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Title: Aquatic Ecology Notes


1
Aquatic Ecology Notes
2
Chapter Overview Questions
  • What are the basic types of aquatic life zones
    and what factors influence the kinds of life they
    contain?
  • What are the major types of freshwater life
    zones, and how do human activities affect them?

3
Chapter Overview Questions
  • What do we know about aquatic biodiversity, and
    what is its economic and ecological importance?
  • How are human activities affecting aquatic
    biodiversity?
  • How can we manage and sustain the worlds marine
    fisheries?

4
Chapter Overview Questions (contd)
  • How can we protect, sustain, and restore
    wetlands?
  • How can we protect, sustain, and restore lakes,
    rivers, and freshwater fisheries?

5
Chapter Overview Questions
  • Why is water so important, how much freshwater is
    available to us, and how much of it are we using?
  • What causes freshwater shortages, and what can be
    done about this problem?
  • What are the advantages and disadvantages of
    withdrawing groundwater?
  • What are the advantages and disadvantages of
    using dams and reservoirs to supply more water?

6
Chapter Overview Questions (contd)
  • What are the advantages and disadvantages of
    transferring large amounts of water from one
    place to another?
  • Can removing salt from seawater solve our water
    supply problems?
  • How can we waste less water?
  • How can we use the earths water more
    sustainably?
  • What causes flooding, and what can we do about it?

7
WATERS 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.

8
WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL
  • Comparison of population sizes and shares of the
    worlds freshwater among the continents.

Figure 14-2
9
WATERS 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.

10

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
11
WATERS 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).

12
Salinity
  • The saltiness.

13
What 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).

14
Phytoplankton
  • Description small drifting plants
  • Niche they are producers that support most
    aquatic food chains
  • Example cyanobacteria many types of algae

15
Zooplankton
  • Description herbivores that feed on
    phytoplankton or other zooplankton
  • Niche food stock for larger consumers
  • Example krill small crustaceans

16
Nekton
  • Description larger, strong-swimming consumers
  • Niche top consumers in the aquatic ecosystem
  • Example fish, turtles, and whales

17
Benthos
  • Description bottom-dwelling creatures
  • Niche primary consumers, decomposers
  • Example barnacles, oysters, and lobsters

18
Freshwater Ecosystems
19
FRESHWATER 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
20
Flowing Water Ecosystems
  • Because of different environmental conditions in
    each zone, a river is a system of different
    ecosystems.

21
Natural 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
22
Freshwater Streams and RiversFrom the Mountains
to the Oceans
  • Water flowing from mountains to the sea creates
    different aquatic conditions and habitats.

Figure 6-17
23
Headwater 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.

24
Downstream Characteristics
  • Slower-moving water, less oxygen, warmer
    temperatures, and lots of algae and
    cyanobacteria.

25
Energy Source
  • Gravity

26
Standing Water Ecosystems
  • Lakes, ponds, etc.

27
Life 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.

28
Lakes 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).

29
Littoral 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.

30
Limnetic Zone
  • Open, sunlit water that extends to the depth
    penetrated by sunlight.

31
Profundal Zone
  • Deep, open water where it is too dark for
    photosynthesis.

32
Lakes Water-Filled Depressions
Figure 6-15
33
Thermal Stratification
  • The temperature difference in deep lakes where
    there are warm summers and cold winters.

34
Lakes 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.

35
Causes
  • During the summer, lakes become stratified into
    different temperature layers that resist mixing
    because summer sunlight warms surface waters,
    making them less dense.

36
Thermocline
  • The middle layer that acts as a barrier to the
    transfer of nutrients and dissolved oxygen.

37
Fall 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.

38
Spring Turnover
  • As top water warms and ice melts, it sinks
    through and below the cooler, less dense water,
    sending oxygen down and nutrients up.

39
Freshwater Wetlands
40
Freshwater 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
41
Freshwater 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.

42
Marshes
  • An area of temporarily flooded, often silty land
    beside a river or lake.

43
Swamps
  • A lowland region permanently covered with water.

44
Hardwood Bottomland Forest
  • An area down by a river or stream where lots of
    hardwoods, like oaks, grow.

45
Prairie Potholes
  • These are depressions that hold water out on the
    prairie, especially up north in Canada. It is a
    very good duck habitat.

46
Peat 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.

47
Importance of freshwater wetlands
  • They filter purify water.
  • Habitat for many animals and plants.

48
Historical 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.

49
Estuaries
50
Definition
  • A partially enclosed area of coastal water where
    sea water mixes with freshwater.

51
Salt 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.

52
Mangrove 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.

53
Importance 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.
  • As a comparison, prime Kansas farmland has a top
    value of 1,200 and an annual production value of
    600.

54
The Everglades
  • Southern Florida to the Keys

55
Case 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.

56
Problems
  • As Miami develops, it encroaches on everglades.
    Plus, it prompts people vs. wildlife. It is
    freshwater and local areas are draining it.

57
Restoring the Florida Everglades
  • The project has been attempting to restore the
    Everglades and Florida water supplies.

Figure 12-10
58
Restoration
  • Build huge aqueduct, or find other sources of
    fresh water an protect it federally under
    endangered species act, etc.

59
The Water Resource
60
Importance
  • 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.

61
Hydrogen Bonds
62
Attraction Between Molecules
  • The strong forces of attraction between molecules
    of water.

63
Heat Capacity
  • Water changes temp very slowly because it can
    store heat. This protects living organisms from
    the shock of abrupt temperature changes.

64
Heat of Vaporization
  • The temperature at which water turns to vapor.

65
Universal Solvent
  • Water can dissolve a wide variety of compounds.
    This means it can easily become polluted by
    water-soluble wastes.

66
Expansion When Frozen
  • Ice has a lower density than liquid water. Thus,
    ice floats on water.

67
Hydrologic Cycle
68
Surface Water
  • Examples streams, rivers, and lakes
  • Source precipitation
  • Watershed Ex. small streams ? larger streams ?
    rivers ? sea

69
Groundwater
  • 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).

70
Water Usage
  • Irrigation watering crops
  • Industry coolant (power plant)
  • Domestic and Municipal drinking, sewage,
    bathwater, dishwater laundry

71
Problems
72
Too Much Water
  • Problems include flooding, pollution of water
    supply, and sewage seeping into the ground.

73
TOO 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.

74
TOO MUCH WATER
  • Comparison of St. Louis, Missouri under normal
    conditions (1988) and after severe flooding
    (1993).

Figure 14-22
75
TOO MUCH WATER
  • Human activities have contributed to flood deaths
    and damages.

Figure 14-23
76

Forested Hillside
Oxygen released by vegetation
Diverse ecological habitat
Evapotranspiration
Trees reduce soil erosion from heavy rain and wind
Agricultural land
Steady river flow
Leaf litter improves soil fertility
Tree roots stabilize soil and aid water flow
Vegetation releases water slowly and reduces
flooding
Fig. 14-23a, p. 330
77

After Deforestation
Tree plantation
Evapotranspiration decreases
Roads destabilize hillsides
Ranching accelerates soil erosion by water and
wind
Winds remove fragile topsoil
Gullies and landslides
Agricultural land is flooded and silted up
Heavy rain leaches nutrients from soil and erodes
topsoil
Rapid runoff causes flooding
Silt from erosion blocks rivers and reservoirs
and causes flooding downstream
Fig. 14-23b, p. 330
78
Too Little Water
79
Examples
  • Examples include drought and expanding deserts.

80
Overdrawing 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
81
Case 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.

82
Aquifer Depletion
  • This harms endangered species, and salt water can
    seep in.

83
Salinization of Irrigated Soil
  • Water is poured onto soil and evaporates. Over
    time, as this is repeated, nothing will grow
    there anymore.

84
U.S. Water Problems
85
Surface 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.

86
Effects 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
87
Effects 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.

88
Effects 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.

89
Mono Lake
  • (like the Dead Sea) This has a huge salt
    concentration due to mans draining.

90
Colorado 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.

91
The 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
92

IDAHO
WYOMING
Dam
Aqueduct or canal
Salt Lake City
Upper Basin
Denver
Grand Junction
Lower Basin
UPPER BASIN
UTAH
Colorado River
NEVADA
Lake Powell
COLORADO
Grand Canyon
Glen Canyon Dam
Las Vegas
NEW MEXICO
Boulder City
CALIFORNIA
Los Angeles
ARIZONA
Albuquerque
LOWER BASIN
Palm Springs
0
100 mi.
Phoenix
San Diego
Yuma
0
150 km
Tucson
Mexicali
All-American Canal
MEXICO
Gulf of California
Fig. 14-14, p. 318
93
Case 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).

94
Case 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
95
Groundwater Problems
  • These include pollution, salt, and draining too
    much.

96
Other Effects of Groundwater Overpumping
  • Sinkholes form when the roof of an underground
    cavern collapses after being drained of
    groundwater.

Figure 14-10
97
Groundwater 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
98
Ogallala 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.

99
Global Water Problems
100
Impacts 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.

101
Core 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
102
Core 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.

103
Stable 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.

104
Drinking Water Problems
105
Coliform 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?).

106
Oxygen 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.

107
Water-Soluble Inorganic Chemicals
  • These include acids, salts, mercury, and lead.
    They make water unfit to drink.

108
Organic Material
  • These include oil, gas, plastics, pesticides, and
    detergents.

109
Population Growth
  • Problems include over-drawing fresh water,
    pollution, and over-building so that water cant
    seep into the ground.

110
Sharing 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.

111
Water Management
112
Dams 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.

113
USING 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.

114

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
115

Powerlines
Reservoir
Dam
Powerhouse
Intake
Turbine
Fig. 14-13b, p. 317
116
Case 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.

117
Dam 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.

118
Water Diversion
  • Description Damming a river to control where
    the water flows
  • Benefits Keeps water where we want it- cities!
  • Problems Drains wetlands, destroys land

119
Desalinization
  • 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?

120
DESALTING 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.

121
DESALTING 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.

122
Harvesting 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.

123
INCREASING 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.

124

Drip irrigation
(efficiency 9095)
Gravity flow
(efficiency 60 and 80 with surge valves)
Center pivot
(efficiency 8095)
Above- or below-ground pipes or tubes deliver
water to individual plant roots.
Water usually pumped from underground and sprayed
from mobile boom with sprinklers.
Water usually comes from an aqueduct system or a
nearby river.
Fig. 14-18, p. 325
125
Conservation
  • 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

126
Fishing Problems Techniques
  • The major decline in the worldwide catch of fish
    since 1990 is because of over-fishing.
  • By-catch- fish or animals that were not meant to
    be caught.

127
Overfishing and Extinction Gone Fishing, Fish
Gone
  • About 75 of the worlds commercially valuable
    marine fish species are over fished or fished
    near their sustainable limits.
  • Big fish are becoming scarce.
  • Smaller fish are next.
  • We throw away 30 of the fish we catch.
  • We needlessly kill sea mammals and birds.

128
Trawler fishing
Fish farming in cage
Spotter airplane
Sonar
Purse-seine fishing
Trawl flap
Trawl lines
Fish school
Trawl bag
Drift-net fishing
Long line fishing
Buoy
Float
Lines with hooks
Deep sea aquaculture cage
Fish caught by gills
Fig. 12-A, p. 255
129
Purse Seines
130
Purse Seines
  • A large purse-like net is put into the ocean and
    is then closed like a drawstring purse to trap
    the fish.
  • Tuna is a fish typically caught in purse seines
  • Dolphins are a by-catch of purse seines

131
Long-line fishing
  • Lines are put out that can be up to 80 miles long
    w/ thousands of baited hooks on them. These are
    left out free-floating for days and then the boat
    comes back and picks them up.
  • Pilot whales, dolphins, sea turtles, and birds
    are by-catch of this technique.

132
Drift-net fishing
  • Each net hangs as much as 50 feet below the
    surface and up to 34 miles long.
  • Anything that comes into contact w/ these nearly
    invisible nets are entangled.
  • This leads to overfishing
  • Many unwanted fish and marine mammals, turtles
    and seabirds are caught.

133
HUMAN IMPACTS ON AQUATIC BIODIVERSITY
  • Area of ocean before and after a trawler net,
    acting like a giant plow, scraped it.

Figure 12-2
134
Population Growth and Pollution
  • Each year plastic items dumped from ships and
    left as litter on beaches threaten marine life.

Figure 12-3
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