of amber snail, which lived in the Far Norths Te Paki , was critically endangered. The second report analysed 48 other land snails, ranking 23 as threatened, 13 at risk, four as not threatened and eight as data deficient. Nine were new listings. DOC slug and snail expert Eric Edwards said many species were only found in a certain region, like one mountain, or a small part or Northland. That makes those species very vulnerable to extinction, especially when other factors come into play whether that be human interference, or climate change. Edwards said the chances of a fire, storm, flood, or even an unexpected snow event tearing through a habitat had risen over the last decade. Introduced pests were a threat too. For larger snails, that meant rodents. Smaller species were vulnerable to argentine ants a colonising species so voracious they could clear out beehives. Edwards said New Zealand was full of interesting invertebrates, unique to the country for millions of years. [They] are part of our ecosystems too. Leaf-veined slugs, for example, are not your garden variety slugs. They dont feed on leaves, but the leafs surface. Theyre cleaning off the gunk, so flax can actually get more sunlight and grow more efficiently. The spider report included assessments of 1157 species, including 37 newly listed ones. It found four were threatened, 182 were at risk, and 428 were not threatened. A total of 494 species were described as data deficient, because there was not enough information to make a decision. Te Papa spider expert Phil Sirvid said many faced the same issue as snails they only seemed to live in a single spot. One example was Migas taierii , a tree trapdoor spider, newly classified as nationally endangered. Its known from a single, unprotected site in Otago, which is prone to coastal erosion. However, just because a species had not been found very often, it did not necessarily mean it was rare. Many have only been found once, and never again. Not a lot of people are actually going out looking for spiders. The list is going to keep growing there are still plenty more species to be found. While the new report had not quantified the impact of climate change, Sirvid said it was increasingly becoming part of DOCs thinking. Spiders that live on coastal strips like katipo, which are an iconic species may become vulnerable to sea level rise. Alpine species, what happens to them when temperatures rise? Do they just keep moving further up the mountain? New Zealands spiders were incredibly special, and worth protecting, he said. Around 95 per cent of these species are only found in New Zealand they're as special as kiwi or kakapo . If you imagine a world without spiders, which some people might like to, just think about how many insects get eaten by spiders annually .