Although it looks like a sponge or algae, D. vex is actually a colony of millions of tiny organisms. The resulting mat can smother other organisms on the sea floor as D. vex spreads. (ADF&G photo)

The state’s campaign against an invasive marine species near Sitka is going on hold, while researchers crunch their data and look for funding to pursue all-out eradication.

Downloadable audio.

Note: Tammy Davis, Katy Newcomer, and Ian Davidson will be giving a presentation on their research Monday, August 27, beginning at 5:30 p.m. in the Sitka Sound Science Center.

The battle against the invasive tunicate Didemnum vexillum, or D. vex, began in earnest in 2015. That summer, biologists tried to figure out what substance best kills D. vex, which carpets the ocean floor in a dense, unsightly mat — earning it the nickname “sea vomit.”

In subsequent years, researchers have worked to refine their methods, to take out as much D.vex as possible, while leaving the rest of the ocean environment unharmed.

A team from the Alaska Department of Fish & Game and the Smithsonian Environmental Research Center anchors one end of a turbidity curtain to the shore of Whiting Harbor. Before chlorinating the test plot to kill the D. vex, divers remove as many non-invasives — like abalone — as possible. (ADF&G photo/Tammy Davis)

Ian Davidson, with the Smithsonian Environmental Research Center, has been on the project since the beginning. He says the team has finally dialed in a technique for killing D. vex, using a floating barrier called a “turbidity curtain,” and a biocide familiar to us all: swimming pool chlorine.

“We’ve had a pretty steep learning curve, learning to use our turbidity curtains,” said Davidson. “This time we covered larger plots. So we deployed our turbidity curtains and applied our biocide within that, with the help of the Kestrel team, which are absolute integral to everything that goes on. So we are getting more confident that we can treat larger areas, that we can spot check different areas, and start reducing cover.”

Before researchers attempt to kill the D. vex in a sample plot, they add rhodamine dye to test the integrity of the curtain. The goal of the eradication effort — if it comes to pass — is to kill D. vex and to leave the rest of the ecosystem unharmed. (ADF&G photo/Tammy Davis)

The Smithsonian team is working with the Alaska Department of Fish & Game aboard the state research vessel Kestrel, which is prominent around Sitka in March, when it serves as the management platform for the Sac Roe Herring fishery. Their target area is Whiting Harbor, just across Sitka’s airport runway, which around 20 years ago was home to a now-defunct oyster farm.

About 3,500 feet of the Whiting Harbor shoreline was contaminated by D.vex from the farm, and although all farm structures have long since been removed, the D.vex remains. It’s growth has been slow, and that’s why we have a chance to stop it.

Katy Newcomer is Davidson’s colleague from the Smithsonian.

“We still kind of see it as the ideal candidate for removal,” Newcomer explains. “It’s the only known population in Alaska. It’s in a small area that we have surveyed many times, and know its extent. And so we feel it’s a really good candidate for removal.”

But it’s still no simple task to deploy a turbidity curtain — accounting for Sitka’s tides and currents. The team opted for heavy, black pvc plastic, rigged to a complicated system of floats. Newcomer and Davidson say it’s difficult to work with, but effective.

Newcomer — So we’ve enclosed a column of water, either inside or against the shoreline, and the space that it covers depends on how well we set the curtain itself. It can be as big five meters by five meters, or eight meters by eight meters. It kind of varies depending on how well we get it to stretch it’s full length.
Davidson — It’s very robust, but for what we got in robustness, it’s not as nimble as we would have liked.

The project is being spearheaded by ADF&G’s Invasive Species coordinator Tammy Davis, in partnership with the Bureau of Land Management, which owns the intertidal area around Whiting Harbor. So far, Davis is relieved that D.vex remains contained in Whiting. The tunicate has turned large areas off of the US Atlantic coast into marine deserts. The state has installed buoys in the area alerting boaters to the hazard, but there is always a danger D.vex could spread.

“Should kayaks or other vessels move into that infested area and then go out into a harbor, and then D.vex move into one of the harbors — that would be a shame,” Davidson said. “Because that would be a vector for moving the tunicate broadly throughout the state.”

To prevent that from happening, Davis would like to consider full eradication. But like everything in state government at the moment, it’s complicated. The top priority of her office is invasive species prevention — eradication is really a different kind of challenge altogether, as is raising the money to do it.

The Smithsonian’s Davidson says that is phase 3.

“So we’ve just completed Phase 2,” he said. “We just got out of the water yesterday so we’re really at a point of review and analysis. Then it’s the time to put the strategy together, estimate how much it would cost, and get those proposals together.”

Tammy Davis says that as far as the state is concerned, this field trial is over for now. She hopes to partner with the University of Alaska Southeast’s dive research program for ongoing monitoring of the control plots. Keeping an eye on D.vex is critical, according to Ian Davidson. “We just don’t know the trajectory of this organism.”

D. vex grows in dense colonies. Although each individual is microscopic, together they form a slimy mat resembling a sponge. (Photo/KCAW/Robert Woolsey)

The Alaska Department of Fish and Game’s Invasive Species Program is back in Sitka this spring, with a new round of research on the best way to kill off an organism called d-Vex.

KCAW’s Robert Woolsey recently spoke with the project director Tammy Davis.

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ADF&G and the Smithsonian Environmental Research Center will give a presentation on the work, 6-8 p.m. Wednesday, May 23 in the Sitka Sound Science Center.

D. vex grows in dense colonies. Although each individual is microscopic, together they form a slimy mat resembling a sponge. (KCAW photo/Robert Woolsey)

The state of Alaska is going to war against an invasive species in Sitka, and its weapon is science.

Earlier this summer, the state Department of Fish & Game and the Smithsonian Environmental Research Center developed a concept for fighting an invasive sea squirt in Sitka’s Whiting Harbor.

This month, they’ve deployed dive teams for a full-scale test. Their objective? To kill off this organism before it affects any other Alaskan waters.

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Whiting Harbor is not a big patch of water — but it’s big enough for D.vex, or Didemnum vexillum, to have gotten a toehold in Alaska. And it’s not letting go. D.vex likely hitched a ride to Sitka over a decade ago on equipment for an oyster farm.

That oyster farm is long gone, but Dvex has spread to the sea floor, and there’s nothing really to stop it except Tammy Davis.

Tammy Davis (r) with fellow biologist Cody Jacobson prepare to send a half-pound of chlorine down to divers preparing the dome. (KCAW photo, Robert Woolsey)

Davis, on VHF radio – Okay… we’ll spike this chlorine, take a sample, then come find him.

Davis is a sportfish biologist with the Alaska Department of Fish & Game who’s leading the effort to eradicate D.vex. The invasive sea squirt has blanketed the seafloor in once-productive fishing grounds on the US Eastern Seaboard, creating underwater deserts. That’s exactly what Davis doesn’t want to see happen in Alaska.

She takes me aboard her dive skiff, one of three working test plots in Whiting Harbor. This boat is piloted by Cody Jacobson, a sportfish biologist from Palmer.

The staff of Dive Skiff 1 (from l to r) Jeff Meucci, Scott Forbes, Cody Jacobson, and Tammy Davis (holding a D.vex sample). The dive teams work test plots on both the rocky slopes of the Whiting causeway, and on its sandy bottom. (KCAW photo/Robert Woolsey)

The divers are Scott Forbes, a commercial fisheries biologist from Juneau, and Jeff Meucci, a dive safety officer with Fish & Wildlife. In the next boat are two more Comfish divers, and a representative from the Bureau of Land Management, which owns the tidelands in Whiting Harbor. The third skiff is manned by two scientists from the Smithsonian Environmental Research Center.

Anchored about a quarter-mile away, outside of the infested area, is the 105-foot state-owned research vessel Kestrel, with three crew members.

For a state that’s having trouble making ends meet, a lot of money is going into stopping D.vex. Davis says it’s a deliberate choice.

“In terms of invasive species, aquatic or terrestrial, do you spend money today to prevent spending a lot more money later to deal with a larger problem?” she asks.

Because several agencies are involved, Davis doesn’t have an exact number. Somewhere in the six-figure range, certainly. D.vex eradication was funded in last year’s state budget for capital projects, with the advocacy of Sitka’s municipal government and both state legislators.

Ian Davidson and Michelle Maraffini, from the Smithsonian, helped design the eradication strategy. Trying to introduce a natural predator is risky: “We could end up with another invasive,” Maraffini says. (KCAW photo/Robert Woolsey)

There is a lot riding on stopping it here in Sitka. We pull alongside the Smithsonian skiff, and I go aboard to talk with Ian Davidson.

“There are things here in the bay that eat it. They just don’t control it,” he says.

Things like leather sea stars. Ian Davidson is originally from the south coast of Ireland. He now works for the Smithsonian in Maryland. He designed this assault on D.vex. It’s chemical warfare. The dive teams are placing fabric domes about 8 feet square on the bottom, and then pouring in either large amounts of salt, chlorine, or lime dust.

The treatments should kill the D.vex, according to Davidson and his colleague Michelle Maraffini, and possibly most everything else under the dome.

Kestrel captain Lito Skeek, of Petersburg, and his engineer, Gary. Skeek says the crew of the Kestrel, which spends the summer supporting commercial fisheries research, supports this eradication effort just as much. (KCAW photo/Robert Woolsey)

“If you want to get rid of this problem, then there’ll be a temporary hit to non-target species in Whiting. But all of the local species will recolonize. So this whole area will go back to the way it was without Dvex in it,” said Davidson.

Maraffini lives in California, where there are hundreds of documented invasions of various species on land, in freshwater, and in the ocean. D.vex is there. It’s also been found in Oregon and Washington. The next-closest site to Sitka is about 600 miles away, in British Columbia.

This distance is the key to beating D.vex in Alaska.

“Usually we catch an invasion too late. It’s already spread farther than we can control. This one is isolated. It’s pretty far from the next population. This is our best chance of success at an eradication experiment,” Marafini says.

The 105-foot Kestrel is one of two research vessels operated by the state in Southeast waters. It visits Sitka every spring to support the renown sac-roe herring fishery. (KCAW photo/Robert Woolsey)

The experiment exposes D.vex to high concentrations of salt, chlorine, or lime for about four hours. The divers will then pull up the domes and, three weeks later, Davidson and Maraffini will return to see what agent was most effective in killing D.vex. Once they have an answer, they’ll design a bay-wide attack.

It takes three weeks to know whether you’ve killed D.vex. It grows in dense colonies that look like slime to the naked eye — it’s sometimes called “sea vomit.”

Just as an army marches on its stomach, research takes food. Kestrel cook Becky Wilson preps chicken burgers for the D.vex team. (KCAW photo/Robert Woolsey)

Tammy Davis has asked her divers — and I’m sorry to use this expression — to bring some up for me.

“This color is variable. When it’s growing on rocks we tend to see this cream color, whereas this is quite orange. It also seems like it gets this orangy color later in the summer.”

D.vex is often mistaken for a native sponge. But it looks dangerous on the deck of the boat — it feels like a lab tech has pulled a vial of measles virus out of storage. The divers joke that I could take it home and put it in my aquarium.

I would do it, if I knew that I could kill D.vex just by pouring in some salt. We won’t know if this trick works, though, for another three weeks.

Davis – We’ll keep in touch.

Although salt may be the most benign of the lethal agents being tested against D.vex, it takes a lot to maintain deadly concentrations for four hours. Divers poured up to 150 pounds of salt under each dome during testing. (KCAW photo/Robert Woolsey)

Ian Davidson, from the Smithsonian Environmental Research Center, explains how the canvas enclosure will kill D.vex. The eradication testing is being led by ADF&G biologist Tammy Davis. Tim Sundlov is coordinating the participation of the Bureau of Land Management, which controls the intertidal areas. Other members of the Smithsonian team diving in Sitka are Michelle Marraffini and Greg Ruiz. (KCAW photo/Robert Woolsey)

A multi-agency effort is underway in Sitka to eradicate an invasive sea organism before it can spread to other parts of the Alaskan coast.

A team of scientists from the Smithsonian Institution is testing several methods of killing an invasive sea squirt called D.vex, before launching a full-scale assault later this summer.

Downloadable audio.

Two years ago D.vex was a threat. Now, it’s a target.

Ian Davidson, originally from Ireland, works for the Smithsonian Environmental Research Center. He’s unfolding a heavy canvas dome on the floor of the Sitka Sound Science Center, while about 20 interested Sitkans look on.

It’s about 6 or 7 feet wide, and it will be used to poison, suffocate, or otherwise kill Didemdum vexillum.

I can’t help but think that we’ve seen this idea before.

1980s TV commercial – Black Flag Roach Motel. Roaches check in, but they don’t check out!

Davidson has designed an underwater D.vex motel.

“This enclosure has a vent pipe on the outside. And then we’ve got a heavy chain inside that gets velcroed right here. And we’ve got sandbags around the rim of it as well. So the idea is to create an enclosure, well-sealed, that anything we put in there, the concentration will be retained for four hours.”

And what Davidson and the other members of the Smithsonian team plan to put under the dome are large amounts of salt, lime dust, or chlorine. All three have proven deadly to D.vex in the lab. This is the first field test.

Right now D.vex is confined to a relatively small area in Sitka’s Whiting Harbor, just off the airport runway, where there used to be an oyster farm. The next closest invasion is over one-thousand kilometers away in Canada.

Davidson says this is an opportunity.

“The occurrence in Sitka represents a really big jump in its distribution on the Pacific Coast of North America. It’s what makes it an interesting candidate for assessing feasibility for eradication. It got up here at one point, possibly through aquaculture activity, the most likely scenario, but it’s not known exactly what it was. But it’s not inevitable that it would come back, if we were able to get rid of it.”

D.vex looks like bad carpeting. It’s nickname is “sea vomit.” This image is from Whiting Harbor. (ADF&G photo)

Other than our conspicuous desire to kill it, D.vex has nothing in common with the cockroach. It’s a small tunicate, or sea squirt, that grows in colonies which cover the ocean floor like bad carpet from the 1970s. D.vex is native to Japan, where it’s controlled by biological mechanisms which aren’t fully understood. It started turning up elsewhere around the globe in the 1990s — the Mediterranean and New Zealand — possibly transported in the bilge water of ships.

On the Eastern Seaboard of the United States, D.vex has blanketed many square kilometers of the famous Georges Banks, once a rich area for scallops and other seafood.

The field test in Sitka is being conducted from the Alaska Department of Fish & Game’s research vessel Kestrel. This is the first of four trips planned by the Smithsonian and ADF&G to Whiting Harbor. Davidson says it will take about 3 weeks to see if D.vex dies under each of the three proposed treatments.

Once the team has a so-called “proof of concept,” they’ll attempt a bay-wide eradication.

And then, hopefully, it will It should be goodbye D.vex.

TV commercial – Don’t worry, we’re sending them to a motel. Motel? Right, the Black Flag Roach Motel.

Contractors with Seattle-based Pacific Pile and Marine set a piling in ANB Habor in mid-December. (KCAW photo/Rachel Waldholz)

In November, work began on Sitka’s ANB harbor. The $7.7 million project will demolish all of the existing structures and replace them with new floats and pilings by early spring. But a small invader in the harbor has added a wrinkle to the usual process.

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Sound of drilling.

Workers with the Seattle-based contractor Pacific Pile and Marine are driving piles into the seafloor at ANB Harbor. Sitka City Engineer Dan Tadic watches from the parking lot at ANB Hall.

In between drilling, workers blow air into the piling to clear out cuttings and advance the drill, sending water and cuttings spitting out of the top of the piling. (KCAW photo/Rachel Waldholz)

“What they’re doing right now, they’ve got the basically the tip of the piling on rock, and they’re starting to drill into the rock,” Tadic says.  “And every few feet or so they’re using air to blow the cuttings back out of the piling, so it almost looks like the water is boiling.”

The contractors are drilling about 13 feet into rock to set the pilings. They stop occasionally to flush out the cuttings. At those moments, with water bubbling up and cuttings spraying from the top of the piling, it looks like they’ve struck oil.

The contractors will put in over 60 new galvanized-steel pilings, ranging from 12 to 24 inches in diameter. Those will be followed by brand new floats. The work has to be done by March 15, in time for herring season.

But there’s a side story to the project. In 2010, volunteers with Sitka’s Bioblitz survey found a pair of invasive tunicates – small marine invertebrates – in ANB harbor, as well as several other Sitka harbors.

These tunicates aren’t d. vex (Didemnum vexillum), an invasive tunicate that many Sitkans have heard about before — and that is sometimes compared to the creature from the 1950’s horror movie, The Blob. D. vex can grow extremely fast, blanketing and smothering entire ecosystems. It was found in Sitka’s Whiting Harbor in 2010 — and that’s still the only place in Alaska that it’s been found.

The tunicates in ANB harbor are called botrylloides, or harbor star and golden chain tunicates. And they’ve been much better behaved than d. vex – so far.

Marnie Chapman is a biologist at the University of Alaska Southeast.

“We’re interested in watching the botrylloides group,” Chapman says.  “Because even though at this point there hasn’t been demonstrated massive growth of these, a lot of times what invasives do is they can hang out at very low levels and then all of a sudden something will change about the environment and then they’re able to grow and expand rapidly.”

The concern is that, given the right conditions, the botrylloides in ANB Harbor could suddenly explode, choking out native species. So though the botrylloides have remained fairly contained thus far, officials hope to avoid spreading them further. Because of this, the ANB Harbor project permit requires that all of the material from the harbor be disposed of in a different way than usual.

“A lot of times what happens in Alaska is bits and pieces of harbors get sent all over the place when harbors are decommissioned,” Chapman said. “And so it’s potentially a really effective way of spreading invasive species to really pristine areas in Alaska, to take pieces of harbors and move them somewhere else.”

Instead, the material from ANB harbor will be barged down to Seattle and disposed of on land. The wood will be taken to a landfill. The steel piling will be recycled. And officials hope the process will prevent the harbor’s  invasive stow-aways from hitching a ride to any other Alaskan ports.