Pathways to Invasion

May 3, 2013

How do invasive species enter North America?

We bring them in.

Our ancestors.The early colonists, brought pigs, which they let range free, and seeds to plant as crops. Others just hitched a ride: on their shoes, in fodder, on animals, on boat hulls, and stowed among ballast cobbles.

Our tax dollars at work. Since the nineteenth century, the U.S. government has introduced several nonnative species, either as food sources or erosion control, always with unforeseen consequences. Then your tax dollars go to work on remediation.

Our military. It is believed that the brown tree snake first got to Guam as a stowaway in the wheel wells of Air Force jets. Invaders travel in military transport, bags, and equipment.

Our love of exotic plants. The nursery industry has a lot to answer for. Imported plants have a way of spreading into the wild. And they have a way of arriving with stowaway insects, fungi, and diseases. Invaders can travel in potting soils and love turf.

Our love of pets. The pet industry also has a lot to answer for. Four hundred fish species and 124 plant species were found in aquarium pet stores of Washington State over the course of a single year. Exotic pets can get too big, or too unruly, for their owners, who release them into the wild. Feral house cats, and their domestic neighbors, kill more than 2 billion birds and 12 billion mammals in the United States each year, most of them native species (alas).

Our love of hunting, fishing, and meat.  Ponds and streams have been stocked with nonnative species for fishing since the 1880s.  Bait has been released in waterways far from its source, resulting in the spread of crayfish, crabs, and other creatures. Hunters have imported wild boar from Europe for their sporting pleasure. After escaping from farms, pigs have damaged soils and plants in the Smokey Mountains. Some hunters are transporting feral pigs across state lines to encourage their spread.  They don’t need your help.

Our love of cheap manufactured goods. The wooden crates in which these goods arrive from Asia can contain invasive insects. These goods arrive on container ships from around the world, which discharge their ballast water at ports as far inland as the Great Lakes. Ballast water contains aquatic invaders.

Our love of fire. Firewood bought from a big-box store often comes from Asia. Buy local and don’t move wood around, as it can carry pests.

Our love of exotic fruit. Shiploads of fruit from Central and South America have arrived with invasive stowaways, whether insects, reptiles, or fruit diseases.

Our love of seafood. Along with ballast water, moving oysters and seaweed around the world for aquaculture has spread dozens of invasive species. Seafood is often packed in seaweed before being transported; the live packing can carry small and juvenile invaders to new waters.

So keep in mind. We can’t consume our way out of every mess.  The best way to stop invaders is prevention.  No new species should be brought in unless they are shown to be noninvasive.  Pathways are diverse and dynamic: strict controls on ballast water and wood imports are essential in saving our coastlines and trees.

    Leave a Comment



    Blue Plate Special Garden Snail

    Summer is coming to a close. It’s time to start harvesting in the garden–and gathering the garden snails.

      EAT ME!
      nopales con huevo

      Prickly Pear

      Fall is here, and the “cactus fig” is in season. Time to plate-up another widespread invader.

        EAT ME!
        Screen Shot 2012-11-18 at 8.02.21 AM

        Sow Thistle

        It’s spring and time to weed. Sow thistle is a delicious invader found throughout the continent.

          EAT ME!

          Lamb’s Quarters

          Lamb’s quarters was a popular spring tonic in the South—an early season edible green—but its leaves are good throughout the summer.       Chenopodium album Native range: Described by Linnaeus in 1753, this European native has been transferred throughout much of the world. Because its spread was rarely recorded, C. album‘s native and invasive [...]

            EAT ME!

            Garlic Mustard

              Alliaria petiolata Native range: Europe, Asia, Northwest Africa Invasive range: Much of the Lower 48, Alaska, and Canada. (See map.) Habitat: Moist, shaded soil of floodplains, forests, roadsides, edges of woods, and forest openings. Often dominant in disturbed areas. Description: Biennial herb. First-year plant has a rosette of green leaves close to the ground. [...]

              EAT ME!




              The common periwinkle, which first appeared in New England in the 1860s, is now found along the coast wherever there’s hard substrate–rocks, riprap, broken concrete, or docks–from Labrador to . . .

                EAT ME!
                Pterois volitans


                Some say it started in 1992 in Miami when Hurricane Andrew smashed an aquarium tank. Don’t blame the weather, others say; in the mid-nineties, disappointed yet softhearted hobbyists…

                  EAT ME!
                  chuka wakame


                    Undaria pinnatifida Native range: Japan Sea Invasive range: Southern California, San Francisco Bay, New Zealand, Australia, Europe, Argentina Habitat: Opportunistic seaweed, can be found on hard substrates including rocky reefs, pylons, buoys, boat hulls, and abalone and bivalve shells. Description: Golden brown seaweed, growing up to nine feet. Forms thick canopy. Reproductive sporophyll in [...]

                    EAT ME!

                    Asian Shore Crab

                    The first sighting of the Asian shore crab in the United States was at Townsend Inlet, Cape May County, New Jersey, in 1988. Though the source is unknown . . .

                      EAT ME!

                      Green Crab

                      Since the green crab was first recorded off southern Massachusetts in 1817, it has been hard to ignore. A few minutes of rock-flipping in Maine can turn up dozens of them, brandishing their claws as they retreat…

                        EAT ME!




                          Nasturtium officianale Native Range: Northern Africa, Europe, temperate Asia, and India Invasive Range: In USA: all lower 48 states, except North Dakota. Found in Alaska, Puerto Rico, and the Virgin Islands. Also southern Canada, Sub-Saharan Africa, South America, Australasia, and parts of tropical Asia. Habitat: Common along stream margins, ditches, and other areas with [...]

                          EAT ME!


                            There are numerous invasive crayfish. We include details for the red swamp crayfish (Procambarus clarkii) and the rusty crayfish (Orenectes rusticus). The same recipes can be used for both species–and many other invasive crayfish. Red Swamp Crayfish Native range: Known as Louisiana crayfish, crawdad, and mudbug, Procambarus clarkii is native to the south central [...]

                            EAT ME!
                            Distinguishing _ Channa argus

                            Northern Snakehead

                            His sister was ailing, and the man in Maryland remembered that, back home in Hong Kong, there was a fish that was considered a delicacy and a restorative. He would make a fish soup…

                              EAT ME!


                              “They live in a wide variety of habitats, colonize new ones readily, and eat everything that fits into their mouths,” says Dr. Peter Moyle of the Center for Watershed Sciences at UC-Davis…

                                EAT ME!
                                Picture 1

                                Common Carp

                                For a bottom-feeder, what is the good life? The common carp isn’t very demanding: any body of water that’s sluggish and murky will do. One catching sewage or…

                                  EAT ME!

                                  Field Notes


                                  Defeating Invaders by Eating Invaders

                                  In some biology classes, students read about invasive species. Last week, in professor Joe Roman’s course, Marine Ecology and Conservation, his students were eating them. Read more here.

                                    EAT ME!

                                    Invaders on the Rise

                                    During the last 200 years, the number of new invasive species has increased worldwide, with more than a third of all first introductions recorded between 1970 and 2014. More new invasions are expected among all groups of species in the near future, with the exception of mammals and fishes. Read the study here.

                                      EAT ME!

                                      Burn the Invaders

                                      Marabu is an invasive plant that has taken over much of Cuba’s abandoned farm lands. Artisinal charcoal from the tree is now the first legal export from Cuba to the United States in more than 50 years. Read more about the plan here.

                                        EAT ME!

                                        Pests for Dinner

                                        New Scientist reports on the annual dinner at the Explorers Club in New York. Gene Rurka, the club’s resident chef, served grilled lionfish, Asian carp sushi, and iguana meatballs with a plum dipping sauce. An actual iguana splayed out on a bed of greens made a feral centerpiece. “I see this as a way of [...]

                                          EAT ME!

                                          Bun Lai, Champion of Change

                                          ETI’s colleague and friend, Bun Lai, is named a White House Champion of Change. His restaurant, Miya’s Sushi, in New Haven, offers the world’s only invasive species menu, featuring dishes made of foraged ingredients that are threatening to the region’s indigenous species. Read more about Bun and the rest of the sustainable seafood champions here.

                                            EAT ME!

                                            It only takes one guy to move the [Asian carp] to a new place because he likes it. . . . A fisherman with a bait bucket intentionally stocking them in a reservoir would be a very bad thing.

                                            Josh Mogerman, National Resources Defense Council

                                            Previous post:

                                            Next post: