How forecasting ‘underwater weather’ could save WA’s shellfish

In this June 21, 2010 file photo, Efrain Rivera uses a pitchfork to harvest Pacific oysters at low tide at a Farm owned by Taylor Shellfish Co. in Oyster Bay, near Olympia. (Photo by Ted S. Warren/AP)

(Photo by Ted S. Warren/AP)

Washington’s waters are under threat from a villain you can’t see. This computer model is giving oyster farmers a lifeline as they seek to adapt to one of the biggest marine crises of our era.

Washington is home to thousands of marine species. Salmon, crabs and bivalve shellfish like oysters and clams fuel both the aquatic food chain and human fisheries — and they thrive under stable levels of acidity, salinity and other marine growing conditions.

But over the past few decades, climate change has acidified the world’s oceans at an unprecedented rate, threatening the biodiversity that defines our region and supports these fisheries. As the concentration of carbon dioxide in our atmosphere increases, the ocean dissolves more of it at the surface — producing conditions in Puget Sound and beyond that exacerbate shell deformation, promote toxic algal blooms and create other hurdles to healthy waters. According to the Washington State Blue Ribbon Panel on Ocean Acidification, 30 percent of Washington’s marine species are in danger from it.

Ultimately, stopping ocean acidification requires unprecedented international mobilization to reduce greenhouse gases. But if scientists and others could predict the complex undersea interactions that enable its worst effects, they could pull the trigger on short-term, local solutions that might help people and wildlife work around them. Researchers at the University of Washington have invented a computer model to do just that. Each day, LiveOcean compiles a vast array of ecosystemic data — currents, salinity, temperature, chemical concentrations, organic particles and more — to create a three-dimensional, 72-hour forecast for the undersea weather of the Pacific Northwest.

This is a particularly welcome tool for the state’s $270 million shellfish industry, which produces more farmed bivalves than the next two most productive states combined, according to the U.S. Department of Agriculture.

On the shores of Puget Sound, carbon emissions, excessive nutrient runoff and warming temperatures have made waters that used to be ideal for shellfish farming less dependable, resulting in catastrophic die-offs of oyster larvae in the late 2000s. According to the University of Washington’s Washington Ocean Acidification Center (WOAC), Willapa Bay hasn’t produced any natural oysters for the majority of the past decade, forcing shellfish farmers to purchase “seeds” from hatcheries.

“We know that the seawater chemistry conditions are different now than in the preindustrial era — we see pteropods with pitting and holes in their shells that are due to corrosive seawater conditions,” WOAC Co-Director Dr. Jan Newton said by email. “The CO2 increase is largely (~90%) due to emissions from fossil fuel combustion.”

But with help from LiveOcean, aquaculture has a shot at adapting farming schedules to the ebbs and flows of mercurial ocean chemistry before more permanent solutions are in place. The state-commissioned model is designed to forecast ocean-circulation patterns and underwater environmental conditions up to three days out. Eventually, it could help everyone in the region get a better understanding of how a changing climate impacts a major source of food, funds, fun and regional pride.

Designed by 10 researchers over the course of 15 years, LiveOcean is finally available to Pacific Northwest shellfish farmers (and the public at large) ahead of the 2019 spring oyster spawning season. LiveOcean was pursued in earnest after Gov. Jay Inslee’s 2012 Blue Ribbon Panel on Ocean Acidification recommended the state “establish the ability to make short-term forecasts of corrosive conditions for application to shellfish hatcheries, growing areas and other areas of concern.” The panel created WOAC and allocated $325,000 toward LiveOcean, which is also funded by the National Science Foundation and the National Oceanic and Atmospheric Administration..

Understanding how water moves is essential to predicting where and when instances of high acidification will be most damaging to shellfish farms, beachgoers and more. The ocean always circulates: The currents scoop up surface water, pull it into the depths of the ocean, then dredge it upward in what LiveOcean lead researcher Parker MacCready calls “underwater rivers.” These cycles circulate water over the course of decades. When water “upwells” back to the surface, carrying nutrients and dissolved carbon dioxide, it’s been out of sight for 30 to 50 years. “It is the biggest thing controlling water properties in the Salish Sea,” MacCready says.

These days, the “river” is returning with more nutrients and carbon dioxide — reflections of increased fossil fuel use, agriculture and other human activities during the 1970s. Because we know atmospheric carbon dioxide has increased since then, scientists say we can expect to see even worse ocean acidification in the future. And the interaction between human fossil fuel output and agricultural runoff with Puget Sound’s natural geography can make things worse.

“Relative to other coastal regions, Puget Sound is somewhat different in its expression of acidification,” Newton says. “Warming can be intensified or prolonged due to Puget Sound’s retentive nature.”

A system as dynamic as Puget Sound needs dynamic monitoring, and that’s where LiveOcean comes in.

“[LiveOcean] models circulation — currents and mixing — and, at the same time, all the things that are moved with the currents: salt, heat, oxygen, nitrate, phytoplankton, zooplankton, detritus, and carbon variables like dissolved inorganic carbon [DIC, like CO2)] and alkalinity,” MacCready says. “You need to have a really big computer, and deep knowledge of many ocean processes — like physics, chemistry and biology.”

LiveOcean draws on lots of types of data. It sources real-time river-flow information from the U.S. Geological Survey and Environment Canada and three forecasts for conditions in rivers, the ocean and surface and atmosphere.

Hannah Weinberger, Crosscut, 20 February 2019. Article.

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