Tag Archives: Jenifer McIntyre

A difference between chum and coho salmon may be in their blood

On the outside, chum and coho salmon don’t seem all that different from one another, not when you consider the variety of fish in Puget Sound — from herring to halibut along with dozens of other odd-looking creatures (EoPS).

But we know that if you place coho in stormwater taken from a heavily traveled roadway, the coho are likely to die within hours. But if you do the same thing with chum, these hardy fish will barely notice the difference.

In this photo taken two years ago, Jenifer McIntyre describes her discoveries about rain gardens at the Washington Stormwater Center in Puyallup. Photo: Meegan Reid, Kitsap Sun
In this photo taken two years ago, Jenifer McIntyre describes her discoveries about rain gardens at the Washington Stormwater Center in Puyallup.
Photo: Meegan M. Reid, Kitsap Sun

Researchers began to observe the varying effects of pollution on different species of salmon years ago. In 2006, I reported on studies by researcher Nat Scholz of the National Marine Fisheries Service, who discovered that coho would swim into Seattle’s heavily polluted creeks to spawn, but they wouldn’t get very far. Within hours, they would become disoriented, then keel over and die. (Kitsap Sun, June 10, 2006)

Later, Jenifer McIntyre, a researcher with Washington State University, collaborated with Scholz to refine the studies, exposing adult coho and later young coho to stormwater under controlled conditions. Much of that work was done at the Suquamish Tribe’s Grover’s Creek Hatchery in North Kitsap. The researchers also measured the physiological effects of pollution on zebrafish embryos during their early stages of development.

Working at the Washington Stormwater Center in Puyallup, Jen made a remarkable discovery that has dramatically changed people’s thinking about stormwater treatment. She found that if you run the most heavily polluted stormwater through a soil medium containing compost, the water will no longer have a noticeable effect on the sensitive coho. Rain gardens really do work.

Jen’s findings and related stormwater issues were described in a story I wrote two years ago for the Kitsap Sun, “Stormwater solutions key in fight for Puget Sound.” The story is part of a two-year project we called “Taking the Pulse of Puget Sound.”

Now, Jen, who recently joined the faculty of WSU, is beginning a new phase of her research, probing deeper into the physiological responses of coho salmon when exposed to polluted stormwater. She told me that the varying responses of coho and chum offer clues about where to look for problems.

“It is very interesting,” she said. “As biologists, we understand that there is variability among species. But we would expect, at least among salmon, that things would be pretty much the same.”

Researchers in Japan have discovered that different kinds of fish have different subunits in their hemoglobin, which are the proteins in red blood cells that carry oxygen to the vital organs. Since coho and other salmon may have different forms of hemoglobin, oxygen transport in the blood is a good place to start this investigation, she said.

From there, the issues of blood chemistry get a little technical, but the ability of red blood cells to carry oxygen can depend not only on the form of hemoglobin but also on the pH (acidity) of the blood, she said, and that can be altered by drugs and other chemicals.

Another thing that researchers may be seeing is “disseminated intravascular coagulation,” a condition that results from clotting in the lining of the capillaries. DIC can reduce or block blood flow where it is most needed and eventually cause organ damage. That’s an area for more research, Jen said, noting that these investigations are moving forward in collaboration with researchers at NMFS and the U.S. Fish and Wildlife Service.

Meanwhile, Jen is working with chemists at the University of Washington’s Center for Urban Waters in Tacoma to figure out which substances — out of hundreds of chemicals found in stormwater — could be causing these deadly effects on fish.

If isolating the dangerous compounds proves too difficult, researchers might be able to start with the original toxic sources, perhaps exposing fish to chemicals found in tires, oil, antifreeze and so on, Jen said. For those effects, it might be good to begin the investigation with the well-studied zebrafish embryos, which are transparent and can be observed closely throughout their embryonic development.

Needless to say, this is a field of intense interest. If researchers can discover what is killing coho, they might begin to understand why the recovery of chinook salmon in Puget Sound has been so slow. Chinook, which could be added to Jen’s studies, are listed as a threatened species under the Endangered Species Act and are the preferred prey of Puget Sound’s killer whales, which are listed as endangered.

Two recent articles discussed the relative hardiness of the chum compared to coho salmon:

Salmon harmed by copper fail to avoid predators

I guess it’s common knowledge among fish biologists that fish can smell death.

It’s a survival mechanism. When the skin of a fish is damaged, a substance is released into the water. Other fish smell the substance and instinctively take evasive action.

When juvenile coho salmon smell death, they tend to stop moving and become more wary of predators, according to a new study by Jenifer McIntyre and colleagues at the University of Washington and National Oceanic and Atmospheric Administration.

But the most important finding is that the coho exposed to minute levels of copper lose their sense of smell. Their brains don’t register the smell of death, and they get eaten at a much higher rate than coho not exposed to copper. For details, check out the story published today in the Kitsap Sun.

The video shows the response of coho salmon when ground-up fish skin is released into the water. Coho not exposed to copper freeze, as you can see in the upper tank. Coho exposed to copper keep on moving, as if unaware of the danger, making them prime targets for predation.

These are interesting findings, but more research is needed to determine what levels of toxic copper may actually be found in urban streams, where copper typically comes from brake pads and pesticides, and rural streams affected by mining operations.

For further reading, check out the slideshow called “Impacts of copper on the sensory biology and behavior of salmon” (PDF 9.2 mb), which reports on findings by the research group of which McIntyre is a member

Other reports:

“An Overview of Sensory Effects on Juvenile Salmonids Exposed to Dissolved Copper: Applying a Benchmark Concentration Approach to Evaluate Sublethal Neurobehavioral Toxicity”

“Effects of Copper on Aquatic Species: A review of the literature” by Phyllis Weber Scannell.

“Control of Toxic Chemicals in Puget Sound: Assessment of Selected Toxic Chemicals in the Puget Sound Basin, 2007-2011”

Some previous blog entries in “Watching Our Water Ways”:

Nov. 4, 2011: “More results, more questions found in toxic studies”

May 18, 2011: “New study refines Puget Sound pollution issues”

March 10, 2010: “Washington is first to tackle toxic copper in brakes”

June 7, 2009: “Barnacle-free hulls would be a dream come true”