Save the otters!

Sea otters live along the coasts of the Pacific Ocean in North America and Asia. Ever since their population plunged in the early 1900s, sea otters have been in danger of extinction. It would be especially devastating for sea otters to go extinct because they are a keystone species. National Geographic defines a key stone specie as, “a plant or animal that plays a unique and crucial role in the way an ecosystem functions.” (1)

Figure 1.

Screen shot 2014-10-10 at 6.39.17 PM

As you can see in Figure 1, sea otter populations reached a low in the early 1900s. As a result of the fur trade, sea otters were almost hunted into extinction.(3) Sea otters populations once numbered several hundred thousand. So even though this graph shows growth, the population now, a mere 2,000, is nowhere near where it once was.

Figure 2.


The reason sea otters are considered to be a keystone species is because of the role they play in their food web. In the figure 2, kelp and other algae serve as primary producers. This means that they are autotrophs and are able to make their own food through photosynthesis. The next trophic level includes sea urchins. They are known as primary consumers because they get their energy from consuming the primary producers. From there, sea otters would be secondary consumers because they eat the sea urchins. When this system works, each level keeps the level below them from overpopulating. However, when one species within the web experiences a decline in population, it affects the entire system. In the case of the sea otter, they are considered the most important, keystone species because they keep the urchin population controlled.

In 1900, when the otters dwindled in numbers, the sea urchin population exploded. This caused the urchins to consume so much kelp that they destroyed the kelp forest.(2) This is an example of a trophic cascade. A trophic cascade happens when population control of prey by their predators affects the next level down, in the case, kelp.(2) This ecosystem needs the otters to prevent another trophic cascade. If the otter population continues to grow, this fragile ecosystem will be restored.






7 thoughts on “Save the otters!

  1. Hi Katie,
    This was a very interesting to read. Just when I was wondering what were the implications of an urchin population increase, you answered it! But, what would happen if the kelp forest were destroyed? What would be its implications? I am also still wondering how could the average day person help save the otter population. I know that otters are caught and sold for their fur, but is it some way that a consumer could be more aware about products made from otters? I think getting the information out about this issue would be most challenging. Also, is there a safe rate to hunt otters by? In this way couldn’t humans become a part of this food web by comprising of the tertiary consumer level?


  2. Hi Katie,
    This post was very interesting and very easy to understand! I really like the topic, and how you explained a real life scenario of what can happen when a certain trophic level is disturbed in the environment. This goes to show how greatly humans can impact the environment, and not even know the implications of their actions. I also really enjoyed how you defined some of the terms to help your readers fully understand what you were talking about.
    I had a similar question to Jazzy. What would happen if the kelp forests were to be completely destroyed, and how would this affect the ecosystem and other animal species?

    Keep posting!
    – Kristin Smith


  3. This is an excellent example of how relevant food webs and trophic levels are to everyday life and the existence of all life on Earth. I liked how you provided the definition of a keystone species to show the inner-mechanisms of a food web and the consequences that arise when one trophic level is allowed to overpopulate. Here is a relevant National Geographic article that takes an in-depth look at the repercussions of the dwindling sea-otter population on the other trophic levels in the ecosystem.


  4. Hello Katie,
    I think that this is a great blog post because it shows how every part of an ecosystem, abiotic or biotic, is important its sustainability. Another example of this that I can think about is the wolves in Yellowstone national park that I learned about in Mrs. Lohwater’s biology class last year. Wolves were needed in the park so that the elk would not over populate the park and consume all of the resources it had to offer. When the wolves were reintroduced to the park, elk populations began to decrease and vegetation began to reappear in places that once did not have any. If the wolves were never reintroduced, I think that eventually the park would have an elk population that it could not sustain because resources like vegetation would go away because the elk would constantly eat it and they would not have to worry about predators. It’s strange to think that wolves saved both the elk and the vegetation of Yellowstone national park just by doing what they do.
    Keep posting,
    Juan Alvarado


  5. Katie!
    I think you did a really good job of relating our current topic of study to your blog post. I now think I have a better understanding of how a change in the food web can dramatically effect an ecosystem. This also relates to what we did last year in AP Bio with the wolves in yellowstone! Thank you for so clearly explaining the way the food web works! It would be interesting to see if someone followed up on your blog post to see what would happen in turn when the kelp forests are destroyed because I think those are a major resource for many organisms in the ocean,..


  6. Katie,
    Your post caught my eye because sea otters are my absolute favorite animal by far! As I was reading your article I was thinking primarily about how the sea otter is an endangered animal and how preserving and increasing their population is key. I mainly have always been concerned about helping them nurture their population back to size because I am just so fascinated by them and think that they are adorable. I had never put much thought into how the dramatic decrease effected their ecosystem. I think that you did a very good job on showing the intricacy of food webs and just how co-dependent these animals and producers are on each other.
    Great Post!


  7. Hey Katie,
    I think that this is so interesting because it provides us with a clear example of how crucial a functioning ecosystem is. It interesting that you only mentioned that there will be an overpopulation of sea urchins, but if you think about it a little more, you will also realize that because there are more sea urchins, there will be less kelp and algae. This could in turn have a larger and more severe effect of the ecosystem. I really think it’s so interesting how one small mistake can have a domino effect. This is really cool stuff and you did a great job!!
    -Pooja Ika


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