Title: Water Quality Notes
1Water
2WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL
- Water keeps us alive, moderates climate, sculpts
the land, removes and dilutes wastes and
pollutants, and moves continually through the
hydrologic cycle. - Only about 0.02 of the earths water supply is
available to us as liquid freshwater.
3WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL
- Comparison of population sizes and shares of the
worlds freshwater among the continents.
Figure 14-2
4WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL
- Some precipitation infiltrates the ground and is
stored in soil and rock (groundwater). - Water that does not sink into the ground or
evaporate into the air runs off (surface runoff)
into bodies of water. - The land from which the surface water drains into
a body of water is called its watershed or
drainage basin.
5 Unconfined Aquifer Recharge Area
Evaporation and transpiration
Evaporation
Precipitation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Water table
Infiltration
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 14-3, p. 308
6WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL
- We currently use more than half of the worlds
reliable runoff of surface water and could be
using 70-90 by 2025. - About 70 of the water we withdraw from rivers,
lakes, and aquifers is not returned to these
sources. - Irrigation is the biggest user of water (70),
followed by industries (20) and cities and
residences (10).
7The Water Resource
8Importance
- Leonardo da Vinci said that Water is the driver
of nature. Without water, the other nutrient
cycles would not exist in their present forms,
and current forms of life on earth could not
exist.
9Hydrogen Bonds
10Attraction Between Molecules
- The strong forces of attraction between molecules
of water.
11Heat Capacity
- Water changes temp very slowly because it can
store heat. This protects living organisms from
the shock of abrupt temperature changes.
12Heat of Vaporization
- The temperature at which water turns to vapor.
13Universal Solvent
- Water can dissolve a wide variety of compounds.
This means it can easily become polluted by
water-soluble wastes.
14Expansion When Frozen
- Ice has a lower density than liquid water. Thus,
ice floats on water.
15Niches
16What Kinds of Organisms Live in Aquatic Life
Zones?
- Aquatic systems contain floating, drifting,
swimming, bottom-dwelling, and decomposer
organisms. - Plankton important group of weakly swimming,
free-floating biota. - Phytoplankton (plant), Zooplankton (animal),
Ultraplankton (photosynthetic bacteria) - Necton fish, turtles, whales.
- Benthos bottom dwellers (barnacles, oysters).
- Decomposers breakdown organic compounds (mostly
bacteria).
17Phytoplankton
- Description small drifting plants
- Niche they are producers that support most
aquatic food chains - Example cyanobacteria many types of algae
18Zooplankton
- Description herbivores that feed on
phytoplankton or other zooplankton - Niche food stock for larger consumers
- Example krill small crustaceans
19Nekton
- Description larger, strong-swimming consumers
- Niche top consumers in the aquatic ecosystem
- Example fish, turtles, and whales
20Benthos
- Description bottom-dwelling creatures
- Niche primary consumers, decomposers
- Example barnacles, oysters, and lobsters
21Freshwater Ecosystems
22FRESHWATER LIFE ZONES
- Freshwater life zones include
- Standing (lentic) water such as lakes, ponds, and
inland wetlands. - Flowing (lotic) systems such as streams and
rivers.
Figure 6-14
23Flowing Water Ecosystems
- Because of different environmental conditions in
each zone, a river is a system of different
ecosystems.
24Natural Capital
Ecological Services of Rivers
- Deliver nutrients to sea to help sustain
coastal fisheries - Deposit silt that maintains deltas
- Purify water
- Renew and renourish wetlands
- Provide habitats for wildlife
Fig. 12-11, p. 267
25Freshwater Streams and RiversFrom the Mountains
to the Oceans
- Water flowing from mountains to the sea creates
different aquatic conditions and habitats.
Figure 6-17
26Headwater Stream Characteristics
- A narrow zone of cold, clear water that rushes
over waterfalls and rapids. Large amounts of
oxygen are present. Fish are also present. Ex.
trout.
27Downstream Characteristics
- Slower-moving water, less oxygen, warmer
temperatures, and lots of algae and
cyanobacteria.
28Energy Source
29Standing Water Ecosystems
30Life in Layers
- Life in most aquatic systems is found in surface,
middle, and bottom layers. - Temperature, access to sunlight for
photosynthesis, dissolved oxygen content,
nutrient availability changes with depth. - Euphotic zone (upper layer in deep water
habitats) sunlight can penetrate.
31Lakes Water-Filled Depressions
- Lakes are large natural bodies of standing
freshwater formed from precipitation, runoff, and
groundwater seepage consisting of - Littoral zone (near shore, shallow, with rooted
plants). - Limnetic zone (open, offshore area, sunlit).
- Profundal zone (deep, open water, too dark for
photosynthesis). - Benthic zone (bottom of lake, nourished by dead
matter).
32Littoral Zone
- A shallow area near the shore, to the depth at
which rooted plants stop growing. Ex. frogs,
snails, insects, fish, cattails, and water lilies.
33Limnetic Zone
- Open, sunlit water that extends to the depth
penetrated by sunlight.
34Profundal Zone
- Deep, open water where it is too dark for
photosynthesis.
35Thermal Stratification
36Lakes Water-Filled Depressions
Figure 6-15
37Definition
- The temperature difference in deep lakes where
there are warm summers and cold winters.
38Lakes Water-Filled Depressions
- During summer and winter in deep temperate zone
lakes the become stratified into temperature
layers and will overturn. - This equalizes the temperature at all depths.
- Oxygen is brought from the surface to the lake
bottom and nutrients from the bottom are brought
to the top.
39Causes
- During the summer, lakes become stratified into
different temperature layers that resist mixing
because summer sunlight warms surface waters,
making them less dense.
40Thermocline
- The middle layer that acts as a barrier to the
transfer of nutrients and dissolved oxygen.
41Fall Turnover
- As the temperatures begin to drop, the surface
layer becomes more dense, and it sinks to the
bottom. This mixing brings nutrients from the
bottom up to the surface and sends oxygen to the
bottom.
42Spring Turnover
- As top water warms and ice melts, it sinks
through and below the cooler, less dense water,
sending oxygen down and nutrients up.
43Freshwater Wetlands
44Freshwater Inland Wetlands Vital Sponges
- Inland wetlands act like natural sponges that
absorb and store excess water from storms and
provide a variety of wildlife habitats.
Figure 6-18
45Freshwater Inland Wetlands Vital Sponges
- Filter and degrade pollutants.
- Reduce flooding and erosion by absorbing slowly
releasing overflows. - Help replenish stream flows during dry periods.
- Help recharge ground aquifers.
- Provide economic resources and recreation.
46Marshes
- An area of temporarily flooded, often silty land
beside a river or lake.
47Swamps
- A lowland region permanently covered with water.
48Hardwood Bottomland Forest
- An area down by a river or stream where lots of
hardwoods, like oaks, grow.
49Prairie Potholes
- These are depressions that hold water out on the
prairie, especially up north in Canada. It is a
very good duck habitat.
50Peat Moss Bog
- A wet area that over time fills in (the last
stage of succession is peat moss). It can be
very deep. In Ireland, they burn this for wood.
51Importance of freshwater wetlands
- They filter purify water.
- Habitat for many animals and plants.
52Historical Aspects
- Developers and farmers want Congress to revise
the definition of wetlands. This would make
60-75 of all wetlands unavailable for
protection. The Audubon Society estimates that
wetlands provide water quality protection worth
1.6 billion per year, and they say if that
wetlands are destroyed, the U.S. would spend 7.7
billion to 31 billion per year in additional
flood-control costs.
53Estuaries
54Definition
- A partially enclosed area of coastal water where
sea water mixes with freshwater.
55Salt Marshes
- The ground here is saturated with water and there
is little oxygen, so decay takes place slowly.
It has a surface inlet and outlet, and contains
many invertebrates. It is also the breeding
ground for many ocean animals. Ex. crabs and
shellfish.
56Mangrove Forests
- These are along warm, tropical coasts where there
is too much silt for coral reefs to grow. It is
dominated by salt-tolerant trees called mangroves
(55 different species exist). It also helps to
protect the coastline from erosion and provides a
breeding nursery for some 2000 species of fish,
invertebrates, and plants.
57Importance of Estuaries
- Just one acre of estuary provides 75,000 worth
of free waste treatment, and has a value of about
83,000 when recreation and fish for food are
included. - Prime Kansas farmland has a top value of 1,200
and an annual production value of 600.
58The Everglades
- Southern Florida to the Keys
59Case Study Restoring the Florida Everglades
- The worlds largest ecological restoration
project involves trying to undo some of the
damage inflicted on the Everglades by human
activities. - 90 of parks wading birds have vanished.
- Other vertebrate populations down 75-95.
- Large volumes of water that once flowed through
the park have been diverted for crops and cities. - Runoff has caused noxious algal blooms.
60Problems
- As Miami develops, it encroaches on everglades.
Plus, it prompts people vs. wildlife. It is
freshwater and local areas are draining it.
61Restoring the Florida Everglades
- The project has been attempting to restore the
Everglades and Florida water supplies.
Figure 12-10
62Restoration
- Build huge aqueduct, or find other sources of
fresh water an protect it federally under
endangered species act, etc.
63Hydrologic Cycle
64Surface Water
- Examples streams, rivers, and lakes
- Source precipitation
- Watershed Ex. small streams ? larger streams ?
rivers ? sea
65Groundwater
- Aquifersporous rock w/ water flowing through
- Water Table the level of earths land crust to
which the aquifer is filled - Renewability the circulation rate of
groundwater is slow (300 to 4,600 years).
66Water Usage
- Irrigation watering crops
- Industry coolant (power plant)
- Domestic and Municipal drinking, sewage,
bathwater, dishwater laundry
67Problems
68Too Much Water
- Problems include flooding, pollution of water
supply, and sewage seeping into the ground.
69TOO MUCH WATER
- Heavy rainfall, rapid snowmelt, removal of
vegetation, and destruction of wetlands cause
flooding. - Floodplains, which usually include highly
productive wetlands, help provide natural flood
and erosion control, maintain high water quality,
and recharge groundwater. - To minimize floods, rivers have been narrowed
with levees and walls, and dammed to store water.
70TOO MUCH WATER
- Comparison of St. Louis, Missouri under normal
conditions (1988) and after severe flooding
(1993).
Figure 14-22
71TOO MUCH WATER
- Human activities have contributed to flood deaths
and damages.
Figure 14-23
72Too Little Water
73Examples
- Examples include drought and expanding deserts.
74Overdrawing Surface Water
- Lake levels drop, recreation use drops, fisheries
drop, and salinization occurs. Ex. Soviet Union
(Aral Sea) the inland sea drained the river that
fed into it. Now its a huge disaster (read pg.
322 in text).
1997
1964
75Case Study The Aral Sea Disaster
- Diverting water from the Aral Sea and its two
feeder rivers mostly for irrigation has created a
major ecological, economic, and health disaster. - About 85 of the wetlands have been eliminated
and roughly 50 of the local bird and mammal
species have disappeared. - Since 1961, the seas salinity has tripled and
the water has dropped by 22 meters most likely
causing 20 of the 24 native fish species to go
extinct.
76Aquifer Depletion
- This harms endangered species, and salt water can
seep in.
77Salinization of Irrigated Soil
- Water is poured onto soil and evaporates. Over
time, as this is repeated, nothing will grow
there anymore.
78U.S. Water Problems
79Surface Water Problems
- The polluted Mississippi River (non-source point
pollution) has too much phosphorus. - In the Eerie Canal, which connects the ocean to
the Great Lakes, lampreys came in and depleted
the fish. The zebra mollusk is also a problem in
the Great Lakes.
80Effects of Plant Nutrients on LakesToo Much of
a Good Thing
- Plant nutrients from a lakes environment affect
the types and numbers of organisms it can support.
Figure 6-16
81Effects of Plant Nutrients on LakesToo Much of
a Good Thing
- Plant nutrients from a lakes environment affect
the types and numbers of organisms it can
support. - Oligotrophic (poorly nourished) lake Usually
newly formed lake with small supply of plant
nutrient input. - Eutrophic (well nourished) lake Over time,
sediment, organic material, and inorganic
nutrients wash into lakes causing excessive plant
growth.
82Effects of Plant Nutrients on LakesToo Much of
a Good Thing
- Cultural eutrophication
- Human inputs of nutrients from the atmosphere and
urban and agricultural areas can accelerate the
eutrophication process.
83Mono Lake
- (like the Dead Sea) This has a huge salt
concentration due to mans draining.
84Colorado River Basin
- These are dams reservoirs that feed from the
Colorado River all the way to San Diego, LA, Palm
Springs, Phoenix Mexico. So far has worked
because they havent withdrawn their full
allocations. See pg306.
85The Colorado River Basin
- The area drained by this basin is equal to more
than one-twelfth of the land area of the lower 48
states.
Figure 14-14
86Case Study The Colorado Basin an Overtapped
Resource
- The Colorado River has so many dams and
withdrawals that it often does not reach the
ocean. - 14 major dams and reservoirs, and canals.
- Water is mostly used in desert area of the U.S.
- Provides electricity from hydroelectric plants
for 30 million people (1/10th of the U.S.
population).
87Case Study The Colorado Basin an Overtapped
Resource
- Lake Powell, is the second largest reservoir in
the U.S. - It hosts one of the hydroelectric plants located
on the Colorado River.
Figure 14-15
88Groundwater Problems
- These include pollution, salt, and draining too
much.
89Other Effects of Groundwater Overpumping
- Sinkholes form when the roof of an underground
cavern collapses after being drained of
groundwater.
Figure 14-10
90Groundwater Depletion A Growing Problem
- Areas of greatest aquifer depletion from
groundwater overdraft in the continental U.S.
- The Ogallala, the worlds largest aquifer, is
most of the red area in the center (Midwest).
Figure 14-8
91Ogallala Aquifer
- This is the worlds largest known aquifer, and
fuels agricultural regions in the U.S. It
extends from South Dakota to Texas. Its
essentially a non-renewable aquifer from the last
ice age with an extremely slow recharge rate. In
some cases, water is pumped out 8 to 10 times
faster than it is renewed. Northern states will
still have ample supplies, but for the south its
getting thinner. It is estimated that ¼ of the
aquifer will be depleted by 2020.
92Global Water Problems
93Impacts of Human Activities on Freshwater Systems
- Dams, cities, farmlands, and filled-in wetlands
alter and degrade freshwater habitats. - Dams, diversions and canals have fragmented about
40 of the worlds 237 large rivers. - Flood control levees and dikes alter and destroy
aquatic habitats. - Cities and farmlands add pollutants and excess
plant nutrients to streams and rivers. - Many inland wetlands have been drained or filled
for agriculture or (sub)urban development.
94Core Case Study A Biological Roller Coaster Ride
in Lake Victoria
- Lake Victoria has lost their endemic fish species
to large introduced predatory fish.
Figure 12-1
95Core Case Study A Biological Roller Coaster Ride
in Lake Victoria
- Reasons for Lake Victorias loss of biodiversity
- Introduction of Nile perch.
- Lake experienced algal blooms from nutrient
runoff. - Invasion of water hyacinth has blocked sunlight
and deprived oxygen. - Nile perch is in decline because it has eaten its
own food supply.
96Stable Runoff
- As water runs off from rain, its supposed to get
into rivers, and finally off to the sea. But
when we dam rivers, less goes to the ocean,
meaning the brackish water (where the river hits
the ocean) becomes more salty. This is the
breeding ground for many fish and invertebrates.
This harms the ecology of the area.
97Drinking Water Problems
98Coliform Bacteria
- The W.H.O. recommends there be zero colonies of
bacteria per 100ml of drinking water and 200
colonies per 100ml of swimming water. The
average human excretes 2 billion organisms per
day (see how easily untreated sewage can
contaminate water?).
99Oxygen Demanding Wastes
- These are organic wastes that can be decomposed
by aerobic bacteria (causes lack of oxygen).
Fish die as a result of a lack of oxygen.
100Water-Soluble Inorganic Chemicals
- These include acids, salts, mercury, and lead.
They make water unfit to drink.
101Organic Material
- These include oil, gas, plastics, pesticides, and
detergents.
102Population Growth
- Problems include over-drawing fresh water,
pollution, and over-building so that water cant
seep into the ground.
103Sharing Water Resources
- There are water wars out west. California bought
the water from the Colorado River, but Arizona
wants it. Who owns it? The same thing is
happening in Texas. More water rights are sold
than the actual amount of water. How do you
share water? This is a problem all over the
world.
104Water Management
105Dams and Reservoirs
- Description A dammed stream that can capture
store water from rain melted snow. - Benefits Hydroelectric power provides water
to towns recreation controls floods downstream - Problems Reduces downstream flow prevents
water from reaching the sea (Colorado River)
devastates fish life reduces biodiversity.
106USING DAMS AND RESERVOIRS TO SUPPLY MORE WATER
- Large dams and reservoirs can produce cheap
electricity, reduce downstream flooding, and
provide year-round water for irrigating cropland,
but they also displace people and disrupt aquatic
systems.
107 Provides water for year-round irrigation of
cropland
Flooded land destroys forests or cropland and
displaces people
Large losses of water through evaporation
Provides water for drinking
Downstream cropland and estuaries are deprived of
nutrient-rich silt
Reservoir is useful for recreation and fishing
Risk of failure and devastating downstream
flooding
Can produce cheap electricity (hydropower)
Downstream flooding is reduced
Migration and spawning of some fish are disrupted
Fig. 14-13a, p. 317
108Case Study Chinas Three Gorges Dam
- There is a debate over whether the advantages of
the worlds largest dam and reservoir will
outweigh its disadvantages. - The dam will be 2 kilometers long.
- The electric output will be that of 18 large
coal-burning or nuclear power plants. - It will facilitate ship travel reducing
transportation costs. - Dam will displace 1.2 million people.
- Dam is built over seismatic fault and already has
small cracks.
109Dam Removal
- Some dams are being removed for ecological
reasons and because they have outlived their
usefulness. - In 1998 the U.S. Army Corps of Engineers
announced that it would no longer build large
dams and diversion projects in the U.S. - The Federal Energy Regulatory Commission has
approved the removal of nearly 500 dams. - Removing dams can reestablish ecosystems, but can
also re-release toxicants into the environment.
110Water Diversion
- Description Damming a river to control where
the water flows - Benefits Keeps water where we want it- cities!
- Problems Drains wetlands, destroys land
111Desalinization
- Description Removing salt from salt water
- Benefits Freshwater
- Problems Uses lots of energy costs 3-5Xs more
money what do we do with the salt?
112DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING
ICEBERGS AND GIANT BAGGIES
- Removing salt from seawater by current methods is
expensive and produces large amounts of salty
wastewater that must be disposed of safely. - Distillation heating saltwater until it
evaporates, leaves behind water in solid form. - Reverse osmosis uses high pressure to force
saltwater through a membrane filter.
113DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING
ICEBERGS AND GIANT BAGGIES
- Seeding clouds with tiny particles of chemicals
to increase rainfall towing icebergs or huge bags
filled with freshwater to dry coastal areas have
all been proposed but are unlikely to provide
significant amounts of freshwater.
114Harvesting Icebergs
- Description Towing massive icebergs to arid
coastal areas (S. California Saudi Arabia) - Benefits freshwater
- Problems Technology not available costs too
high raise temperatures around the earth.
115INCREASING WATER SUPPLIES BY WASTING LESS WATER
- Sixty percent of the worlds irrigation water is
currently wasted, but improved irrigation
techniques could cut this waste to 5-20. - Center-pivot, low pressure sprinklers sprays
water directly onto crop. - It allows 80 of water to reach crop.
- Has reduced depletion of Ogallala aquifer in
Texas High Plains by 30.
116Conservation
- Description Saving the water we have
- Methods recycling conserving at home
xeriscaping fix leaks - Benefits Saves money Saves Wildlife
- Problems bothersome to people lack of caring
laziness
117Importance of the Ocean Environment
Marine Ecology
118Area
- Saltwater makes up 97 of the water on earth
Life There are 250,000 known species of marine
plants and animals, many are food for other
organisms, like us.
119Temperature
- Solar heat is distributed by ocean currents as
ocean water evaporates. - The oceans are major players in the earths
climate are a gigantic reservoir for carbon
dioxide therefore they help regulate the temp.
of the troposphere.
120Zones of the Marine Environment
- Two major zones that break up into smaller zones
coastal and the open sea
121Intertidal or Beach Zone
- Broken up into five areas
122Lower Shoreface
- The deepest part of the beach farther into the
water, before the breaker bar that forms waves
123Upper Shoreface
- Shallow zone where the waves begin to form
124Forebeach
- Contains the swash zone place where the waves
crash.
125Backbeach
- Only under water during high tide
126Fore-Island Dunes
- Sand dunes doesn't flood often, except during
hurricanes, etc. Constantly changing due to the
wind
127Estuary
- Where fresh water and salt water meet
An estuary is a coastal body of water, partly
surrounded by land, with access to the open ocean
and a large supply of fresh water from a river
128Characteristics
129Salinity
- Salinity fluctuates with tidal cycles, the time
of year, precipitation. The organisms that live
here must be able to tolerate these conditions
130Fertility of Estuaries
- Estuaries are the most fertile ecosystems in the
world - Greater productivity than either the adjacent
ocean or the fresh water upriver
131Reasons for High Fertility
- Nutrients are transported from the land into
rivers that flow into the estuary - Tidal action circulates nutrients and helps
remove wastes - A high level of light due to shallow water
- Many plants provide an extensive photosynthetic
carpet
132Difficulties
- Sandy beach Life must deal with a shifting
environment that threatens to engulf them no
protection against wave action. Most animals
bury into the sand. They move with the tides, so
theyre always underwater dont dry out.
133Difficulties (Continued)
- Rocky shore high wave action at high tide
drying out temperature changes during low.
Animals have a way of sealing in moisture like
a shell find a way to cling to the rocks so
they dont get washed away with waves.
134Pelagic
The Open Ocean
- The open ocean environment divided into neritic
(open ocean from the shoreline to a depth of
200m) and oceanic provinces (depths gt 200m).
135Euphotic Zone
- Lots of light. From 0 - 200 meters.
Photosynthesis takes place here.
136Bathyal Zone
- The dimly lit part of ocean. From 200 - 1500
meters.
137Benthic Characteristics (ocean floor)
- The ocean floor consists of sediments (mostly
sand and mud) - Many marine animals, like worms and clams, burrow
- Bacteria are common can go down 500 meters
below ocean floor. The Benthic environment
extends from the shore to the deep.
138Sea Grass Beds
- Flowering plants that have adapted to complete
submersion in salty water.
139Location of sea grass
- Found in shallow water to depths of 10 meters
where they can photosynthesize. Sea grasses are
found in quiet, temperate, tropical, and
subtropical waters not in polar waters.
Examples
Eel, turtle, and manatee grass.
140Ecological Importance
- Reduce surface erosion, provide food, provide
habitats for many marine organisms. - Animals that eat sea grass are manatees, green
turtles, parrotfish, sturgeon fish, and sea
urchins.
141Abyssal Zone
- Completely dark. Extends to a depth of 4000 to
6000 meters (2.5 to 3.7 miles). Water here is
very cold has little dissolved oxygen.
142Kelp
- The largest of the brown algae, many reach
lengths of 60 meters (200 feet). Common in cooler
water are found along rocky coasts. Provide
habitat for many animals like tubeworms, sponges,
clams, fish, mammals. Some animals eat the
kelp.
143Characteristics
Coral Reefs
- Built from layers of calcium carbonate, coral
reefs are found in warm, shallow sea water. The
living portions must grow in shallow waters where
light hits. They are the most diverse of all
marine ecosystems.
144Examples
- Many coral reefs are made of red coralline algae
that photosynthesize. - Others have zooxanthellae (symbiotic algae) that
live and photosynthesize in their tissues. - Not all corals have zooxanthellae, but only those
with it build reefs. - Coral animals also capture food at night with
stinging tentacles that paralyze zooplankton and
small animals that drift nearby.
145Coral Reef Waters
- The waters where coral reefs are found are often
poor in nutrients. Yet, other factors are
favorable such as temperature, sunlight year
round, and zooxanthellae.
146Growth
- Coral reefs grow slowly as one dies, another
organism grows on it.
147Fringing Reef
Types of Coral Reefs
- The most common type of coral reef. It is
directly attached to the shore of a volcanic
island or continent.
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149 Fringing
Reef Bora Bora NASA JPL Satellite Space Shuttle
Sensor SIR-C/X-SAR
150Atoll
- A circular reef that surrounds a central lagoon
of quiet water. - An atoll forms on top of the cone of a submerged
volcanic island. - More than 300 atolls are found in the Pacific
and Indian Oceans.
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152 View of Midway Atoll
from Space Shuttle
153 Atolls in The
Maldives Landsat 7
154Barrier Reef
- A lagoon of open water separates the land from
the barrier reef. - The largest barrier reef is the Great Barrier
Reef off the coast of Australia. - The second largest is off the coast of Belize.
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157Provides a Habitat
Ecological Importance of Coral Reefs
- Provides a habitat for a wide variety of marine
organisms.
158Coastline Protection
- Protects coasts from shoreline erosion.
159Benefits for Humans
- Provides humans with seafood, pharmaceuticals,
and recreational/tourism dollars