(9) AP Environmental Science 8.2 (pt. 1) - Human Impacts on Ecosystems

Human Disturbances in Marine Ecosystems

Introduction

  • Focus on human activities impacting aquatic ecosystems.

  • Objective: Describe the effects of human activities on marine ecosystems.

  • Skill Development: Apply mathematical relationships and solve problems via unit conversion or dimensional analysis.

Range of Tolerance

  • Definition: All organisms have a range of tolerance concerning their habitat conditions.

    • Conditions include:

      • pH levels

      • Temperature

      • Salinity (water salinity)

      • Sunlight availability

      • Nutrient levels

  • Tolerance extends to pollutants or toxicants introduced by humans.

Effects of Pollutants on Organisms

  • Specific effects of pollutants to consider in FRQs:

    1. Limited Growth: Pollutants may hinder access to food or growth processes.

    2. Limited Reproductive Function: Pollutants may affect sexual organs or hormonal systems, impairing reproduction.

    3. Difficulty Breathing: Low oxygen levels can lead to suffocation.

    4. Hormonal Disruption: Endocrine disruptors can severely impact growth and reproductive health.

    5. Potential Mortality: Organisms may die if pollutant concentration exceeds lethal doses.

  • General principle: "Solution to pollution is dilution."

Acid Rain and Its Effects on Aquatic Species

  • Acid rain impacts species based on their pH tolerance.

    • General trends in tolerance among species:

      • Insensitive Insects: Can survive at pH 4.

      • Fish (Eel and Brook Trout): Tolerate lower pH compared to crustaceans.

  • Mortality causes due to low pH:

    • Aluminum Toxicity: Increased solubility in acidic conditions harmful to organisms.

    • Disrupted Blood Regulation: H+ ions interfere with osmolarity and tonicity, leading to death.

Indicator Species

  • Definition: Species sensitive to environmental changes used to gauge health of ecosystems.

    • Examples:

      • Indicator of Low pH: White moss or filamentous algae thrive in lower pH.

      • Indicators of Higher pH: Crustaceans and mollusks thrive above pH 6.

Coral Reef Ecosystems

  • Coral reefs rely on mutualistic relationships (Coral and zooxanthellae algae).

  • Temperature shifts threaten these ecosystems:

    • Zooxanthellae have narrow temperature tolerances; warming oceans cause coral bleaching.

    • Bleaching leads to weakened coral and increased disease susceptibility.

Human Impacts on Coral Reef Ecosystems

  • Greenhouse Gas Emissions: Drives ocean warming, resulting in coral bleaching.

  • Overfishing and Bottom Trawling:

    • Removes beneficial fish; damages coral physically by dragging nets.

    • Causes sediment increase, impairing light penetration.

Urban and Agricultural Runoff

  • Types of Pollutants Affecting Coral Reefs:

    1. Sediment Pollution: Increases turbidity, blocking sunlight essential for photosynthesis, damaging producers.

    2. Toxicants: Chemicals like sunscreen, pesticides, and oil can directly harm marine life.

    3. Nutrients: Ammonia, nitrates, and phosphates promote harmful algal blooms and negatively impact reef health.