Seattle set an all-time heat record of108 degrees on June 28 as temperatures soared to well above 100 degrees.
Scientists and community members alike noticed a disturbing increase in the number of dead and dying oysters on some beaches in Washington and British Columbia during the heat wave. They organized to document the die-offs as they happened in real time after they realized they were living through an unprecedented event.
The first comprehensive report of the impacts of the heat wave on shellfish was produced by a team led by the University of Washington. The researchers found that the lowest low tides of the year occurred during the year's hottest days and at the warmest times of day. The results were published in the journal ecology.
The lead author said that he couldn't have come up with a worse scenario for intertidal organisms. This analysis has given us a good picture of how the heat wave affected shellfish, but we know this isn't the whole story.
The research team was able to leverage existing collaborations. They asked participants to give ratings based on their knowledge of a species in the area, and then created a survey and rating system. They gathered 203 observations from different locations in British Columbia.
The co-author of the study said that the study highlights the importance of local knowledge and understanding natural history. If you will, this is the first step in the process of taking a snapshot of what the beach environment was like during the heat wave.
The success or failure of each species was determined by their ecology. Butter clams are usually better than cockles that ride out low tide just below the sand's surface.
The location mattered to them. Low tide was four hours earlier for shellfish on the outer coast. When the sun is overhead, low tide is when the most shellfish are exposed.
The stress on inland populations was caused by the higher air temperature at inland sites. Bay mussels are more likely to die from heat exposure than California mussels, which are mostly found on the outer coast. More water movement and wave action on the outer coast may have mitigated the effects of the heat on the shellfish.
The researchers found that where they naturally live in the intertidal zone was a factor in their success or failure. corn barnacles that live higher on the shore were more impacted than clams and oysters that are lower on the beach
There is hope that can be found in this work despite the negative effects of this event. Annie Raymond said that not all locations and species were affected the same.
There were interesting patterns in survival rates among the shellfish on the same beach. In some places, the shellfish in the path of the water survived, while others died. The shellfish made it if the tree shaded the sand. Julie Barber remembers seeing those patterns while walking the beaches of Skagit Bay and being surrounded by dead cockles.
"I've never seen anything like that before, and it was pretty unnerving," he said. She remembers exchanging emails with colleagues from around the region as they noticed similar mass die-offs on their local beaches and realized they needed to coordinate and document what was happening.
"This effort was a beautiful demonstration of how collaboration can come together with one common cause, which in our case was trying to understand what happened to these shellfish."
The need for long-term monitoring is highlighted by the fact that the mass die-offs could impact the populations for at least several years. Shellfish deaths like those of last summer may become more common as climate change produces more extreme heat events.
The Swinomish Indian Tribal Community is proud to be a leader in this important scientific research that assessed in real time the devastating impacts to our shellfish resources. Our tribe relies on fish for spiritual and sustenance. The Swinomish Tribal Chairman said that last summer's extreme weather event reinforced the need to act faster to ensure climate resilience.
After the effects of the heat wave became apparent, the collaboration that emerged was amazing as managers and scientists worked quickly to put together a rapid response to capture information. We still have a lot to learn about the effects of the heat wave on the marine environment and how to prepare for the next one. It is our hope that we will be better prepared for whatever happens next.
Megan Dethier of the University of Washington is one of the co- authors. People contributed data to this project.
More information: Wendel W. Raymond et al, Assessment of the impacts of an unprecedented heatwave on intertidal shellfish of the Salish Sea, Ecology (2022). DOI: 10.1002/ecy.3798 Journal information: Ecology
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