Unit A Lesson 15: Human Activities and Biodiversity
Completion requirements
Unit A Lesson 15: Human Activities and Biodiversity
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Learning Targets |
Inquiry Question: How do human activities affect
biodiversity
?
Species constantly fight against extinction, but some human activities increase the pressure to survive.
Species constantly fight against extinction, but some human activities increase the pressure to survive.
At the end of this inquiry, you should be able to answer the following questions:
- What is extinction?
- What is extirpation?
- What does it mean for a species to be threatened?
- What causes extinction and extirpation?
- What is a bio-indicator species?
- What happens when a non-native species is introduced to an area?
Page 56 - 65 in your textbook will help you answer these questions about the relationship between human activities and biodiversity.
Introduction
In the last 600 million years, five major declines in Earth's
biodiversity have occurred.
Species have been declining in numbers at increasingly rapid rates. During the last 65 million years, one species became extinct per year. However, currently it is estimated that up to 70 extinctions occur per day!
Species have been declining in numbers at increasingly rapid rates. During the last 65 million years, one species became extinct per year. However, currently it is estimated that up to 70 extinctions occur per day!
Connections
Connections: Nature and History
>> Why did dinosaurs become extinct?
One of the most well-known biodiversity declines occurred when the dinosaurs were wiped out 65 million years ago. Many scientists speculate about the cause of the dinosaurs’ extinction, but to date no one knows for sure what actually ended the reign of the thunder lizards.
>> Why did dinosaurs become extinct?
One of the most well-known biodiversity declines occurred when the dinosaurs were wiped out 65 million years ago. Many scientists speculate about the cause of the dinosaurs’ extinction, but to date no one knows for sure what actually ended the reign of the thunder lizards.
Watch
The videos "New Study Says that Comet Caused Dinosaur Extinction" and "How
Dinosaurs went Extinct" cover some of the possible causes behind the dinosaurs’ disappearance.
Try It!
Practice Worksheet: Declining Biodiversity
- DOWNLOAD this practice worksheet (S9_UA_S4_L15_declining_diodiversity). If you prefer to use a Google Drive or PDF version of the worksheet, click here.
- As you work through the readings and videos in this lesson, complete the worksheet questions.
- When you are satisfied with your responses you can check your work by clicking on the "SUGGESTED ANSWERS" button at the bottom of this lesson.
Wait! Don't view the suggested answers first.
This practice work is not for marks, it is meant to help you check your
understanding. Check the answers AFTER doing the questions! Keep the
practice worksheet for study purposes. If you don't understand
something, contact your teacher!
Watch
The video "Euronews Science:
Extinction
of
Species
Accelerating" examines the rapid rate of species decline.
Recall from Grade 7 that extinction is the disappearance of a species from the planet, and that organisms in jeopardy of becoming extinct are said to be endangered. Species on the verge of becoming endangered are called threatened species. To review the
meaning of these words visually, watch the video "Endangered Animals".
Interactive
Extinctions
Species go extinct all the time; did you know that 99% of all species that have ever lived are now extinct? Species can become extinct through natural processes, but is it fair for human actions cause an extinction?
Click here to go to the BrainPOP website to watch the video "Extinction".
You will need a username and password to access the video.
Species go extinct all the time; did you know that 99% of all species that have ever lived are now extinct? Species can become extinct through natural processes, but is it fair for human actions cause an extinction?
Click here to go to the BrainPOP website to watch the video "Extinction".
You will need a username and password to access the video.
- Username: 0099
- Password: students
Watch
Some species are wiped out in a specific area but they still can exist in other areas. This is called extirpation. The California grizzly bear used to roam mid-western United States, but with the increase in urbanization, they have been
extirpated from that area. The grizzly bears are now in the western provinces of Canada and in the Northwest Territories and Yukon.
Watch more about the extirpation of the Grizzly Bear in the video "California's Lost Grizzly".
Watch more about the extirpation of the Grizzly Bear in the video "California's Lost Grizzly".
Environmental Effects and Bioidicator Species
As the human population increases, we put more stresses on the environment and the surrounding species either adapt or die. This can have devastating effects on biodiversity and the health of our ecosystems. Often, we use bioindicator species
to help us measure the health of our ecosystems.
An example is the frog population. Frogs have semi-permeable skin, which means they have increased ability to absorb molecules through their skin. If they live in areas where pollutants have increased, the frogs generally will show negative effects before other animals do.
An example is the northern leopard frog in Central Alberta. Look at the picture of a northern leopard frog born with three back legs. Due to increased pollutant levels in the environment, birth defects are on the rise, and the northern leopard frog populations are declining.
An example is the frog population. Frogs have semi-permeable skin, which means they have increased ability to absorb molecules through their skin. If they live in areas where pollutants have increased, the frogs generally will show negative effects before other animals do.
An example is the northern leopard frog in Central Alberta. Look at the picture of a northern leopard frog born with three back legs. Due to increased pollutant levels in the environment, birth defects are on the rise, and the northern leopard frog populations are declining.
Watch
To learn more about bioindicator species, watch "Keystone Species vs. Indicator Species".
auses of extinction may be natural or human, but both lead to a reduction in biodiversity. Natural causes of extinction include volcanic eruptions, earthquakes, floods, fire, lack of food due to overpopulation, and disease.
Human activities increase the destruction of natural habitats. The levels of pollutants and increased global warming are both major contributors to declining biodiversity. Increasing industrialization, agriculture production, human populations, over-hunting, and introduction of non-native species are a few human activities that have detrimental effects on the Earth.
Human activities increase the destruction of natural habitats. The levels of pollutants and increased global warming are both major contributors to declining biodiversity. Increasing industrialization, agriculture production, human populations, over-hunting, and introduction of non-native species are a few human activities that have detrimental effects on the Earth.
Watch
For a deeper look at both natural and human causes of biodiversity decline, watch the videos "Learn Biology: Threats to Biodiversity" and "The Crisis of Life 3/4: The Destruction of Biodiversity":
When humans introduce a non-native species into an area, native species must compete with them for resources. This can have devastating effects on the native species. Such non-native species often are called invasive species. This is the
case of zebra mussels in the Great Lakes of Canada and other bodies of water across the country.
The mussels were introduced inadvertently by cargo ships from Europe a long time ago. Over time, they have multiplied to the point where scientists estimate more than 4 quadrillion mussels live on the floor of Lake Michigan. Zebra mussels clog pipes and eat tonnes of plankton, which affects the food chain for other species in the lakes.
Ultimately, this affects the ecosystem and then the biodiversity of organisms. For a deeper look at the effects of zebra mussels, watch "Silent Invaders: Zebra Mussels 2013".
The mussels were introduced inadvertently by cargo ships from Europe a long time ago. Over time, they have multiplied to the point where scientists estimate more than 4 quadrillion mussels live on the floor of Lake Michigan. Zebra mussels clog pipes and eat tonnes of plankton, which affects the food chain for other species in the lakes.
Ultimately, this affects the ecosystem and then the biodiversity of organisms. For a deeper look at the effects of zebra mussels, watch "Silent Invaders: Zebra Mussels 2013".
"Invasive Species" looks closely at several non-native species and the effects they have on the environment.
Try It! - Answers
1. Natural causes of declining biodiversity could be: earthquakes, floods, decreases in food supply associated with poor environmental conditions (such as drought), increasing predator populations, forest fires, disease.
2. Human causes of declining biodiversity are pollution, over-hunting, habitat destruction, introduction of invasive species, increasing human population, logging, global warming. These are just suggested answers, did you think of any other causes?
3. One example – Purple loosestrife:
2. Human causes of declining biodiversity are pollution, over-hunting, habitat destruction, introduction of invasive species, increasing human population, logging, global warming. These are just suggested answers, did you think of any other causes?
3. One example – Purple loosestrife:
- Brought in by the Europeans on their shoes and through seeds deliberately planted in gardens.
- Very abundant in Western Canada and is a fast-growing weed.
- Takes over habitat of other natural plants and interferes with the natural balance of the ecosystem as other native species are squeezed out. (These native species can be food to local species and, therefore, the food chain is affected. Ultimately, this affects the biodiversity population.)
- Difficult to get rid of - a noxious weed.
- You can help the situation by participating in a not-for-profit group educating the public on the negative effects of the introduction of non-native species.
