Cracking the Case of the Vanishing Oyster Larvae

Olympic Peninsula, WA

July 28-August 1, 2013

Algae grown in these tanks will feed oyster larvae at Taylor Shellfish's hatchery

Algae grown in these tanks will feed oyster larvae at Taylor Shellfish’s hatchery

The algae tanks that line the walls of Taylor Shellfish Farms hatchery in Quilcene, Washington are varying shades of emerald greens and beer-like browns. Each one holds a different gourmet meal for oyster larvae. The chief hatchery scientist, Benoit Eudeline, weaves through the tanks looking relieved.

“These look good,” he says. “We’ve been having some trouble growing algae lately. If it’s not problems with the larvae it’s always something else.”

When we visited the Olympic Peninsula, some of the oysters were spawning naturally in the beds

When we visited the Olympic Peninsula, some of the oysters were spawning naturally in the beds.

This hatchery has been around for 23 years, supplying Taylor Shellfish Company, the largest producer of farmed shellfish in the United States, with the oyster seed it needs. Before hatcheries came into play in the ’70s, oyster farms relied mostly on chance that the shells (also called culch) they put out in the water would be in the right place at the right time under the right conditions when the oyster larvae transform from limbed swimmers into sedentary mollusks—a good natural ‘set’. The hatchery, Eudeline tells us, is supposed to take the uncertainty of a good oyster set out of the equation. But a few years ago, that whole plan went to pieces.

The mystery of the dying larvae

A tank of oyster larvae at Taylor Shellfish hatchery in Quilcene, WA.

A tank of oyster larvae at Taylor Shellfish hatchery in Quilcene, WA.

The West Coast oyster industry crisis began at the Whiskey Creek Shellfish Hatchery, a popular seed-seller on the Oregon Coast. In 2007, almost all of the oyster larvae died—they disintegrated in the hatchery tanks. No one knew why.

A scientific investigation by Oregon State University researchers determined that the larvae loss was definitively linked to ocean acidification. The pH of ocean water historically hovered around 8.16 (7 is a neutral pH), but over the last two centuries, the oceans have absorbed a third to half of the carbon dioxide emitted through the burning of fossil fuels. This has resulted in increasingly acidic water, and the average pH of the world’s

The world's ocean's are absorbing carbon dioxide emissions, making them more acidic.

The world’s ocean’s are absorbing carbon dioxide emissions, making them more acidic.

oceans is now 8.05. This may not seem like a big change, but since the pH scale is logarithmic, the ~0.1 drop indicates a 30% increase in ocean acidity. With the current carbon emissions pathway we’re on, ocean acidification is expected to jump by 150% compared to historical averages by the end of the century. And ocean organisms aren’t used to this rapid rate of change. Though the pH of the world’s oceans has shifted over millennia, the current rate of ocean acidification is at least 10 times faster than anything the Earth has experienced over the last 50 million years.

The carbonate cycle was written on a white board next to monitoring equipment at Taylor Shellfish's hatchery

The carbonate cycle, which explains how the oceans are acidifying, is written on a white board next to monitoring equipment at Taylor Shellfish’s hatchery.

When the extra carbon dioxide bonds with seawater, it releases hydrogen ions that then bond with carbonate ions in the water. This carbonate would otherwise be available for shellfish and other marine organisms to make calcium carbonate—the main ingredient in their shells and skeletons. So, at Whiskey Creek and other hatcheries, the effect of an acidifying ocean is that the seawater the hatcheries suck into their tanks to hatch and grow the larvae now contains fewer building materials for the metamorphosing oyster larvae to make their first shells.

Benoit Eudeline of Taylor Shellfish stands next to a vat of his prized oyster larvae.

Benoit Eudeline of Taylor Shellfish stands next to a vat of his prized oyster larvae.

“The larvae don’t eat much for the first few weeks—they mostly use the energy they got from the egg. So, if you [an oyster larvae] are suddenly faced with less carbonate, you’re spending more of that precious energy on trying to make a shell and you have less energy to survive,“ said Eudeline as he toured us around Taylor Shellfish’s hatchery.

The ghost of water past

Road tripper Allie Goldstein poses next to a Taylor Shellfish truck

Road tripper Allie Goldstein poses next to a Taylor Shellfish truck

But why did the larvae all die in 2007 specifically? While Washington’s Hood Canal and Puget Sound provide some great oyster-growing conditions—brackish, moving water and a decent algae food source—the Pacific Northwest coast also gets northern winds in the summer which bring with them upwellings of water from deep in the ocean. This deeper water is naturally more acidic because it has been out of contact with the atmosphere for several decades, and marine organisms have been filling it with carbon dioxide as they respire. Anthropogenic emissions are compounding this phenomenon.

“We used to think the larvae were being blown away by the North winds, but we’ve come to realize it’s probably always been the upwellings of acidic water that killed the larvae,” said Bill Dewey, the director of public policy and communications for Taylor Shellfish.

The Pacific Northwest is an acidification hotspot.

The Pacific Northwest is an acidification hotspot. Source: NRDC

So, though ocean acidification is occurring all over the world, these upwellings and other local conditions make the Pacific Northwest an acidification hotspot. 2006 was an especially strong year for upwelling—and therefore a tumultuous one for the shellfish industry. However, since the current upwelling events are bringing 30- to 50-year-old water to the surface, the impacts shellfish farmers are seeing now actually reflect the milder atmospheric CO2 concentration of the 1960s to 1980s.

“It’s like we sent ourselves a FedEx package 50 years ago and we’re just receiving it now,” Dewey said of the upwelling events.

Carbon dioxide emissions have increased by about 80 parts per million over the last half-century, topping the dreaded 400 ppm threshold this past May. So, it’s conceivable that 30 to 50 years in the future, the ocean waters on the surface today, that have absorbed even greater carbon dioxide concentrations, will be showing up from the depths on Washington’s coast. In other words, ocean acidification is locked in to getting worse—possibly much worse—before it gets any better. So, for the shellfish industry, adapting to the expected impacts of ocean acidification is a necessity, no matter how much humans reduce global carbon emissions in the future.

Seeing underwater

Prior to 2006, none of the shellfish companies monitored water chemistry, which made pinpointing the cause of the larvae mortality quite difficult. They didn’t know the pH of their water intake was lower during upwelling events, so they didn’t make the connection between mortality and acidity.

“In hindsight, it was kind of stupid of us. We had this multi-million dollar investment and we weren’t even keeping track of what’s going on in the water,” Dewey said.

A monitoring station set up at Taylor Shellfish hatchery shows real time acidity of the water as it changes with parts per million of carbon in the atmosphere.

A monitoring station set up at Taylor Shellfish hatchery shows real time acidity of the water as it changes with parts per million of carbon in the atmosphere.

The industry argued that the State should be paying attention too. After lobbying Senator Cantwell (D-WA) for funding to set up monitoring systems across the Coast, Congress appropriated $500,000 for the equipment. One of the systems, installed at the Taylor Shellfish hatchery, continuously tracks the pH of the water at different depths. Dewey was also selected to participate on a statewide, multi-stakeholder Blue Ribbon Panel on Ocean Acidification, which released policy recommendations to the Governor last winter. In response to those recommendations, the Washington State legislature appropriated over $1.8 million to build a new ocean acidification center at the University of Washington that will coordinate research and monitoring efforts to better understand the impacts to shellfish.

“We realized, as an industry, that we need to focus on monitoring and adaptation,” Dewey told us. “I remember Mark Wiedgart, the co-owner of Whiskey Creek hatchery, said that as soon as we started monitoring, it was like putting headlights on a car.”

The industry banded together to lobby for federal funds for research and monitoring.

The industry banded together to lobby for federal funds for research and monitoring.

Fighting carbon with carbonate

A bucket of sodium carbonate sits at Taylor Shellfish hatchery.

A bucket of sodium carbonate sits at Taylor Shellfish hatchery.

Not only did the initial monitoring efforts help hatchery scientists understand the root cause of the die-off, it also allowed them to come up with a solution that would recover the larval populations. At the Taylor Shellfish hatchery, sodium carbonate is added to the water pipes at the hatchery to increase the pH level, reducing the acidity and providing the larvae with more carbonate to work with. In 2012, the hatchery installed an automated system to maintain the desired carbonate levels.

The new automated carbonate system at Taylor Shellfish hatchery detects the pH of the water and adds the appropriate amount of sodium carbonate to reach the desired pH.

The new automated system at Taylor Shellfish hatchery detects the pH of the water intakes, which flow through these pipes, and adds the appropriate amount of sodium carbonate to reduce acidity.

It works like this: Eudeline sets the desired pH around 8.2, and the computer pumps the corresponding amount of sodium carbonate into the water. Taylor’s hatchery has two water intake pipes that are set at different depths—a shallow intake is a few feet below the surface and the deeper intake sits at 100 feet. The deep intake brings in significantly more acidic water than the shallow intake—7.45 compared to 8.1—so the deep water gets an extra dose of sodium carbonate.

“The system is basically a buffer against upwelling. You would never know the deep, more acidic water was coming in,” Eudeline said.

Ready, ‘set,’ and hope they grow

To avoid the uncertainty of upwelling events and the acidic water they bring and to keep up with the skyrocketing demand for oysters in the restaurant industry, more commercial growers now depend on the hatcheries and nurseries to provide them with seed for their oyster beds. The nurseries, however, often run out of seed in times of high demand, and after the seed crisis in 2006, this became an even bigger problem.

“The times when we wanted to buy seed, there wasn’t seed available, and that was when things started to kind of unravel,” said Adam James, the manager at Hama Hama Oyster Company, which is located on the Hood Canal.

Adam James tells road tripper Kirsten Howard about how his family's oyster farm has changed its practices.

Adam James of Hama Hama Oyster Company tells road tripper Kirsten Howard about how his family’s oyster farm has changed its practices.

We woke up for low tide at 6:30 a.m. to crunch through the Hama Hama oyster beds. The fog that enveloped the nearby mountain peaks was just beginning to burn off with the morning. James knelt down to pick up an oyster. He cracked it open with the expert speed of someone who has been harvesting shellfish since childhood. Hama Hama, a family oyster company in operation since 1922, relies on a combination of a natural set and pre-set seed that they buy from a supplier like Whiskey Creek. Now, James has started buying 2 millimeter oyster seed instead of 12 millimeter seed from these growers because it was all he could get.

“To combat the issue, we’ve built our own nurseries.” he said, explaining that they’ll keep the small seed in their own tanks until they’re big enough to survive on the beds. “But now it’s becoming more competitive to get even the smaller sizes.”

Adam James shows us a young oyster at Hama Hama.

Adam James shows us a young oyster at Hama Hama.

Cultural survival on the coast

James and his family’s struggles are a reflection that, on Washington’s coast, shellfish farming is not just a multi-billion-dollar industry, but a way of life. While families like the Taylors and Jameses have been farming shellfish since the early 1900s, many Native American tribes on the Coast have harvested oysters for sustenance for centuries, and a few have now started commercial farms.

Allie rides with Sue Shotwell of the Nisqually Tribe's commercial shellfish farm.

Allie rides with Sue Shotwell of the Nisqually Tribe’s commercial shellfish farm.

The Nisqually Nation, for instance, opened a commercial shellfish farm in Olympia, Washington in 2012. Their elders wanted the oyster farm so they could have consistent access to safe seafood and supply their own tribal events and the local casino. As an economic development project, the farm is doing quite well. They employed five Nisqually youth this summer, and Sue Shotwell, the farm manager, says they could use at least five more employees because they are expanding quickly. However, like the bigger farms, the Nisqually farm is facing challenges in getting oyster seed for their beds.

“Our first year in operation, we wanted 2 million seeds and got 100,000. The next year was a little better: we got 500,000 seeds,” she told us.

Cleaning oyster cages at the Nisqually oyster farm.

Cleaning oyster cages at the Nisqually oyster farm.

Right now, the Nisqually purchase seed from several hatcheries, but they want to give as much of their business as they can to the Lummi Nation’s shellfish hatchery in Bellingham, Washington. Dewey of Taylor shellfish says that the Lummi may have unintentionally discovered a strategy that buffers against the impacts of ocean acidification: the intake to their hatchery is from a saltwater pond (originally used for salmon), which allows them to avoid the upwelling events that bring in more acidic water. Shotwell says that relationships with people—or social capital—are often what help her to secure seed in times of scarcity.

Paddle to Quinault

A tribe is welcomed ashore by the Quinault Nation after the two week canoe paddle.

A tribe is welcomed ashore by the Quinault Nation after the two week canoe paddle.

This sense of solidarity among tribes on the Coast was apparent at the Paddle to Quinault, a two-week ocean odyssey by cedar canoes that concluded in a six-day celebration at the beginning of August. The Nisqually shellfish farm supplied oysters for the paddlers partway through the journey. On the afternoon of August 1, we joined thousands of people who gathered to watch strong arms propelled by the tide carry 89 canoes of tribal members from across the Pacific Northwest to the Quinault Nation’s shores. Drummers and dancers beckoned the paddlers through the last few hard pulls and then helped them hoist their heavy vessels overhead to carry them up the beach.

A boy looks on as a tribe arrives on the Quinault shores.

A boy looks on as a tribe arrives on the Quinault shores.

The canoe journey is not an ancient tradition—the first one was in 1989—but rather a way for Pacific Northwest tribes to celebrate their ever-adaptive cultures and to share information. So among the rows of artisan and food booths at the Paddle to Quinault festival, one booth displayed the familiar graph that shows carbon dioxide concentrations in the atmosphere fluctuating over the last many thousand years until, after the Industrial Revolution, the line takes off like a rocket ship. Behind the booth, Paul Williams, a shellfish manager advisor for the Suquamish Tribe, was distributing information on ocean acidification.

Paul Williams and his interns stand at the Suquamish Tribe booth about ocean acidification.

Paul Williams and his interns stand at the Suquamish Tribe booth about ocean acidification.

At last year’s canoe paddle, Williams conducted an informal survey and found that about half the people had heard of ocean acidification. In general, “they are aware it’s a problem but don’t know the details,” he said. Students at the Suquamish tribal high school are now working with Williams to get the word out about the threat to local species and food sources.

Adult oysters grow in the Hood Canal. If acidification worsens, it's possible their growth will be affected.

Adult oysters grow in the Hood Canal. If acidification worsens, it’s possible their growth will be affected.

While the larvae problem seems to be patched up for now, no one knows for sure what will happen if the pH of the oceans gets so low as to affect shellfish at later stages of development. Hatcheries can pump in some extra carbonate to counter acidity in their larvae-growing tanks, but they can’t pump the oceans full of the white powdery compound.

“The world is changing already—there is going to be a lot of loss,” Williams said. “Species are probably going to disappear, but I think people here will figure out how to survive.”

People wait to greet the paddlers in the 2013 Paddle to Quinault.

People wait to greet the paddlers in the 2013 Paddle to Quinault.

See more photos.

2 thoughts on “Cracking the Case of the Vanishing Oyster Larvae

  1. Pingback: Oceans Face a Rocky Future

  2. Pingback: Vanishing Oyster Larvae | Our Community Table

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s