We found introduced species!

This is an update to my previous post: On the look for invasive species.

Have you ever wondered what was growing under the docks up and down our coast?

Well 25 scientists set out to answer just that.  Scientists (including Sara, Seth, and myself), in a six-day sweep, scoured the docks from Maine to Rhode Island looking for and identifying introduced species.

You may be asking ‘Why should I care about introduced species?’

Map of the central New England.  Locations mentioned in this blog post are marked on the map for reference.  Map courtesy of Christopher D. Wells.

Introduced species pose a serious threat to the environment, economy, and public health.  Marine species clog pipes, damage piers, and can negatively affect the seafood industry.  They disturb the balance within an ecosystem.  Introduced species aren't always for the worst and Alena Warren gives a great example in her post: Invasive plants: if we can't beat 'em....

These surveys are meant to be used as an early warning system for new introductions.  Over thirty introduced species were found on past surveys and more species are added each year.  This past survey was the fifth of its kind in New England.  Surveys have been carried out every three years since 2000, but if funding permits, these surveys will be happening more frequently.

The introduced tunicate Ciona intestinalis at Hampton River Marina in Hampton, NH.  Introduced tunicates were found at almost every site during the rapid assessment and were usually the dominant space holder.  Photo courtesy of Adriaan Gittenberger (GiMaRIS).

Now onto some of the results...

The dominant group on the docks was colonial and solitary tunicates (aka sea squirts).  Tunicates filter the water through a fine mucus netting and are efficient enough to remove bacteria!  They crowd out and aggressively grow over bivalves (such as mussels and oysters) and may smother them or interfere with their growth.  Ignoring fish, tunicates are your closest relatives on the docks (we are both within the same phylum)!

We found the European rock shrimp Palaemon elegans, first found in 2010 during the last rapid assessment, has since spread much farther north and south.  A close relative, the Japanese oriental shrimp P. macrodactylus was not found on the last survey, but was found at one site during this survey.

The introduced European oyster Ostrea edulis surrounded by introduced tunicates and bryozoans at Hampton River Marina in Hampton, NH.  The European oyster was found at all coastal sites north of Cape Cod and several sites south.  Photo courtesy of Adriaan Gittenberger (GiMaRIS).

We also found an abundance of the intentionally introduced European oyster Ostrea edulis.  The European oyster was first introduced during a failed aquaculture venture in northern Maine in the 1950s and later by the Division of Marine Fisheries in Salem, Massachusetts in the 1980s.  They are now spreading southward quickly (we found them as far south as Newport, RI).

Also found to be spreading at a rapid pace during the survey is an arborescent (branching) bryozoan Tricellaria inopinata first found in September 2010 in Eel Pond in Woods Hole, MA.  It has since spread as far north as Gloucester, MA.  In Gloucester, I’ve seen T. inopinata form dense aggregations crowding out other native and introduced species.  This animal is impossible to identify without looking at it under a microscope although it has a “crunchy” feeling, something most arborescent bryozoans in the area don’t have.

The newly introduced bryozoan Tricellaria inopinata found at Rowes Wharf in Boston, MA.  Tricellaria inopinata was originally found at Woods Hole in 2010 and has spread rapidly north and south.  Photo courtesy of Adriaan Gittenberger (GiMaRIS).

The striped barnacle Amphibalanus amphitrite.  Photo courtesy of Melissa Frey on marineinvaders.lifedesks.org.


This year’s survey had a strong warm-water touch to it; there were many species from more southern regions.  For example we found a population of the beautiful striped barnacle Amphibalanus amphitrite.  The striped barnacle is normally found in tropical and subtropical areas around the world.  We’ve never found striped barnacles on the previous surveys.  Another new (and exciting) find was the pink-spotted sea anemone Aiptasiogeton eruptaurantia.  It was only found at one site: Point Judith Marina in Wakefield, RI.  We also found that three species of warm-water hydroids have increased in abundance since the last survey in 2010.

The pink-spotted sea anemone Aiptasiogeton eruptaurantia.  The anemone was only found at one marina: Point Judith Marina in Wakefield, RI.  Photo courtesy of Adriaan Gittenberger (GiMaRIS).

Along with all the interesting animals around 100 species of algae and vascular plants were found growing attached to the docks including at least 10 introduced species!

Surveys like these provide a baseline inventory of what’s out there so we know when new animals and plants are introduced.  The surveys also provide an opportunity to rapidly respond as new introduced species appear.  It is important to respond immediately because as soon as introduced species start to spread it becomes exceedingly difficult to eradicate them.  Eradication is only a reasonable response to an introduced species during the earliest stages of introduction and should be considered as an option if the species has been demonstrated to cause economic harm.

Stay tuned for more as data and images come rolling in, we are still tallying up the number of species we found. 

Thanks for reading.  If you like what you see or have any questions leave a comment below.  Don’t forget to subscribe to our blog!  Stay hungry.

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