Lesson Plan

Piecing Together the Fjord Estuary Ecosystem Puzzle

A Park Ranger shows a plankton sample to a child with a magnifying glass.

NPS photo

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Grade Level:
Fifth Grade-Seventh Grade
Art, Biology: Animals, Biology: Plants, Ecology, Geology, Science and Technology
1.5 - 2 hours in the field, 2 - 3 classroom periods back at school
Group Size:
Up to 24 (4-8 breakout groups)
ecosystems, Kenai Fjords Coast, lesson plan, fjord, alaska


By exploring the coast of Resurrection Bay, students will learn about the formation of a fjord, the relationships within an estuary ecosystem, and the importance of conserving the biodiversity within Kenai Fjords National Park.


Students will gain a better understanding of the local glaciology, geology, and ecology within a fjord estuary ecosystem. They will compare tests of water temperature and salinity between a brackish stream and the ocean in order to understand the importance of abiotic factors in supporting a diverse marine habitat. Hand held microscopes will be used to examine plankton and provide students with a better picture of the food chain base. Students will focus on detail by attempting to create scientifically accurately drawings of intertidal invertebrates, seaweeds, and plankton.


Fjords are glacially carved U-shaped valleys. Resurrection Bay was carved by a massive tidewater glacier during the late Wisconsin Glaciation (approx. 23,000 years ago). Local bathymetry shows that the ice that carved out Resurrection Bay stretched about 40 miles in to the Gulf of Alaska.

An estuary is where fresh and salt water mix together. Estuaries are transition zones between river ecosystems and ocean ecosystems, they are subject to marine influences, such as tides, waves, and the influx of saline water; and riverine influences- such as flows of fresh water and sediment. The mixing of saltwater and freshwater provides high levels of nutrients in both the water column and sediment, making estuaries one of the most bio diverse habitats in the world. Sea water generally has a salinity of 31-38 parts per thousand (PPT). And distilled fresh water should have a salinity of 0 PPT. Water in an estuary has more salinity (diluted salt) than fresh water, and can be referred to as brackishwater. In places where estuaries are formed by glacial melt-water mixing in to seawater, water temperatures tend to be cooler. The coldest water in the estuary can be found near the mouths of glacial streams. Often plumes of glacial silt settle out from melt-water streams when they reach larger bodies of water. 

Ecosystems are habitats in which abiotic and biotic elements interact with each other. A few of the abiotic elements of Resurrection Bay are water, air, wind, temperature, weather, wave action, and rocks. The abundance of marine mammals, fish, marine invertebrates, seabirds, and microscopic plankton make up the biotic elements of the ecosystem. 

Plankton are microscopic free floating plants (phytoplankton) and animals (zooplankton). Plankton are an extremely important support piece in the fjord estuary food web. Fish rely on great density and distribution of plankton to match that of their new larvae (plankton stage) which would otherwise starve because plankton cannot control where it swims. Natural and man-made factors can strongly affect zooplankton, which can in turn strongly affect larval survival, and therefore breeding success. 


Trophic levels are a way of identifying where species exist on the food chain. Plankton is generally divided in to three trophic groups: phytoplankton are considered primary produces, zooplankton-consumers and bacterioplankton-decomposers. 

There are global and local impacts that estuary ecosystems must face. Impacts of climate change on this environment can be seen in warming ocean temperatures impacting fragile life cycles, melting ice leading to loss of habitat for seals and certain sea birds. Other human caused impacts: pollution, marine debris-one of the largest killer of marine mammals (give students an idea of how difficult it can be for marine animals to escape from debris in water where there aren't objects to rub against with activity: put rubber band around thumb, behind hand and around pinkie finger and have them try to remove the rubber band without using anything but the hand it is on), overfishing and fishing key trophic species, involuntary and voluntary introduction of marine invasives.



  • Scientific drawings include measurements and scale.
  • Students have taken notes on both temperature and salinity of brackish water and seawater.


Park Connections

Other national parks could be incorporated by discussing the fjord estuary ecosystems of Glacier Bay National Park and differences in rates of melting for standalone glaciers vs. glaciers fed by an icefield. Many national parks throughout Alaska and the lower 48 boast glacially carved landscapes. Expand by comparing older and newer glacial landscapes (i.e. Yosemite to Kenai Fjords).



This lesson could be adapted to lower age groups by downsizing some of the vocabulary,also adapted to be a junior ranger badge/fjord patch program.


Additional Resources

Elias, Scott. Alaskan National Parks. Washington and London: Smithsonian Institution Press, 1995.

Field, Carmen and Conrad Field. Alaska's Seashore Creatures: A Guide to Selected Marine Invertebrates.Anchorage: Alaska. Alaska Northwest Books. 1999.

Kenai Fjords National Park Teachers Resource Manual. Forging Connections: An Educational Resource for Kenai Fjords National Park. Seward, Alaska.

Lindeberg, Mandy and Sandra Lindstrom. Field Guide to Seaweeds of Alaska. Fairbanks: Alaska. Alaska Sea Grant College Program, 2010.

National Geographic Environmental Literacy Teacher Guide. One Ocean: A guide for teaching the Ocean in Grades 3 to 8.National Geographic Education Beta website.

Wiley, Sally. Blue Ice in Motion: The Story of Alaska's Glaciers. Anchorage: Alaska Natural History Association, 1990. 


Tidewater glacier, bathymetry, fjord, estuary, tides, waves, sediment, nutrients, habitat, salinity, brackish water, ecosystem, abiotic, biotic, marine mammals, invertebrates, food web, density, distribution, intertidal zone, trophic levels, consumer, producer, decomposer, marine mammals, marine debris, overfishing, marine invasive species, pollution, conservation.

Last updated: March 30, 2018