3 Bumps 5 spines Picture by John Southern The green crabs distinguishing features are 5 spines, or teeth, on each side of its fan shaped shell and 3 rounded lobes between its eyes. The two backmost legs are flattened. The abdomen (underside) color ranges between green, orange, and red, and the dorsal (top) side of its shell is a mottled dark green with yellow patches. Why are they a problem? As their name suggests, this species is native to European waters. Over time it has been introduced to multiple new habitats, including the Atlantic and Pacific coasts of North America. Although green crabs have been detected only as far north as Vancouver Island in British Columbia thus far, models indicate that the species will be able to survive in coastal Alaskan waters. European green crabs are aggressive predators, eating clams, mussels, marine worms, and crustaceans that are important foods for native marine animals. If green crabs invade Alaskan waters, they could be a serious threat to native crabs and fisheries. What is a tunicate? Tunicates, or sea squirts, are marine invertebrates (lacking a back bone) that grow attached to surfaces. They might be confused with a sponge, but they are more resistant to touch. They can range in color, including orange, red, yellow, black, translucent, cream, and blue. They can be solitary (completely independent and generally fairly large) or colonial (congregations of zooids that aggregate by budding, like corals). Tunicates filter feed by siphoning plankton from the water. Tunicates belong to the Phylum Urochordata, which are more closely related to vertebrates (including humans) than any other invertebrate group. There are a number of native species in Alaskan waters; however, several non-native species have been detected. Invasive tunicates documented in Pacific waters: Botrylloides violaceus, Botryllus schlosseri, Styela clava, Didemnum sp., and Ciona intestinalis. Why are they a problem? Tunicates are a fouling organism that can smother other marine organisms and coat surfaces, such as boats and docks. They filter out the waters phytoplankton, thus depriving other species of their nutrition. Since larval tunicates can be transported in ballast water and adults can foul boat hulls, tunicates can easily disperse to new waters, where they can readily establish in the absence of natural predators. In the coastal Pacific waters of North America, the Smithsonian Environmental Research Center (SERC) coordinates a monitoring program ranging from Tijuana Slough, CA to Port Valdez, AK. Smithsonian Environmental Research Center (SERC) National Park Service U.S. Department of the Interior Glacier Bay National Park and Preserve Marine Invasive Species Monitoring Program What is an invasive species? What is an invasive species? Invasive species come from other parts of the world and can be harmful to the environment, natural resources, humans, and the economy. Invasive species are transferred between regions by people intentionally or accidentally. For marine invasive species, common forms of transfer include ships ballast water, hull fouling, and aquaculture. "Invasive species have large effects on native biodiversity, cause hundreds of billions of dollars in economic damages, and complicate the management of natural ecosystems around the world." (Strayer, 2006) What is an invasive species? What is an invasive species? Invasive species come from other parts of the world and can be harmful to the environment, natural resources, humans, and the economy. Invasive species are transferred between regions by people intentionally or accidentally. For marine invasive species, common forms of transfer include ships ballast water, hull fouling, and aquaculture. "Invasive species have large effects on native biodiversity, cause hundreds of billions of dollars in economic damages, and complicate the management of natural ecosystems around the world." (Strayer, 2006) Botrylloides violaceous (orange morph) – an invasive colonial tunicate. SERC Ciona intestinalis – an invasive solitary tunicate. SERC What about Glacier Bay? What about Glacier Bay? So far, no invasive green crabs or tunicates have been detected in Glacier Bay through our monitoring efforts. For green crabs, we set out traps once a month during the summer in the lower intertidal area of Bartlett Cove. For tunicates, we suspend settlement plates from our three docks quarterly to detect whether any tunicates colonize the surfaces. Atlantic Salmon are the only marine invasive species detected within park waters to date. We will continue collaborating with partner agencies to detect marine invasive species. What about Glacier Bay? What about Glacier Bay? So far, no invasive green crabs or tunicates have been detected in Glacier Bay through our monitoring efforts. For green crabs, we set out traps once a month during the summer in the lower intertidal area of Bartlett Cove. For tunicates, we suspend settlement plates from our three docks quarterly to detect whether any tunicates colonize the surfaces. Atlantic Salmon are the only marine invasive species detected within park waters to date. We will continue collaborating with partner agencies to detect marine invasive species. For more information: Whitney Rapp, Invasive Species Coordinator, Glacier Bay National Park and Preserve, Gustavus, AK – What should you do if you find one? If you find a green crab, dont throw it back in the water! Keep it in a container with information about where and when you found it. Then put it into a freezer or preserve it with alcohol. Contact INVASIV for more information.