Week 5 Freshwater aquatic systems
Human Impacts on Freshwater Aquatic Systems & Oceans
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Course title: Human impacts on freshwater aquatic systems & oceans
Instructor: Professor R. McLeman
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Weekly Activities
Reading chapters 9, 10
Lecture focus: Human impacts on freshwater aquatic systems
Quiz scheduled for later in the lecture.
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In-Class Quiz Details
Format: Written quiz during the second half of the lecture.
Content: 10 multiple-choice questions based on food systems lectures and chapter 8.
Quiz method: 1 question displayed every 90 seconds on lecture screen; responses indicated on a bubble sheet.
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Quiz Important Notes
Students permitted a 1-page (double-sided) memory aid (handwritten).
Memory aid must include name and student number.
Memory aid must be submitted with the bubble sheet.
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Quiz Conduct Guidelines
No speaking allowed during the quiz; violators will be removed and receive a zero.
Academic misconduct for looking at others' papers, under surveillance by a lecture hall camera.
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Current Events
Recall the water quality problems at the Paris Olympics.
Many urban rivers in Canada face serious water quality issues.
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Chapter Exclusions for Midterm Test
Excluded content: “Our Environment” boxes numbered: 10-1, 10-2, 10-4, 10-6, 10-9, 10-10, 10-11, 10-12, Envirofocus box 10, “Making a difference” feature on Daniel Pauly.
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Water Uses
Agriculture
Transportation
Industry
Drinking water
Sanitation/Waste management
Importance of leaving water for other organisms to maintain biodiversity.
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Types of Aquatic Environments
Saltwater (marine)
Freshwater
Together comprise more than 70% of Earth's surface.
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Global Water Availability
Oceans: 97%
Frozen Water: 70%
Freshwater: 3% (RVers <1%)
Groundwater: 29%
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Freshwater Aquatic Systems
Types: Standing (lakes, ponds, marshes) and flowing.
Can be either permanently wet or intermittent/seasonal (e.g., Grand River, Ontario).
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Key Properties of Fresh Water
Density: At 4°C water is densest, which allows ice to float and supports life under the ice.
Oxygen Levels: Cold water holds more dissolved oxygen than warm water; warming leads to decreased oxygen, harming aquatic life.
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Dissolved Oxygen (DO)
Air holds >200,000 ppm of oxygen; water ~10 ppm at 15°C.
DO levels are critical for aquatic life, where drops of more than half can lead to species die-off.
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Human Impacts on Freshwater Systems
Damming or diverting watercourses.
Draining wetlands and ephemeral ponds.
Alterations to shore environments.
Chemical and nutrient pollution from industrial and agricultural sources.
Waste water management issues from households.
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Dams and Their Impacts
Alters water levels and flows above and below the dam.
Changes in water chemistry, temperature, turbidity.
Block migratory species from movement.
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Wetland Drainage
Wetlands collect drainage, slowing water movement into streams.
Ontario: Majority have been drained for agricultural and urban development.
Increases flood risk and reduces habitats for aquatic species and migratory birds.
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Nutrient Pollution Effects
Nutrients (nitrogen, phosphorus) from fertilizers wash into waterways, promoting algae growth.
Results in decreased clarity, increased temperature, and lowered oxygen levels impacting aquatic biodiversity.
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Bioaccumulation and Biomagnification
Bioaccumulation: Toxins accumulate in organism tissues.
Biomagnification: Increased toxin concentration in apex predators.
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Global Access to Safe Drinking Water
1.7 billion people consume potentially contaminated water.
500,000 die annually from water-related illnesses.
33 First Nation communities in Canada under boil-water advisories.
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Strategies for Water Pollution Management
Reduce pollution at the source.
Collect and treat polluted water.
Preventing non-point source pollution is a significant challenge.