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I was recently asked by a researcher in Hawaii to identify some spiders collected  during a study of introduced arthropods on a coral atoll in the Pacific.  The specimens arrived from the researcher in good condition.  I have to say that am by no means an expert on the arthropod fauna of Pacific islands, but I had agreed to look at the six spiders, all of the same species, which had been collected from shrubs on the atoll. My suspicion was that they could not be native, and I was soon proven right!  Using the literature I had at hand and the power of the Internet I easily nailed down the identification - it was a spider species that probably originated in New Guinea, but was now distributed from Burma to Hawaii!

This is not the first time apparent "native" arthropods turned out to be introduced.  On the island of Puerto Rico I spent a week with the late describer of the red imported fire ant, Dr. William Buren, sampling ants and other arthropods during a study of a pest that had been introduced to Florida from the Caribbean. We were interested in possible predators of the pest, a weevil known for its broad host range.  Ants were among the most effective predators of both young larvae and eggs.  Interestingly, some of the ant fauna actually originated from as far away as New Caledonia!  The tropical fire ant (Solenopsis geminata), super abundant especially at Caña Gorda, was soon to be faced with the introduction of the dreaded red imported fire ant (Solenopsis invicta), which we discovered and reported for the first time from near Ponce on the Caribbean shore!  Within a year or so the ants had made it all around the island to San Juan!

Although especially vulnerable to invading biota, islands are not by any means the only invasion sites.  Florida has had numerous introductions, from pythons and monitor lizards to walking catfish and beefwood trees. The number of introductions (in part because of exotic animal hobbyists releasing their "pets" into the wild and in part because hurricanes sometimes devastated wild animal farms and roadside zoos) could easily fill a book. Similarly, on a visit to a biodiversity center in the Mexican state of Chiapas in 1999 I was asked to identify some spiders that a graduate student was studying.  Two of the three species were cosmotropical tramp species, one of which I also found near Las Cruces in New Mexico (as well as all over Florida!)

Some introductions have for the most part been benign, or even beneficial, but some have been spectacular disasters and introducing any new organism can lead to ecological consequences that are often not easy to assess, even if human interests are initially benefitted. The Asiatic pill clam Corbicula manilensis was at first a curiosity when it showed up in Southwestern U.S. canals, but soon it was displacing native clams and even plugging up irrigation lines.  When on a field trip to Baja California Sur in the early 1970s our group found no native clams in any stream or river, but lots of Asiatic pill clams.  This caused our resident pelecypod specialist to become a bit depressed to the point he ate coctel de almejas (clam cocktail) in La Paz and was the only one of us to get sick!

Some other introductions have been much more destructive. Among these were water hyacinths (from South America) to the the Southeast United States (and many other places), the introduction of rabbits to Australia, the introduction of goats to numerous islands, and the feral hogs that are now spreading in New Mexico, not to mention the numerous other flora and fauna, such as pythons, monitor lizards and iguanas to Florida. I first saw water hyacinths in a canal near Toplobampo, Sinaloa, in the early 1970s.  When I moved to Florida in 1973 I got involved in helping another graduate student in his study of organisms associated with these tenacious plants, which were blocking waterways all over the state.  Of course the previously mentioned red imported fire ant (introduced from Brazil) has cost millions  (if not billions) of dollars and exposed vast areas of the Southeast to persistent pesticides like Aldrin.  

Water Hyacinths at Lake Okeechobee

Water Hyacinths cover part of Lake Okeechobee in Florida.

New Mexico has had several invertebrate invaders, including the Russian wheat aphid, the sowbug-eating spider, the Mediterranean squint-eyed spider, the false black-widow, the pill bug, the sowbug, the boll weevil, the pecan weevil, the pepper weevil, the red imported fire ant, the Africanized honey bee and a number of others. Not to mention the numerous Eurasian weeds like London rocket, Russian thistle, leafy spurge, yellow star thistle, Syrian rue, and many others.  I found Eurasian horehound growing quite happily only a stone's throw from the Gila Wilderness. African Lemann love grass has been deliberately planted in the deserts of Arizona and New Mexico to control erosion, at the cost of native grasses. Finally, some people had the grand and glorious idea that we needed to be able to hunt oryx (African gemsbok) and ibex here in the Land of Enchantment and so they brought them in with the blessing of the state, with some not so wonderful results.

Unfortunately a full exposition of all the alien flora and fauna that have been imported even to the United States would easily fill several books and I can only mention a few.  Their legion is growing larger every year and many pose some serious problems for land managers, among others.  

Thus, in addition to royally shafting the planet with greenhouse gasses and numerous pollutants, we are altering the very biodiversity by the deliberate and accidental introduction of exotic species!  Welcome to the new earth - the Anthropogenic Age if you will - to be followed, many of us think, by a post-anthropogenic age of uncertain characteristics that are likely to not be ideal for human civilization. The very wealthy may "go Galt" as they say, but they may find it a bit of a difficult, if not impossible, existence. Even they cannot control the weather, at least outside their mansions (or domes if things get really bad), and those require energy.  Species that they would not prefer to contact may impinge on their little biospheres, such as rats, coyotes, starlings, crows, and feral cats and dogs.  Even if they can keep these out they may be plagued by microorganisms and arthropods like bed bugs and African bees, many of whom can enter through almost invisible cracks in any manufactured structure or enter on supplies or even humans (especially microorganisms).  We would be wise to avoid such a world if we can.

Originally posted to Desert Scientist on Tue Nov 13, 2012 at 10:21 PM PST.

Also republished by Backyard Science, SciTech, J Town, and Community Spotlight.

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