Posted: January 16th, 2017

What challenges could occur within a food web when a new predator like this is introduced into an ecosystem?

Most biological energy here on Earth can be traced back to one single source: the sun. Plants and blue-green algae use photosynthesis to trap the electromagnetic wave energy generated by the sun, transforming it into chemical energy in the form of food for themselves and for other creatures that eat them.

Sounds simple so far, right? In an effort to simplify the way you think about creatures and their energy relationships, you often use food chains that show a very clear link between creatures and the things that eat them. Here is one example:

Rose bush > Beetle > Robin > Domestic Cat > Coyote

Organisms are connected by an arrow that points toward the creature consuming it.

While this kind of chain is great for visualizing how some creatures eat, it is not very realistic since most creatures eat a variety of foods. Most robins, for example, like to eat many kinds of insects, not just beetles. It also does not take into account other organisms that contribute like parasites, detritivores or decomposers.

To demonstrate how real creatures behave and to better portray the flow of energy through an ecological community, food webs are often used as described within the energy flow section of the module above.

Please respond to the following questions throughout the week.

1. Provide an example of a food chain in the area where you live.
2. Humans are parts of food chains and food webs, too. Where on a food web would you typically find humans (near the bottom with the producers, at the top with carnivores, or somewhere in between)? Explain.
3. What are some advantages of being part of a food web rather than a food chain?

For Questions 4–6, use the following food web for Lake Michigan:

Lake Michigan Food Web. (2016). Retrieved from https://www.glerl.noaa.gov//pubs/brochures/foodweb/LMfoodweb.pdf

To see this PDF, you will need to download the free Adobe Reader.

1. In the Lake Michigan food web, is it possible to identify the most important producer? Why or why not?
2. Provide at least two types of impacts that humans could have on this food web.
3. Read the description of the sea lamprey on page 2 of the food web. This species is described as non-native. They reached the lake through canals and locks built in the 1800s.
   • What challenges could occur within a food web when a new predator like this is introduced into an ecosystem?
   • Do you think steps should be taken to eradicate this species from the food web? Explain why or why not? If so, what steps can be implemented?