Thermodynamics and Ecosystems Quiz

Thermodynamic Laws in Ecosystems

• Law of Conservation of Mass: Mass cannot be created or destroyed, only rearranged within an ecosystem.
• First Law of Thermodynamics: Energy cannot be created or destroyed, but can change forms.
• Second Law of Thermodynamics: Entropy (disorder) increases over time, leading to systems tending towards equilibrium.

Trophic Levels and Energy Flow

• Trophic Levels: Steps in a food web representing energy transfer.
  • Autotrophs (primary producers): Produce their own energy through photosynthesis.
  • Heterotrophs: Obtain energy by consuming other organisms.
    • Primary consumers: Eat primary producers.
    • Secondary consumers: Eat primary consumers.
    • Tertiary consumers: Eat secondary consumers.
• Other Heterotrophs:
  • Omnivores: Eat across multiple trophic levels.
  • Detritivores: Consume dead organisms, returning nutrients to the ecosystem.
• Energy Flow: Energy flows one way through ecosystems, captured initially by primary producers.
  • Gross Primary Productivity (GPP): 0.8% of the sun's energy is captured by photosynthesis.
  • Photosynthesis Requirements: Sunlight, water, carbon dioxide.
  • Energy Allocation:
    • 45% of absorbed energy supports growth.
    • 55% lost through cellular respiration.
    • 34% goes to decomposers.
• Net Primary Productivity (NPP): GPP minus cellular respiration.
  • Global Patterns: NPP varies geographically, influenced by climate and factors like desert conditions.
• Trophic Efficiency: Only about 25% of NPP is captured by herbivores.
  • Herbivore Net Loss: Significantly high energy loss due to respiration (80.7%), only a small portion used for growth and reproduction.
• Trophic Pyramids: Depict the decrease in energy (or mass) at each trophic level.

Nutrient Cycling in Ecosystems

• Macronutrients: Components making up the majority of an organism (e.g., carbon, hydrogen, oxygen, etc.).
• Essential Minerals: Support biochemical processes and cell structure/function (e.g., phosphorus, calcium, potassium).
• Trace Minerals: Function as enzyme cofactors (e.g., copper, zinc).
• Nutrient Movement:
  • Primary producers: Absorb nutrients from the environment.
  • Consumers: Transfer nutrients by consuming other organisms.
  • Decomposers: Break down nutrients from waste and dead organisms, returning them to the environment.

Key Nutrient Cycles: Carbon, Nitrogen, Phosphorus

• Carbon (C): Essential for all living organisms, forming the backbone of organic molecules.
  • Reservoirs: Atmosphere, oceans, rocks, and living organisms.
  • Keeling Curve: Demonstrates the seasonal variation in atmospheric CO2 levels.
• Nitrogen (N): Important for lipids, proteins, and DNA.
  • Nitrogen Cycle:
    • Nitrogen Fixation: Atmospheric N2 converted to usable forms (ammonia, nitrates) by certain bacteria.
    • Nitrification: Conversion of ammonia to nitrates and nitrites by bacteria.
    • Ammonification: Decomposition of organic nitrogen back to ammonia.
    • Denitrification: Return of nitrogen to the atmosphere as N2.
  • Organic Nitrogen Distribution: Varies across terrestrial ecosystems, with more nitrogen found in aboveground plant biomass in warmer, more favorable climates.
• Phosphorus (P): Essential for ATP, DNA, and phospholipids.
  • Phosphorus Cycle: Relatively scarce, released from rocks and sediments through weathering and leaching.
  • Eutrophication: Excessive nutrient input (nitrogen, phosphorus) into aquatic ecosystems, leading to algal blooms and oxygen depletion.

Ecosystem Dynamics: Bottom-Up and Top-Down Effects

• Bottom-Up Effects: Primary producers influence higher trophic levels, directly affecting consumer populations.
• Top-Down Effects: Higher trophic levels control lower trophic levels through predation.

Biodiversity and Ecosystem Function

• Island Biogeography: Islands often exhibit high biodiversity due to unique conditions.
  • Endemic Species: Species found only in a specific, limited area.
  • Speciation: Formation of new species, often accelerated on islands.
• Biodiversity Patterns: Increased biodiversity is often associated with:
  • Greater NPP (bottom-up effects).
  • Greater predator diversity (top-down effects).
  • Larger habitat area.
  • Closer proximity to source populations.
  • Regular disturbances.
  • Greater spatial diversity.
  • More stable environments.
• Biodiversity and Ecosystem Stability: Biodiversity enhances ecosystem productivity and stability.
  • Greater Resistance: Reducing the impact of disturbances on NPP.
  • Greater Resilience: Faster recovery of NPP after disturbance.
• Ecosystem Services: Biodiversity provides essential services to humans.
  • Food production.
  • Raw materials.
  • Nutrient cycling.
  • Waste decomposition.
  • Soil formation.
  • Pollination.

Climate Change

• Greenhouse Gasses:
  • Carbon Dioxide (CO2): The primary greenhouse gas, contributing to global warming.
    • Sources: Fossil fuel combustion, deforestation, and industrial activities.
  • Methane (CH4): A potent greenhouse gas, trapping more heat than CO2.
    • Sources: Livestock, rice cultivation, fossil fuel extraction, and biomass burning.
  • Nitrous Oxide (N2O): Also contributes to global warming.
    • Sources: Fertilizer use, combustion, and industrial processes.
• Climate Change Effects:
  • Positive Feedback Loops: Effects of climate change that worsen the consequences (e.g., reduced ice cover, increased methane production, more frequent fires).
  • Negative Feedback Loops: Effects that mitigate climate change (e.g., cloud formation, forest regrowth).
• Marine Productivity: Warmer waters due to climate change are impacting primary production in marine ecosystems.
  • Stratification: Warmer surface waters lead to less mixing and nutrient availability for phytoplankton.
• Species Ranges and Distributions: Climate change is causing shifts in species ranges and distributions, leading to challenges for adaptation and survival.
• Phenology: Climate change is altering the timing of seasonal events, affecting species interactions.
• Coral Bleaching: Higher water temperatures, ocean acidification, and pollution are leading to widespread coral bleaching and mortality.
• Ocean Acidification: Increased CO2 in the atmosphere is absorbed by the ocean, decreasing the pH and impacting marine organisms that use calcium carbonate.

Human Impact on Ecosystems: Deforestation, Agriculture, Invasive Species

• Deforestation: Widespread tree loss, primarily driven by agriculture and logging, with significant consequences for biodiversity and climate regulation.
• Agricultural Practices: Extensive land use for agriculture can degrade soil quality and contribute to greenhouse gas emissions.
• Wetland Conversion: Wetlands are often converted for other land uses, resulting in habitat loss and ecological disruption.
• Fragmentation: Habitat fragmentation reduces the size and connectivity of habitats, leading to isolation and increased edge effects.
• Biomagnification: The accumulation of toxins in higher trophic levels, posing risks to top predators.
• Invasive Species: Non-native species introduced by humans that can outcompete native species, disrupt ecosystems, and cause ecological damage.

Conservation

• Conservation: An interdisciplinary field focused on protecting biodiversity and ecosystems.
  • Priorities: Prioritizing conservation efforts based on species rarity, decline rates, and ecological value.
  • Conservation Strategies: Implementation of strategies to reduce threats, manage habitats, and promote species recovery.

Test your understanding of the thermodynamic laws and energy flow in ecosystems. This quiz covers the principles of mass conservation, energy transformation, and trophic levels. Explore how different organisms interact and contribute to ecological balance.