Maybe these are the alien populations we should be worried about

By Tom Baxter

By far the weirdest story in the world this year — it makes “The Shape of Water” sound plausible — begins with a little critter which lives only on the tributaries of the Satilla River in Georgia and Florida.

More than a quarter century ago, as nearly as scientists have been able to piece the story together through DNA research, some examples of Procambarus fallax, the slough crayfish, were taken from the river where they are native and ended up in a German aquarium. In 1995, a rare fish collector told Frank Lyko, a geneticist at the German Cancer Research Center in Heidelberg, about some strange specimens he’d purchased called “Texas crayfish.” They were very big, and produced a lot of eggs — all of them produced eggs.

This would go on to be recognized as an entirely new species, Procambarus virginalis, the marbled crayfish, or Marmokrebs in German. Researchers have speculated that a crayfish from the Satilla may have ended up in a tank with a related species from somewhere else in the world, increasing the genetic randomness of their tryst. What they are sure of is that a single encounter between two mudbugs produced a mutant female crayfish capable of cloning herself. Every egg she produced, and all those in succeeding generations, is an exact genetic duplicate of that first mutation.

By the time scientists had traced the origins of this new species back to the Satilla, marbled crayfish, which made a nuisance of themselves in collector’s tanks, had spread into rivers and lakes across much of Germany and Eastern Europe. They’ve turned up as far away as Japan, and in Madagascar, despite considerable harvesting for food, they are overwhelming the existing species of crayfish.

The new species hasn’t shown up in the Satilla, which is one way we know the mutation happened somewhere else. But Georgia has more than its share of foreign invaders to contend with. For all that our politics centers around human illegal immigration, the cumulative impact from migrating plants, animals and bugs may be our greater concern, particularly in a time when conditions are ripe for them.

Some of the species we still class as invasives have been around a long time, longer even than kudzu, which got here in the late 1800s. Many species, like the Chinese Tallow tree, which arrived in the 1700s, were imported because somebody thought they were a good idea. Over time, however, invasives have crowded out native species and created more problems than they solve.

More recent arrivals have shown their ability not only to establish themselves, but to change their behavior to adapt to their new environs. Scientists from the University of Georgia’s Warnell School of Forestry recently conducted the largest-ever study of coyotes in the Southeast noted a change in the habits of these recent arrivals.

The first coyotes to arrive in the state were mostly scavengers, preying on the newborn fawns of white-tail deer in the spring and the occasional suburban pet. Michael Chamberlain, the lead scientist on the study, estimated there now are abut now some 90,000 “transients” in Georgia, moving along the edges of urban settlement and scavenging for food.

But back in the country, in the “deep, wet woods,” as Chamberlain put it, a much larger population of coyotes, perhaps a quarter-million in this state, have become “residents,” staking out their territory and beginning to hunt white-tail deer year-round in an organized fashion.

If it has been a while since you’ve heard of someone hitting a deer with their car, this may be part of the reason. Coyotes have had enough impact on the deer population, and thus the deer-hunting population, that the state has launched its second-annual “Georgia Coyote Challenge,” which offers trappers the opportunity to exchange coyote carcasses for the chance to win a lifetime hunting license.

Even aside from the contest, hunters in Georgia are killing an estimated 30,000 to 40,000 coyotes a year, without having a severe impact on the growing population.

Invasive species look for weaknesses in established environments, for changes they can exploit. That means that in a time of climate change and environmental distress, newcomers can move faster, and the weeds, trees, bugs and other species that have been here a while can gain new strength. If we aren’t yet being overrun by mutant crayfish, we still have plenty to worry about.

 

Tom Baxter has written about politics and the South for more than four decades. He was national editor and chief political correspondent at the Atlanta Journal-Constitution, and later edited The Southern Political Report, an online publication, for four years. Tom was the consultant for the 2008 election night coverage sponsored jointly by Current TV, Digg and Twitter, and a 2011 fellow at the Robert J. Dole Institute of Politics at the University of Kansas. He has written about the impact of Georgia’s and Alabama's immigration laws in reports for the Center for American Progress. Tom and his wife, Lili, have three adult children and seven grandchildren.

3 replies
  1. Gil Robison says:

    Not mentioned is that the coyotes’ prey, white tail deer, is itself an exotic invasive introduced repeated by GA Department of Natural Resources for hunting despite the ecological damage it causes.Report

    Reply
  2. Kay Stephenson says:

    The insanity is that you can still purchase some of the worst invasives at any garden center. It could be the lifework of half the population and I bet we still couldn’t erradicate all of the English ivy.Report

    Reply
  3. Brian Williams says:

    Point of fact: the white-tail deer is not invasive to Georgia. This is a native deer that was virtually exterminated from the state by the early 1900s due to habitat destruction (logging), overhunting (year-round), and extermination of natural predators (mountain lions, wolves). The Forest Service reintroduced it starting in 1928.

    The white-tail deer can be a pest, but it is a native pest, not an exotic, and has its place in the scheme of things. The coyote is filling a predator niche that has been wide open since the decline of the red wolf, and should help balance the deer population.Report

    Reply

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