environmental systems and ecosystem ecology. photosynthesis
TRANSCRIPT
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Environmental Systems and
Ecosystem Ecology
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Photosynthesis
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Photosynthesis
• Autotrophs (producers): produce their own food from the sun’s energy • Green plants, algae, and cyanobacteria
• Photosynthesis: the process of turning light energy from the sun into chemical energy• Carbon dioxide + water + sun’s energy
is converted into sugars and high-quality energy.
• Low-quality energy is turned into high-quality energy.
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Photosynthesis produces food
6CO2 + 6H20 + the sun’s energy C6H12O6 + 6O2
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Cellular respiration releases chemical energy
• Organisms can use chemical energy created by photosynthesis through cellular respiration.• Oxygen is used to convert glucose into water + carbon
dioxide + energy.• Only 2/3 of the original energy input per glucose molecule is
gained in respiration.• Occurs in autotrophs and organisms that feed on others
• Heterotrophs (consumers): organisms that gain energy by feeding on others• Animals, fungi, microbes
C6H12O6 + 6O2 6CO2 + 6H20 + energy
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Cellular respiration
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This unit will help you understand:
• Describe the nature of environmental systems
• Explain how human impact is affecting environmental systems.
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Central Case: The Gulf of Mexico’s “Dead Zone”
• Gulf of Mexico used to bring in 600 million kg/year shrimp, fish, and shellfish
• Gulf “dead zone”: a region of water so depleted of oxygen that marine organisms are killed or driven away
• In 2000, this zone encompassed 22,000 km2 (8,500 mi2) — an area larger than New Jersey.
• Hypoxia: low concentrations of dissolved oxygen water • Caused by fertilizer, runoff, sewage
• The U.S. government proposed that farmers reduce fertilizer use.
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The Earth’s systems
• System: a network of relationships among components that interact with and influence one another • Exchange of energy, matter, or information • Receives inputs of energy, matter, or information,
processes these inputs, and produces outputs
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System : Receives inputs of energy, matter, or information, processes these inputs, and produces outputs
How is the Gulf of Mexico a system?- what are the inputs?- what are the outputs?
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System : Receives inputs of energy, matter, or information, processes these inputs, and produces outputs
How is the Gulf of Mexico a system?- what are the inputs?
fresh water, sediments, nutrients- what are the outputs?
shrimp, fish
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Feedback loop
Feedback loopThe return of part of the output from a system as input to the same system- so as to affect succeeding outputs.
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Negative feedback loop
• Negative feedback loop: output resulting from a system moving in one direction acts as an input that moves the system in the other direction• Input and output neutralize one another• Stabilizes the system• Example: snowshoe hare and
lynx• Most systems in nature
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Positive feedback loop
• The white surface of glaciers reflects sun light (heat) back into space. Melting glaciers such as this one in Norway exposes more land and water to sun light.
• The dark land and water absorbs heat and causes more melting of the glaciers.
• This is a positive feedback which results in both warmer weather and higher sea level.
Melting glacier pictures
Positive feedback loop: instead of stabilizing a system, it drives it further toward an extreme Rare in nature But are common in natural systems
altered by humans
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Explain how this series of events is a positive feedback loop?
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Environmental systems interact
• Natural systems are divided into categories• Lithosphere: rock and sediment• Atmosphere: the air surrounding the planet• Hydrosphere: all water on earth• Biosphere: the planet’s living organisms
• Categorizing systems allows humans to understand earth’s complexity.• Most systems overlap
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The Gulf of Mexico & the Mississippi River-an example of how systems overlap
Very high levels of nutrients such as nitrogen and phosphorus from a variety of sources cause the abnormally low levels of oxygen in the Gulf of Mexico.
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Eutrophication
• Eutrophication: the process of nutrient over-enrichment, blooms of algae, increased production of organic matter, and ecosystem degradation
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Eutrophication in the Gulf of Mexico
• Nutrients (nitrogen and phosphorus) from various Midwestern sources enter the Mississippi River, which causes….
• Phytoplankton (microscopic algae and bacteria) to grow, then…
• Bacteria eat dead phytoplankton and wastes and deplete oxygen, causing…
• Fish and other aquatic organisms to suffocate
• Eutrophication: the process of nutrient overenrichment, blooms of algae, increased production of organic matter, and ecosystem degradation