Ecology and Human Impact
Abiotic Components of Ecosystems
Abiotic factors are non-living components crucial for ecosystems.
Examples: energy, nutrients, wind, temperature, water, fire.
Energy Input
Sunlight is the primary energy source for most ecosystems.
Photosynthesizers (producers) convert sunlight into sugars (plant tissue).
Equation:
Sunlight + CO2 + H2O \rightarrow C6H{12}O6 + O2Some ecosystems rely on chemical energy from the Earth's core (e.g., hydrothermal vents).
Hydrothermal Vents
Deep ocean ecosystems where sunlight doesn't penetrate.
Microbes utilize chemicals (sulfur, hydrogen) expelled from the Earth as energy sources.
Organisms have adapted to use energy in chemical form.
Ocean Zones and Sunlight Penetration
Euphotic Zone (0-200m):
Sunlight is abundant.
Majority of photosynthetic organisms (algae, bacteria).
Produces 50-60% of Earth's oxygen.
Dysphotic Zone (200-1000m):
Limited sunlight; insufficient for photosynthesis.
Predatory organisms (e.g., swordfish) present.
Aphotic Zone (below 1000m):
No sunlight penetration; dark environment.
Little is known about this zone; less explored than outer space.
Unique organisms (e.g., anglerfish, massive squid).
Nutrient Availability
Soil is crucial in terrestrial environments.
Plants need nitrogen and phosphorus for tissue production and energy.
Carnivorous Plants
Live in nitrogen and phosphorus-deficient soil.
Supplement diet with insects.
Example: Venus flytrap traps and digests insects using enzymes to obtain nutrients.
Eutrophication
Caused by excess nitrogen and phosphorus (e.g., fertilizer runoff) in marine ecosystems.
Leads to algal blooms that block sunlight.
Algae die and are decomposed by bacteria, which consume oxygen.
Oxygen depletion results in fish suffocation.
Too much of a good thing can disrupt the ecological balance and homeostasis.
Analogy to type II diabetes: excess glucose leads to disease.
Fire Ecology
Fire is a crucial component of many ecosystems.
Clears the way for new plant growth.
Some trees (e.g., lodgepole pine) require fire to open pine cones.
Fire melts the resin sealing the pine cone scales, allowing seed dispersal.
Impact of Fire Suppression
Historical fire suppression has led to fuel accumulation.
Densely packed, small trees have increased the severity of wildfires.
Logging practices that remove larger, flame-resistant trees exacerbate the issue.
Factors Contributing to Increased Wildfires
Climate change: drought and rising temperatures.
Increased human habitation with flammable materials.
Rethinking Forest Management
Shift towards viewing fire as a natural part of ecosystems.
Managing forests to reduce fuel accumulation.
Statistics on Wildfires.
From 1984-2000 average acres burned per year was 800,000 acres.
From 2001-2017 average acres burned per year was 1,600,000 acres.
Irreversible Damage
Extremely hot fires can irreversibly destroy ecosystems.
Some forests may not recover due to climate change and altered rainfall patterns.
Soil Composition and Health
Healthy soil filters and stores water, stores carbon, supports biological diversity, and is full of nutrients.
Composed of fungi, microbes, and tangled roots; a complex ecosystem on its own.
Hot fires can kill soil organisms, leaving behind barren dirt lacking nutrients.
Destruction of soil leads to primary succession.
Ecological Succession
Primary Succession:
Occurs after complete devastation (e.g., extremely hot fire).
Begins with rock; requires moss and lichen to break down rock and create soil.
Slow process leading to grasses, shrubs, and eventually trees.
Secondary Succession:
Occurs when some life survives a fire.
Ecosystem recovers more quickly as soil and some plant life remain.
Interspecies Interactions
Competition: can lead to mutually exclusive survival due to competition for the exact same resources, which is know as the competitive exclusion principle.
Mutualism, predation, or parasitism.
Competitive Exclusion Principle.
Competition over resources can lead to:
Speciation.
Adaptation of species to different environments.
Extinction.
Example: Lizard species adapt to different niches (sunny/dry, shady/moist) to avoid direct competition.
Mutualism
Symbiosis where both species benefit.
Examples:
Mycorrhizae: fungi provide nutrients and water to plant roots; plants provide sugars to fungi.
Coral and algae: algae provides photosynthesis; coral provides a home.
Angiosperms (flowering plants) and pollinators (e.g., bees).
Other Interspecies Interactions
Predation: eating other animals.
Herbivory: eating plants.
Pathogens: disease-causing microorganisms, can result in death.
Parasites: extract nutrients without killing the host.
Keystone Species
A species whose removal can cause ecosystem collapse.
Sea Otters:
Hunted for pelts, leading to sea urchin overpopulation.
Sea urchins decimated kelp forests, the photosynthetic basis of ecosystem.
Recovery occurred when otter populations rebounded.
Wolves in Yellowstone:
Elimination led to elk/deer overgrazing, damaging riparian (riverside) environments.
Reintroduction restored balance, allowing plant and river ecosystems to recover.
Invasive Species
Species introduced from a different environment.
Lack of natural checks and balances can cause ecological damage.
Examples:
Rabbits in Australia: multiplied rapidly, causing widespread environmental damage.
Zebra mussels: clog waterways, damage infrastructure, and outcompete native species.
Burmese pythons in Florida: decimate local wildlife, including endangered species (Florida panther).
Biological Control
Using one species to control another.
Examples:
Success: Chinese stingless wasp to control European corn borer.
Failure: Indian mongoose introduced to control rats in Hawaii and the Caribbean; harmed native species instead.
Consequences of Biodiversity Loss
Loss of potential medicines
Most drugs have natural origins (antibiotics).
Destroying ecosystems eliminates undiscovered medicinal compounds.
Examples of natural derived medicines: painkillers, anticancer, anti-infectives, cough suppressants, muscle relaxants, stimulants.
Vulnerability of crops
Monoculture leads to susceptibility to pests and disease (Irish potato famine, corn blight, banana fungus).
Ecosystem collapse can occur from extinction of keystone species.
Loss of ecosystem services
Water filtration, pollination, climate regulation provided by ecosystems are essential and often underestimated.
Factors Leading to Biodiversity Loss
Habitat Destruction:
Agriculture, mining, dams, clear-cutting, deforestation.
Overexploitation:
Overfishing, hunting (otters, bison, birds).
Pollution:
Industrial chemicals, plastic waste (microplastics from clothing), oil spills, acid rain.
Climate Change:
Shifting seasons, rising temperatures, melting ice sheets.
Invasive species.
Energy Flow
Inefficient energy transfer between trophic levels leads to loss of energy as heat.
Example: 2,000,000 calories of sunlight $\rightarrow$ 20,000 calories of plant material $\rightarrow$ 2,000 calories of beef (10% efficiency at each level).
Implication: 100 plants support 10 giraffes which support 1 lion.
Biomagnification
Higher-order predators require more energy and consume more prey, leading to accumulation of harmful chemicals in their tissues.
Example: PCBs in Puget Sound accumulate in orcas through the food chain.
Another Example: Methylmercury accumulate in tissues of tuna and halibut.
EPA suggests limiting tuna consumption due to mercury levels.
Chemical Cycling
Abiotic reservoirs (atmosphere, water, soil) store chemicals like carbon.
Geological processes shift chemicals through ecosystems.
Biotic components (living organisms) temporarily store chemicals.
Producers (plants) fix inorganic compounds into organic materials.
Consumers incorporate nutrients into their tissues.
Decomposers (fungi, bacteria) return nutrients to abiotic reservoirs.
Nitrogen Cycle
Nitrogen Needed for nucleic acids (DNA) and amino acids (proteins).
Excess Sources: smog, acid rain, eutrophication, drinking water contaminations from industrial products.
Nitrogen Fixation: Bacteria convert nitrogen gas to ammonia and ammonium for plant use.
Denitrification: Bacteria convert nitrogen compounds back to atmospheric nitrogen gas.
Carbon Cycle
Carbon is fundamental to biology (four bonding sites allow for complex molecules).
Photosynthesis fixes carbon dioxide into sugars (glucose).
Burning fossil fuels releases stored carbon into the atmosphere and contributing to the greenhouse effect.
Greenhouse Gas Effect
Accumulation of gases (carbon dioxide, nitric oxide, methane, water vapor) in the atmosphere.
Traps heat and warms the Earth.
The burning of fossil fuels disrupts balance by releasing carbon, overloading the system past its limits.
Global Impact and Potential Actions
If the whole world adopted the United States's standard of living, we would would require resources from five Earth's.
Ecological services such as healthy soil, forests to store carbon, fresh water, flood control, and climate regulation is required for a properly functioning Earth.
Utilizing the urban environment temperature regulation via strategic plant placement can have a powerful impact.
Vote with wallets. Purchase products from companies that are working towards a sustainable business practice.
Start discussions with people you impact locally by sharing information and documentary viewership.
Cut back on red meat and fish but focus more on plant based foods.
Turn off lights or leave items off when they are not in use to save on electricity.
Don't let the media sway doom and gloom. Try and take some easy steps towards making small changes in individual life.
Push for community involvement in, composting, and greater access to better, and easier recycling facilities.
Stay hopeful and believe in exciting technologies that can possibly turn this thing around in the next couple of decades.