UBC scientists have developed the breakthrough at which this post is directed. They are now closer to answering the mystery behind the die-offs of Pacific oysters across the coast of British Columbia. Kevin Zhong and his team isolated a new virus, which they named Pacific Oyster Nidovirus 1 (PONV1). This virus is associated with the rising mortality rates reported in oyster populations. Overall, this finding has the potential to provide important information for the shellfish industry. Yet in recent years it has suffered calamitous losses from recurring mass mortality events.
Pacific oysters, originally from the Western Pacific Ocean, are now the most farmed shellfish in the world. In addition to these countries, they are widely grown in Australia, Canada, China, France, South Korea, and the U.K. In British Columbia, this species accounts for approximately 80% of the region’s shellfish production, with the coastal area responsible for about 60% of the province’s overall shellfish output.
Investigating the Die-Offs
In 2020, Kevin Zhong and his colleagues embarked on a crucial study across the Salish Sea to investigate the recent oyster die-offs that have plagued local farms. Researchers found that nearly 90% of the shellfish were dead or dying at three farm sites in Baynes Sound on Vancouver Island. This shocking discovery brings to the forefront an underreported environmental crisis. The terrifying numbers are making way for a deeper look into the diseases plaguing these incredible sea animals.
The research team collected dozens of samples from multiple oyster industries. Supplementing their experiments, they took blood and tissue samples from wild oyster populations throughout the Salish Sea. Harvard marine microbiologist Amy Chan shepherded comprehensive comparative analyses of cultivated microbes. The researchers primarily targeted samples collected from live, healthy sea stars as well as moribund or sick individuals. This ecosystem-based and precautionary approach allowed them to investigate the ecological relationships among different marine species. They looked at how contagion might flow through these diverse, yet connected, communities.
“Literally every basket of oysters being brought up, every one was dead or dying,” – Curtis Suttle
In addition to the virus, as part of their research, the team isolated the PONV1 virus on a separate evolutionary branch. This novel development presents a dangerous risk to an industry sector already battered from the damaging effects of climate change. Warming waters only compound the injustices they already face.
The Impact on Oyster Farmers
The impact of these die-offs have been devastating for oyster growers in British Columbia. Many have struggled with years of catastrophic mortality events, leading some small farmers to cease purchasing oyster seed during warmer months or even leave the industry altogether. Unfortunately, for many farmers, this has already become a crisis situation.
“They die right before you can market them. When you have two or three bust seasons in a row, you go out of business,” – Prins.
The discovery shared in Zhong’s study offers an important, impactful chance for industry players involved in shellfish. With increased knowledge about PONV1 and its implications, farmers may be better positioned to adapt their practices to mitigate future losses.
PONV1 comes with pressing challenges that we need to tackle right away. New research reveals just how important oysters are to their ecosystem. One tonne of harvested Pacific oysters can filter more than three kilograms of nitrogen and 0.35 kilograms of phosphorus from the water. What’s more, they sequester over 70 kg of carbon. This underlines the need to keep oyster populations healthy for both ecological health and coastal community’s economic health.
Future Directions and Solutions
The discovery of PONV1 is a watershed moment for oyster research and management. UBC Suttle Lab Director Curtis Suttle. He was encouraged by the findings and the impact they will have on directing future strategies to restore and protect the health of our marine environment.
“Knowing the virus is there, we can open up a whole new box of tools to understand what’s happening,” – Curtis Suttle.
As you might imagine, researchers are all over this new virus. They are doing it in the hopes that it sets a baseline to better combat the rising epidemics in oceanic settings. As recently as five years ago, the B.C. Shellfish Growers Association started its own local breeding programs. Their aim, in part, is to genetically select more resilient oyster lineages which can withstand hard environmental knocks.
Zhong expressed his enthusiasm about their findings: “We found a new virus that has never been found before.” This newly emergent realization is what some have said needs to be the long-term hope for farmers facing an unpredictable future.
“I’m hoping it can serve as a baseline on how we deal with increasing epidemics in the marine environment,” – Prentice.
Academics and activists alike are exploring this relatively new terrain. They acknowledge that we have a great deal more research to do in order to figure out what’s driving these die-offs.
“We don’t know what those particular triggers are,” – Suttle.
