Eelgrass Habitat

Quick links

  1. introduction
  2. lesson objectives
  3. vocabulary
  4. 'story'
  5. summary
  6. vocabulary review
  7. self test
  8. student activity

Introduction

eelgrass

This webpage will familiarize students with the eelgrass habitat. Students will learn what eelgrass is, why it is important, and how it is related to other organisms.

grade level: 7th thru 9th

for the teacher: Background information on eelgrass habitats may be found at these resource sites:

for everyone:

This webpage uses JavaScript to provide several extra functions.

  1. Words which appear as underlined maroon text (e.g. angiosperm) will pop-up a definition box when you move your mouse over them. Try it!
  2. The pictures on this page are 'thumbnail' images. Click on the picture to the larger version.
  3. Once you've answered the self-test, you can immediately find out the percentage you answered correctly by pressing the 'Score it' button.
  4. The detailed answer sheet shows you your answer and the correct answer for each question. It also provides a link back to the point in the text which dicusses the material for the question.

 

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Lesson
Objectives

The objectives of this lesson are:

  1. Students will be able to describe eelgrass in terms of what kind of plant it is, its structure and conditions it needs for life.
  2. Students will be able to explain relationships between eelgrass and other biotic and abiotic components in a coastal or estuarine ecosystem.
  3. Given a group of organisms and physical environment factors, students will be able to construct a diagram representing relationships among them.
  4. Students will be able to explain how functions performed by eelgrass habitats make them important both ecologically and economically.

 

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Vocabulary
new words

| angiosperm | ecosystems | detritus | estuaries | genus | larvae | perennial | rhizomes | photosynthesis |


 

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Story

What is eelgrass?

eelgrassEelgrass is a common name for a group or genus of plants called Zostera that grow under water in estuaries and in shallow coastal areas. Eelgrass may also be referred to as SAV, or Submerged Aquatic Vegetation.

Eelgrass is neither a grass nor a seaweed. It is an angiosperm, or flowering plant that can live for many years, a perennial.

Why is eelgrass so important?

Eelgrass habitats are among the most productive and biologically diverse ecosystems on the planet. Materials from these habitats can support many organisms locally and far offshore, as deep as 30,000 feet in the ocean.

Eelgrass has many valuable ecological functions.

  • It helps prevent erosion and maintain stability near shore by anchoring sediment with its spreading rhizomes.
  • Its leaves projecting upward have a slowing effect on water flow. This promotes deposition of suspended particles and larvae, which, in turn, increase productivity through increased photosynthesis in clearer water and larger animal populations from the settling and growth of larvae.
  • Eelgrass provides food, breeding areas, and protective nurseries for fish, shellfish, crustaceans and many other animals.

Eelgrass habitats have great economic impact worldwide.

  • For example, in the Chesapeake Bay, eelgrass provides nourishment and nursery beds for scallops.
  • In Australia, the $100 million dollar prawn industry depends on healthy eelgrass, as do salmon and cod fisheries in our Pacific Northwest.

As food, eelgrass has far-reaching effects. Because it is a primary producer, it forms the base of a food web. Many different kinds of organisms depend on it directly or indirectly. These include:

  • some waterfowl
  • snails
  • urchins
  • lobsters
  • crabs
  • scallops
  • jellyfish
  • sea anemones
  • flounder
  • and many other fish species.

Less than 5% of eelgrass is eaten by grazers because it has a high amount of cellulose, which most animals cannot digest.

Its main function as food is to produce detritus, or decaying plant matter. Bacteria, worms, and crabs feed on this material locally and pass it up to other animals in the food web. Some of the detritus is carried offshore many miles where it is fed upon by fish and other animals thousands of feet below the ocean's surface.

Where does eelgrass grow?

Eelgrass grows in estuaries, bays, lagoons, and other marine environments where water is clear and light is plentiful. Eel grasses grow in shallow salty waters with muddy or sandy bottoms.

Eelgrass habitats can be found from Alaska to Australia, in the Chesapeake Bay and off the coasts of Florida, California, and coastal areas of Europe and Asia.

Eelgrass may be found growing just a few feet under water or at depths up to 100 feet or more if the water is unusually clear (e.g. some areas along the California coast). How deep eelgrass grows depends on the amount of light available and on the clarity of the water. Temperature and salinity also affect eelgrass health.


 

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Summary

Eelgrass is a flowering plant that grows under water in estuaries and in shallow coastal areas. Eelgrass forms the base of some biologically rich ecosystems and thus supports many varieties of organisms, including some economically valuable fish and shellfish.

Eelgrass performs many important ecological functions.

  1. Prevents erosion
  2. Provides safe breeding grounds and nurseries for fish, crustaceans and shellfish
  3. Slows water flow to promote more photosynthesis

Most animals cannot eat eelgrass because they cannot digest the cellulose in it, but as detritus, eelgrass is a rich source of nourishment throughout the food web. Eelgrass habitats are found in most of the world's coastal regions except at extremely high latitudes.


 

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Vocabulary
review

| angiosperm | ecosystems | detritus | estuaries | genus | larvae | perennial | rhizomes | photosynthesis |


 

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Self test

Now that you have read through the material on this page, how about a little quiz to confirm that you've learned the major points about eelgrass habitats?

Once you've answered the questions, you can press the 'Score it' button and immediately find out how you did. You can also get a detailed explanation of which questions you answered incorrectly.


 

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Student activity

Create a card game.


 

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Additional lessons

If you liked this lesson, be sure to visit the other lessons in the series.

 

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Thanks to Dr. Michael J. Kennish of Rutgers University IMCS for his generous assistance in locating resources.

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