Download Exercise: Trophic Levels and Food Webs

Exercise: Trophic Levels and Food Webs. YOU MAY WORK WITH ONE PARTNER ON THE
TROPHIC EXERCISE
Instructions: Ecosystems consist of trophic levels, or feeding levels, which comprise complex networks
of food chains called food webs. Evidence is accumulating that the more diverse the ecosystem, the
healthier and more viable it is.
• What is your favorite ecosystem? (Some example include tidal zones, oceans, coral reefs, tropical
forest, kelp forest, grassland, Savanna, alpine meadow, arctic or Antarctic ocean, tidal zones,
Temperate rain forest—you can get geographically specific and examine any of these or another
you think of in a specific area – for example for savannas- you could look at the trophic levels of
the African savanna or of the Brazilian cerrado for tidal zones you could look at Pacific
Northwest tidal zones or even more specifically Puget Sound tidal zones). The more specific you
are, the easier this assignment will be.
• Find information about your chosen ecosystem on the Internet or in a book or magazine. Draw
the food web and answer the questions below (TYPE YOUR ANSWERS)
•
To receive full credit on this exercise you must include a drawing of your food web (downloads
from the computer or photocopies from books, magazines etc.. are NOT acceptable). You must
also cite your source(s) and answer all of the following questions.
1) What are some of the key species whose presence is crucial for ecosystem stability?
2) What would happen if you were to remove all individuals belonging to one of these key species?
Choose one specific example and describe the impact on other organisms in the ecosystem as well as on
the abiotic environment.
4) If you could save from extinction only one of the following: the carnivores or the primary producers in
an ecosystem, which would you protect?
5) How does what you now know about food webs and trophic levels affect your response to campaigns
to save the habitats of such uncharismatic organisms as fungi, insects, and snakes?