Mono Lake

Mono Lake

Middle School

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Learning Objectives

• Describe the abiotic factors of Mono Lake and how they provide matter.

• Model the cycling of matter and energy flow in the Mono Lake ecosystem.

• Identify producers, consumers, and decomposers in the Mono Lake food web.

• Analyze how energy and matter transfer creates consistent life patterns like seasonal cycles.

Key Vocabulary

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Ecosystem

A community of living organisms interacting with their nonliving environment all around them.

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Abiotic Factor

A non-living part of an ecosystem, like the water, salt, or even the minerals.

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Producer

An organism, like algae, that produces its own food, and usually does so using sunlight.

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Consumer

An organism that obtains its energy by feeding on and consuming other living organisms.

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Decomposer

An organism that breaks down any dead organic matter, which helps recycle essential nutrients.

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Food Web

A model showing how energy and essential matter move through an entire ecosystem.

Key Vocabulary

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Cycling of Matter

The continuous movement of atoms between living and nonliving parts of an ecosystem.

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Flow of Energy

The one-way transfer of energy through an ecosystem's food web.

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Salinity

The concentration of dissolved salts in a body of water.

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Alkalinity

A measure of water’s ability to resist changes in pH when acids or bases are added is called its buffering capacity or alkalinity

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Tufa Towers

Limestone structures formed over underwater calcium-rich springs.

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An Ancient and Unique Lake

• Mono Lake is an ancient ecosystem and the oldest lake in the US.

• It is a small remnant of a huge, ancient lake system.

• The lake has no outlet, so water only leaves by evaporation.

• This process leaves minerals behind, making the lake's water very salty.

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Multiple Choice

What is a defining characteristic of Mono Lake?

• It is the oldest lake in the United States.

• It is the largest lake in the world.

• It is a man-made reservoir.

• It is filled with fresh water from glaciers.

Multiple Choice

Why is the water in Mono Lake very salty?

• Water leaves only by evaporation, which leaves minerals behind.

• It is a small remnant of a much larger, saltier ocean.

• Rivers deposit large amounts of salt into the lake each year.

• The lake has no fish to consume the minerals in the water.

Multiple Choice

What would most likely happen if a new river formed that flowed out of Mono Lake?

• The lake's water would become less salty over time.

• The lake would be able to support more plant life.

• The water level of the lake would rise significantly.

• The rate of evaporation from the lake would increase.

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Abiotic Factors: The Lake's Nonliving Parts

• Evaporation makes the lake three times saltier than the ocean, with a high pH of 10.

• Fresh water from streams provides essential matter, like water and minerals, for living things.

• Underwater springs release calcium, which forms the lake's unique limestone tufa towers.

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Multiple Choice

What are abiotic factors in an ecosystem?

• The nonliving parts of an ecosystem.

• The plants and animals in a habitat.

• The flow of energy between organisms.

• The temperature and weather patterns.

Multiple Choice

How are the lake's limestone tufa towers formed?

• They are formed by calcium released from underwater springs.

• They are created by freshwater streams depositing minerals.

• They result from high levels of salt due to evaporation.

• They are the remains of ancient living organisms.

Multiple Choice

If the rate of freshwater flowing into the lake from streams increased significantly, what would be the most likely effect on the lake's water?

• The lake would become less salty and have a lower pH.

• The limestone tufa towers would grow faster.

• The lake would become saltier and have a higher pH.

• There would be no change to the lake's water.

The Mono Lake Food Web

• Planktonic algae are the producers in this ecosystem.

• Brine shrimp and brine flies are the primary consumers.

• Millions of birds act as secondary consumers.

Multiple Choice

What is the role of planktonic algae in the Mono Lake food web?

• They are the producers that form the base of the food web.

• They are primary consumers that eat brine flies.

• They are secondary consumers that are eaten by birds.

• They are decomposers that break down dead organisms.

Multiple Choice

What is the relationship between primary and secondary consumers in an ecosystem?

• Primary consumers eat producers, and secondary consumers eat primary consumers.

• Secondary consumers are producers, and primary consumers eat them.

• Primary and secondary consumers both eat planktonic algae.

• Primary consumers are eaten by producers.

Multiple Choice

If a sudden environmental change caused a massive decline in the planktonic algae population, what would be the most likely impact on the brine shrimp and bird populations?

• The brine shrimp population would decrease, leading to a decrease in the bird population.

• The bird population would increase because there would be fewer shrimp to eat.

• The brine shrimp population would increase because their main predator is gone.

• There would be no change to either the shrimp or bird populations.

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The Flow of Energy

• The sun is the main source of energy for the Mono Lake ecosystem.

• Producers like algae use photosynthesis to capture the sun’s energy.

• This energy is then transferred from producers to the consumers.

• At each level, much of the energy is lost from the ecosystem as heat.

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Multiple Choice

What is the primary source of energy for the Mono Lake ecosystem?

• The sun

• The water

• The algae

• The consumers

Multiple Choice

What is the relationship between producers and consumers in the flow of energy?

• Energy is transferred from producers to consumers.

• Consumers use photosynthesis to create their own energy.

• Energy is lost by producers as they consume other organisms.

• The sun provides energy directly to the consumers.

Multiple Choice

Based on the flow of energy described, what can be concluded about the energy available to organisms at different levels of the food chain?

• The amount of available energy decreases at each level.

• The amount of available energy increases at each level.

• Producers at the bottom are less efficient at capturing energy.

• Consumers at the top store energy instead of using it.

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The Cycling of Matter

• Unlike energy, matter is recycled and never lost in an ecosystem.

• Atoms are constantly cycled between living and nonliving parts of the ecosystem.

• Decomposers, like bacteria, break down waste and dead organisms like algae or birds.

• This process releases and recycles important nutrients back into the ecosystem for producers.

Multiple Choice

What is the main principle of how matter moves in an ecosystem?

• Energy flows in one direction through an ecosystem.

• Atoms are continuously reused between the living and nonliving parts of an ecosystem.

• Living organisms create new matter that is then used by others.

• Only nonliving things are involved in the cycling of matter.

Multiple Choice

What is the specific function of decomposers in the cycling of matter?

• To serve as a primary food source for producers.

• To convert sunlight into energy for other organisms.

• To break down dead organisms and return their nutrients to the ecosystem.

• To consume living producers and release energy.

Multiple Choice

What would be the most likely long-term consequence if all decomposers were removed from an ecosystem?

• The producers would eventually run out of the nutrients they need to live.

• The amount of matter in the ecosystem would begin to increase.

• Energy would stop flowing through the ecosystem.

• Dead organisms and waste would be converted directly into energy.

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The Seasonal Cycle of Life

• From winter to spring, a lake turnover brings rich nutrients to the surface.

• This cycling of matter allows producers like algae to grow rapidly.

• In summer, brine shrimp and flies eat the algae, transferring matter and energy.

• Birds eat the insects, and decomposers recycle nutrients from waste in the fall.

Multiple Choice

What is the direct result of a lake turnover bringing nutrients to the surface in the spring?

• It causes rapid growth of producers like algae.

• It makes the water colder for fish.

• It provides food directly for birds.

• It helps brine shrimp and flies to hatch.

Multiple Choice

What is the relationship between algae, brine shrimp, and flies in the summer ecosystem?

• The shrimp and flies consume the algae as a source of matter and energy.

• The algae and the insects compete for the same nutrients.

• The shrimp and flies help the algae to reproduce.

• The algae provide shelter for the shrimp and flies.

Multiple Choice

Which statement best explains why decomposers are essential for the lake's seasonal cycle to continue year after year?

• They recycle nutrients from waste, which can then be used by producers in the spring.

• They are the main food source for birds during the fall.

• They consume the algae that would otherwise take over the lake.

• They help to mix the water, causing the lake turnover.

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Common Misconceptions

Misconception	Correction
When an organism dies, its matter disappears.	Matter is cycled. Decomposers return atoms to the ecosystem for producers to use.
Energy is created in an ecosystem.	Energy is transferred, not created. It flows from the sun to organisms.
Tufa towers grow in the air.	Tufa towers form exclusively underwater and are visible when water levels drop.
The lake's water is just like ocean water.	The water is nearly three times saltier than the ocean and is highly alkaline.

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Summary

• Mono Lake is an ancient, saline ecosystem where living and nonliving parts are interconnected.

• Energy flows one way, from the sun to producers, and then to consumers.

• Matter is continuously cycled between living and nonliving parts by decomposers.

• The lake follows a seasonal cycle and is a critical resource for migratory birds.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4