Online Lesson: Toxic chemicals

It’s all connected: life in the sea, the marine food web, and impacts of humans on land. Grade level: 7 -12, Lesson time: 30 minutes - 2 hours. |
April 30, 2020

Protect what we love!

Our beloved Orcas aren’t doing so well here in the Salish Sea. Like humans, these dolphins are apex predators, meaning they don’t have natural predators. However, what makes them vulnerable is their connection and dependence on the health of the Salish Sea and the ripple effects of our actions on land pouring into this body of water.

Several factors contribute to the declining health of the Southern Resident Orcas, but we are going to focus on one, toxic chemicals. In 2018 Washington state governor Jay Inslee created the Orca Task Force, made up of about 50 members from around the state, who collaborated to provide recommendations about how best to help these Orcas recover.

The Southern Resident Orcas face 3 main threats:

  1. ​Availability of Chinook salmon
  2. Toxic contaminants in the environment
  3. Disturbance from noise and vessel traffic

Watch this video to learn more about the Southern Resident Orcas here in the Salish Sea.

That broadcast from 2018, stated there were 75 Southern Resident Orcas. There are now only 73 Orcas remaining.

To gain an understanding of how toxic chemicals affect the orca population, let’s first dive deeper into the marine food web.

Marine Food Web

The image above illustrates a predator/prey relationship. The arrows go from a food source to a consumer. When one species declines in numbers, other animals and plants are impacted by this unbalance. The food web is fragile.

Looking at the image above, several species rely on forage fish and squid for food. Herring and surf smelt are an example of forage fish. These fish are small, can be found in large schools in the Salish Sea, and herring, in particular, need kelp and eelgrass to successfully thrive. Cherry Point (just north of Bellingham) is a critical herring spawning habitat where a proposed coal terminal was blocked thanks to the Lummi Nation. It’s all connected, life in the sea and our life here on land.

Herring spawning at Cherry Point

What do Orcas, in particular the Southern Resident Orcas of the Salish Sea, mainly eat?
  • Chinook salmon

What do Chinook salmon mainly eat?

  • Herring and other small fish and squid

What do herring eat?

  • Phytoplankton and zooplankton

If the zooplankton aren’t healthy and start declining in numbers, how is this web of life (pictured above) impacted? Name 3 ways, GO!

Toxic chemicals in the food web

Now let’s take a broader look at toxic chemicals and how they infiltrate the marine food web. Energy is transferred through the food chain but what else might move through the web?

  • Pesticides
  • Mercury
  • Oil and grease (from vehicles)
  • PBDE’s (flame retardants)
  • Toxic heavy metals like copper (from brake pads on vehicles)
  • Zinc (from tires)
  • Lead

Yikes, so many toxic chemicals!

How do these chemicals find their way into the Salish Sea? Stormwater runoff carries pollutants from land into the creeks, streams, and the ocean when it rains or snow melts. Once these chemicals enter the waterways, they can move into and then up the food chain putting the top predators at great risk of accumulating these contaminants in their bodies. This can cause neurological, endocrine, or reproductive problems, and can weaken the immune system of Orcas.

But wait, how do these toxic chemicals end up in the bodies of Orcas? Looking at the graphic below, follow the stormwater that pours from neighborhoods into the ocean. Follow the pollutants from industries along the shoreline. Once they enter the ocean, these chemicals get absorbed by phytoplankton, who serve as the base of the food web. The zooplankton eats the phytoplankton who absorbed the toxic chemicals. The herring or forage fish eat large amounts of plankton, who transferred these chemicals into the bodies of forage fish. Then salmon consume large quantities of forage fish, now quadrupling the number of pollutants into their bodies, and finally, the Orcas feed on the salmon. So by default, the Orcas are ingesting five times the amount of pollutants starting with phytoplankton.

This is called biomagnification. Biomagnification is the process by which a compound (such as a pollutant or pesticide) increases its concentration in the tissues of organisms as it travels up the food chain.

From phytoplankton to Orcas the number of toxic chemicals can increase exponentially.

In what ways can we help the Orcas?

We can help reduce pollution at its source
  • Drive less.
  • Fix oil leaks in vehicles.
  • Wash our cars at a carwash because the wastewater is filtered and/or treated.
  • Build rain gardens to help stop pollutants from entering waterways.

Take Action

Take a walk or bike ride along Bellingham’s waterfront to learn about how toxic sites are being cleaned up. If you aren’t able to leave your place, you can still do this online — it’s up to you.

Learn about what measures are being taken to clean up the contaminated sites here in Bellingham. Follow along with this interactive map created by Kirsten McDade, RE Sources Pollution Prevention Specialist.

  1. Once you have the map up on the screen, read the introduction.
  2. Click the icon on the map or on the bar on the left to learn what industry used to occupy the site, the contaminants still found on site, and then what is being done or has been done to clean it up.
  3. For more information about the cleanup site, click the link to the Department of Ecology provided in the sidebar.


Show us what you learned!

Tell us what you learned on your walking, biking, or virtual tour of Bellingham Bay!

    1. What surprised you the most?
    2. Share 5 things you learned.

Take a picture or video of your tour and what you learned or were surprised by, and send them to us or tag us on Instagram (@resources_protects)!

Upload your project!


Continue Learning!

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