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How do changes in the ecosystem effect the community? Enter a kelp forest and explore the various threads that connect species together in food webs.

A Video with a Problem-Solving Scenario

Otter, Urchan, and Kelp Chart

In addition to showcasing live footage from a unique ecosystem, each of the three videos in the Exploring Ecosystems series features an opportunity for students to actively participate in a problem-solving scenario based on an ongoing research project of an Academy scientist.

As you watch the video, be prepared to pause at key points to participate fully!

The Coastal Food Web video investigates the following questions:

  • How do you predict the effects of a change in the community’s populations on the community as a whole?
  • How will a change in an ecosystem affect energy flow, nutrient cycling, population growth, or community structure?
  • How will loss of an organism from a food chain or web affect flow of energy?

Check for Understanding

Describe two concrete examples of community interactions, being sure to describe the relationships between species.

Key Scientific Terms

  • community: two or more different species occupying the same geographical area and interacting in some way
  • ecosystem: the community of different species in a particular geographic area and all of their interactions with each other and the physical environment; ecosystems are also called ecological networks
  • herbivore: an animal that eats plants; also called a primary consumer
  • population: all the individuals of a particular species that live in a specific geographic area; a species may be made up of one or more populations
  • predator: an organism that hunts, catches, kills, and eats other animals
  • prey: an organism that is caught, killed and eaten by a predator
  • species: a distinct type of organism

Remember: Food Webs are Dynamic

There are many different ways the removal of sea otters could impact species in the food web featured in the video. The example shown is meant to represent just one of those potential trophic cascade scenarios.

When discussing with your students, encourage them to think about the complexity of food webs, which are formed and impacted by a multitude of abiotic and biotic factors. As such, each time the system is disturbed, a different result may occur. That's not to say scientists can't make conclusions based on data, such as the classic example presented in this video: when a top predator like the sea otter is removed we know that sea urchin populations explode and their predation reduces kelp populations.

If you'd like to know more about the example shown in the video, check out this scientific paper by Steneck et al., which Academy educators used as a reference for the content in the video.

Connections to High School Standards

AP Biology

  • LO 4.13: The student is able to predict the effects of a change in the community’s populations on the community.
    • (1) Interpreting graphs and other quantitative data that represent community and ecosystem interactions.
    • (2) Reading curves that represent community interactions (e.g., predator-prey) and using them to infer relationships between species.
    • (1) Working with ecological models and using them to predict how a change in an ecosystem will affect energy flow, nutrient cycling, population growth, or community structure.
    • (2) Predicting how loss of an organism from a food chain or web will affect flow of energy.

Next Generation Science Standards

  • DCI: LS2.C: Ecosystem Dynamics, Functioning, and Resilience
  • Crosscutting Concepts: Energy and Matter; Stability and Change; Systems and System Models
  • Science and Engineering Practices: Using Mathematics and Computational Thinking; Using Models

Related Reading

Kelp Forest Ecosystems: Biodiversity, Stability, Resilience and Future
This research article formed the basis for the trophic cascade featured in the video!

Food Webs Before the Impact
In this Science News article, explore what killed the dinosaurs 65 million years ago. Could it have been the health of ecosystems from 13 million to 2 million years prior to the impact?

Healthy Ecosystems Limit Disease in Humans and Wildlife
Ecosystem services in the form of food, water, shelter, and even medicines are key to our lives, but furthermore, studies have determined that diseases emerge from damaged environments. In this article learn how our human health depends on a healthy environment.

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