Mystic Aquarium

Info

What Is An Invasive Species?

The United States Department of Agriculture maintains the National Invasive Species Information Center (NISIC).  They define an invasive species as a species that is:

“Non-native (or alien) to the ecosystem under consideration AND whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”

In the United States alone, there are around 4,300 species of invasive plants and animals.  There is not one area of the country where invasives are not present; however some areas are more heavily affected than others.  It is important for those who enjoy the outdoors to know about the issues caused by invasive species.

How Does a Species Become Invasive?

You may ask why invasive species have become such a widespread problem.  The answer is: people.  We are the sole culprit behind most introductions of invasive species.  Lots of animals are introduced into new habitats because they end up as stowaways in shipping crates, ballast water, or a traveler’s belongings.  Others are set free from holding equipment due to natural disaster or human error.

These previous methods of introduction are all unintentional.  However, many invasive species were introduced on purpose.  Sometimes animals are introduced to combat native nuisance animals (cane toads for agricultural pest control).  Others get introduced because exotic pet or home aquarium owners cannot handle certain animals anymore, and release them into the wild – but not their native habitat (Burmese pythons in Florida).

We must remember that not every species that is introduced into a new environment will survive.  Those that become invasive have special adaptations: they are tolerant of varying environmental conditions, they can reproduce quickly, and can consume a wide variety of food.  These traits also make them very difficult to eradicate.

What You Can Do

The most important thing you can do is to prevent future introductions of invasive species.  Although large scale control or eradication is often unrealistic, there are many actions you can take to help combat invasives and the problems that they cause:

• Be aware of local invasives and report any unusual sightings – know which agencies or officials to contact regarding invasives.
• Check your clothing, baggage, and belongings when traveling to prevent hitchhiking invasives.
• Wash any type of outdoor recreational equipment after use (boats, trailers, boots, waders, backpacks, scuba equipment, angling supplies,
• Spread the word to your friends and family.  The more awareness, the better!

See the “Links” page for more details on local organizations and volunteer opportunities.

Expert Q&A

Nancy Balcom is the Associate Director of the Connecticut Sea Grant.  She is an expert on invasive species in Connecticut.  Have a look at her answers to some interesting invasive species questions!

What problems do invasive plants raise?  How do they affect local habitats?
“Invasive plants have the ability to grow and reproduce quickly under a variety of conditions, crowding out native plants. Often lacking predators in the new habitat, they have the ability to disperse widely by seed and plant fragments. The affected ecosystem cannot function normally as the new plant species takes over and becomes dominant, and other organisms that rely on the displaced native plants for food or shelter are harmed as well.”

How are invasive plants introduced?
“Invasive plants are typically introduced as seeds or plant fragments, and may be transported to new habitats by wildlife, wind and water. Human activities, both accidental and intentional, commonly lead to the introduction and spread of invasive plants. Some non-native plants initially introduced as new ornamentals or crops, for example, revealed invasive characteristics that led them to spread quickly. Many states now restrict or prohibit the sale of certain known invasive plant species.”

If I see an invasive plant or animal, should I kill it?
“In most cases, absolutely not.  If there are invasive plants in your yard, you can certainly try to remove them. If there are aquatic plant fragments caught on your boat, canoe, or trailer, you should remove them and put them in the trash. Beyond that, you should not attempt to kill any plants or animals for the following important reasons. First, many invasive and native species look alike and identification by experts is required to determine which is which. Second, there are strict regulations governing how animals may be caught and if necessary, killed, and who has the authority to do so. If you find something unusual that you think is an invasive plant or animal, the best things to do are to take note of its location, take a picture of it, and report your findings to the Department of Energy and Environmental Protection.”

Why is it so hard to eradicate invasive species?
“By their very nature, invasive species are those that easily adapt to new environments. They tolerate widely varying environmental conditions, have broad food preferences, mature quickly and reproduce often in large numbers.  They often lack control by predators and spread easily. Often they are found only after they have established a strong presence in an area, making it more difficult to attempt control. Efforts to remove invasive plants means returning year after year to the same spot to make sure no seeds or plant fragments survived to re-establish the population. Particularly in aquatic environments, sometimes there are no known controls available for a species, or the control requires the sacrifice of other living organisms at the same time to be successful.  Preventing new introductions and preventing the spread of invasive species to new areas is more easily done and less costly by far than removal after they become established.”

I have an exotic pet, not native to this area and do not wish to care for it anymore - I do not want to release it to the wild.  What can I do?
“This can be tricky to address, but you should by no means release a pet into the wild. There is a national campaign called Habitatitude that encourages people to contact the original retailer to see if they will take the animal back, to contact a nature center or aquarium to see if they will accept the animal, or to contact local hobbyists to see if anyone is interested in taking the pet. However, concerns about disease and the need to quarantine the animal, its species or size, cost, or other factors may lead retailers and nature centers/aquaria to refuse. If the only remaining option is to kill the animal, then a licensed veterinarian should be approached to do so as humanely as possible. Detailed research should be undertaken before purchasing any exotic pet, in order to fully understand the responsibility you are taking on and what to expect as the animal grows and matures.”

Local Aquatic Examples

Indo-Pacific Lionfish (Pterois volitans)

Image Courtesy of NOAA

These voracious and venomous predators, native to Indo-Pacific reefs, now have established populations over almost the entire western Atlantic Ocean.  They can be found off the coast of Bermuda, the Caribbean, Gulf of Mexico, and the entire eastern seaboard of the United States as far north as Rhode Island.  The reason for their success – and the reason for concern – is their incredible appetite and hunting skill.  In the Caribbean they are known to prey on at least 40 different species of fish.  This intense predation has put stress on many fish species in the areas they have invaded.

The exact method of lionfish introduction is not known, but the most likely culprit is the aquarium trade – lionfish are a popular ornamental fish, and research shows the most likely cause to be home aquarium owners in Florida releasing them to the wild.  Some even theorize that Hurricane Andrew had a significant impact, by shattering tanks and flushing the animals into Floridian waters.  You are probably aware that we house lionfish at Mystic Aquarium.  These beautiful fish are lovely additions to the Aquarium; what we must keep in mind is that in their native habitat they are in a perfect balance with the ecosystem – but in the Atlantic, their existence is not naturally controlled.

There is a very unique control effort happening with lionfish.  Many organizations host “lionfish derbies”, where fishermen and divers venture out and try to catch as many lionfish as possible.  They then market the flesh for locals to eat.  Although poisonous in their barbs, the flesh of lionfish is quite palatable and some believe that developing the taste and popularity of eating lionfish will help decrease the impacts they have on native ecosystems.

Common Reed (Phragmites australis)

Image Courtesy of the United States Geological Survey

This plant is a common fixture of marsh habitats around much of the eastern United States, and it may surprise you to know it is an invasive species.  Although some species of Phragmites (pronounced frag-MIGHT-ees) may have been native to this area, a different variety – one from Europe – has emerged as a threat to native ecosystems.

The fact that this organism is a plant may deceive you.  They can seriously disturb ecosystems in a number of ways.  They grow in thick strands, and serve as physical barriers to animals wanting to access water.  In fact, Phragmites marshes have less diversity and abundance of aquatic animals due to their presence.  They degrade the habitat for birds as few can use them for nesting.  Phragmites grows tall (perhaps 20 feet) and can shade other plants, which need the sun to grow and produce.  They decompose slowly and become serious fire hazards.  All these effects may seem subtle, but our local marshes that are not adapted to cope with the effects Phragmites has, and overall ecosystem health has suffered.

Asian Shore Crab (Hemigrapsus sanguineus)

Image Courtesy of the National Parks Service

These animals are now extremely common along rocky intertidal habitats here in the Northeast.  After the introduction in 1994, densities of the native flatback mud crab (Eurypanopeus depressus) decreased by 95%, and common periwinkle (Littorina littorea) density decreased by 80%.  Their invasive abilities are extraordinary; even another invasive crab, the European green crab (Carcinus maenas) has been displaced by the Asian shore crabs.  Their introduction is likely due to ballast water.

The Asian shore crabs prey on a wide variety of molluscs and crustaceans, especially juveniles.  One main reason for their abundance here is the lack of natural parasites that regulate their population in their native range.  In addition, many animals here are not accustomed to feeding on them.  Research has shown that these crabs are here to stay – large scale eradication is simply not possible.  Scientists will continue to monitor and research the impacts that these animals have on native populations of molluscs and crustaceans.

Links

If you have more questions, the US Fish and Wildlife Service has an extensive Frequently Asked Questions page with lots of useful information.

Access the National Invasive Species Information Center!  This site has lots of info, including species profiles and identification guides.

The US Fish and Wildlife Service has advice for preventing the spread of invasives, based on the outdoor activities that you enjoy!

Check out a local group, the Connecticut Invasive Plant Working Group!

Check out an NPR article discussing the lionfish invasion.  Read about how their invasion has been so deadly – relentless predators, and resistant to local parasites!

The Burmese python invasion of the Florida Everglades has captured the attention of the national media.  Have a look at some of these articles, discussing the spread of these animals and their impacts.
Study: Invasive pythons wiping out native Everglades animals - Reuters
Stopping a Burmese python invasion – The Nature Conservancy
Invasive pythons put a squeeze on Everglades’ animals - NPR