Invasive species have massive impacts on our natural ecosystems and economy. They are among the leading threats to native wildlife. Approximately 42 percent of threatened or endangered species are at risk due to invasive species. They may also threaten human health and create a heavy financial burden to affected community. These combined impacts cost billions of dollars each year.

What Makes a Species "Invasive"?

Species that grow and reproduce quickly, and spread aggressively with potential to cause harm, are given the label “invasive.” They can be amphibian, plant, insect, fish, fungus, bacteria, or even an organism’s seeds or eggs which are not native to an ecosystem and turn out to be harmful.

Even within one country, species may become invasive in another location. For example, lake trout are native to the Great Lakes, but are considered to be invasive in Yellowstone Lake in Wyoming because they compete with native cutthroat trout for habitat.

Learn more about the invasive species Seaside monitors:


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Phragmites Australisis a non-native grass present along the marshes of the North Shore. These plants often grow very densely, blocking out the sunlight native species need. As these plants continue to be a problem, Seaside Sustainability is monitoring their populations on the North Shore to experiment with organic alternatives to the current eradication methods. This initiative is used as a means of restoring the marsh, organically, safely, and responsibly. 

Ways to Reduce

Because phragmites can reduce biodiversity and threaten the native flora and fauna in the invaded habitat, it is important to know a few methods to reduce the phragmites population.​

Landowners can
eliminate or reduce fertilizer, herbicide and pesticide use

Do not purposely planting it; instead consider planting only native species in gardens 

Avoid transporting Phragmites either via equipment or as compost


Green and Asian Crabs

It is important to measure the effects the rise in this invasive crab's population has on other marine animals. To conduct this study, Seaside Sustainability has set traps off the waters of the North Shore that are monitored periodically; where we record the number of crabs that are present in the water. Local students also get to help out as part of their science education. This program also offers a chance for a sustainable economy by providing green crabs to businesses, so they can be used for a sustainable and local meal.

Retrieved from Walker Creek Media, LLC

Ways to Reduce

Because Green and Asian crabs can threaten other native species and add to predation pressures, it can create long term effects such as a reduction in biodiversity, thereby causing the rocky inter-tidal communities to suffer.

Mitigate through removal processes like eating them or using them as bait

Prevent the spread through ballast water and other sea transportation methods

Spread awareness of the damages that is caused by these invasive crabs



Every Spring and Summer, Seaside Sustainability partners with a local Audubon official, Liz Duff. We survey islands and beaches around the North Shore to map and mitigate the invasive perennial known as Pepperweed. To engage youth in citizen science, Liz’s students join us to map the coast from Essex to Marblehead, ensuring the Pepperweed population is under control. Through these efforts, we strongly believe that the marsh can be restored.

Ways to Reduce

Like phragmitespepperweed can reduce biodiversity and threaten the native flora and fauna in the ecosystem it inhabits. There are also negative impacts on local waterfowl and fish populations; therefore, it is important to know some ways to fight this invasive species.

Treating with herbicides is most effective during flower bud/flowering stage

If within small patches*, repeated pulling of small patches is effective

After removal, plant or re-vegetate desirable and competitive species

*Note: Pulling pepperweed in patches is only an available option if the landowner designates the land as a "pull only" area, so be sure you have landowner permission to pull.


Our Green Crab project is in partnership with the city of Gloucester and the Merrimack Valley Planning Commision (MVPC).

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EIN 47-4993870     978.381.3302   INFO@SEASIDESUSTAINABILITY.ORG

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