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"Gulf Dead Zone"
- = a region of water so depleted of oxygen
- that kills or drives away marine organisms
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Hypoxia
low concentrations of dissolved oxygen water
Caused by fertilizer, runoff, sewage
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System
a network of relationships among parts elements or 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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Feedback loop
a system’s output serves as input to that same system
A circular process
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Negative Feedback Loop
output that results from a system moving in one direction acts as input that moves the system in the other direction.
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Positive feedback loop
•instead of stabilizing a system, it drives it further toward one extreme or another
•Examples: exponential growth in human population, spread of cancer, erosion
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Dynamic Equilibreum
system processes move in opposing directions at equivalent rates, balancing their effects
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Homeostasis
a system maintains constant or stable internal conditions
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Emergent Properties
- system characteristics not evident in the components alone
- “The whole is more than the sum of the parts”
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Lithosphere
rock and sediment
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Hydrosphere
liquid, solid, or water
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Biosphere
all the planet’s living organisms and the abiotic portions of the environment
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Gross Primary Production
assimilation of energy by autotrophs
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Net Primary Production
energy remaining after respiration, and is used to generate biomass
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Secondary Production
biomass generated by heterotrophs
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Productivity
rate at which ecosystems generate biomass
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High Net Productivity
ecosystems whose plants rapidly convert solar energy to biomass
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Nutrients
elements and compounds required for survival that are consume by organisms
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Macronutrients
nutrients required in relative large amounts
-Nitrogen, carbon, phosphorus
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Micronutrients
nutrients needed in smaller amounts
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Ecotones
transitional zones between two ecosystems in which elements of different ecosystems mix
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Landscape Ecology
the study of landscape structure and how it affects the abundance, distribution, and interaction of organisms
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Metapopulation
- a network of subpopulations
- Most members stay within patches but may move among patches or mate with those of other patches
- Individuals in small patches risk extinction
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Habitat Fragmentation
breaking habitat into small, isolated patches due to human impact
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Pools
where nutrients reside for varying amounts of time
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Flux
movement of nutrients among pools, which change over time and are influenced by human activities
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Sources
pools that release more nutrients than they accept
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Sinks
accept more nutrients than they release
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Carbon Cycle
describes the routes that carbon atoms take through the environment
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Phospherous Cycle
describes the routes that phosphorus atoms take through the environment
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Nitrogen Cycle
describes the routes that nitrogen atoms take through the environment
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Nitrogen Fixation
Nitrogen gas is combined (fixed) with hydrogen by nitrogen-fixing bacteria to become ammonium
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Nitrification
bacteria that convert ammonium ions first into nitrite ions then into nitrate ions
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