Statewide Data Sharing

Share the investigation of your local ecosystem with students statewide via the Alaska Seas and Watersheds Website Forum. Take a picture of something important at your field site and post it, along with a description. Be sure to include the time and date that it was taken and the weather that day.

You can also share the data and conclusions from your ecosystem investigation at the site, and post questions that your class has generated.

Investigate the Web site to see the ecosystem discoveries that students have made in other parts of the state. How are their ecosystems different from yours?

A School-Wide Celebration of our Aquatic Ecosystem

Present your learning to other students in the school and to the community by organizing a school-wide celebration. Include a scientific poster session that teaches people about the sea otter’s ecosystem and about your local ecosystem. Make a mural, make costumes, have an art show, put on a dramatic production, have a feast, sing songs about the aquatic environment. Use your imagination to help your whole school learn and celebrate.

A quadrat is a frame used by marine biologists to perform counts of the density of organisms or the percentage of cover in a standard area. You may use quadrats made with 4 meter sticks for an area of one square meter, or you may use quadrats that are smaller. Hula hoops also work as quadrats if you have access to those. A scientist always knows the area of his or her quadrat, since it is used for sampling and making estimates of what will be found in a bigger area.

To make a ¼ square meter quadrat, use pvc tubing and elbow joints. Cut tubing so that the inside dimensions of your square measure 25 cm x 25 cm. You will need one quadrat for each group of sampling students.

This activity will help students to learn and review proper field etiquette. Students will be properly prepared for both the field trip experience and the ways in which their presence and activities in the field could impact the habitat they are trying to study.

You Will Need:

• Field etiquette grab bag (see content list below)
• Field etiquette handout

What to Do:

Introductions:

Prepare students for their field trip by discussing possible impacts their presence at the beach might have and ways in which they can help to minimize the impact and prepare themselves for a successful trip.

Procedures:

Have students come up, one at a time, and pull an item out of the grab bag. Ask the student to try to think of a way that their item symbolizes a field etiquette "rule" that should be followed or action they should take at the field site.

Once all of the items have been pulled from the bag, distribute the Field Etiquette Handout and discuss any other items that are useful to your group

Field Etiquette Grab Bag Contents

Results

(Adapted from Estes and Palmisano. 1974.)

Conclusions:

1. The differences between the two benthic (bottom) communities on the Near and Rat islands are probably related to the presence or absence of sea otters.

2. The otters control the sea urchin populations, and the absence of grazing pressure allows the kelp beds to flourish.

3. Reducing the population of sea otters makes it possible for sea urchin populations to increase, and this leads to a significant reduction in the size of kelp beds and associated animals.

Evaluation:

James Estes and his colleagues did repeat the study in 1986-87 (when otters had reached the Near Islands and were thought to be at maximum density), and during the 1997-2000 period. In the ten-year period between 1987 and 1997, they found that sea urchin size and density increased to produce 8 times the amount of biomass, while kelp density decreased to one-twelfth. The percentage of kelp grazed increased from 1.1% per day in 1991 to 47.5% in 1997—all indicative of an “urchin barrens” in the absence of a high density of otters.

The data they collected at Amchitka in 1997 were similar to those for Adak (high urchin numbers, small urchin size, sparse kelp beds, high grazing rates on kelp).

Sample Data Table:

1990s Observations