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Student Worksheet: Human Impacts on River Ecosystems
The Athabasca River in Jasper National Park, Alberta.
Credit: iStockphoto.com/The Power of Forever Photography
Introduction
Rivers are freshwater ecosystems. This means that they contain water with less than 0.5 parts per thousand of
dissolved salt, and provide habitat for many plants and animals. These plants and animals make up river
biodiversity.
The term biodiversity comes from the words biological and diversity. It means "variety of life". Biodiversity
refers to all the living things, including plants, animals and micro-organisms, and their unique characteristics, in
a particular place. At the largest scale, it includes all life on the planet.
Species diversity refers to the variety of species in a given area, and is the most common type of biodiversity
talked about. Other levels of biodiversity include ecosystem diversity, which refers to habitats, living
communities and ecological processes, and genetic diversity, which refers to the genetic characteristics within a
species.
Why is river biodiversity important? Biodiversity provides us with inspiration, beauty and wonder, and it
represents life that has evolved so that it is in balance with its environment. Ecosystems depend on the
combined contributions and interactions of the individual organisms within them, and the loss of any species
can prevent that ecosystem from operating optimally. Furthermore, an ecosystem with a high level of
biodiversity is more resistant to environmental changes.
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River biodiversity also provides us with food, materials and medicines, as well as recreational and economic
opportunities. It also helps clean the air and filter water. A biodiverse river contributes to good water quality,
which is important to farms, businesses and homes.
What can affect biodiversity in rivers? There are many factors. Species need an acceptable range of
temperature, pH, dissolved oxygen and mineral levels. Latitude—the distance north or south of the equator—
affects temperatures, although biodiversity is affected by latitude to a much higher degree in terrestrial
ecosystems than it is in freshwater ecosystems. This is because of the lesser amount of nutrients available to
terrestrial species, as well as the extreme temperature changes that make higher latitudes on land a much more
difficult place than water for living things to exist.
Biodiversity in rivers can also be affected by human activities that change the levels of chemical or biological
components in the water. This is often the result of leaching from industrial, agricultural or urban sources, and
alteration to the shoreline and river flow.
Activity 1: Types of Water Pollution
Researchers taking water samples from a river.
Credit: Diane Martz
Visit the website The Nature of the Rideau River at http://nature.ca/rideau/index-e.html and look for the
pages about water quality. Then answer the questions below.
1.1 Name four components (chemical and biological) found in natural bodies of water.
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1.2 What happens when there is too much nitrogen and phosphorus in a river?
Mallards (Anas platyrhynchos).
Credit: iStockphoto.com/Arpad Benedek
1.3 What are two sources of increased nitrogen and phosphorus in a river that result from human activities?
1.4 How do pesticides affect aquatic plants and animals?
1.5 List four possible sources of harmful bacteria in a river.
1.6 What could cause the level of dissolved oxygen in water to become dangerously low for fish and other
organisms?
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1.7 Where might excessive amounts of metals found in a river come from?
Activity 2: Bioaccumulation
Great Blue Heron (Ardea herodias).
Credit: pix2go/Shutterstock.com
Visit the web site Diving In at http://nature.ca/explore/di-ef/wcef_e.cfm and look for the pages about
bioaccumulation. Then answer the questions below.
2.1 What is bioaccumulation?
2.2 Explain how even relatively small amounts of toxins in rivers can affect animals that are higher up in the
food web.
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Activity 3: Impacts on Rivers from Human Activities
3.1 Research a negative impact on river biodiversity resulting from a human activity, and complete a written
report based on a minimum of three sources of information. The report must be two to three pages long and
include:
a) an overview of the problem that you are researching
b) specific examples and data
c) a summary of the data
d) recommendations of what must be done to counteract the problem
e) a list of references.
3.3 Prepare to present your report to the rest of your class. You can use slides, photos, video, audio, posters or
other teacher-approved media.
Resources
• Video: The Invaders (3 min. 1 sec.)
Canadian Museum of Nature scientist André Martel talks about an example of the impact on rivers by an
invasive species.
http://nature.ca/education/cls/video/vinv_e.cfm
• Video: The Importance of Documenting Biodiversity (2 min. 52 sec.)
Canadian Museum of Nature scientist Noel Alfonso talks about the importance of documenting river
biodiversity in order to better understand environmental change.
http://nature.ca/education/cls/video/vimportance_e.cfm
• The Nature of the Rideau River
http://nature.ca/rideau/index-e.html
• Frenchman River Biodiversity Project
http://nature.ca/en/research-collections/our-research/research-projects/frenchman-river-biodiversity-project
• Mackenzie River aquatic ecosystem report
http://www.swa.ca/Publications/Documents/3%20Whole%20Basin.pdf
• Global Environment Outlook Report, United Nations Environment Programme
http://www.unep.org/geo/geo4/media
• Why Can't I Eat the Fish I Catch in Some Rivers and Lakes?
http://nature.ca/explore/di-ef/wcef_e.cfm
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• Pollution of Water Tied to Oil in Ecuador
http://query.nytimes.com/gst/fullpage.html?res=9907E0D9153CF931A15750C0A962958260&partner=rssnyt&e
mc=rss
• Fish Farming
http://www.mnr.gov.on.ca/en/Business/LetsFish/2ColumnSubPage/STEL02_165904.html
• Urbanization
http://www.canadiangeographic.ca/cea/archives/archives_individual.asp?id=31
• Threats to aquatic ecosystem health
http://www.ec.gc.ca/inre-nwri/default.asp?lang=En&n=235D11EB-1&offset=1&toc=show
• Threats to water and water quality
http://www.statcan.gc.ca/pub/16-201-x/16-201-x2003000-eng.pdf
http://nature.ca/education/cls/lp/lpha_e.cfm