Human Impact

Human Impact

Middle School

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Learning Objectives

• Define biodiversity and its role in measuring the health of an ecosystem.

• Explain the importance of ecosystem services like water purification and nutrient recycling.

• Analyze how human activities like habitat loss and invasive species threaten biodiversity.

• Evaluate design solutions for maintaining biodiversity by considering various constraints.

Key Vocabulary

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Biodiversity

The variety of life in an ecosystem, which is often used as a measure of its health.

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Ecosystem Services

These are the many benefits that humans get from ecosystems, like clean water and nutrient recycling.

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Keystone Species

A keystone species is an organism that has a very large effect on its entire ecosystem.

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Invasive Species

An invasive species is a non-native organism that is introduced to and harms its new environment.

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Habitat Loss

Habitat loss is the destruction of a natural environment, making it unable to support the species there.

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Extinction

Extinction is the complete and permanent disappearance of a species of animal or plant from Earth.

Key Vocabulary

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Ecological Footprint

The measure of human demand on an ecosystem's resources.

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Nutrient Recycling

The natural process of breaking down organic matter to be used by other organisms.

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Soil Erosion

The wearing away of topsoil, which can be prevented by plant roots.

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Design Solution

A plan or strategy developed to solve a specific problem.

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Design Constraint

A limitation or restriction on a design solution, such as cost or social factors.

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What is Biodiversity?

• Biodiversity is the variety of all living organisms in a particular ecosystem.

• High biodiversity is a sign of a healthy and resilient ecosystem.

• All species are interdependent, helping the ecosystem recover from any potential disasters.

• It impacts our access to food, medicine, and other ecosystem services.

Multiple Choice

Which statement best defines biodiversity?

• The variety of all living things in a specific area

• The total number of animals in an ecosystem

• The non-living factors that support life

• The way different ecosystems interact with each other

Multiple Choice

What is the primary benefit of having high biodiversity in an ecosystem?

• It makes the ecosystem more resilient to disasters.

• It prevents changes to the climate.

• It guarantees that humans will have more food.

• It reduces the number of living things in an area.

Multiple Choice

A forest ecosystem loses many of its plant and animal species due to a new disease. What is the most likely consequence for this ecosystem?

• The ecosystem will become healthier for the remaining species.

• The ecosystem will be less able to recover from future challenges.

• There will be no significant change to the ecosystem's health.

• It will increase human access to important resources.

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What are Ecosystem Services?

• Ecosystem services are the many benefits humans get from healthy ecosystems.

• ​These services include water purification, nutrient recycling, and preventing soil erosion.

• Pollination by animals like bees is also essential for growing food.

• Maintaining biodiversity is critical for these important services to continue.

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Multiple Choice

What are ecosystem services?

• The benefits that humans receive from healthy ecosystems.

• The process of animals moving from one ecosystem to another.

• The way humans change the environment to build cities.

• The diseases that can spread within an ecosystem.

Multiple Choice

What is the primary role of services like water purification and pollination?

• They increase the amount of land available for building.

• They provide essential resources like clean water and food.

• They help animals adapt to new environments.

• They create new types of rocks and minerals.

Multiple Choice

What would most likely happen to services like water purification and food production if the biodiversity of an ecosystem was significantly reduced?

• The ecosystem would produce more food than before.

• The ecosystem's ability to provide clean water and support food growth would decrease.

• There would be no significant change to the ecosystem's benefits.

• The number of new animal species would suddenly increase.

Keystone Species

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Top Predators

• ​Wolves are top predators that help control populations of their prey.

• ​​This prevents overgrazing of plants by animals like deer or elk.

• ​Their presence helps keep the entire ecosystem healthy and in balance.

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Pollinators

• ​Bees are pollinators essential for the reproduction of many different plants.

• ​​They transfer pollen between flowers, which allows the plants to reproduce.

• ​This process is necessary for many plants to create fruits and seeds.

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Ecosystem Engineers

• ​Beavers are ecosystem engineers that physically change their environment to live.

• ​​They build dams on rivers and streams, creating new wetland habitats.

• ​These wetlands then provide homes for many other different types of species.

Multiple Choice

What is the primary role of a keystone species in an ecosystem?

• To help keep an ecosystem healthy and in balance.

• To be the most numerous species in an ecosystem.

• To physically change the environment for all other species.

• To compete with other animals for food resources.

Multiple Choice

How do the functions of bees and beavers as keystone species compare?

• Bees support plant reproduction, while beavers construct new habitats.

• Bees build dams to create new habitats, while beavers pollinate flowers.

• Bees control prey populations, while beavers help plants create seeds.

• Both bees and beavers primarily help control animal populations.

Multiple Choice

If wolves, a top predator, were suddenly removed from the ecosystem, what would be the most likely consequence?

• The population of deer would likely increase, leading to a decrease in plants.

• The population of plants would likely increase because of fewer predators.

• The population of bees would decrease because of changes in the flowers.

• New wetland habitats would be created for other species.

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Threats to Biodiversity

• The primary threat to biodiversity is extinction, which is currently caused by humans.

• Habitat loss from construction, agriculture, and deforestation is a major threat.

• Changing river flows with dams also destroys the habitats of many species.

• Other threats include overhunting, pollution, and ongoing climate change.

Multiple Choice

What is the main driver of the current primary threat to biodiversity?

• Human activities

• Natural disasters

• Changes in weather

• Competition between species

Multiple Choice

How does the construction of new buildings and dams impact biodiversity?

• It causes an increase in hunting.

• It introduces pollution into the air and water.

• It destroys the habitats where animals and plants live.

• It directly causes the climate to change.

Multiple Choice

If a large forest is cleared for agriculture, what is the most likely consequence for that ecosystem?

• Biodiversity will decrease because of the loss of animal and plant homes.

• Biodiversity will increase because agriculture provides more food.

• Biodiversity will be threatened primarily by increased pollution from farm equipment.

• Biodiversity will remain the same, but the types of animals will change.

Invasive Species and Their Impacts

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Brown Tree Snake

• ​This invasive snake is a powerful predator with no natural enemies.

• ​​It is responsible for wiping out most of Guam's native birds.

• ​It also causes frequent power outages by climbing on electrical wires.

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Zebra Mussels

• ​These creatures outcompete native organisms for essential resources like food.

• ​​They attach to hard surfaces, which can clog pipes and damage boats.

• ​Zebra mussels have driven many native mussel species toward extinction.

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Chestnut Blight Fungus

• ​This invasive fungus was introduced to North America from imported trees.

• ​​It caused a disease that killed nearly all American chestnut trees.

• ​This affected every animal that depended on the chestnut trees.

Multiple Choice

Based on the examples, what is the primary, shared impact of invasive species?

• They cause harm to the native species and environment.

• They are all predators with no natural enemies.

• They only damage human-made structures like pipes or wires.

• They are all fungi that spread diseases to plants.

Multiple Choice

How does the ecological impact of the brown tree snake differ from that of the zebra mussels on native species?

• The snake acts as a direct predator, while the mussels reduce the availability of food.

• The snake only harms birds, while the mussels only harm other mussels.

• The snake damages electrical wires, while the mussels damage boats.

• The snake is an animal, while the mussels are a type of plant.

Multiple Choice

What broader conclusion about ecosystems can be drawn from the effects of the chestnut blight fungus?

• The loss of a single species can lead to negative consequences for many other organisms.

• Invasive species are only a threat to trees and other plants.

• All invasive species are introduced to a new area on imported trees.

• An invasive species' only impact is causing the extinction of a similar species.

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Evaluating Design Solutions

Criteria

• Criteria are the standards used to judge how well a design solution solves the intended problem.

• A key criterion is whether the solution effectively increases biodiversity in the target area.

• Another is whether it helps restore the natural benefits that are provided by the ecosystem.

Constraints

• Constraints are real-world limitations or restrictions that a design solution must operate within.

• This can include economic constraints, such as if the proposed solution is affordable.

• It also includes social factors, like whether the community will support the project.

Multiple Choice

In the context of evaluating a design, what are 'criteria'?

• The standards used to judge how well the solution solves the problem

• The real-world limitations or restrictions on a solution

• The economic or social factors affecting a project

• The person or group who first designed the solution

Multiple Choice

What is the main difference between the criteria and constraints of a design solution?

• Criteria are goals for success, while constraints are limitations

• Criteria are limitations, while constraints are goals for success

• Criteria refer to social factors, while constraints refer to economic factors

• Criteria and constraints are both standards used to judge a solution

Multiple Choice

A city proposes a plan to restore a wetland, which will effectively increase biodiversity. However, many people in the community are opposed to the project. Which statement best evaluates this design solution?

• The plan meets a key criterion but may fail to meet a social constraint.

• The plan meets an economic constraint but fails to meet any criteria.

• The plan is limited by a criterion and supported by a constraint.

• The plan successfully meets all possible criteria and constraints.

Solutions for Invasive Species

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Prevention

• ​This is the most effective and least expensive management strategy.

• ​​It uses education and regulations to prevent species from arriving.

• ​For example, cleaning boats can stop aquatic hitchhikers from spreading.

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Eradication

• ​If a new invasive species is found, the goal is removal.

• ​​This involves trying to remove the entire population from the area.

• ​Eradication works best when the invasive population is still very small.

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Mitigation

• ​This is used when a species is too widespread to eradicate.

• ​​The main goal is to control and manage the population size.

• ​This helps to reduce its harm to the local environment.

Multiple Choice

What is the primary goal of the strategies used for managing invasive species?

• To control, remove, or prevent the spread of harmful non-native species.

• To help new species adapt to the local environment.

• To study how different types of species interact with each other.

• To increase the number of species in an ecosystem.

Multiple Choice

How does the size of an invasive species population affect the choice between eradication and mitigation?

• Eradication is for small, new populations, while mitigation is for large, widespread ones.

• Eradication uses regulations, while mitigation uses education.

• Eradication is the least expensive option, while mitigation is the most effective.

• Eradication aims to control a population, while mitigation aims to remove it completely.

Multiple Choice

An aquatic invasive species is spreading towards a new lake system. Officials decide to start a campaign to teach boaters to clean their boats thoroughly. Which strategy does this represent, and why is it the best first step?

• Prevention, because it is the most effective and least expensive way to stop a species from spreading.

• Eradication, because the species is already present and must be removed.

• Mitigation, because the species is found in water and needs to be controlled.

• A combination of eradication and mitigation to manage the harm.

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Common Misconceptions

Misconception	Correction
The fastest or most powerful environmental solution is always the best one.	The best solutions consider long-term effects, cost, and social impact.
All species from other places (non-native) are harmful and invasive.	A non-native species is only invasive if it harms the new environment.
Extinction is only a natural process that happens over a long time.	Human activities are causing extinctions to happen much faster than is natural.
One person's actions are too small to help environmental problems.	Collective individual actions can create powerful, large-scale positive change.

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Summary

• Biodiversity is critical for ecosystem health but is threatened by human activities.

• Invasive species and the loss of keystone species can severely damage ecosystems.

• Protecting biodiversity requires evaluating design solutions based on scientific and social criteria.

• Conserving resources and reducing our ecological footprint help protect vital habitats.

Poll

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

• 1

• 2

• 3

• 4