Welcome to Louisiana's Invasive Species Website

Invasive species threaten not only Louisiana’s economy and environment, but also its unique cultural identity in America - one based on our bayous and backswamps, our rich history and famous cuisine, and our core industries. In recent years, aquatic plants from around the world - hydrilla, water hyacinth and salvinia - have clogged the waterways that make Louisiana a "sportsman’s paradise." Henderson Lake near Lafayette had to be drained to eliminate a mat of hydrilla so thick that marinas, swamp tour operators, and fishermen could no longer use the lake. Muskrat, once trapped for their valuable fur throughout Cajun country, have been crowded out by South American nutria. In New Orleans, Formosan termites have weakened thousands of historical structures and hollowed the city’s graceful live oaks. And in the summer of 2000, masses of Australian spotted jellyfish along the Louisiana coast raised the possibility that the gulf shrimp industry may be disrupted by a species from half-a-world away.

Invasive Species Portals and PathwaysFrom places like China, Brazil, and the South Pacific, these species are "introduced" to Louisiana, having evolved outside our natural ecosystems. Some introduced species (also called exotic, alien, or nonindigenous species) prove to be beneficial, such as sugarcane and cotton, our biggest crops. Others are benign, such as azaleas and crape myrtles, our favorite ornamentals. But other introduced species—called invasive species—prove to be astonishingly problematic and costly. Brought here accidentally or intentionally, through trade and transport, they have multiplied rapidly and disrupted local environments and economies. Who are these uninvited guests, how did they arrive and spread, what impact are they having on Louisiana, and how can this problem be addressed? The purpose of these interactive maps, created by the Tulane/Xavier Center for Bioenvironmental Research with support from The Coypu Foundation, is to answer these questions.

North America has already been transformed by the plants, animals and pathogens of faraway continents, at times with devastating consequences. Colonization brought not just people but new domestic animals, crops, weeds and diseases. One could argue that smallpox was the continent's first invasive species, moving into Indian communities in the interior far faster than the Europeans who first brought it. Perhaps the greatest human health crises to afflict our state, the yellow fever epidemics of the nineteenth century that killed well over 100,000 Louisianians, was caused by an introduced virus carried by the Aedes aegypti mosquito brought over from Africa. Today, globalization has increased the opportunities for species to move into new environments: from 1950-1998, exports have increased from $311 billion to $5.4 trillion, while international travel has grown from 25 million to 635 million border crossings annually. Introduced species can tag along in packaging, ride in a ship's ballast water, travel in the baggage of returning passengers, or be shipped and sold as products. This map shows how invasive species have entered ("portals") and moved ("pathways") through Louisiana, and why the Bayou State is especially vulnerable to species invasions.

Louisiana Invasive Species MapThe phenomenal diffusion of species in new environments has many ecologists contemplating the possibility of a "global McEcosystem." Just as franchised fast food has homogenized local cuisines, species introduction may homogenize the world’s biodiversity. Invasive species are a major cause of the extinction of native species (second only to habitat loss), and the arrival of a single alien species can alter an entire ecosystem. Cogon grass, which is entering Louisiana along roadways, increases the amount of fuel in forests, so that fires burn hotter and kill native longleaf pines. Southern Louisiana is already losing 25 square miles of coastal lands each year; a crisis exacerbated by the nutria, a large South American rodent that eats the roots and stems of marsh plants.

An early study of invasive species in the United States estimated that damage and control efforts cost $137 billion annually. Formosan termites alone cause $1 billion in damage nationally each year, with $300 million spent in the New Orleans area alone. One may argue that invasive species are simply one of the costs that accompany the many benefits of a modern, industrialized society. But, as in any endeavor, costs can and must be minimized. The problem of invasive species is especially daunting in Louisiana, but is not beyond the power of Louisianians to solve it. Various solutions are underway and others are planned. With knowledge of the geography of species introduction, we can better design strategies of prevention. On another level, the problem of invasive species in Louisiana calls for recovering a particular kind of environmental knowledge: simply knowing and appreciating the native plants and animals with which we share this place. Even as we develop effective policies and technologies for preventing and slowing the spread of introduced species, we need to learn enough about our local ecosystems to recognize new species that may create problems.