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