• Sunset view of Glacier Bay and the surrounding Fairweather Mountains.

    Glacier Bay

    National Park & Preserve Alaska

The Marine Environment: Activity #1 - Setting The Scene

Glacier Bay contains a highly complex oceanographic system within a relatively small area. This in large part explains the unusual variety of marine life that is found here. The ocean's invasion as the glaciers retreated created a complex array of underwater environments, each hosting distinct but overlapping biological communities.

Student Resource: The Ocean-Glacier Bay

The Ocean-Glacier Bay National Park


1. The Complex Oceanography of Glacier Bay
Tell students that oceanographers classify Glacier Bay as a "recently deglaciated, tidally mixed, fjord estuarine system with [many] underwater sills."To help them better understand this description, have them read the Student Resource: The Ocean - Glacier Bay National Park and Preserve in groups.Then, briefly discuss their reading. What is meant by the terms deglaciated, tidally mixed, fjord estuarine systems and underwater sills.

Answer: Check the Marine Environment Glossary for the meanings of these terms.

2. Influences on the Oceanography of Glacier Bay
Next, put the following information on the chalkboard:

  • Physical – tides, currents, salinity, temperature, light, precipitation
  • Chemical – salinity, nutrients, density, pH
  • Geological – glaciation, depth, sedimentation rates, marine substrate
  • Biological – phytoplankton, zooplankton, fish, invertebrates, marine mammals, humans

Explain to students that each of the four topics is defined by the terms listed under them. For example, under Physical, you would list information about an ocean's tides, currents, salinity, temperature, light, precipitation, etc.

Note: Students will notice that salinity shows up under both Physical and Chemical. Under Physical salinity means the range of saltiness of the water in any given area of the bay. Under Chemical, salinity refers to salt's effect on the density of the water.

Ask students to find statements that describe the Physical, Chemical, Geological or Biological influences on Glacier Bay's ocean environment. As they make suggestions, write these under each category.

Student Worksheet: Interactions in the Oceans

Interactions in the Ocean worksheet

3. Interactions in the Ocean
Distribute copies of the Student Worksheet: Interactions in the Ocean to student groups.

Ask them to briefly discuss interactions they found as they read the Student Resource: The Ocean - Glacier Bay National Park and Preserve. For example, because Glacier Bay has a large sill at its entrance, (Geological) water entering the bay from the deep, cold and salty ocean is well mixed with water returning to the ocean from the upper bay (Physical).

Working in groups, have them complete the Student Worksheet: Interactions in the Ocean. They can use the Student Resource: The Ocean - Glacier Bay National Park and Preserve and any of the Internet Resources needed to report as many interactions as possible. They will need to read one or both of the following Internet Resources in order to find an interaction between the Biological parameter and the Physical parameter.

Answer: Answers to the worksheet are found immediately following the worksheet.


4. Glacier Bay - The Amazing Biodiversity Machine
After students have completed the worksheet, briefly introduce the idea of a Rube Goldberg machine (see Rube Goldberg http://www.rube-goldberg.com/). Explain to students that they are going to draw or build a Rube Goldberg machine that illustrates the interactions among all the elements of Glacier Bay's unique oceanography.

Note: Rube Goldberg machines are linear; that is, each cog in the machine affects one and only one other cog. Glacier Bay is non-linear; that is, cogs in the machine interact with other cogs often simultaneously and sometimes randomly.

Divide students into groups; give them time to examine the Rube Goldberg machines at the Internet site. Groups are expected to build or design a non-linear machine in which they illustrate the oceanographic interactions they found in Glacier Bay.


5. Resources:

GLBA: Nature and Science, Oceans

Glacier Bay National Park and Preserve: Intertidal and Subtidal zones

USGS Marine Habitat

Marine Substrates
(Student Resource based on the information in Geologic characteristics of benthic habitats in Glacier Bay)

Fjord Processes and Oceanographic Dynamics
(Recommended for Advanced Students Only)

Web of Life

Kelp Forests

Extension 1:
Using data from the Internet and Student Resources, challenge students to create a scale model or relief map of Glacier Bay's ocean floor topography (bathymetry). Use the model to illustrate the definitions of the following terms:

bathymetry turbidity mixing zones upwelling zones
contraction sill water column basin
tidewater glacier fjord intertidal zone subtidal zone

Extension 2:
(Recommended for Advanced Students)
Using a water table demonstrate why water at the mouth of Glacier Bay and at the Sitikaday Narrows are mixing zones. Next, using colored water to represent different salinities, illustrate the stratification of the water column in deeper basins.


>>Activity #2
Prime Real Estate for Phytoplankton

Did You Know?

Red Squirrel

A red squirrel eats the seeds of about 144 spruce cones each day. This diet allows red squirrels to thrive in the spruce-dominated forests of Lower Glacier Bay. How many spruce cones do you eat each day?