Invasive species could reap benefits from extreme weather

PARIS: Extreme weather might be wreaking havoc across the globe, but some non-native plants and animals could be benefiting from the disasters, adding risk to already threatened local species, according to a new study on Monday.

Invasive species, often transported by human activity, are thought to be playing a major role in global extinction rates and the catastrophic declines of biodiversity threatening the well-being of people and planet.

Heatwaves, droughts, floods and other extremes accelerated by global warming might be giving the often destructive invasive species an undesirable advantage, researchers found. The harmful invaders experienced positive impacts from extreme weather almost a quarter of the time, nearly double that of natives, according to the study published in Nature Ecology & Evolution.

Local species were also more likely to suffer negative consequences from the weather disasters. “EWEs (extreme weather events) might facilitate the establishment and/or spread of non-native species and these two processes may combine together to pose high threats to biodiversity under continuing global change,” lead author Xuan Liu of the Chinese Academy of Sciences in Beijing, told AFP.

Invasive species were only vulnerable to heatwaves and storms, the study found. But native animals on land and in fresh water were negatively impacted across several factors -- including survival rates, reproduction and body size -- from all extreme weather except cold spells in freshwater.

The researchers looked at hundreds of previously-published studies on responses of 187 non-native and 1,852 native animal species to extreme weather patterns in different habitats.

They found that differences in responses to unusual weather in species could be due to the death of native species during weather extremes, leaving a gap for invasive species to exploit. Severe droughts, for example, increase the salt content of water, killing local invertebrates and fish while providing an opportunity for more salt-tolerant species to move in.