271 terms
AP Environmental Science Review
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superposition
The principle that any given rock layer is probably older than those above it and younger than those below it
continental crust
Extends from surface of Earth down to 20-30 miles. Continental crust (granite) is less dense then ocean crust (basalt).
oceanic crust
Extends down from the surface of the Earth to 7 miles. Crust is layered and very uniform. Composed of basalt.
mantle
Contains most of Earth's mass. Composed of iron, magnesium, aluminum, and silicon-oxygen compounds
core
Composed mostly of iron and is so hot that the outer core is molten. The inner core is under such extreme pressure that it remains solid.
Continental Drift Theory
1915- Alfred Wegener proposed that all present-day continents originally formed one landmass (Pangaea).
lithosphere
Lithosphere (crust and upper mantle) is divided into massive sections known as plates, which float and move on the asthenosphere.
transform boundaries
Occur where plates slide PAST each other.
San Andreas Fault
Found near the western coast of North America. Where the Pacific and North American plates move relative to each other.
divergent boundaries
Occur where two plates slide APART from each other with the space that was created being filled with molten magma from below.
Mid-Atlantic Ridge and Pacific Rise
Examples of oceanic divergent boundaries.
East African Great Rift Valley
Examples of areas of continental divergent boundaries
convergent boundaries
Occur where two plates slide TOWARD each other, commonly forming either a subduction zone or orogonic belt.
subduction zone
Occurs when a denser oceanic plate moves underneath (subducts) a less-dense continental plate.
e.g. Cascade Mountain range (includes Mount Saint Helens)
e.g. Cascade Mountain range (includes Mount Saint Helens)
island arc
A curved chain of volcanic islands created when two oceanic plates converge.
e.g. Japan and the Aleutian Islands in Alaska
e.g. Japan and the Aleutian Islands in Alaska
mountain range
Created when two continental plates collide.
e.g. Himalayas (Nepal and China)
e.g. Himalayas (Nepal and China)
earthquakes
Caused by friction and stress buildup from the sliding plates, a common feature along transform boundaries.
e.g. Haiti Earthquake 2010
e.g. Haiti Earthquake 2010
seismic waves
energy released in the form of vibrations when there is abrupt movement on an existing fault; they move in all directions through the surround rock
P waves (Primary waves)
Are body waves that travel through the interior of the Earth.
S waves (Secondary waves)
Are produced when material moves either vertically or horizontally and travel only within the uppermost layers of Earth.
The severity of an earthquake depends on:
-The amount of potential energy that had been stored
-The distance the rock mass moved when the energy was released
-How far below the surface the movement occured
-The makeup of the rock material
-The distance the rock mass moved when the energy was released
-How far below the surface the movement occured
-The makeup of the rock material
liquefaction
The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud.
tsunami
A series of waves created when a body of water is rapidly displaced usually be an earthquake.
e.g. Tōhoku, Japan Earthquake and Tsunami 2011 (also led to nuclear meltdown at Fukushima)
e.g. Tōhoku, Japan Earthquake and Tsunami 2011 (also led to nuclear meltdown at Fukushima)
volcano
A mountain or hill having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust
What do volcano eruptions do to our atmosphere?
-Release CO2, SO2, HCl
-debris and particulates can block sunlight, making a cooler climate
-debris and particulates can block sunlight, making a cooler climate
Factors that affect the amount of solar energy at the surface of the Earth:
-Earth's rotation (once every 24 hours)
-tilt of Earth's axis (23.5 degrees)
-revolution around the sun (once per year)
-closest to sun in winter, furthest in summer
-tilt of Earth's axis (23.5 degrees)
-revolution around the sun (once per year)
-closest to sun in winter, furthest in summer
O Horizon
Surface litter: leaves and partially decomposed organic debris. Thick in deciduous forests, thin in the tundra.
A Horizon
Topsoil: organic matter (humus), living organisms, inorganic minerals. Topsoil is very thick in grasslands.
E Horizon
Zone of leaching: dissolved and suspended materials move downward. In-between A and B horizon.
B Horizon
Subsoil: tends to be yellowish in color due to the accumulation of Fe, Al, humic compounds, and clay leached down from A and E horizons. Can be rich in nutrients in areas with lots of rainwater.
C Horizon
Weathered parent material: partially broken-down inorganic minerals
parent material
The rock and minerals from which the soil derives. Nature of parent rock can be native to the area or transported by wind, water, glaciers, etc.
clay
-very fine particles
-compacts easily
-forms large, dense clumps when wet
-low permeability to water, thus upper layers bcome waterlogged
-compacts easily
-forms large, dense clumps when wet
-low permeability to water, thus upper layers bcome waterlogged
gravel
-coarse particles
-consists of rock fragments
-consists of rock fragments
loam
-about equal mixtures of clay, sand, silt, and humus
-rich in nutrients
-holds water but does not become waterlogged
-rich in nutrients
-holds water but does not become waterlogged
sand
-sedimentary material coarser than silt
-water flow through too quickly for most crops
-good for crops and plants requiring low amounts of water
-water flow through too quickly for most crops
-good for crops and plants requiring low amounts of water
silt
-sedimentary material consisting of very fine particles between the size of sand and clay
-easily transported by water
-easily transported by water
What color soil is most fertile?
a rich dark brown
waterlogging
saturation of soil with water resulting in a rise of the water table
problems of waterlogging
salty water envelops deep roots killing plants; lowers productivity; eventual destruction of plant life
solutions of waterlogging
switch to less water-demanding plants in susceptible areas; utilize conservation-tillage farming; plant waterlog-resistant plants; install drainage popes
salinization
a soil degradation process caused by repeated annual application of irrigation water in dry climates, which leads to the gradual accumulation of salts in the upper soil layers
problems of salinization
stunted crop growth; lower yield; eventual destruction of plant life
solutions of salinization
take land out of production for a while; install drainage pipes; flush soil with freshwater; planted halophytes (salt-loving plants) like barley, cotton, sugar, or wheat
desertification
occurs when the productive potential of soil, especially on arid or semiarid land, falls by 10% or more because of a combination of prolonged drought and human activities that reduce or degrade topsoil
problems of desertification
loss of native vegetation; increased wind erosion; salinization; drop in water table; reduced surface water supply
solutions of desertification
reduce overgrazing; reduce deforestation; reduce destructive forms of planting, irrigation, and mining; plant trees and grasses to hold soil
Soil erosion
is the movement of soil components, especially surface litter and topsoil, from one place to another by the actions of wind and water
What is most harmful human activity?
Agriculture has a greater harmful environmental impact than any other human activity
igneous
formed by cooling and classified by their silica content.
-majority of rocks in Earth's crust are igneous
-Intrusive igneous rocks solidify deep underground, cool slowly and have large-grained texture.
-Extrusive igneous rocks solidify on or near the surface, cool quickly, and have fine-grained smooth texture.
-Igneous rocks are broken down by weathering and water transport.
e.g. granite and basalt
-majority of rocks in Earth's crust are igneous
-Intrusive igneous rocks solidify deep underground, cool slowly and have large-grained texture.
-Extrusive igneous rocks solidify on or near the surface, cool quickly, and have fine-grained smooth texture.
-Igneous rocks are broken down by weathering and water transport.
e.g. granite and basalt
metamorphic
formed by intense heat and pressure
e.g. diamond, marble asbestos, slate, anthracite coal
e.g. diamond, marble asbestos, slate, anthracite coal
sedimentary
formed by piling and cementing of various materials over time in low-lying areas. Fossils form only in sedimentary rock.
e.g. conglomerate, breccia, sandstone
e.g. conglomerate, breccia, sandstone
What seven primary compounds is the Earth's atmosphere composed of?
-nitrogen (78%)
-oxygen (21%)
-water vapor (0-4%)
-carbon dioxide (<<1%)
-methane (<<<1%)
-nitrous oxide (<<<1%)
-ozone (<<<1%)
-oxygen (21%)
-water vapor (0-4%)
-carbon dioxide (<<1%)
-methane (<<<1%)
-nitrous oxide (<<<1%)
-ozone (<<<1%)
Nitrogen (N2)
Fundamental nutrient for living organisms. Deposits on Earth through nitrogen fixation and reactions involving lightning and subsequent precipitation. Returns to the atmosphere through combustion of biomass and denitrification.
Oxygen (O2)
Oxygen molecules are produced through photosynthesis and are utilized in cellular respiration.
Water vapor (H2O)
Largest amounts occur near equator, over oceans, and in tropical regions. Areas where atmospheric water vapor can be low are polar areas and deserts.
-most voluminous greenhouse gas, cannot be added or reduced
-most voluminous greenhouse gas, cannot be added or reduced
Carbon dioxide (CO2)
Volume of CO2 has increased about 25% in the last 300 years due to the burning of fossil fuels and deforestation. CO2 is produced during cellular respiration and the decay of organic matter. It is a reactant in photosynthesis. CO2 is also a major greenhouse gas.
-stays in atmosphere 100 years
-stays in atmosphere 100 years
Methane (CH4)
Methane contributes to the greenhouse effect. Since 1750, methane has increased about 150% due to use of fossil fuels, coal mining, landfills, grazers, etc.
-stays in atmosphere 12 years
-stays in atmosphere 12 years
Nitrous oxide (NO2)
Concentration increasing about 0.3% per year. Sources include burning of fossil fuels, use of fertilizers, burning biomass, deforestation, etc. Can come from livestock farts.
-stays in atmosphere 120 years
-stays in atmosphere 120 years
Ozone (O3)
97% of ozone is found in the stratosphere (ozone layer). Ozone absorbs UV radiation. Ozone is produced in the production of photochemical smog. CFC's have contributed to ozone layer depletion. Ozone is a pollutant in the troposphere.
troposphere
-75% of atmosphere's mass is in the troposphere
-temperature decreases with altitude
-weather occurs in this zone
-temperature decreases with altitude
-weather occurs in this zone
stratosphere
-temperature increases with altitude due to absorption of heat by ozone
-ozone is produced by UV radiation and lightning
-contains the ozone layer
-ozone is produced by UV radiation and lightning
-contains the ozone layer
mesosphere
-temperature decreases with altitude
-coldest layer
-ice clouds occur here
-meteors (shooting stars) burn up in this layer
-coldest layer
-ice clouds occur here
-meteors (shooting stars) burn up in this layer
thermosphere (ionosphere)
-temperature increase with height due to gamma rays, X rays, and UV radiation
-molecules are converted into ions
-causes Northern lights
-molecules are converted into ions
-causes Northern lights
Relationship between altitude, pressure, and temperature within the zones
weather
is a LOCAL area's short-term temperature, precipitation, humidity, wind speed, cloud cover, and other physical conditions of the lower atmosphere as measured over hours or days
-caused by movement of heat energy
-caused by movement of heat energy
climate
is an area's GENERAL pattern of atmospheric of weather conditions measured over long periods of time ranging from decades to thousands of years
radiation
the flow of electromagnetic radiation. Method by which Earth receives solar energy.
conduction
involves transfer of heat through a substance that results from a difference in temperature
convection
is the primary way energy is transferred from hotter to colder regions in the Earth's atmosphere and determines weather patterns
Relationship between cold and hot air
Cold air is more dense, hot air is less dense and more spread out
albedo
is the diffuse reflectivity or reflecting power of a surface
specific heat
is the amount of heat per unit mass required to raise the temperature by one degree Celsius (water has a high specific heat)
temperature inversion
stops atmospheric convection (which is normally present) from happening in the affected area and can lead to the air becoming stiller and murky from the collection of dust and pollutants that are no longer able to be lifted from the surface. Worsens pollution.
(COLD air) OVER (WARM air)
(COLD air) OVER (WARM air)
formation of clouds
when rising air, through expansion, cools to the point where some of the water vapor molecules "clump together" faster than they are torn apart by their thermal energy. Some of that (invisible) water vapor condenses to form (visible) cloud droplets or ice crystals.
dew point
is the temperature below which the water vapor in a volume of humid air condense into liquid water
Rain shadow (orographic) effect
the loss of moisture from the landscape and the resulting semiarid or arid conditions on the leeward side of high mountains
-Windward= lush, green, clouds, precipitation, ocean...leedward= deserts, sinking air, dry
-Windward= lush, green, clouds, precipitation, ocean...leedward= deserts, sinking air, dry
Coriolis Effect
an effect whereby a mass moving in a rotating system experiences a force (the Coriolis force) acting perpendicular to the direction of motion and to the axis of rotation.
monsoons
a seasonal prevailing wind in the region of South and Southeast Asia, blowing from the southwest between May and September and bringing rain (the wet monsoon), or from the northeast between October and April (the dry monsoon)
El Niño and La Niña (Southern Oscillation (ENSO))
large-scale weather phenomenon occurs every few years when prevailing winds in the tropical Pacific Ocean weaken and change direction
o Above-average warming of Pacific waters affects populations of marine species by changing the distribution of plant nutrients, hurting fishing industry
o Low nutrients, low dissolved oxygen (in South America, but in Australia during La Niña)
o Severe flooding, storms, drought, mudslides, $ damage, human health hazards (dehydration, diarrhea, zoonotic diseases [lyme, Hanta])
o Above-average warming of Pacific waters affects populations of marine species by changing the distribution of plant nutrients, hurting fishing industry
o Low nutrients, low dissolved oxygen (in South America, but in Australia during La Niña)
o Severe flooding, storms, drought, mudslides, $ damage, human health hazards (dehydration, diarrhea, zoonotic diseases [lyme, Hanta])
Grasshopper effect
occurs when volatile air pollutants are transported by evaporation and winds from tropical and temperate areas though the atmosphere to the earth's polar areas, where they are deposited.
natural sources of pollution
• dust blown by wind
• pollutants from wildfires and volcanic eruptions
• VOCs (volatile organic chemicals) released by some plants
• Removed naturally by chemical cycles, precipitation, and gravity
• pollutants from wildfires and volcanic eruptions
• VOCs (volatile organic chemicals) released by some plants
• Removed naturally by chemical cycles, precipitation, and gravity
manmade sources of pollution
• Industry, cars, electrical plants, coal
• Burning of fossil fuels
• Burning of fossil fuels
primary pollutants
are harmful chemicals emitted directly into the air from natural processes and human activities
e.g. SOx, NOx, CO, VOCs, particulates, Lead
e.g. SOx, NOx, CO, VOCs, particulates, Lead
secondary pollutants
formed by some primary pollutants reacting with one another and with the basic component of air to form new harmful chemicals
e.g. O3, HNO3 (nitric acid), H2SO4 (sulfuric acid [acid rain])
e.g. O3, HNO3 (nitric acid), H2SO4 (sulfuric acid [acid rain])
Ways Air Pollution is Increased:
• Urban buildings can slow wind speed and reduce dilution and removal of pollutants
• Hills and mountains can reduce the flow of air in valleys and allow pollutant levels to build up at ground level
• High temperatures promote the chemical reactions leading to photochemical smog formation (global warming increases smog!)
• Emissions of VOCs from certain trees and plants (e.g. oak, sweet gums, poplars, and kudzu) can play a large role in photochemical smog formation
• Grasshopper effect
• Temperature inversions
• Hills and mountains can reduce the flow of air in valleys and allow pollutant levels to build up at ground level
• High temperatures promote the chemical reactions leading to photochemical smog formation (global warming increases smog!)
• Emissions of VOCs from certain trees and plants (e.g. oak, sweet gums, poplars, and kudzu) can play a large role in photochemical smog formation
• Grasshopper effect
• Temperature inversions
Industrial smog
(gray color) consists mostly of sulfur dioxide, suspended droplets of sulfuric acid, and a variety of suspended solid particles
Photochemical smog
(brown color) is a mixture of primary and secondary pollutants formed under the influence of UV radiation from the sun; formation of this smog begins when exhaust from morning commuter vehicles releases large amounts of NO and VOCs into the air over a city
• VOCs + NOx + heat + sunlight → ground level ozone (03) + other photochemical oxidants + aldehydes + other secondary pollutants
• VOCs + NOx + heat + sunlight → ground level ozone (03) + other photochemical oxidants + aldehydes + other secondary pollutants
Properties of Water:
• strong hydrogen bonds
• high specific heat
• high boiling point
• needs a lot of energy to evaporate
• expands when freezes
• high specific heat
• high boiling point
• needs a lot of energy to evaporate
• expands when freezes
Where is our water?
• 70% of Earth's surface is covered by water
• oceans hold about 97% of all water
• 3% is freshwater
• majority of freshwater is stuck in glaciers
• 71% is saltwater, 0.024% is readily available freshwater
• 60% of the human body is water
• oceans hold about 97% of all water
• 3% is freshwater
• majority of freshwater is stuck in glaciers
• 71% is saltwater, 0.024% is readily available freshwater
• 60% of the human body is water
Lake zonation:
• littoral zone
• limnetic zone
• photic zone
• profundal zone
• benthic zone
(some zones are also applicable to oceans)
• limnetic zone
• photic zone
• profundal zone
• benthic zone
(some zones are also applicable to oceans)
littoral zone
• top layer, near the shore
• consists of the shallow sunlit waters to the depth at which rooted plants such as cattails stop growing
• most productive zone because of sunlight and nutrients from the surrounding land
• high biological diversity
• consists of the shallow sunlit waters to the depth at which rooted plants such as cattails stop growing
• most productive zone because of sunlight and nutrients from the surrounding land
• high biological diversity
limnetic zone
• sunlit surface away from shore that extends the depth sunlight penetration
• the main photosynthetic body of the lake
• produces the food and oxygen that support most of the lake's consumers
• the main photosynthetic body of the lake
• produces the food and oxygen that support most of the lake's consumers
photic zone
• also called euphotic zone
• sunlight zone is the depth of the water in a lake or ocean that is exposed to sufficient sunlight for photosynthesis to occur
• sunlight zone is the depth of the water in a lake or ocean that is exposed to sufficient sunlight for photosynthesis to occur
profundal zone
• deep open water where it is too dark for photosynthesis
• without sunlight and plants, oxygen levels are low
• without sunlight and plants, oxygen levels are low
benthic zone
• bottom layer
• inhabited by decomposers, detritus feeders, and some fish
• dead matter falls here
• inhabited by decomposers, detritus feeders, and some fish
• dead matter falls here
oligotrophic lakes
lakes that have a small supply of plant nutrients
e.g. glaciers, mountains, lakes
e.g. glaciers, mountains, lakes
eutrophic lakes
lakes that are well-nourished; have large supply of plants nutrients; are shallow with murky brown or green water
mesotrophic
no nutrients in lakes
hypereutrophic
too many nutrients
phytoplankton
"drifting plants"- primary producers that support aquatic foods webs
e.g. many types of algae
e.g. many types of algae
zooplankton
"drifting animals"-primary consumers that feed on phytoplankton and secondary consumers that feed on other zooplankton; daily vertical migration for food
e.g. range from single-celled protozoa to large invertebrates like jellyfish
e.g. range from single-celled protozoa to large invertebrates like jellyfish
ultraplankton
extremely small photosynthetic bacteria that are responsible for 70% of the primary productivity near the ocean surface
nekton
strongly swimming consumers such as fish, turtles, and whales
benthos
consists of bottom dwellers such as oysters, clams, worms, lobsters, and crabs
limiting factors that determine where a species will live:
• temperature
• dissolved oxygen content
• availability of food
• availability of light and nutrients for photosynthesis
• dissolved oxygen content
• availability of food
• availability of light and nutrients for photosynthesis
euphotic zone
the upper layers where photosynthesis is largely confined because sunlight can penetrate
aphotic zone
zone where there is no sunlight
turbidity
when the water is clouded by excessive algal growth or natural/human disturbances like waves, wind, currents, boats, tides, storms, etc.
• can prevent sunlight from penetrating the water for photosynthetic plants
• can clog fish kills
• can prevent fish/organisms from properly hunting prey
• can prevent sunlight from penetrating the water for photosynthetic plants
• can clog fish kills
• can prevent fish/organisms from properly hunting prey
ocean zonation:
• coastal zone
• intertidal zone
• continental shelf
• euphotic zone
• bathyal zone
• abyssal zone
• intertidal zone
• continental shelf
• euphotic zone
• bathyal zone
• abyssal zone
coastal zone
• warm temperature, nutrient-rich, extends from shallow water to continental shelf
intertidal zone
• area of shoreline between low and high tides
• organisms must be able to avoid being swept away or crushed by waves; must deal with being immersed in high tides and left dry during low tides; must deal with changing levels of salinity
• most intertidal organisms: hold onto something, dig in, or hide in protective shells
• organisms must be able to avoid being swept away or crushed by waves; must deal with being immersed in high tides and left dry during low tides; must deal with changing levels of salinity
• most intertidal organisms: hold onto something, dig in, or hide in protective shells
wetlands (estuaries, swamps, marshes)
• water table stands at or near the land surface
• soil is either permanently or seasonally saturated
• most biologically diverse of all ecosystems
• water can be saltwater, freshwater, or brackish
• breeding grounds, storm protection, reduce wave impacts, support marine life, stabilize shorelines
• productive-high nutrient input from rivers and nearby land and rapid circulation of nutrients
• ample sunlight in shallow waters
• plant life includes: mangroves, cattails, cypress
• animal life includes: birds, mammals, amphibians, etc.
• soil is either permanently or seasonally saturated
• most biologically diverse of all ecosystems
• water can be saltwater, freshwater, or brackish
• breeding grounds, storm protection, reduce wave impacts, support marine life, stabilize shorelines
• productive-high nutrient input from rivers and nearby land and rapid circulation of nutrients
• ample sunlight in shallow waters
• plant life includes: mangroves, cattails, cypress
• animal life includes: birds, mammals, amphibians, etc.
mangrove forests
• reduce the impacts of rising sea levels and more intense storm surges, which may become more powerful with global warming
• help maintain water quality through filtration
• produce food, habitats, and nursing sites
• reduce storm damage
• adapted to changing salinity within tides
• threatened by rising sea levels, a result of global warming
• largest mangrove area is in Indonesia
• help maintain water quality through filtration
• produce food, habitats, and nursing sites
• reduce storm damage
• adapted to changing salinity within tides
• threatened by rising sea levels, a result of global warming
• largest mangrove area is in Indonesia
barrier islands
• low, narrow, sandy islands that form offshore, parallel to some coastlines
• generally have one or more rows of natural sand dunes (protection)
• generally have one or more rows of natural sand dunes (protection)
economic and ecological services provided by marine ecosystems:
• value of goods and services yearly is about $12 million
• oil and natural gas, food, animal/pet food, pharmaceuticals, transportation/harbors, employment
• reservoirs of biodiversity
• climate moderation (CO2 absorption)
• waste treatment
• nutrient recycling
• reduced storm impact
• oil and natural gas, food, animal/pet food, pharmaceuticals, transportation/harbors, employment
• reservoirs of biodiversity
• climate moderation (CO2 absorption)
• waste treatment
• nutrient recycling
• reduced storm impact
threats to aquatic biodiversity:
• dams and canals fragment natural biodiversity and destroy wildlife
• cities and farms add pollutants and excess plant nutrients
• cities and farms add pollutants and excess plant nutrients
trawler fishing
• drags funnel-shaped nets weighted down with heavy chains and steel plates over ocean bottoms to harvest a few species of bottom fish and shellfish
• crushes organisms, buries them in sediment, exposes them to predators
• catches shrimp, cod, flounder, and scallops
• crushes organisms, buries them in sediment, exposes them to predators
• catches shrimp, cod, flounder, and scallops
bycatch
the unwanted fish and other marine creatures caught during commercial fishing for a different species
purse-seine fishing
• used to catch surface-dwelling species by having ships senclose on large schools of fish and throw nets
• tuna, mackerel, anchovies, herring
• tuna, mackerel, anchovies, herring
longlining
• putting out lines up to 80 miles long, hung with thousands of baited hooks, to catch open-ocean fish species
• swordfish, tuna, sharks, halibut, cod
• also bycatch (hook and kill accidentally) endangered sea turtles, dolphins, and seabirds
• swordfish, tuna, sharks, halibut, cod
• also bycatch (hook and kill accidentally) endangered sea turtles, dolphins, and seabirds
drift-net fishing
huge fish are caught by huge drifting nets that can hang as deep as 50 feet below the surface and extend 40 miles long. This method can lead to overfishing of the desired and unwanted species.
commercial extinction
the decline in the population of a wild species, used as a resource, to a level where it is no longer profitable to harvest the species
biological extinction
occurs whenever a species of animal or plant life is permanently lost
ecosystem approach
to protect and sustain whole marine ecosystems for current and future generations instead of focusing primarily on protecting individual species
maximum sustained yield
model to project the maximum number of fish that can be harvested annually from a fish stock without causing a population drop
optimum sustained yield
takes into account interactions among species and provides more room for error
multispecies management
takes into account their competitive and predator-prey interactions
precautionary principle
sharply reducing fish harvests and closing some overfished areas until they recover and until we have more information about what levels of fishing can be sustained
Three general patterns of marine biodiversity:
• The greatest marine biodiversity occurs in coral reefs, estuaries, and the deep-ocean floor
• Biodiversity if higher near coasts than in the open sea because of the great variety of producers and habitats in coastal areas
• Biodiversity is higher in the bottom region of the ocean than in the surface region because of the great variety of habitats and food sources on the bottom
• Biodiversity if higher near coasts than in the open sea because of the great variety of producers and habitats in coastal areas
• Biodiversity is higher in the bottom region of the ocean than in the surface region because of the great variety of habitats and food sources on the bottom
Hydrologic cycle
the movement of water in the seas, in the air, and on land, which is driven by solar energy and gravity
groundwater
water held underground in the soil or in pores and crevices in rock
Zone of saturation
spaces in soil and rock are completely filled with water
Zone of aeration
lies between the earth's surface and the water table; the surface is marked by the presence of vegetation
water table
top of the groundwater zone; can fall or rise depending on weather
aquifers
• underground caverns and porous layers of sand, gravel, or bedrock through which groundwater flows
• most aquifers recharge extremely slowly because urban development prevents water from easily penetrating the ground
• most aquifers recharge extremely slowly because urban development prevents water from easily penetrating the ground
confined aquifers
is bounded above and below by less permeable beds of rock, and its water is confined under pressure
unconfined aquifers
is an aquifer with a permeable water table
deep aquifers
some of these aquifers hold enough water to support billions of people; water quality is higher than most rivers and lakes; people must experiment to see if salt or fresh
artesian well
is a confined aquifer containing groundwater under positive pressure
natural recharge
process in which aquifers are replenished naturally by precipitation that percolates downward through soil and rock
lateral recharge
process in which aquifers are recharged from the side from nearby rivers and streams
spring
is any natural situation where water flows to the surface of the Earth from underground; a spring is a site where the aquifer surface meets the ground surface
saltwater intrusion
movement of saltwater into an aquifer, which may cause contamination
cone of depression
occurs in an aquifer when groundwater is pumped from a well
surface runoff
precipitation that does not infiltrate the ground or return to the atmosphere by evaporation
reliable surface runoff
the amount of surface runoff that we can generally count on as a source of freshwater from year to year
watershed or drainage basin
the land from which surface water drains into a particular river, lake, wetland, or other body of water
• 70% of water is used for agriculture, 20% of water is used for industry, 10% of water is used by humans and cities
• 70% of water is used for agriculture, 20% of water is used for industry, 10% of water is used by humans and cities
drought
a prolonged period in which precipitation is at least 70% lower and evaporation is higher than normal in an area that is normally not dry
• dries out soils, reduces stream flows, decreases tree growth and biomass, lowers net primary productivity, reduces crop yields, and causes a shift in some biomes towards relatively dry conditions
• political/legal conflicts, depression for farmers
• dries out soils, reduces stream flows, decreases tree growth and biomass, lowers net primary productivity, reduces crop yields, and causes a shift in some biomes towards relatively dry conditions
• political/legal conflicts, depression for farmers
main factors causing water scarcity:
• dry climate, drought, too many people using a normally reliable supply of water, and wasteful use of water
• farmers, cities, and car owners are increasingly competing for access to the world's grain and water supplies, which in turn can degrade some of the natural capital that provides these resources
• farmers, cities, and car owners are increasingly competing for access to the world's grain and water supplies, which in turn can degrade some of the natural capital that provides these resources
Water Privatization: Pros
• Private companies have the money and expertise to manage water resources better and more efficiently than governments
• Some private water management companies have done a good job in the past
• Some private water management companies have done a good job in the past
Water Privatization: Cons
• Because private companies make money by delivering water, they have an incentive to sell as much a possible rather than conserving it
• Because they have too little money to pay water bills, the poor will continue to be left out
• Water should be a public resource
• Because they have too little money to pay water bills, the poor will continue to be left out
• Water should be a public resource
Withdrawing Groundwater: Advantages
• Useful for drinking and irrigation
• Available year-round
• Exists almost everywhere
• Renewable if not overpumped or contaminated
• No evaporation losses
• Cheaper to extract than most surface waters
• Available year-round
• Exists almost everywhere
• Renewable if not overpumped or contaminated
• No evaporation losses
• Cheaper to extract than most surface waters
Withdrawing Groundwater: Disadvantages
• Aquifer depletion from overpumping
• Sinking of land (subsidence) from overpumping
• Aquifers polluted for decades or centuries
• Saltwater intrusion into drinking water supplies near coastal areas
• Reduced water flows into surface waters
• Increased cost & contamination from deeper wells
• Sinking of land (subsidence) from overpumping
• Aquifers polluted for decades or centuries
• Saltwater intrusion into drinking water supplies near coastal areas
• Reduced water flows into surface waters
• Increased cost & contamination from deeper wells
land subsidence
withdrawing large amount of water sometimes causes sand and rock in aquifers to collapse, which causes the land above the aquifer to subside or sink
sinkholes
large craters that form when the roof of an underground cavern collapses after being drained of the groundwater that supports it
Groundwater Depletion: Solutions
• Waste less water
• Subsidize water conservation
• Limit number of wells
• Do not grow water-intensive crops in dry areas • Raise price of water to discourage waste
• Tax water pumped from wells near surface waters
• Set and enforce minimum stream flow levels
• Divert surface water in wet years to recharge aquifers
• Subsidize water conservation
• Limit number of wells
• Do not grow water-intensive crops in dry areas • Raise price of water to discourage waste
• Tax water pumped from wells near surface waters
• Set and enforce minimum stream flow levels
• Divert surface water in wet years to recharge aquifers
dam
• a structure built across river to control the river's water flow
• ¼ of the world's damn produce about 20% of the world's electricity
• ¼ of the world's damn produce about 20% of the world's electricity
reservoir
an artificial lake created by the river's flow after it is dammed; behind dam
Damming the Waterways: Advantages
• Provides irrigation water above and below dam
• Provides water for drinking
• Reservoir useful for recreation and fishing
• Can produce cheap electricity (hydropower)
• Reduces downstream flooding
• Capture and store runoff
• Provides water for drinking
• Reservoir useful for recreation and fishing
• Can produce cheap electricity (hydropower)
• Reduces downstream flooding
• Capture and store runoff
Damming the Waterways: Disadvantages
• Flooded land destroys forests or cropland and displaces people
• Large losses of water through evaporation
• Deprives downstream cropland and estuaries of nutrient-rich silt
• Risk of failure and devastating downstream flooding
• Disrupts migration and spawning of some fish
• Sediments build up behind dam in reservoirs
• Higher rates of evaporation
• Downstream people have less water
• Large losses of water through evaporation
• Deprives downstream cropland and estuaries of nutrient-rich silt
• Risk of failure and devastating downstream flooding
• Disrupts migration and spawning of some fish
• Sediments build up behind dam in reservoirs
• Higher rates of evaporation
• Downstream people have less water
Water in Saudi Arabia
• Saudi Arabia is as water-poor as it is oil-rich, so it gets about 70% of its drinking water at a high cost from the world's largest system for removing salt from seawater, located on its eastern coast
• Saudi Arabia has the world's largest number of desalination plants
• Saudi Arabia has the world's largest number of desalination plants
desalination
• removes dissolved salts from ocean water of from brackish water in aquifers of lakes for domestic use
-High cost and energy footprint
-Pumping large volumes of seawater through pipes and using chemicals to sterilize water and keep down algal growth kills many marine organisms
-Produces large quantities of briny wastewater that contain lots of salt and other minerals...dumping this water into the ocean is bad
-High cost and energy footprint
-Pumping large volumes of seawater through pipes and using chemicals to sterilize water and keep down algal growth kills many marine organisms
-Produces large quantities of briny wastewater that contain lots of salt and other minerals...dumping this water into the ocean is bad
distillation
heating saltwater until it evaporates, leaving behind salts in solid form and condensing freshwater
reverse osmosis (microfiltration):
uses high pressure to force saltwater through a membrane filter with pores small enough to remove the salt
flood irrigation
water is distributed over the soil surface by gravity; the most common form of irrigation and most inefficient; loses 40% of water
center-pivot, low-pressure sprinkler
uses pumps to spray water on a crop; results in a series of circular irrigated areas; 80% of water reaches crops
low-energy, precision application (LEPA) sprinklers
another form of center-pivot irrigation, put 90-95% of the water where crops need it
drip or trickle irrigation (micro irrigation)
method that saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters; MOST efficient method because least evaporation; 90-95% of water reaches the crops
Reducing Irrigation Water Waste: Solutions
• Line canals bringing water to irrigation ditches
• Irrigate at night to reduce evaporation
• Monitor soil moisture to add water only when necessary
• Grow several crops on each plot of land (polyculture)
• Encourage organic farming
• Avoid growing water-thirsty crops in dry areas
• Irrigate with treated urban wastewater
• Import water-intensive crops and meat
• Irrigate at night to reduce evaporation
• Monitor soil moisture to add water only when necessary
• Grow several crops on each plot of land (polyculture)
• Encourage organic farming
• Avoid growing water-thirsty crops in dry areas
• Irrigate with treated urban wastewater
• Import water-intensive crops and meat
xeriscaping
uses drip-irrigation and copies nature by replacing green lawns with plants that need little water; reduces water use by 30-85% and sharply reduces need for labor, fertilizers, and fuel
rainwater harvesting
involves running pipes from rooftops and digging channels to catch rainwater
Reducing wastewater:
• Redesign manufacturing processes to use less water
• Recycle water in industry
• Fix water leaks, use water meters, raise water prices
• Use drip irrigation
• Use waterless composting toilers
• Require water conservation in water-short cities
• Purify and reuse water for houses, offices, buildings
• Recycle water in industry
• Fix water leaks, use water meters, raise water prices
• Use drip irrigation
• Use waterless composting toilers
• Require water conservation in water-short cities
• Purify and reuse water for houses, offices, buildings
Sustainable water use:
• Waste less water and subsidize water conservation
• Do not deplete aquifers
• Preserve water quality
• Protect forests, wetlands, mountain glaciers, watersheds, and other natural systems
• Get agreements among regions and countries sharing surface water resources
• Raise water prices
• Slow population growth
• Do not deplete aquifers
• Preserve water quality
• Protect forests, wetlands, mountain glaciers, watersheds, and other natural systems
• Get agreements among regions and countries sharing surface water resources
• Raise water prices
• Slow population growth
floodplain
• is an area of land adjacent to a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge
• Pros: amble water for irrigation; availability of nearby rivers for transportation; flat land suitable for crops; include highly productive wetlands; help to provide natural flood and erosion control; maintain high water quality; recharge groundwater; fertile soil
• Cons: floods kill people; damage to property
• Pros: amble water for irrigation; availability of nearby rivers for transportation; flat land suitable for crops; include highly productive wetlands; help to provide natural flood and erosion control; maintain high water quality; recharge groundwater; fertile soil
• Cons: floods kill people; damage to property
Reducing Flood Damage: Solutions
• Preserve forests on watersheds
• Preserve and restore wetlands in floodplains
• Tax development on floodplains
• Use floodplains primarily for recharging aquifers, sustainable agriculture, and forestry
• Straighten and deepen streams (channelization)
• Build levees or floodwalls along streams
• Build dams
• Preserve and restore wetlands in floodplains
• Tax development on floodplains
• Use floodplains primarily for recharging aquifers, sustainable agriculture, and forestry
• Straighten and deepen streams (channelization)
• Build levees or floodwalls along streams
• Build dams
biodiversity
is the variety of the earth's species, the genes they contain, the ecosystems in which they live, and the ecosystem processes that sustain all life
functional diversity
the variety of processes such as matter cycling and energy flow taking place within ecosystems
ecology
the study of how organisms interact with their living (biotic) environment
biological evolution
the process whereby earth's life changes over time through changes in the genes of populations
fossil record
is incomplete because of decomposers, nonideal conditions, natural disasters, asteroids or meteors, etc.
natural selection
occurs when some individuals of a population have genetically based traits that enhance their ability to survive and reproduce
differential reproduction
enables individuals with the trait to leave more offspring than other members of the population leave (a trait must do this and MUST BE HERITABLE for natural selection to occur)
genetic resistance
the ability of one or more organisms in a population to tolerate a chemical designed to kill it (e.g. bacteria with regard to hand sanitizer)
Geological processes that affect natural selection:
• Tectonic plates- locations of continents and oceanic basins greatly influence the earth's climate and movement of continents spread animals to new places (new resources)
• Earthquakes- disruptions in earth's crust that can isolate species
• Volcanic eruptions- can reduce or wipe out populations
• Natural catastrophes
• Earthquakes- disruptions in earth's crust that can isolate species
• Volcanic eruptions- can reduce or wipe out populations
• Natural catastrophes
speciation
process when two species arise from one
geographic isolation
occurs when different groups of the same population of a species become physically isolated form one another for longs period
reproductive isolation
mutation and change by natural selection operate independently in the gene pools of geographically isolated population
background extinction
species disappearing at a low rate throughout history
species diversity
the number of different species a community contains (species richness) combined with the relative abundance of individuals within each of those species (species evenness)
endemic species
species that are found in only one area; vulnerable to extinction
generalist species
broad niches (e.g. deer)
specialist species
narrow niches; more vulnerable (e.g. panda bear)
indicator species
species that provide early warnings of damage to a community or an ecosystem (e.g. amphibians [because their breath through skin])
keystone species
have a large effect on the types and abundance of other species in an ecosystem (e.g. shark, bumblebee, sea otters in kelp forests)
foundation species
role in shaping communities by creating and enhancing their habitats in way that benefit other species (e.g. kelp forest)
biomass
the amount of living material, or the amount of organic material contained in living organisms, both as live and dead material, as in the leaves (live) and stem wood (dead) of trees
productivity
the rate of production; that is, the amount of increase in organic matter per unit of time (for example, grams per meter squared per year)
ecological succession
the process of the development of an ecological community or ecosystem, usually viewed as a series of stages: early, middle, late, mature (or climax), and sometimes post-climax
primary succession
the gradual establishment of biocommunities in a lifeless area that has NO soil or sediment
early successional species/pioneer species
species that occur only or primarily during early stages of succession. With vegetation, these are typically rapidly growing and short-lived with high reproductive rates.
secondary succession
a series of communities or ecosystems with different species that evolve where there's soil
late successional species
species that occur only or primarily in, or are dominant in late stages in succession. With plants, these are typically slower growing and long-lived species.
Early, Middle, and Late Successionary Stages:
• Early: biomass and biological diversity increase organic matter.
• Middle: biomass increases; diversity remains increases, organic matter increases.
• Late: biomass decreases, diversity decreases, and organic matter decreases.
• Middle: biomass increases; diversity remains increases, organic matter increases.
• Late: biomass decreases, diversity decreases, and organic matter decreases.
island biogeography
• proposes that the number of species found on an undisturbed island is determined by immigration and extinction
• Distance from mainland: closer island, higher immigration
• Size of island: small island have fewer sepcies than large islands and smaller target for immigration...higher extinction because less resources and diversity
• Distance from mainland: closer island, higher immigration
• Size of island: small island have fewer sepcies than large islands and smaller target for immigration...higher extinction because less resources and diversity
interspecific competition
occurs when members of two or more species interact to gain access to the same limited resources (e.g. food, light, or space)
competitive exclusion principle
no two species can occupy exactly the same ecological niche for very long (e.g. cheetahs and lions)
predation
occurs when a member of one species (the predator) feeds directly on all or part of a member of another species
Techniques to avoid predation:
camouflage, chemical warfare, warning coloration, mimicry
coevolution
evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo adaptations
e.g. bats and insects
e.g. bats and insects
resource partitioning
occurs when species competing for similar scarce resources evolve specialized traits that allow them to use shared resources at different times, in different ways, or in different places
population dynamics
the study of how characteristics (distribution, numbers, age, structure, density) of populations change in response to change in environmental conditions (temperature, resource availability, presence of diseases)
Patterns of population distribution:
• Clumping- beneficial because 1. Species tend to cluster where resources are available, 2. Moving in groups increases chances of encountering resources, 2. Living in groups protects some animals from predation, 4. Hunting in packs increases chance of catching prey
• Uniform dispersion
• Random dispersion
• Uniform dispersion
• Random dispersion
biotic potential
• is the maximum reproductive capacity of a population if resources are unlimited
• Large animals (e.g. elephants), low potential
• small animals (e.g. bacteria), high potential
• Large animals (e.g. elephants), low potential
• small animals (e.g. bacteria), high potential
Intrinsic rate of increase (r)
• rate at which a population would grow if it had unlimited resources
• High rate= reproduces early, short generation times, reproduces many times, many offspring
• High rate= reproduces early, short generation times, reproduces many times, many offspring
environmental resistance
the combination of all factors that act to limit the growth of a population (e.g. of limiting factors: light, water, space, nutrients, amount of water)
carrying capacity (K)
maximum population of a given species that a particular habitat can sustain indefinitely without being degraded
exponential growth (J curve)
• growth that increases at a constant rate per unit of time
• starts slowly, but accelerates as population increases
• starts slowly, but accelerates as population increases
logistic growth (S curve)
rapid population growth, followed by a steady decrease in population growth until the population size levels off
genetic drift
random changes in gene frequencies in a population that can lead to unequal reproductive success, some individuals will breed more, thus their genes will dominate the gene pool
inbreeding
occurs when individuals in a small population mate with one another
minimum viable population size
long-term survival species...the number of individuals need for long-term survival
founder effect
occurs when only a few individuals in a population colonize a new habitat that is geographically isolated (e.g. finches on Galapagos Islands)
demographic bottleneck effect
occurs when only a few individuals in a population survive catastrophic events, and then the population lacks genetic diversity
density-dependent factors:
infectious disease, parasitism, predation, competition
density-independent factors:
habitat destruction, pollution, temperature change
r and k selected species:
http://ecomburak.files.wordpress.com/2011/11/r-k1.png
commensalism
+, /
relationship in which one benefits and the other derives neither benefit nor harm
relationship in which one benefits and the other derives neither benefit nor harm
mutualism
+, +
symbiosis that is beneficial to both organisms involved
symbiosis that is beneficial to both organisms involved
parasitism
+, -
relationship between organisms where one organism, the parasite, benefits at the expense of the host
relationship between organisms where one organism, the parasite, benefits at the expense of the host
National Wildlife Refuges
areas that have been set aside for the protection of threatened or endangered species
biodiversity hotspot
is a biogeographic region with a significant reservoir of biodiversity that is under threat from humans
habitat fragmentation
is when large areas of habitat are divided typically by roads, crop fields or projects; blocks animals migration routes; animals are more vulnerable to die because of the small, enclosed space
habitat island
small patches of habitat surrounded by areas of unsuitable habitat, "habitat fragmentation"
background extinction
the continuous natural extinction rate of species which is typically balanced by the formation of new species
ecological extinction
the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species
biological extinction
occurs whenever a species of animal or plant life is permanently lost
local extinction
when a species is no longer found in an area it once inhabited but is found elsewhere in the world
economic value
the value of an organism, species, or ecosystem based on its usefulness to humans
intrinsic value
value of an organism, species, ecosystem, or the earth's biodiversity based on its existence, regardless of whether it has any usefulness to humans
instrumental value (or extrinsic value)
is the value of objects, not as ends-in-themselves, but as means of achieving something else
CITES
(Convention on International Trade in Endangered Species)
an international treaty banning the hunting and trade of endangered species; Created a list of animals in which countries who sign are forced to protect them
an international treaty banning the hunting and trade of endangered species; Created a list of animals in which countries who sign are forced to protect them
Endangered Species Act 1973
designed to identify and protect endangered species in the United States; most far-reaching environmental act ever
HIPPCO
Habitat destruction, Invasive Species, Population growth, Pollution, Climate Change, Overexploitations
*habitat destruction is #1 threat to animals
*habitat destruction is #1 threat to animals
old-growth forest
an uncut or regenerated primary forest that has not been seriously disturbed by human activities or natural disasters for 200 years or more—36% of world's forests
second-growth forest
a stand of trees resulting from secondary ecological succession; these forests develop after the trees in an area have been removed by human activities (e.g. clear-cutting or fire)—60% of world's forests
tree plantation (aka tree farm or commercial forest)
• is a managed tract with uniformly aged trees of one or two genetically uniform species that usually are harvested by clear-cutting as soon as they become commercially valuable
• land is replanted and clear-cut again in a regular cycle; wood goes to paper mills and natural wood
• land is replanted and clear-cut again in a regular cycle; wood goes to paper mills and natural wood
selective-cutting
intermediate-aged or mature trees in an uneven-aged forest are cut singly or in small groups
clear-cutting
removal of all trees; the most efficient way for a logging operation to harvest trees, but the most harmful; increased runoff, increased soil erosion, loss of nutrients
strip-cutting
clear-cutting a strip of trees along the contour of land within a corridor narrow enough to allow natural regeneration
surface fires
• usually burn only undergrowth and leaf litter on the forest floor
• Burn away flammable ground material, help prevent more destructive fires, free valuable mineral nutrients, control diseases
• Burn away flammable ground material, help prevent more destructive fires, free valuable mineral nutrients, control diseases
crown fires
an extremely hot fire that leaps from treetop to treetop, burning whole trees, usually occurs in areas that haven't had small fires in a long time
prescribed fires
• intentional small, contained surfaces fires created to remove flammable small trees and underbrush in the highest-risk forest areas
• Other approaches: use animals to eat the underbrush, allow many fires on public lands to burn, protect houses and other buildings in fire-prne areas by thinning a zone around, thin forest areas vulnerable to fire
• Other approaches: use animals to eat the underbrush, allow many fires on public lands to burn, protect houses and other buildings in fire-prne areas by thinning a zone around, thin forest areas vulnerable to fire
deforestation
is the temporary or permanent removal of large expanses of forest for agriculture, settlements, or other uses
Basic Causes of Natural Capital Degradation
not valuing ecological services, crop and timber exports, government policies, poverty, population growth
Secondary Causes of Natural Capital Degradation
roads, fires, settler farming, cash crops, cattle ranching, logging, tree plantations
range-lands
are unfenced grasslands in temperate and tropical climates that supply forage, or vegetation, for grazing and browsing animals
pastures
managed grasslands or enclosed meadows usually planted with domesticated grasses or other forage
overgrazing
occurs when too many animals graze for too long and exceed the carrying capacity of range-land area; it reduces grass cover, exposes the soil to erosion by water and wind, and compacts the soil
undergrazing
absence of grazing for long periods can reduce the net primary productivity of grassland vegetation and grass cover
rotational grazing
cattle are confined by portable fencing to one area for a short time and then moved to a new location
riparian zones
lush vegetation along streams or rivers
conservation easements
deed restrictions that bar future owners from developing the land
buffer zone concept
protecting an inner core of a reserve by usually establishing two buffer zones in which local people can extract resources sustainably without harming the inner core
habitat corridors
establishing protected habitat corridors between isolated reserves helps to support more species and allows migration
ecological restoration
the process of repairing damage caused by humans to the biodiversity and dynamics of natural ecosystems
• Restoration: returning habitat or ecosystem to its prior self
• Rehabilitation: making the habitat or ecosystem functional
• Replacement: replacing a degraded habitat or ecosystem
• Creating artificial ecosystems
• Restoration: returning habitat or ecosystem to its prior self
• Rehabilitation: making the habitat or ecosystem functional
• Replacement: replacing a degraded habitat or ecosystem
• Creating artificial ecosystems
biomes
are a major regional or global biotic community characterized by the dominant forms of plants life and the climate
Antarctic
-area surrounding south pole
-rainfall <2 inches per year
-rainfall <2 inches per year
Benthos (Hadal)
-bottoms of oceans
-no sunlight, therefore no plant life
-primary input of energy comes from dead organic matter settling and chemosynthesis
-no sunlight, therefore no plant life
-primary input of energy comes from dead organic matter settling and chemosynthesis
Coastal Zones
-includes estuaries, wetlands, and coral reefs
-high diversity and counts of animals and plant species due to runoff from land
-high diversity and counts of animals and plant species due to runoff from land
Coral Reefs
-warm, clear, shallow ocean habitats near land and in the tropics
-fringing reefs (on continental shelves), barrier reefs (parallel to the shore), coral atolls (rings of coral that grow on top of sunken oceanic volcanoes)
-disappearing because of an increase in sea temperature, pollution, dredging, and sedimentation
-very sensitive to environmental changes
-fringing reefs (on continental shelves), barrier reefs (parallel to the shore), coral atolls (rings of coral that grow on top of sunken oceanic volcanoes)
-disappearing because of an increase in sea temperature, pollution, dredging, and sedimentation
-very sensitive to environmental changes