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Common chemical in tires caused mass Coho salmon deaths in Puget Sound, scientists say

In a healthy ecosystem, salmon provide food for orcas and spawn in urban creeks. Their decomposing corpses also provide nourishment for soil and forests.

It’s this critical role that led scientists on a journey of searching for the mystery killer and one that ended in western Washington.

With more than 2,000 chemicals found in the water, it took researchers three years to narrow those thousands of chemicals to one.

Jen Mcintyre.

A few months after the initial discovery, the team brought a sample of the chemical to Jen McIntyre over at Washington State University in Puyallup where it was put to the test.

“The fish would start to come to the surface of the water, they’d start swimming at the surface of the water, they would start to lose equilibrium and swim on their side and then upside down and eventually settle to the bottom of the tank and die,” said McIntyre who also explained how much testing was done to ensure accurate reporting and data.

What they discovered was a toxin called 6PPD-quinone produced when the common tire preservative 6PPD mixes with oxygen. As tires age, the rubber starts to peel off leaving bits and pieces in their path.

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Ask Dr. Universe: How did life begin?

The universe is a big place. Thinking about how we fit into it is part of what makes humans (and cats like me) special.

Afshin Khan.

I talked about your question with my friend Afshin Khan who studied astrobiology and environmental science at Washington State University. Astrobiologists explore how life began. They also look for signs of life outside Earth.

Khan told me your question is a huge mystery.

“We have very good ideas about what could have happened,” she said. “In different labs around the world, we’ve gotten very close to simulating some of those conditions. But simulations can only get so close to what was happening on early Earth.”

We have a good sense of when life started. We know Earth formed about 4.5 billion years ago. The oldest fossils on Earth are stromatolites, basically layers of rock and microbes. They’re at least 3.5 billion years old. So, there must have been living microbes on Earth at that time.

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Dr. Universe

Drones show potential to improve salmon nest counts

Struggling salmon populations could get some help from the sky. A Washington State University study showed that drone photography of the Wenatchee River during spawning season can be effective in estimating the number of rocky hollows salmon create to lay their eggs, also called “redds.”

The drone imagery appeared to find roughly double the number of potential redds than ground-level observations, but uncertainty remains because of the ongoing challenge of determining what is and isn’t a true redd. Short of taking the nest apart, there is no way to know for sure if salmon eggs are present.

Daniel Auerbach.

Still, the research showed some advantages to using drones, said Daniel Auerbach, lead author of the study published in the journal River Research and Applications.

“There’s no denying that salmon populations are in decline, so we want to do the best job and use the best technology that we can to help this species out,” said Auerbach a doctoral candidate in the WSU School of the Environment. “While ground redd counts are less intrusive than other counts, drones are even less invasive, and we can use these images for many things.”

In addition to a one-time count, researchers can use drone images to look at changes in habitat over time, including mitigations humans put in place to help salmon, which range from planting shrubs to removing whole dams.

Alex Fremier.

“These technologies will give us more data to really find out if what we’re doing is working,” said Alex Fremier, study co-author and an associate professor in SoE. “A drone provides a bird’s eye view and high-resolution images. Because we can get so much information from these images, we could be more cost effective and help determine if a restoration project helped build salmon habitat.”

Salmon are known for their epic upstream journeys to return to places they were born to lay their eggs. Female salmon will sweep aside rocks to lay their eggs, which the males then fertilize. Then the female salmon will often guard the eggs in these redds until they die.

Current methods of counting redds involve field biologists walking lengths of river or floating downstream in a boat. Some places use helicopters to let scientists observe from above, which can be dangerous in steep canyons.

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With a few cups of water, scientists use eDNA to study reclusive, rare creatures off West Coast

Some critters in the ocean are reclusive, hiding from human probes and trawls. Other critters are rare, driven close to extinction from warming and increasingly acidic waters.

Studying rare and reclusive creatures has posed problems for scientists in the past. In recent years, environmental DNA, or eDNA, has helped. To isolate eDNA, scientists scoop water from the ocean.

Meghan Parsley.

Meghan Parsley has collected eDNA samples for her doctoral work at WSU Pullman, one part of which involves using the quantity of eDNA to estimate the population size of wood frog tadpoles in Connecticut.

“This is where the magic happens,” Parsley said, walking into a sparse, clean lab at Washington State University.

Keeping unwanted DNA out of the lab is tough and involves a lot of bleach. “I have lots of bleach-stained clothes,” Parsley said.

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Ask Dr. Universe: What is octopus ink?

An octopus has three hearts and long arms with suction cups. It probably seems very different from you. But you have the main ingredients of octopus ink in your body, too!

Gretchen Rollwagen-Bollens.

I talked about octopus ink with my friend Gretchen Rollwagen-Bollens, associate professor in WSU’s School of the Environment. She told me that ink isn’t just an octopus thing. Most animals called cephalopods (sef-uh-luh-pods) make it. These include octopus, squid and cuttlefish.

Cephalopods including octopuses use color a lot. They have sacs of colored pigments all over their bodies. They use those sacs to change their body color. That helps them blend into their environment.

They also make and store a dark pigment in special ink sacs.

“Squid ink looks dark because it contains molecules of melanin, which is a pigment,” Rollwagen-Bollens said. “It’s the same pigment that you find in human skin. The more melanin skin cells contain, the darker they are.”

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Dr. Universe