Stanford study on whales, microplastics reveals concerning level of food chain contamination

ByDan Ashley and Tim Didion via KGO logo
Wednesday, November 2, 2022
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Whales migrate past our Bay Area coastline. But now a team from Stanford's Hopkins Marine Station is raising concern about a possible threat to their food chain from microplastics

STANFORD, Calif. (KGO) -- They migrate past our Bay Area coastline, following a trail that's mostly invisible to us. A path laced with the food sources that keep multiple species of whales alive. But now, a team from Stanford's Hopkins Marine Station is raising concern about a potential threat to that food chain, and possibly the whales themselves. The issue: microplastics.

"And so these whales filter lots of water and eat lots of prey," said Matthew Savoca Ph.D., of Stanford's Hopkins Marine Station. "So we had two questions. The one question is, how much plastic might these whales be eating? And the second question is, where are they getting most of their plastic from?"

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Savoca and Stanford colleagues, including Shirel Kahane-Rapport, Ph.D., set out to track where the whales feed and the food they're eating. But first, it helps to understand that microplastics can flush though the San Francisco Bay and other urban areas in high concentrations, originating from items many of us might be wearing right now.

"And almost all the components of the particles that we think these whales are eating tend to be synthetic fibers or fibers of some synthetic nature," Savoca said. "So the clothes we're wearing, our rugs, our furniture, our car seats, things like that, but clothes are a big one."

The Stanford team used multiple methods to track the whales, including non-invasive tags, backed up with aerial drones and a host of monitoring equipment.

The team also collected samples of microplastics from the water as well. But they say there was another critical piece of the puzzle, the prey different whale species feed on. To learn what that prey itself might be ingesting, researchers used a specialized technology to essentially eavesdrop.

"It's an echo sounder," Kahane-Rapport explained. "So basically, it's these big orange porcelain discs."

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She says the echo-sounder pings the water with a bouncing signal. The readings are ultimately decoded with software sophisticated enough to identify the presence of tiny sea creatures like krill.

"So we know that there was krill there, we know the density, we know the size of the patch, and then we also know where the ocean floor is," she adds.

By combining the data, the Stanford team determined that whales, particularly blue whales, have been ingesting far higher levels microplastics than previously believed. In some cases, millions of pieces per day, mostly from their prey.

And although the study does not focus on the direct health threat to the whales, they say it reveals a level of food chain contamination that should concern us all.

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"But what I really want people to know is that the risk is there, and it's ever increasing," Kahane-Rapport said. "And it's in the whale's prey, which is something we also consume as people who use the ocean food chain. If it's in krill, and it's in fish, and we eat fish like anchovies and sardines, there's a good risk that it will get to us too."

And besides working to protect the health of the whales, the Stanford team believes the study could also act as a wake-up call for humans, to begin attacking the sources of microplastic pollution that ultimately finds its way into the ocean.

"We're all in this together,' said Savoca. "That's my main message to people, we're all in this together."

The Stanford team says research is already in the works to determine the effects that microplastics could be having on the individual whales that ingest them.

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