The Science of Sustainability

Lionfish, Pythons, and Garlic Mustard — Oh My!

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This invasive Burmese pythons was found in the Florida Everglades in the spring of 2012.  Stretching 17 feet, 7 inches, she broke the records for length—7 feet, 7 inches—and the number of eggs she contained—87. Photo courtesy USGS.

This invasive Burmese python found in the Florida Everglades in 2012 broke records for length at 17 feet, 7 inches, and for the number of eggs she contained—87. Photo courtesy of USGS.

The list of “America’s Least Wanted” keeps growing. Garlic mustard was listed in 1991, red lionfish in 2000, and Burmese pythons in 2004. These three organisms join a long list of alien invaders to the Americas that began (according to the written record) with the arrival of the Nina, the Pinta, and the Santa Maria. While many of us might find things to enjoy about aliens — like the murmurations of starlings, the fragrance of honeysuckle, or the Godzilla-like kudzu caricatures in our landscape — ecologists are not amused. In fact, they're worried, wondering if the latest least-wanteds might be capable of triggering a cascading ecological collapse on a scale that will be visible in the future rock formations of our time.

The concept of a cascading collapse, when a minor incident unexpectedly triggers a major calamity, is not unique to the natural world.

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Ecologists worry that niches are like electrical junctions, where the loss of one could halt energy flow and collapse the entire ecosystem. Courtesy of Stickulator via Wikipedia.

The summer of 2013 marked the 10-year anniversary of the cascading collapse of the Northeast power grid. A simple spot of contact between a drooping power line and a tree branch in Walton, Ohio, was able to halt all electrical activity across eight states because a software bug kept an alarm system from working. It took an hour for the first unnoticed failure to trigger a second, and 40 minutes for the second to trigger an additional 15 failures. It took another 28 minutes for officials to begin cutting ties to the flailing system in Ohio, but by then it was too late. Three minutes later, railroads, traffic, television, cell phones, air conditioning, and industry from Ontario to Philadelphia went silent.  It took less than three hours to put 50 million people in the dark.

Could invasive species like lionfish, pythons, and garlic mustard trigger a similar kind environmental “blackout”?

Invasive Lionfish feed on practically anything that swims and can easily devour the young of important commercial fish species, such as snapper, grouper and sea bass.  Photo courtesy NOAA.

Lionfish are snapping up anything that swims reducing commercial fish species such as snapper, grouper and sea bass by 70%. Photo courtesy of NOAA.

Red lionfish are dazzling, clothed in vibrant contrasting colors and armed with 13 neurotoxin-tipped spines. They add majesty to any home aquarium. But since lionfish were inadvertently released into the wild, they have spread from the tropical reefs off Florida to the temperate reefs off North Carolina. Vacuuming up lobsters, crabs, shrimp, wrasses, bogies, juvenile snapper, and juvenile grouper, they decimate the reef’s herbivores and leave the seaweed unchecked. Unbridled seaweed then flourishes and smothers the coral animals. Stifled corals eventually die and the physical structure of the reef community crumbles.

Pythons are strangling herbivores, omnivores, insectivores, and even top carnivores like the American alligator.  Photo courtesy USGS.

Pythons are strangling herbivores, omnivores, insectivores, and even top carnivores like the American alligator. Photo courtesy of USGS.

Burmese pythons sport an invisibility cloak of muted colors, come equipped with multiple rows of small, sharp teeth, and pack 150 pounds of muscle into a 21-foot ribbon of constricting skill. They impress the heck out of family and friends when draped across shoulders, but when they are inadvertently released into the Everglades they find a habitat they can plunder. Stomach analysis has revealed evidence of consumed mice, cotton rats, wrens, rabbits, squirrels, ibises, little blue herons, deer, bobcat, opossum, raccoon, and alligators. Pythons are squeezing the life out of the entire food web.

Garlic mustard is crowding out the seedlings of the next generation of trees near a stream bank in Illinois. Photo courtesy of Adam Davis, University of Illinois.

Garlic mustard is crowding out the seedlings of the next generation of trees near a stream bank in Illinois. Photo courtesy of Adam Davis, University of Illinois.

Garlic mustard lives most of its two-year life in low, tight bunches of overlapping heart-shaped leaves. First collected in Long Island in 1868, it was thought settlers brought it from Europe for medicinal purposes. During its second spring it bolts, blooms, and sets hundreds of seeds. Thriving in low light, stinking of garlic, and distasteful to deer, garlic mustard smothers moss, ferns, flowers, and the seedlings of future pine, oak, maple, hickory, ash, and beech trees. Once established, the odiferous oils repel the beneficial fungi in the soil that ensure the regeneration of oaks, maples, and beeches in the forest.

Yikes!  Is there an app for that?

There is nothing intrinsically evil about lionfish, pythons, and garlic mustard. A close look at their life histories reveals they have several generalist characteristics like humans — prolific reproduction, broad food and terrain tolerances, and wide dispersal mechanisms. In their home habitats where these organisms evolved, they are kept in check by a host of competitors, predators, pests, or diseases with which they coevolved. It is only when they travel to new continents without those restraining relationships that havoc is wreaked.

So what is a post-Silent Spring, GMO-wary, sustainability-minded, globalized invasive species like us supposed to do to check these “pests”? Crop dust with poisons? Import diseases? Bioengineer infertility?

Welcome to the anthropocene — the Age of Man — where all the ecosystems are transforming, the temperatures are above average, and all the decisions are ours to make.

 

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Category: Biodiversity, Biology, Blog, Environment

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Lucy Laffitte

About the Author ()

Lucy B. Laffitte, PhD has been a science communicator and environmental educator for over thirty years. She has produced in-class and on-line instructional design, curriculum development, and certificate programs to a variety of conservation organizations, including the Oregon Museum of Natural History, Tall Timbers Research Station, North Carolina Museum of Natural Science, Salt River Project, New England Wildflower Society, Rachel Carson Institute, and Nicholas School of the Environment. She has published in print and on air—writing a nature column for The Cape Codder and was the founding radio producer for the environmental program the Allegheny Front. She has a bachelor’s degree in natural science, from the University of Oregon, a Master’s in adult education and graphic design and a PhD in environmental resources from North Carolina State University. She has been science education consultant for UNCTV working on QUEST and NC Science Now since April 2013.
  • Russ Cohen

    FYI, in case you don't already know, many invasive species are edible and offer "guilt-free" foraging opportunities (i.e., you can harvest as many of them as you want, as long as you don't help spread them around in the process, which is usually easily avoidable). There's an article I wrote about the comestible qualities of Garlic Mustard that appeared in Mass. Audubon's Sanctuary Magazine awhile back. Here's the link to it: http://www.massaudubon.org/content/download/8987/152961/file/Sanctuary%20spring%202011.pdf (the article begins on p.18). Let me hasten to add, however, that I doubt that (for garlic mustard, and for most other invasive species) harvesting them to eat them will prove to be an effective way to control them, no matter how widespread the practice becomes.