Energy and Matter Transfer and Conservation Biology Study Guide to Conservation Biology

Foundations of Ecosystem Ecology and Energy Flow

• Ecosystem Ecology Overview

  • Core Definition: Ecosystem ecology is the scientific study of the interactions between living organisms (biotic factors) and their nonliving environment (abiotic factors).

  • Ecosystem Hierarchy:

    • Individual: A single organism (e.g., one fox).

    • Population: All members of the same species living in a specific area (e.g., all foxes in a forest).

    • Community: All populations of various species living together in a specific area (e.g., foxes, rabbits, and plants).

    • Ecosystem: The total community of living organisms combined with the physical environment, including water, soil, and atmosphere.

• Abiotic vs. Biotic Factors

  • Abiotic Factors: These are the nonliving components of an environment that influence ecosystems.

    • Examples: Temperature (e.g., Phoenix heat), the presence of water/rivers, sunlight levels, environmental toxins, and soil nutrients.

  • Biotic Factors: These are the living organisms or the interactions between them.

    • Examples: Predators, parasites, competition between species, plants, and animals.

    • Interaction Example: A hawk hunting a mouse is considered a biotic interaction.

• Energy Transfer and the 10% Rule

  • Trophic Levels: Represent feeding positions in a food chain.

    • 1st Level: Autotrophs (plants).

    • 2nd Level: Herbivores (primary consumers).

    • 3rd Level: Primary predators (secondary consumers).

    • 4th Level: Secondary predators (tertiary consumers).

  • Energy Dynamics: Energy flows in a one-way direction and does NOT cycle. It is lost at every successive trophic level.

  • The 10% Rule: On average, only about $10\%$ of the energy from one trophic level is transferred to the next level.

    • Numerical Example: If plants (1st level) contain $10,000$ units of energy:

      • Herbivores receive $1,000$ units.

      • Primary predators receive $100$ units.

      • Secondary predators receive $10$ units.

  • Reasons for Energy Loss:

    • Heat release through metabolism (entropy).

    • Energy used for internal life processes (growth, movement).

    • Not all organisms are consumed by the level above.

    • Materials that cannot be digested or are excreted as waste/feces.

  • Thermodynamics in Ecology:

    • First Law: Energy cannot be created or destroyed; it only changes form (e.g., food energy transforming into movement).

    • Second Law: Every energy transfer increases entropy, with some energy lost as heat (e.g., body heat generated during exercise).

  • Energy Pyramid Requirements: To support a biomass of $30\text{ kg}$ of foxes (top predators), an ecosystem would require approximately $300\text{ kg}$ of primary predators, $3,000\text{ kg}$ of herbivores, and $30,000\text{ kg}$ of plants.

• Nutrient Cycling vs. Energy Flow

  • Nutrients Cycle: Elements like Carbon ($C$) and Nitrogen ($N$) move through the ecosystem repeatedly via consumption, waste release, death, and decomposition.

  • Example Cycle: Plant → rabbit → fox → decomposer → soil → plant.

• Case Study: Bald Eagles and DDT (Bioaccumulation)

  • Context: Historically, bald eagles resided on the Channel Islands near Southern California.

  • The Problem: The pesticide DDT was dumped into the ocean, entering the food chain.

  • Process of Bioaccumulation:

    1. DDT enters the ocean water.

    2. Small organisms absorb the toxin.

    3. Fish consume these small organisms.

    4. Larger predators consume the fish.

    5. Bald eagles consume contaminated prey.

  • Outcome: Toxins became concentrated at the highest trophic level, causing eagles to produce thin eggshells that broke easily, leading to population failure.

Biological Components and Biogeochemical Cycles

• The Importance of Carbon

  • Structure: Carbon can form $4$ chemical bonds, providing extreme flexibility in molecular structures; it is known as the "backbone of life."

  • Molecules: Found in carbohydrates, proteins, fats (lipids), and DNA.

  • Body Composition: Carbon, Oxygen, Hydrogen, and Nitrogen make up approximately $94\%$ of human body mass.

• Macromolecules and Energy Content

  • Carbohydrates: Provide quick energy.

  • Lipids: Provide long-term energy storage; they contain many carbon bonds and thus high energy density.

  • Proteins: Essential for structure and enzyme function.

  • Nucleic Acids: Constitute DNA and RNA.

  • Bonding: Energy is stored in the chemical bonds of these food molecules; bonds are broken during digestion to release energy for cellular use.

• The Carbon Cycle

  • Definition: The movement of carbon through living (biotic) and nonliving (abiotic) systems.

  • Small-Scale Cycle:

    • Photosynthesis: Autotrophs (plants/algae) take in $CO_2$ and $H_2O$ to produce glucose and Oxygen ($O_2$).

    • Cellular Respiration: Organisms use glucose and $O_2$ to release energy, yielding $CO_2$ and $H_2O$ as byproducts.

  • Large-Scale Carbon Reservoirs (Storage Pools):

    1. The Atmosphere: Stored as $CO_2$.

    2. Biosphere: Living plants.

    3. Pedosphere: Soil.

    4. Oceans: The ocean stores about $50$ times more carbon than the atmosphere. Sources include decaying organisms, deep ocean storage, and sediments.

    5. Fossil Carbon Pool: Carbon trapped in coal, oil, rocks, and sediments for millions of years.

  • Keeling's Measurements: Charles David Keeling observed a predictable yearly pattern in atmospheric $CO_2$: levels rise during the spring (when photosynthesis removes less in winter/early spring) and fall during the autumn (after maximum summer plant growth). The overall long-term trend has been a steady increase since the $1950s$.

• The Nitrogen Cycle

  • Necessity: Nitrogen makes up $3\%$ of the human body and $78\%$ of the atmosphere. It is a critical component of proteins (amino groups) and nucleic acids.

  • Limitation: Plants cannot directly use atmospheric Nitrogen ($N_2$).

  • Nitrogen Fixation Process:

    1. Atmospheric $N_2$ is converted by special nitrogen-fixing bacteria into ammonia/ammonium.

    2. Nitrifying bacteria convert these into nitrates.

    3. Plants absorb nitrates, which then travel through the food chain (herbivores → carnivores).

    4. Decomposers return nitrogen to the soil, and some bacteria return it to the atmosphere.

  • Limiting Nutrients: Nitrogen is often a limiting nutrient, meaning its scarcity restricts ecosystem productivity and plant growth.

• The Phosphorus Cycle

  • Function: Necessary for DNA, RNA, and ATP (the cell's energy molecule).

  • Unique Feature: Unlike carbon and nitrogen, phosphorus has almost no atmospheric phase.

  • Process: Most phosphorus is trapped in rocks and sediments. It enters the cycle through weathering, allowing plants to absorb it from the soil. This cycle is much slower than the others.

• The Water Cycle (Hydrologic Cycle)

  • Biological importance: Humans are over half water; cells are over $70\%$ water.

  • Processes:

    • Evaporation: Liquid to vapor.

    • Condensation: Vapor to clouds.

    • Precipitation: Rain/snow.

    • Transpiration: Plants releasing vapor.

    • Sublimation: Ice directly to gas.

    • Runoff and Infiltration: Water moving across or into land/soil.

    • Groundwater Storage: Water collected in underground aquifers.

Human Impact on Ecosystems and Climate

• Enhanced Greenhouse Effect

  • Mechanism: Sunlight warms the Earth; heat attempting to escape into space is trapped by greenhouse gases (such as $CO_2$) and redirected back toward the surface.

  • Necessity vs. Excess: Naturally, greenhouse gases keep Earth warm enough for life. Excess gases from human activity (burning coal, oil, and natural gas) trap too much heat, leading to rising global temperatures.

  • Atmospheric Facts: Human activities currently release approximately $100$ times more $CO_2$ than volcanic activity.

• Weather vs. Climate

  • Weather: Short-term, daily conditions (e.g., "It is $105^\circ F$ today").

  • Climate: Long-term patterns observed over decades (e.g., "The Southwest is becoming drier").

• Economic and Biological Consequences of Climate Change

  • Regional Variations: Some areas like Scandinavia or New England may see longer growing seasons, while the Desert Southwest (Arizona) faces extreme heat, drought, and water scarcity.

  • Financial Costs: Costs arise from property damage (floods/wildfires), disease spread, lower crop yields, and increased energy demand for cooling.

  • Ocean Acidification: As the ocean absorbs more atmospheric $CO_2$, the water becomes more acidic. This harms corals and organisms that form shells.

• Eutrophication and Dead Zones

  • Definition: Eutrophication is the condition where excess nutrients (excess nitrogen and phosphorus from fertilizers/waste) enter water systems.

  • Step-by-Step Effect:

    1. Excess nutrients enter the water.

    2. Algae population explodes (algal bloom).

    3. Algae block sunlight, killing deep aquatic plants.

    4. Algae die and are decomposed.

    5. Decomposers use up all available Oxygen ($O_2$).

    6. A dead zone is created where most organisms cannot survive.

  • Statistics: The Gulf of Mexico dead zone covers $6,000$ to $7,000$ square miles. Worldwide, there are over $762$ recognized eutrophication sites.

• Water Supply Depletion

  • Groundwater: Humans are pumping water from aquifers faster than natural replenishment. This causes lower water tables and long-term freshwater shortages.

  • Dams: While useful for hydroelectric power and storage, they alter natural flows and ecosystems. Lake Powell serves as an example where visible "bathtub rings" indicate serious water level declines.

Case Study: Sustainable Coffee Farming in Costa Rica

• Observations from Monteverde

  • Climate Change Impacts: The region has seen a temperature increase of approximately $2^\circ C$ over the last $40$ years.

  • The Disease Challenge: Higher temperatures and intense, erratic rainfall promote the spread of Coffee Rust (Roja), a fungus that damages leaves and fruits, reducing yields even on plants that look healthy.

  • Shifting Rainfall: Historically steady rain has been replaced by massive storms followed by longer dry spells. This leads to soil erosion, landslides, and nutrient leaching.

  • Biological Shifts: Species previously seen at lower elevations (snakes, plants) are moving uphill as those areas warm. Coffee flowering has shifted from a predictable season to occurring over many months (March through June).

• Sustainability and Adaptation Strategies

  • Diversification: The farm maintains revenue through tourism and education as well as coffee.

  • Genetic Variety: Growing $13$ different coffee varieties ensures that if one is hit by disease, others might survive.

  • Conservation: Keeping $50\%$ of the land as forest provides natural pest control by supporting birds, bats, and spiders, and acts as a buffer against disease spread.

  • Soil Health: Utilizing composting and organic fertilizers to improve nutrient retention.

Conservation Biology and Biodiversity

• The Study of Conservation Biology

  • Goal: To protect the variety of life on Earth (biodiversity) and the ecosystems they inhabit.

  • Endemic Species: Species found only in one specific location.

  • Biodiversity Hotspots: Areas that must contain at least $1,500$ endemic plant species and have lost much of their original habitat. They cover only $2\%$ of Earth's land but contain over $50\%$ of plant species and $43\%$ of vertebrate species.

• Four Levels of Biodiversity

  1. Functional: The variety of ecological roles organisms perform (e.g., water/air purification by mangroves).

  2. Genetic: Variation within a species. High genetic diversity prevents catastrophe from disease.

     • Example: The Irish Potato Famine was severe because the Irish Lumper potato lacked genetic diversity, allowing the disease Phytophthora infestans to destroy the entire crop.

  3. Species: The variety of species within an area, including their relative abundance.

     • Microbiome: The community of microorganisms in the human body is a form of species diversity essential for health.

  4. Ecosystem: The variety of habitats in a region (e.g., Arizona's desert, pine forests, and riparian zones).

• Ecosystem Services

  • Supporting: Nutrient cycling, soil formation, photosynthesis.

  • Provisioning: Food, freshwater, medicine, building materials.

  • Regulating: Water purification, pollination, carbon storage, flood control.

    • Water Quality Example: Portland, Oregon protected the Bull Run Watershed to avoid building a treatment plant; NYC protects reservoirs $125$ miles away to serve $9$ million people.

  • Cultural: Tourism, recreation, mental health.

• The Importance of Pollination

  • Dependence: Crops like almonds, blueberries, and cocoa are highly dependent on pollinators (bees, birds, butterflies).

  • Colony Collapse Disorder: Threatens global food security. In Sichuan, China, the loss of bees forced humans to hand-pollinate pear trees with brushes.

• Five Major Threats to Biodiversity

  1. Habitat Loss/Fragmentation: Land change for agriculture or cities is the number one threat to wild species.

  2. Pollution: Includes plastic waste and nutrient pollution. Amphibians are particularly sensitive as they absorb water through their skin.

  3. Overexploitation: Harvesting faster than reproduction can occur.

     • Bushmeat: Wild animals (cane rats, lemurs) hunted for food.

     • Shark Fin Trade: Sharks killed only for fins, causing population crashes.

     • Folk Medicine: Poaching of pangolins and rhinos for treatments with no scientific evidence.

  4. Global Climate Change: Shifts ecological niches and habitats.

  5. Invasive Species: Harmful non-native species like cane toads in Australia or zebra mussels in North America. They may be introduced intentionally (pest control) or unintentionally (shipping).

Wildlife Corridors and Habitat Connectivity

• Fragmentation Consequences

  • Habitat fragmentation breaks large habitats into smaller pieces, leading to genetic isolation, inbreeding, and increased roadkill.

• Corridor Functions

  • Large Corridors: Connect major parks or forests.

  • Urban Corridors: Green strips or tree-lined paths that help birds and insects move.

  • Wildlife Crossings:

    • Banff National Park (Canada): Crossings reduced collisions by $80\%$.

    • Montana: Fencing and crossings reduced deer-vehicle collisions by over $90\%$.

    • Liberty Canyon (California): Constructing the world's largest crossing to reconnect mountain lion populations.

  • Landscape Features: Native grasslands, fence-line vegetation, rivers, and "stepping stones" (small habitat patches) facilitate movement.

Environmental Ethics in Conservation

• Core Ethical Perspectives

  • Contractarianism: Morality is based on human agreements. Nature is protected only if it benefits humans.

  • Utilitarianism: Goal is the greatest good for the greatest number. Evaluates consequences (e.g., culling starving deer to prevent widespread agony).

  • Animal Rights: Focuses on the moral status of individual animals. Argues animals should not be manipulated or controlled, often opposing captive breeding.

  • Respect for Nature: Values the whole ecosystem and species diversity. Supports interventions like captive breeding if they save a species from extinction.

  • Contextual (Relational) Ethics: Duties depend on our relationship with the animal (e.g., higher duty to pets than wild animals).

  • Ethical Pluralism: Using multiple ethical frameworks together to solve conservation problems.

• Case Study: The California Condor

  • The Crisis: By the $1980s$, populations crashed due to shooting, poisoning, and habitat loss.

  • Ethical Conflict: Animal Rights advocates preferred leaving the birds in the wild even if they went extinct; Respect for Nature advocates supported capturing them to save the species.

  • The Intervention: In $1987$, the last wild condor was captured ($27$ birds total remained). A captive breeding program was initiated.

  • Success: The population rose to over $500$ birds today, though they still require human assistance and management.**