Tag Archives: Crab Team

Green crabs entrenched at Dungeness Spit, but new issues are emerging

Dungeness Spit on the Strait of Juan de Fuca near Sequim remains a hot spot for the invasive European green crab, which first showed up in Puget Sound during the fall of 2016.

This small male crab is one of the European green crabs caught last year in traps at Dungeness Spit.
Photo: Allen Pleus

The green crab, one of the most dreaded invasive species in the world, brings with it the potential to destroy shellfish beds and disrupt key habitats essential to native species in Puget Sound.

Thankfully, except for the Dungeness Spit, new findings of green crabs have been almost zero since a massive volunteer trapping effort resumed in April throughout most of Puget Sound.

I do have some additional news about green crabs to share, so please read on for a discussion of these topics:

  • Green crabs on Dungeness Spit
  • New findings on Whidbey Island
  • Where the crabs are NOT coming from
  • New efforts with Canada
  • First scientific paper on the green crab program
  • New assessment tool on the horizon

Green crabs on Dungeness Spit

So far this year, 42 of the invasive crabs have been found on Dungeness Spit, compared to 96 for all of last year, according to Lorenz Sollman, deputy project leader for the Washington Maritime National Wildlife Refuge Complex.

European green crabs have been found on Graveyard Spit, the small spit that juts off the main Dungeness Spit.

So far, nobody knows if the first crabs to arrive on the spit are reproducing or if the young ones being found there are new arrivals. Crabs can travel great distances through the water in larval form before they settle down and take on the familiar appearance of a full-grown crab.

“We don’t have any reason to think that they are not reproducing (at Dungeness),” said Emily Grason, Crab Team coordinator for Washington Sea Grant. The Crab Team is a group of volunteers and experts who monitor 54 trapping sites in the region.

Just this morning, Crab Team members found a new green crab at Dungeness Landing County Park, west of the Dungeness River and just outside the Dungeness National Wildlife Refuge.

“We’ve had our eye on that site, since it’s so close to the Dungeness Spit and assumed it was only a matter of time before one showed up there,” Emilly wrote me in an email.

Meanwhile, in Makah Bay just outside the Strait of Juan de Fuca in the Pacific Ocean, nearly 400 crabs have been captured in an intensive trapping effort this year alone. The first crab was spotted in the bay last fall. Matthew Nash of the Olympic Peninsula News Group updated the situation this week — although it is Makah Bay, not Neah Bay. The latter, which is technically inside Puget Sound, has not been found to have any green crabs.

New findings on Whidbey Island

At the beginning of this month, one of the most intensive trapping programs yet in Puget Sound was conducted over three days at Lagoon Point on Whidbey Island, where two green crabs were caught on different days last year. Working in deep sticky mud, only one green crab was caught in the enclosed lagoon during the latest effort.

Crab Team leaders Sean McDonald, Kelly Martin and Emily Grason following their three-day trapping effort on Whidbey Island.

“While we might have been happier not to catch any green crab, we are certainly glad that we only found one,” wrote Kelly Martin for the Crab Team Blog. Kelly, the newest member of the Crab Team management group, goes on to talk about the trapping adventure — including her accidental sit-down in the mud.

In a previous blog post, Kelly, who is a graduate student at the University of Washington, introduced herself to readers and talked about her background.

Where the crabs are NOT coming from

It has been suspected that the European green crabs found at Dungeness Spit as well as those on San Juan Island and Padilla Bay may have originated from Sooke Inlet at the southern tip of Vancouver Island, where a large infestation of green crabs has become well established.

After all, Sooke Inlet is physically close to areas in Puget Sound where green crabs have been found, at least when compared to infested areas along the coast. Although a large channel separates the U.S. from Canada, that might not be much of an obstacle for crab larvae, which drift with the currents.

To the surprise of many, a research project involving crab DNA showed that the green crabs in Puget Sound were NOT closely related to those in Sooke. Instead, the crabs at Dungeness Spit came from coastal populations, according to genomics work by Carolyn Tepolt of Woods Hole Oceanographic Institution. The Sooke population is considered genetically isolated and very different, probably because it started some time ago by a small number of crabs that did not mix with others.

Lagoon Point, Whidbey Island: Blue dots are minnow traps; orange dots are larger fukui traps; large orange circles are where two European green crabs were found last year; and the yellow circle is where the one crab was found this year. // Map: Crab Team

At the same time, studies of the tidal currents in the area showed that Sooke was no more likely to be a source of crab larvae than coastal areas. Crab larvae coming from Sooke are likely to be swept toward the ocean, whereas rare conditions called “reversals” can bring larvae from the Washington Coast along the southern shore of the Strait of Juan de Fuca, according to a study by Elizabeth Brasseale, a graduate student in oceanography at the University of Washington. See the Crab Blog from April 25.

New efforts with Canada

Knowing that Sooke is not the source of the green crabs in Puget Sound changes the dynamic with Canada.

“It was a relief to find out that crabs (from British Columbia) were not inundating our shores,” Emily Grason told me. “If that had been the case, the necessary management action would be to throw everything at Sooke Basin.”

The cost of eradicating green crabs from Sooke would be enormous and probably would not help the situation in the U.S. On the other hand, the Canadians may learn some things from the extensive trapping program taking place in Puget Sound, which seems to be keeping the crab population in check. Sooke may be somewhat of a lost cause, but there could be hope for other B.C. inlets at risk of being invaded.

A cross-boundary task force has been discussing the green crab problem on both sides of the border. Meanwhile, an expert panel at April’s Salish Sea Ecosystem Conference discussed the pros and cons of international cooperation as well as political realities of dealing with the problem. Kelly Martin summarized that session for the Crab Blog on April 27.

First scientific paper on the green crab effort

The first publication addressing Puget Sound’s European green crab invasion documents the early stages of a horrific invasive species while celebrating the collaborations of hundreds of people making detection and control possible, according to Emily. Allen Pleus, coordinator of Washington’s Aquatic Invasive Species Program.

“If you are familiar with Crab Team, you might wonder why this scientific paper, which only covers the findings through the end of 2016, is important,” Emily Allen wrote in the Crab Team Blog. “We have certainly been sharing news about findings through our blog, the media and other outlets.

“So, what does this publication add?” she asked. “This paper will help scientists track how European green crab has spread across the globe. Because of the rigorous review conducted on the paper by multiple experts – and believe me, it was rigorous – the information can be used to inform policy and management of this species, both here, and in other locations.”

As with most scientific papers, the information shared with the world lags behind current events, yet it reaches a depth of information that will be most helpful for those working with European green crabs, invasive species and related subjects.

Here’s the paper: “Citizen science program detects range expansion of the globallyinvasive European green crab in Washington State (USA)” (PDF 1.4 mb) in the publication “Management of Biological Invasions”

New assessment tool on the horizon

Although trapping European green crabs has been effective at locating the early stages of an invasion in Puget Sound, imagine instead taking a water sample and sending it to a lab. After a short wait, a technician using DNA techniques would tell you the likelihood of finding crabs in that location.

This is the ultimate test that I’m imagining as a new effort gets underway to identify invasive species by looking for DNA floating in the water. The technique is known as environmental DNA testing, or simply eDNA, and it is increasingly being used in freshwater to look for the presence of species of interest.

Developing a technique for saltwater adds the complexity of tides and currents moving DNA around, chemical breakdown of DNA, and determining if the DNA signal is coming from the larval form of a species or reproductive adults.

Alison Watts, an environmental engineer at the University of New Hampshire, has received a two-year, $500,000 grant to study eDNA in marine estuaries. She is collaborating with researchers at sample sites in Oregon, Maine and New Hampshire. The idea is to use eDNA techniques alongside traditional methods of biological sampling, such as seining, trapping and electrofishing.

The eDNA samples undergo both “meta-barcoding,” which can identify DNA from multiple species in a single sample, and single-species PCR amplification, which is designed to test for the presence or absence of a target species, Alison told me.

The eDNA techniques might provide an early warning of green crabs — say in South Puget Sound, where they have not been found before — but it would not provide information about the number of crabs or their physical conditions.

“We are developing and testing the methods this summer, then will validate and develop guidance materials next summer,” she said in an email. “Once the initial methods are developed, it is our hope that they will be useful for a range of applications, including early detection of green crabs or identifying their range within a system.”

For information about the grant, check out:

New bridges provide improved habitat in two Kitsap County creeks

Contractors are putting the final touches on two new bridges in Kitsap County, both of which are expected to improve the local environment.

A new bridge over the Carpenter Creek Estuary near Kingston helps to restore the upper salt marsh.
Photo; Stillwaters Environmental Center

One is a 150-foot bridge that crosses the Carpenter Creek Estuary on West Kingston Road near Kingston. The other is a 50-foot bridge that crosses Big Anderson Creek on Seabeck-Holly Road near Holly.

Among local residents, the Carpenter Creek bridge may best be known as the bridge that blocked traffic and forced a detour near Kingston for more than a year — much longer than originally planned. (Recall reporter Nathan Pilling’s story in the Kitsap Sun.) While contract issues remain in dispute, the environmental benefits are clear, according to Joleen Palmer of the nearby Stillwaters Environmental Center.

The old roadway across the estuary acted like a dam to impede flows upstream and downstream.
Photo: Stillwaters Environmental Center

Replacement of a 5-foot culvert with the bridge over the estuary has obvious benefits for salmon that must fight the current to go upstream to spawn, Joleen told me, but people may not appreciate the importance of the much-expanded salt marsh.

When the roadbed was installed nearly a century ago, it formed a dam, causing water in the stream to back up, which encouraged freshwater vegetation. The saltwater influence was greatly reduced, and critical nutrients coming downstream were deposited before they reached Puget Sound.

The new bridge will allow saltwater to come and go with the tides and for nutrients to flow out more freely. Juvenile salmon coming downstream can pause to grow and acclimate to the saltier conditions they will face.

Salt marshes, which were filled in all too often years ago, are considered highly productive, because dead organic material — detritus — from the stream and estuary feeds bacteria, insects, worms and a multitude of other tiny creatures at the base of the food web.

“Salt marshes are really detritus-based ecosystems,” Joleen said. “You have many invertebrates that eat the detritus and other decomposers. The food sources reach out into the estuary and nearshore habitat to fuel the marine food web. It is not insignificant that the area is now opened up.”

Side channels in the marsh will provide refuge for young fish to grow before they head out to sea. To varying extents, the stream, marsh and estuary are expected to support coho, chinook and chum salmon along with steelhead and cutthroat trout.

Volunteers and students have been monitoring conditions in the watershed to measure the changes taking place. The latest addition to the monitoring effort is an ongoing search for the invasive European green crab. The volunteer program, called the Crab Team, is managed by Washington Sea Grant.

“The estuary is still some distance from known populations of invasive European green crab,” writes Cindi Nevins, a North Kitsap resident who joined the team, “but if the green crabs ever do arrive at Carpenter Creek, they will find exactly the kind of space they love: salt marsh channels, marsh vegetation and quiet lagoon-like waters. Why do we think they’ll love it? Because hairy shore crabs (Hemigrapsus oregonensis) do!”

Throughout Puget Sound, Crab Team members catch and identify hundreds of thousands of crabs in marsh habitat suitable for both the natives and the invaders. The volunteers hope never to catch a green crab, but some green crabs have been found in a few places in Northern Puget Sound and the Strait of Juan de Fuca. By intensifying the trapping effort, the Crab Team hopes to eradicate the invaders, or at least keep them under control.

Cindi’s report, published in the Crab Team’s newsletter, goes on to describe the challenge of catching crabs in the Carpenter Creek marsh, which often drains completely at low tide. Because the traps must be kept submerged to be effective, the volunteers are often forced to set the traps in the evening as the tide comes in and retrieve them early the next morning before the tide goes out.

To celebrate completion of the new bridge, everyone is invited to celebrate “Estuary Restoration Day” on Saturday, June 9, from 11 a.m. to 1 p.m. at Stillwaters Environmental Center, 26059 Barber Cut Off Road, Kingston.

The program will include guided tours to the marsh, live music, food and a native plant sale. Those involved with various aspects of the project will receive special recognition.

For information and videos about the marsh, visit the Stillwaters website.

The new bridge over Big Anderson Creek near Holly is nearly twice as long as the old one.
Photo: Christopher Dunagan

The bridge over Big Anderson Creek near Holly is more of a highway-safety project than an ecosystem-restoration effort. The wooden bridge, 67 years old, was the last bridge in Kitsap County to be rated structurally deficient because of its overall poor condition. Check out the story in the Kitsap Sun by reporter Ed Friedrich.

Still, the new concrete bridge, which spans 50 feet of stream, is nearly twice as long as the old bridge. That will allow the stream to meander more naturally and at a rate that sandbars can form nearby. At high flows, the stream won’t be squeezed as much through the space under the bridge.

The old wooden bridge over Big Anderson Creek was rated structurally deficient by inspectors.
Photo: Kitsap County Public Works

By the way, the official name of the stream is “Anderson Creek,” allowing confusion with two other streams named “Anderson” in Kitsap County alone. I prefer to call it “Big Anderson,” in conformance to tradition by area residents and local institutions. For a further explanation of the issue, read Water Ways, June 22, 2017.

Green crab invaders settle in on Dungeness Spit, Olympic Peninsula

An invasion of the European green crab, which started last summer in northern Puget Sound, appears to be continuing this spring with 16 green crabs caught in traps at one location on Dungeness Spit near Sequim.

European green crab
Photo: Gregory C. Jensen, UW

The new findings are not entirely unexpected, given that invasive green crabs have established a viable population in Sooke Inlet at the southern end of Vancouver Island in Canada. From there, young crab larvae can move with the currents until they settle and grow into adult crabs. Last summer and fall, green crabs were found on San Juan Island and in Padilla Bay.

The big concern now is that a growing population of invasive crabs could spread quickly to other parts of Puget Sound, causing damage to commercial shellfish beds and disrupting the Puget Sound ecosystem.

“It knocks the wind out of your sails for sure,” said Emily Grason when I asked how she felt about the latest discovery. “You feel kind of powerless, and you want to get out there and start doing things.”

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Crab Team training will foster the upcoming hunt for green crab invaders

A European green crab invasion may be taking place in Puget Sound, and Washington Sea Grant intends to enhance its Crab Team this summer with more volunteers looking in more places than ever before.

The second European green crab identified in Puget Sound was found in Padilla Bay, where three others were later trapped.
Photo: Padilla Bay Reserve

Training is about to get underway, and anyone with an interest in furthering science while being exposed to the wonders of nature may participate. It’s not always good weather, but I’ve been inspired by the camaraderie I’ve witnessed among dedicated volunteers.

The work involves going out to one or more selected sites each month from April into September with a team of two to four other volunteers. It is helpful to have folks who can carry the crab traps, plastic bins and other equipment. For details, check out the Washington Sea Grant website.

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