Close up view of a Chinese mystery snail.

As threats go, being overrun by an invasive snail species is about as frightening as, say, being run over by a glacier.
But that — the snail invasion, not the runaway glacier — is just what’s happening in some western Missouri waterways.
The culprit: A poetically named invertebrate called the Chinese mystery snail.
First discovered in the Blue River near Kansas City a few years ago, the snails now have been confirmed in five other waterways. They recently were found in the Niangua River. Reporter Kim McGuire wrote about their spread in Monday’s Post-Dispatch.
Despite the name, there’s very little mysterious about Chinese mystery snails. The animals, which are about the size of chicken eggs, were first imported as a food sold in Asian groceries more than a century ago.
They’ve since become popular in fresh water aquariums because they eat algae. They probably were released into the wild by careless dumping, joining a host of non-native species that have established niches in our state.
Unfortunately, increased competition between native and non-native species probably are the wave of the future.

There’s nothing new about invasive species. Animals and plants have been jumping geographic and political boundaries since humans first began exploring the world hundreds of thousands of years ago.
Missouri already is home to dozens of non-native species, including Asian carp and zebra mussels — not to mention kudzu and armadillos.
These invaders are, in some cases, nothing more than a curiosity. But in other cases, they can be expensive pests.
Zebra mussels reproduce so prolifically that they can clog inflow and outflow pipes in rivers and lakes, requiring expensive maintenance. They also encrust the hulls of boats and barges, requiring that the vessels be taken out of service and cleaned.
Other imported pests, especially gypsy moths and Asian longhorn beetles, threaten Missouri hardwood forests and the timber industry those forests support.
Biologists worry that new species will out compete or crowd out native plants and animals, many of which are uniquely adapted for our environment.

It takes time for animals and plants to adapt to the environment in places like Missouri and Southern Illinois.
It takes a lot less time for non-native species to move in and displace those plants and animals.
Biologists say that one likely effect of global warming is increased competition between local and imported species. That’s because the environment to which those native plants and animals adapted is changing quickly.
Take Missouri’s average winter temperature as just one example. Over the past decade, it’s been about two degrees higher than it was during the previous peak in the 1930s.
That has important implications for wildlife and agriculture. Migratory patterns of ducks and other birds have changed as a result, with their peak arrival occurring about a week earlier.
Climatologists predict that by the end of the century the climate in Southern Illinois will be similar to that now experienced in eastern Louisiana or South Texas.
No wonder species like armadillo, once only found much farther south, have begun turning up here.
A new snail species may not seem like a big threat — just as slightly warmer average winter temperatures don’t seem like a big deal.
But each little change has the potential to disrupt the delicate ecological balance.
Ultimately, those little disruptions can create very large — and very undesirable — changes.