National Invasive Species Week is
this week February 26th- March 4th. What a great time to raise
awareness about some local invaders and how we can help to stop the spread of
invasive species. Let me start by answering the question of what exactly is an
invasive species? By definition, an invasive species a one that is not native
to the ecosystem and when introduced has negative effects. Some invaders in
Washington include plants and animals such as Scotch broom, the Wood-boring Beetle,
and the European Green Crab.
The European Green Crab is native to the Atlantic coast of Europe and Northern Africa. It is a relatively small crab with a carapace ( back shell) growing only 3.5-4 inches across. Green crabs were first documented on the east coast of the US in 1817. They are relatively new to the west coast with their first appearances showing up in the San Francisco Bay in 1989. It didn’t take long for them to make their way up the coast to Washington. In 1997-1998 an El Nino event pushed them north up the coast into Oregon, Washington, and British Columbia.
So what’s the all fuss with a tiny
crab? Well, this crab may be small but is quite durable and able to adapt to a
number of different environments. It can adapt to many temperatures and enjoys
eating and disturbing eelgrass habitat. Eelgrass is a very important nursery habitat
for a number of aquatic young animals including salmon and Dungeness crabs. To
learn more about the importance of eelgrass check out this blog post by our
Marine Exhibit AmeriCorps Educator. Green crabs also enjoy some of the very seafood which humans have a palate for.
These crabs love to eat soft shelled clams, scallops, young oysters, as well as
native crab species.
So now that we are up to speed on
these little guys takeover of the country’s coastal waters, the next question
is, where does that leave us here in the Salish Sea region? On August 30th 2016, one European green crab was found in Westcott
Bay, on the northwest end of San Juan Island. Since then, the crabs have been
spotted in Padilla Bay. At this point in time there is no evidence of
established green crab communities.
Thankfully, there is a dedicated
group of individuals who have made it their mission to help stop this arthropodic
invasion. Crab team is a group who partners with Washington Sea Grant, the
department of Washington Fish and Wildlife, and numerous citizen science
volunteers. They survey a number of different sites in the Salish Sea looking for signs
of the European Green Crab. With Crab team working hard, they are on the
leading edge of a potential species invasion, which is a good place to be says
Emily Grason, the Crab Team’s project coordinator.
 |
| European Green Crab (Carcinus maenas) Photo by Sean McDonald |
With this new awareness of the invasive
green crab there are some steps you can take to help prevent the invasion in
the Salish Sea area. Anytime you are out on a beach walk, take a look at the
crabs and crab molts you are seeing.
How to Identify a European Green
Crab:
- 5 spines on the outside of each eye
- Up to 4 inches across the carapace or back shell
- Wider at the front of the carapace
*The
color of this crab can range from dark green to orange or red*
If you find a crab that looks
like it could be a European green crab, here are the steps you can take:
1.
Take photos
2.
Record your location
3.
Leave the crab where you found it
