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

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:

• Eelgrass restoration aids overall recovery of coastal bays
• Virginia Institute of Marine Science SAV page -- suggested by Lee Karrh
• Educational and cultural approaches for sustaining eelgrass health

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.

Vocabulary
new words

Story

What is eelgrass?

Eelgrass 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.

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

Vocabulary
review

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?

Student activity

Additional lessons

Administrivia:

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

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