Second invasive green crab found in Puget Sound

Carcinus maenas. Photo: Brent Wilson (CC BY-NC-SA 2.0) https://www.flickr.com/photos/59048895@N06/5409329320/

Carcinus maenas. Photo: Brent Wilson (CC BY-NC-SA 2.0) https://www.flickr.com/photos/59048895@N06/5409329320/

Last month, Puget Sound Institute senior writer Christopher Dunagan’s series on invasive species in Puget Sound highlighted some of the state’s worries about the arrival of the European green crab. The article noted that “the threat could be just around the corner.” It could not have been more timely.

Several weeks after the article was published, volunteer crab spotters led by Washington Sea Grant made the region’s first green crab sighting. The crab was found on San Juan Island and it led to a rapid response coordinated by the state to find out if others had spread further. This week, another crab has been spotted in Padilla Bay.

Emily Grason of Sea Grant said in a news release that there is little evidence so far of a larger population of the invasive crabs on San Juan Island, “but finding an additional crab at a site more than 30 miles away suggests that ongoing vigilance is critical across all Puget Sound shorelines.”

Green crabs are listed as one of 12 aquatic animals of greatest concern by the Washington Invasive Species Council. They cause an estimated $22 million each year in damage to fisheries on the East Coast and have started to disrupt fisheries in California as well.

Scientists suspect that green crabs may be spreading because of warming temperatures, but little is known for sure. Green crab larvae can also survive in the ballast water of ships entering Puget Sound, a major—and at times unregulated—pathway for a variety of invasive species. You can catch up on green crabs and other emerging threats from invasive species in our August series in Salish Sea Currents.

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New in Salish Sea Currents: Invasive stowaways threaten Puget Sound ecosystem

A state inspector boards a container ship at the Port of Seattle to check on ballast water and determine whether procedures were followed to reduce the risk of invasive species being released into Puget Sound. Photo: WDFW

A state inspector boards a container ship at the Port of Seattle to check on ballast water and determine whether procedures were followed to reduce the risk of invasive species being released into Puget Sound. Photo: WDFW

Invasive species are among the three greatest threats to the environment worldwide, according to the International Union for Conservation of Nature. Species ranging from microscopic viruses to larger creatures like rodents and non-native fish can alter the balance of entire ecosystems. The threat is well-known in Puget Sound and the Salish Sea, which face their own unique challenges.

This week, our magazine Salish Sea Currents looks at some of the ways that invasive species get into local waters. Senior writer Christopher Dunagan reports on two leading pathways that have caught the attention of regulators. Studies show that many invaders are literally shipped into our ports. They arrive as stowaways in ballast water, or attach themselves to the outer hulls of boats and ships, a condition known as biofouling.

Despite this knowledge, there remain significant gaps in regulations of these two pathways. Most ships are required to exchange their ballast water in the open ocean, which offers some protection. But in the case of ships coming from the mouth of the Columbia River — a known hot-spot for potential invaders — ballast water can still be dumped directly into Puget Sound. Researchers worry that this could open the door for species of concern such as the green crab, or tiny crustaceans known as copepods that may already be interfering with the Puget Sound food web. The other major pathway, biofouling, is almost entirely unregulated.

Officials are just starting to develop—and debate—plans to address these issues. You can read the entire series on the Encyclopedia of Puget Sound.

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Still no zebra mussels in Washington

Hard to tell if this news is positive or foreboding, but the Puget Sound region starts another year with a clean bill of health on at least one front. The Washington Invasive Species Council reports that Washington is one of only five Western states remaining with no invasion of zebra mussels.

Photo courtesy of USFWS

That’s good for Washington as far as it goes, but in its recently released 2012 Annual Report to the Legislature, the council writes: “If introduced, the mussels can quickly spread through rivers and lakes, impacting native species, recreation, and infrastructure for power generation, irrigation, municipalities, and industrial use… an invasion of these mussels in the Columbia River will cost the region hundreds of millions of dollars a year.” The other Western states free of zebra mussels are Oregon, Idaho, Montana, and Wyoming.

The report also spotlights invasive spartina, the emerald ash borer, the New Zealand mud snail, viral hemorrhagic septicemia (a fish disease), and a host of other non-native species ranging from yellow starthistle and cheat grass to bullfrogs. Invasive species are a major factor in worldwide declines in biodiversity and cause billions of dollars worth of damage in the United States each year. Download a copy of the 2012 report to read more.

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