It’s hard to imagine the common earthworm as an “alien invader,” but those near Colgate are not native to North America, and it’s been found that they could be harmful to the environment.

The presence of exotic earthworms has led to a host of potential concerns, including a change in the carbon and nitrogen cycles as well as the accelerated breakdown of organic material on the forest floor surface. These changes often reduce habitat for animals, decrease nutrient availability, and contribute to soil erosion.

Colgate professors and students have been working to better understand the spread of exotic earthworms in the region.

Most recently, geography professor Peter Klepeis and his former student, Dara Seidl ’10, have published a study in the journal Human Ecology that helps uncover the human dimensions of earthworm invasion. It has since garnered the attention of BBC News and many other media outlets.

Setting the stage for Klepeis and Seidl’s study, in 2009, biology professor Tim McCay and his team explored how soil characteristics in the Adirondacks — the largest unbroken temperate forest in the world — affect the incidence of invasive earthworms.

McCay’s research, published in the Northeastern Naturalist, confirmed his hunch that people are key players in the earthworm story.

McCay called on Klepeis to take a closer look at the role of humans, who have been identified as the main culprits of earthworm dispersal. People spread earthworms both inadvertently — via horticulture, land disturbance, and in the tires and underbodies of vehicles — and voluntarily, through composting and the improper disposal of fish bait.

Despite humans’ negative impact on forest ecology, a survey by Seidl and Klepeis showed that only 17 percent of residents in Webb, N.Y., (located in the western Adirondacks) know that earthworms in the town are exotic invasive species. In fact, the use of earthworms in gardening and composting is perceived as beneficial to ecosystem services, and using worms as fishing bait is part of the region’s culture.

The authors concluded that mitigating the introduction of exotic earthworms in the Adirondacks requires not only information campaigns about the problems they cause, but also efforts empowering people to change their behavior, such as the provision of non-live bait and proper disposal methods of unused earthworms.