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Ecotoxicology Lab Review

Lab Objectives

  • Explore impacts of various pollutants on Daphnia as an indicator species.
  • Demonstrate how to determine the LD₅₀ for a specific pollutant affecting Daphnia.
  • Describe effects of acid and organic pollution on producers and consumers in aquatic ecosystems.

Activities

  • Activity #1: Ecotoxicology Bioassay
  • Activity #2: Aquatic Microecosystems

Ecosystem Basics

  • Ecosystem Definition: Interaction of organisms (populations) and abiotic factors in a specific environment at a given time.
  • Components:
    • Abiotic: Nonliving components (e.g., sunlight, temperature, precipitation, soil/water chemistry)
    • Biotic: Living things affecting organisms (e.g., animals, plants)

Pollution

  • Definition: Unnatural by-products of human activities accumulating in the environment at harmful levels for living organisms.
  • Sources: Vary widely, leading to different types of pollution such as:
    • Acid
    • Organic
    • Thermal
    • Pharmaceuticals

Acid Pollution

  • Definition: Formed when sulfur and nitrogen oxides react with air to create sulfuric and nitric acids, returning to the environment as acid rain.
  • Impact: Extremely harmful to all organisms.
  • Acid Rain: Rainwater with a pH < 5.6 is considered acidic; a consequence of air pollution.

Organic Pollution

  • Definition: Persistent compounds resistant to environmental degradation (e.g., pesticides, fertilizers).
  • Effects:
    • Long-lasting presence and accumulation in tissues.
    • Significant impacts on human health and ecosystems.
    • Can lead to algal blooms due to nutrient overloading.

Eutrophication

  • Process: High concentrations of nutrients (phosphates and nitrates) in water bodies resulting in excessive algae growth.
  • Consequences:
    • Decomposition of algae leads to oxygen depletion.
    • Loss of habitat and food sources.

Bioaccumulation and Biomagnification

  • Bioaccumulation: Accumulation of chemical substances at rates greater than loss rates, from the environment or diet.
  • Biomagnification: Increase in concentration of toxins as you move up the food chain, higher trophic levels see greater concentrations.

Thermal Pollution

  • Definition: Degradation of water quality due to changes in temperature, often caused by industrial processes.
  • Example: Power plants using water as coolant.

Ecotoxicology

  • Definition: Study of effects of toxic chemicals on biological organisms and ecosystems. Multi-step process includes:
    • Entry, distribution, and fate of pollutants.
    • Effects on biota and ecosystems.
  • Levels of Assessment:
    • Organism level includes mortality, physiological changes, behavioral effects.
    • Population structure changes such as biomass or species diversity.
    • Ecosystem structural changes affecting community dynamics.

Bioassays

  • Definition: Analytical method to determine the potency of a substance based on its effects on living organisms.
  • Indicator Organism: Organisms used to monitor environmental quality (e.g., Daphnia).
  • Lethal Dose (LD₅₀): Dose required to kill 50% of a test population after a specified time, used to assess acute toxicity.

Activities Overview

Activity #1: Ecotoxicology Bioassay

  • Focus: Toxicity effects on Daphnia magna with pollutants.
  • Procedure: Set up vials with various pollutant concentrations, incubate Daphnia, and calculate LD₅₀ based on survival rates.

Activity #2: Aquatic Microecosystems

  • Setup: Simulate regular, acid, and organic nutrient ecosystems.
  • Purpose: Observe autotrophs and heterotrophs, assessing ecosystem health and interactions.

Post Lab Actions

  • Completed post-lab quiz within 48 hours.
  • Prepare for upcoming Lab Practical #2 covering previous lab material.
  • Review materials and ensure understanding of concepts related to ecotoxicology.