Invasive Apple Snails

Invasive Apple Snails

Don’t let the title of this column fool you. Despite the title of apple snails, I am not sharing the latest escargot recipe offered up at a fancy restaurant here in The Last Green Valley. Today’s column is about a recently discovered invasive species – this time of both the aquatic and terrestrial variety.

Over the years I have used this column to share information about invasive species of plants having a negative impact on our forests and fields, as well as invasive insects that likewise have a deleterious effect on our environment. This time we consider our region’s lakes and ponds to examine the invasive apple snail.

When it comes to understanding our region’s water quality, I rely on Jean Pillo from the Eastern Connecticut Conservation District. She also serves as the Coordinator for TLGV’s Volunteer Water Quality Monitoring Program. Each year she and dozens of dedicated volunteers venture forth to our lakes, ponds, rivers and streams to gather data through a variety of methods and provide important and timely information to the CT Department of Energy and Environmental Protection Water Quality biologists. She is a wonderful resource, and occasionally sends me tips for future columns. A few weeks back she mentioned apple snails had been accidently introduced into a pond situated between Eastford and Woodstock. This initially mouthwatering discovery soon turned to concern when I learned more.

“As the coordinator of The Last Green Valley Volunteer Water Quality Monitoring Program, I train the volunteers to be observant and report unusual sightings to me. Sometimes we help to document rare freshwater mussels in a place they were not known to be. In other cases, we report invasive species, such as the Chinese mystery snail. I recently learned that apple snails have been introduced to Crystal Pond by an unknown mechanism (probably from a fish tank). I emailed CT DEEP this morning to learn if this is a common occurrence and how to report the data.”

So, what exactly is an “invasive species” be it plant, insect, animal or, in this case, snail or mollusk? Basically, when a species of plant, insect, mollusk, reptile or bird that evolved in and is native to one region or ecosystem is then introduced into another region in can become invasive.

All too frequently the problem occurs when the introduced species has no natural predators and easily survives to outcompete native species for space and food. They can outgrow their new habitat and increase in numbers to the point of decreasing the biodiversity of surrounding life, sometimes destroying entire ecosystems.

The most visible and pernicious are plants. Countless landowners with a bit of woods, field or roadside know all too well what Japanese Barberry, Asian Bittersweet, Buckthorn, Autumn Olive, Garlic Mustard, Multiflora Rose, Japanese Knotweed and Winged Euonymus or Burning Bush (to name a few) can do to our native habitat. The following link provides a list of invasive plants from the Connecticut Invasive Plant Working Group at UCONN: I suggest you click on the link “meet the plants” for an eye opener.

When it comes to aquatic plants and water creatures, the list is also extensive. The CT DEEP website link to Aquatic Invasive Species in Connecticut can be found at:

Regarding apple snails, Jean forwarded to me information provided by Solitude Lake Management, a nationwide environmental firm with offices throughout the country. Here is the important information from the company.

“Apple snails are a large, freshwater species that are part of the family Ampullariidae. When introduced to non-native areas, they can rapidly alter the ecological makeup of aquatic ecosystems due to their aggressive feeding style and rapid growth rate. They are voracious and opportunistic, feasting on multiple types of aquatic vegetation and other snail species, which can drastically alter nutrient dynamics in aquatic ecosystems. These freshwater snails are also amphibious, meaning they can survive seasonally in both terrestrial and aquatic environments, including lakes, ponds and wetlands. They have an unusual gill and lung adaptation, which they utilize during their reproductive cycles. In response to seasonal changes in water levels, this adaptation allows them to lay eggs outside of the water column, preventing predation by native aquatic predators.”

“While it’s not fully known how apple snails originally entered the United States, one theory is that the aquarium trade industry is responsible for their introduction. Apple snails are popular among aquarium enthusiasts due to their decorative shells and rapid growth rates. Unfortunately, irresponsible aquarium dumping, and careless trading have allowed the species to infiltrate new ecosystems.”

The full article from Solitude Lake Management can be found at:

Jean also indicated “we don’t know how these snails may impact the native freshwater species, the best thing to do is not to introduce them where they don’t belong. Clean boats and clean boots and other equipment is the best way to stop their spread.”

In my adult life I have experienced and done battle (mostly a losing battle) with various invasive plant species. The spread of newer species such as the apple snail may well continue. This is the unfortunate price we pay for living in a global, interconnected economic system with active trade in living species from around the world. What we must consider is how this is impacting ecological balance in our region’s terrestrial and aquatic habitats, and how can we best work together to understand these threats, provide educational and mitigation resources and seek to work together to ensure ecological balance.

Despite the many challenges of invasive species of plants and animals, we still live in a beautiful place called The Last Green Valley National Heritage Corridor. I hope you join me and others as we care for it, enjoy it and work together to pass it on.

Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor. He can be reached at of 860-774-3300.

Exploring The Last Green Valley, Sunday, September 18, 2022

The Norwich Bulletin is granted first serial rights and associated electronic rights to publish the following article.  The Last Green Valley, Inc. retains all other rights to the work.


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