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.