Question of the Day Which of the following elements is most likely to limit primary production in...

Question of the DayQuestion of the Day

Which of the following elements is most likely to limit primary production in freshwater lakes?

oxygen calcium phosphorus carbon iron

Aquatic Ecology Aquatic Ecology NotesNotes

Chapter Overview Chapter Overview QuestionsQuestions

What are the basic types of What are the basic types of aquatic life zones and what factors aquatic life zones and what factors influence the kinds of life they influence the kinds of life they contain?contain?

What are the major types of What are the major types of freshwater life zones, and how do freshwater life zones, and how do human activities affect them?human activities affect them?


What do we know about aquatic What do we know about aquatic biodiversity, and what is its biodiversity, and what is its economic and ecological economic and ecological importance?importance?

How are human activities affecting How are human activities affecting aquatic biodiversity?aquatic biodiversity?

How can we manage and sustain How can we manage and sustain the worldthe world’’s marine fisheries?s marine fisheries?

Chapter Overview Chapter Overview Questions (contQuestions (cont’’d)d)

How can we protect, sustain, and How can we protect, sustain, and restore wetlands?restore wetlands?

How can we protect, sustain, and How can we protect, sustain, and restore lakes, rivers, and restore lakes, rivers, and freshwater fisheries?freshwater fisheries?


Why is water so important, how much freshwater Why is water so important, how much freshwater is available to us, and how much of it are we is available to us, and how much of it are we using?using?

What causes freshwater shortages, and what can What causes freshwater shortages, and what can be done about this problem?be done about this problem?

What are the advantages and disadvantages of What are the advantages and disadvantages of withdrawing groundwater?withdrawing groundwater?

What are the advantages and disadvantages of What are the advantages and disadvantages of using dams and reservoirs to supply more water?using dams and reservoirs to supply more water?

Chapter Overview Chapter Overview Questions (contQuestions (cont’’d)d)

What are the advantages and disadvantages of What are the advantages and disadvantages of transferring large amounts of water from one transferring large amounts of water from one place to another?place to another?

Can removing salt from seawater solve our water Can removing salt from seawater solve our water supply problems?supply problems?

How can we waste less water?How can we waste less water? How can we use the earthHow can we use the earth’’s water more s water more

sustainably?sustainably? What causes flooding, and what can we do about What causes flooding, and what can we do about

it?it?

WATERWATER’’S IMPORTANCE, S IMPORTANCE, AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL

Water keeps us alive, moderates Water keeps us alive, moderates climate, sculpts the land, removes climate, sculpts the land, removes and dilutes wastes and pollutants, and dilutes wastes and pollutants, and moves continually through the and moves continually through the hydrologic cycle.hydrologic cycle.

Only about 0.02% of the earthOnly about 0.02% of the earth’’s s water supply is available to us as water supply is available to us as liquid freshwater.liquid freshwater.


Comparison of Comparison of population sizes population sizes and shares of and shares of the worldthe world’’s s freshwater freshwater among the among the continents.continents.

Figure 14-2Figure 14-2

WATERWATER’’S IMPORTANCE, S IMPORTANCE, AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL Some precipitation infiltrates the ground Some precipitation infiltrates the ground

and is stored in soil and rock (groundwater).and is stored in soil and rock (groundwater). Water that does not sink into the ground or Water that does not sink into the ground or

evaporate into the air runs off (surface evaporate into the air runs off (surface runoff) into bodies of water.runoff) into bodies of water. The land from which the surface water drains The land from which the surface water drains

into a body of water is called its into a body of water is called its watershedwatershed or or drainage basindrainage basin..

Fig. 14-3, p. 308

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpiration Evaporation

Confined Recharge Area

Runoff

Flowing artesian well

Recharge Recharge Unconfined Unconfined AquiferAquifer

Stream Well requiring a pumpInfiltration Water

table LakeInfiltration

Unconfined aquifer

Confined aquiferConfining impermeable rock layer Confining impermeable rock layer

Less permeable Less permeable material such as claymaterial such as clay

Groundwater plays a key Groundwater plays a key rolerole

GroundwaterGroundwater = any precipitation that does not evaporate, = any precipitation that does not evaporate, flow into waterways, or get taken up by organismsflow into waterways, or get taken up by organisms Groundwater makes up one fifth of the EarthGroundwater makes up one fifth of the Earth’’s s

freshwater supplyfreshwater supply AquifersAquifers = Porous sponge-like formations of rock, sand, or = Porous sponge-like formations of rock, sand, or

gravel that hold groundwater gravel that hold groundwater Zone of aerationZone of aeration = pore spaces are partially filled with = pore spaces are partially filled with

water water Zone of saturationZone of saturation = spaces are completely filled with = spaces are completely filled with

waterwater Water tableWater table = boundary between the two zones = boundary between the two zones Aquifer recharge zoneAquifer recharge zone = any area where water infiltrates = any area where water infiltrates

EarthEarth’’s surface and reaches aquiferss surface and reaches aquifers


We currently use more than half of the We currently use more than half of the worldworld’’s reliable runoff of surface water and s reliable runoff of surface water and could be using 70-90% by 2025.could be using 70-90% by 2025.

About 70% of the water we withdraw from About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to rivers, lakes, and aquifers is not returned to these sources.these sources.

Irrigation is the biggest user of water Irrigation is the biggest user of water (70%), followed by industries (20%) and (70%), followed by industries (20%) and cities and residences (10%).cities and residences (10%).

SalinitySalinity

The saltiness.The saltiness.

NichesNiches

What Kinds of Organisms Live What Kinds of Organisms Live in Aquatic Life Zones?in Aquatic Life Zones? Aquatic systems contain floating, Aquatic systems contain floating,

drifting, swimming, bottom-dwelling, drifting, swimming, bottom-dwelling, and decomposer organisms.and decomposer organisms. Plankton: important group of weakly Plankton: important group of weakly

swimming, free-floating biota.swimming, free-floating biota. Phytoplankton (plant), Zooplankton (animal), Phytoplankton (plant), Zooplankton (animal),

Ultraplankton (photosynthetic bacteria)Ultraplankton (photosynthetic bacteria) Necton: fish, turtles, whales.Necton: fish, turtles, whales. Benthos: bottom dwellers (barnacles, Benthos: bottom dwellers (barnacles,

oysters).oysters). Decomposers: breakdown organic Decomposers: breakdown organic

compounds (mostly bacteria).compounds (mostly bacteria).

PhytoplanktonPhytoplankton

Description – small drifting plantsDescription – small drifting plants Niche – they are producers that Niche – they are producers that

support most aquatic food chainssupport most aquatic food chains Example – cyanobacteria & many Example – cyanobacteria & many

types of algaetypes of algae

ZooplanktonZooplankton Description – herbivores that feed on Description – herbivores that feed on

phytoplankton or other zooplanktonphytoplankton or other zooplankton Niche – food stock for larger Niche – food stock for larger

consumersconsumers Example – krill; small crustaceansExample – krill; small crustaceans

NektonNekton Description – larger, strong-Description – larger, strong-

swimming consumersswimming consumers Niche – top consumers in the Niche – top consumers in the

aquatic ecosystemaquatic ecosystem Example – fish, turtles, and Example – fish, turtles, and

whaleswhales

BenthosBenthos

Description – bottom-dwelling Description – bottom-dwelling creaturescreatures

Niche – primary consumers, Niche – primary consumers, decomposersdecomposers

Example – barnacles, oysters, Example – barnacles, oysters, and lobstersand lobsters

River Food ChainsRiver Food Chains

Freshwater Freshwater EcosystemsEcosystems

Freshwater EcosystemsFreshwater Ecosystems

FRESHWATER LIFE ZONESFRESHWATER LIFE ZONES

Freshwater life Freshwater life zones include:zones include: Standing (lentic) Standing (lentic)

waterwater such as such as lakes, ponds, and lakes, ponds, and inland wetlands.inland wetlands.

Flowing (lotic) Flowing (lotic) systemssystems such as such as streams and rivers. streams and rivers.


Flowing Water Flowing Water EcosystemsEcosystems

Because of different Because of different environmental conditions in environmental conditions in

each zone, a river is a each zone, a river is a system of different system of different

ecosystems.ecosystems.

Fig. 12-11, p. 267

• Deliver nutrients to sea to help sustain coastal fisheries

• Deposit silt that maintains deltas

• Purify water

• Renew and renourish wetlands

• Provide habitats for wildlife

Natural Capital

Ecological Services of Rivers

Freshwater Streams and Freshwater Streams and Rivers:Rivers:From the Mountains to the From the Mountains to the OceansOceans

Water flowing from mountains to the sea Water flowing from mountains to the sea creates different aquatic conditions and creates different aquatic conditions and habitats.habitats.


Headwater Stream Headwater Stream CharacteristicsCharacteristics

A narrow zone of cold, clear water A narrow zone of cold, clear water that rushes over waterfalls and that rushes over waterfalls and rapids. Large amounts of oxygen rapids. Large amounts of oxygen are present. Fish are also present. are present. Fish are also present. Ex. trout.Ex. trout.

Downstream Downstream CharacteristicsCharacteristics

Slower-moving water, less Slower-moving water, less oxygen, warmer temperatures, oxygen, warmer temperatures, and lots of algae and and lots of algae and cyanobacteria.cyanobacteria.

Changes is River FlowChanges is River Flow

Energy SourceEnergy Source

GravityGravity

WatershedWatershed

Standing Water Standing Water EcosystemsEcosystems

Lakes, ponds, etc.Lakes, ponds, etc.

Life in LayersLife in Layers

Life in most aquatic systems is found Life in most aquatic systems is found in surface, middle, and bottom layers.in surface, middle, and bottom layers.

Temperature, access to sunlight for Temperature, access to sunlight for photosynthesis, dissolved oxygen photosynthesis, dissolved oxygen content, nutrient availability changes content, nutrient availability changes with depth.with depth. Euphotic zone (upper layer in deep water Euphotic zone (upper layer in deep water

habitats): sunlight can penetrate.habitats): sunlight can penetrate.

Lakes: Water-Filled Lakes: Water-Filled DepressionsDepressions

Lakes are large natural bodies of standing Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, freshwater formed from precipitation, runoff, and groundwater seepage consisting of:and groundwater seepage consisting of: Littoral zoneLittoral zone (near shore, shallow, with rooted (near shore, shallow, with rooted

plants).plants). Limnetic zoneLimnetic zone (open, offshore area, sunlit). (open, offshore area, sunlit). Profundal zoneProfundal zone (deep, open water, too dark for (deep, open water, too dark for

photosynthesis).photosynthesis). Benthic zoneBenthic zone (bottom of lake, nourished by dead (bottom of lake, nourished by dead

matter).matter).

Littoral ZoneLittoral ZoneA shallow area near the shore, to the A shallow area near the shore, to the

depth at which rooted plants stop depth at which rooted plants stop growing. Ex. frogs, snails, insects, growing. Ex. frogs, snails, insects, fish, cattails, and water lilies.fish, cattails, and water lilies.

Limnetic ZoneLimnetic Zone

Open, sunlit water that extends Open, sunlit water that extends to the depth penetrated by to the depth penetrated by sunlight.sunlight.

Profundal ZoneProfundal ZoneDeep, open water where it Deep, open water where it

is too dark for is too dark for photosynthesis.photosynthesis.

Zones in Lakes and PondsZones in Lakes and Ponds


Which of the following is the zone of a Which of the following is the zone of a pond or lake in which rooted emergent pond or lake in which rooted emergent plants such as cattails and rushes are plants such as cattails and rushes are located?located?

BenthicBenthic LimneticLimnetic LittoralLittoral ProfundalProfundal RiparianRiparian

Thermal Thermal StratificationStratification

DefinitionDefinitionThe temperature difference in The temperature difference in

deep lakes where there are deep lakes where there are warm summers and cold warm summers and cold winters.winters.


During summer and winter in deep During summer and winter in deep temperate zone lakes the become temperate zone lakes the become stratified into temperature layers stratified into temperature layers and will overturn.and will overturn. This equalizes the temperature at all This equalizes the temperature at all

depths.depths. Oxygen is brought from the surface to Oxygen is brought from the surface to

the lake bottom and nutrients from the the lake bottom and nutrients from the bottom are brought to the top.bottom are brought to the top.

CausesCauses During the summer, During the summer,

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

ThermoclineThermocline The middle layer The middle layer

that acts as a that acts as a barrier to the barrier to the transfer of transfer of nutrients and nutrients and dissolved oxygen.dissolved oxygen.

Fall TurnoverFall Turnover

As the temperatures begin to As the temperatures begin to drop, the surface layer becomes drop, the surface layer becomes more dense, and it sinks to the more dense, and it sinks to the bottom. This mixing brings bottom. This mixing brings nutrients from the bottom up to nutrients from the bottom up to the surface and sends oxygen to the surface and sends oxygen to the bottom.the bottom.

Spring TurnoverSpring Turnover As top water warms and ice As top water warms and ice

melts, it sinks through and melts, it sinks through and below the cooler, less dense below the cooler, less dense water, sending oxygen down water, sending oxygen down and nutrients up.and nutrients up.

Freshwater Freshwater WetlandsWetlands

Freshwater Inland Wetlands: Freshwater Inland Wetlands: Vital SpongesVital Sponges

Inland wetlands Inland wetlands act like natural act like natural sponges that sponges that absorb and absorb and store excess store excess water from water from storms and storms and provide a provide a variety of variety of wildlife wildlife habitats.habitats. Figure 6-18Figure 6-18

Freshwater Inland Wetlands: Freshwater Inland Wetlands: Vital SpongesVital Sponges Filter and degrade pollutants.Filter and degrade pollutants. Reduce flooding and erosion by Reduce flooding and erosion by

absorbing slowly releasing overflows.absorbing slowly releasing overflows. Help replenish stream flows during dry Help replenish stream flows during dry

periods.periods. Help recharge ground aquifers.Help recharge ground aquifers. Provide economic resources and Provide economic resources and

recreation.recreation.

MarshesMarshesAn area of temporarily flooded, An area of temporarily flooded,

often silty land beside a river or often silty land beside a river or lake. Only green herbacious lake. Only green herbacious plants.plants.

SwampsSwampsA lowland region permanently A lowland region permanently

covered with water. Have woody covered with water. Have woody plants (Trees)plants (Trees)

Hardwood Bottomland Hardwood Bottomland ForestForestAn area down by a river or An area down by a river or

stream where lots of hardwoods, stream where lots of hardwoods, like oaks, grow.like oaks, grow.

Prairie PotholesPrairie Potholes These are depressions that hold These are depressions that hold

water out on the prairie, especially water out on the prairie, especially up north in Canada. It is a very good up north in Canada. It is a very good duck habitat.duck habitat.

Peat Moss BogPeat Moss Bog A wet area that over time fills in (the A wet area that over time fills in (the

last stage of succession is peat last stage of succession is peat moss). It can be very deep. In moss). It can be very deep. In Ireland, they burn this for wood.Ireland, they burn this for wood.

Importance of freshwater Importance of freshwater wetlandswetlands

They filter & purify water.They filter & purify water.Habitat for many animals Habitat for many animals

and plants.and plants.Flood Control along riversFlood Control along rivers

Liquidity: The Value of Liquidity: The Value of WetlandsWetlands

https://youtu.be/zLymJKYOWzQhttps://youtu.be/zLymJKYOWzQ

Historical AspectsHistorical Aspects

Developers and farmers want Developers and farmers want Congress to revise the definition of Congress to revise the definition of wetlands. This would make 60-75% of wetlands. This would make 60-75% of all wetlands unavailable for all wetlands unavailable for protection. The Audubon Society protection. The Audubon Society estimates that wetlands provide water estimates that wetlands provide water quality protection worth $1.6 billion quality protection worth $1.6 billion per year, and they say if that wetlands per year, and they say if that wetlands are destroyed, the U.S. would spend are destroyed, the U.S. would spend $7.7 billion to $31 billion per year in $7.7 billion to $31 billion per year in additional flood-control costs.additional flood-control costs.


Defining characteristics of a wetland involve which of the following.

(I. Hydrology, II. Soil type, III. Species composition) I only II only I and II only II and III only I, II, and III only

EstuariesEstuaries

DefinitionDefinitionA partially enclosed area of A partially enclosed area of

coastal water where sea water coastal water where sea water mixes with freshwater.mixes with freshwater.

Salt MarshesSalt Marshes The ground here is saturated with water The ground here is saturated with water

and there is little oxygen, so decay takes and there is little oxygen, so decay takes place slowly. It has a surface inlet and place slowly. It has a surface inlet and outlet, and contains many invertebrates. outlet, and contains many invertebrates. It is also the breeding ground for many It is also the breeding ground for many ocean animals. Ex. crabs and shellfish.ocean animals. Ex. crabs and shellfish.

Mangrove ForestsMangrove Forests These are along warm, These are along warm,

tropical coasts where tropical coasts where there is too much silt for there is too much silt for coral reefs to grow. It is coral reefs to grow. It is dominated by salt-tolerant dominated by salt-tolerant trees called mangroves trees called mangroves (55 different species (55 different species exist). It also helps to exist). It also helps to protect the coastline from protect the coastline from erosion and provides a erosion and provides a breeding nursery for some breeding nursery for some 2000 species of fish, 2000 species of fish, invertebrates, and plants.invertebrates, and plants.

Importance of EstuariesImportance of Estuaries

Just one acre of estuary provides Just one acre of estuary provides $75,000 worth of free waste treatment, $75,000 worth of free waste treatment, and has a value of about $83,000 when and has a value of about $83,000 when recreation and fish for food are included. recreation and fish for food are included.

Prime Kansas farmland has a top value Prime Kansas farmland has a top value of $1,200 and an annual production of $1,200 and an annual production value of $600.value of $600.

Water & The Water & The Hydrologic CycleHydrologic Cycle

Surface WaterSurface Water

Examples – streams, rivers, and lakesExamples – streams, rivers, and lakes Source – precipitationSource – precipitation Watershed – Ex. small streams Watershed – Ex. small streams

larger streams larger streams rivers rivers sea sea

GroundwaterGroundwater Aquifers–porous rock w/ water flowing Aquifers–porous rock w/ water flowing

throughthrough Water Table – the level of earthWater Table – the level of earth’’s land s land

crust to which the aquifer is filledcrust to which the aquifer is filled Renewability – the circulation rate of Renewability – the circulation rate of

groundwater is slow (300 to 4,600 years).groundwater is slow (300 to 4,600 years).

Two categories of aquifersTwo categories of aquifers Confined or artesianConfined or artesian = water-bearing, = water-bearing,

porous rocks are trapped between layers porous rocks are trapped between layers of less permeable substrate (i.e., clay) of less permeable substrate (i.e., clay) Is under a lot of pressureIs under a lot of pressure

Unconfined aquiferUnconfined aquifer = no upper layer to = no upper layer to confine itconfine it Readily recharged by surface waterReadily recharged by surface water

Groundwater becomes surface water Groundwater becomes surface water through springs or human-drilled wellsthrough springs or human-drilled wells

Groundwater may be ancient: the Groundwater may be ancient: the average age is 1,400 yearsaverage age is 1,400 years

A typical aquiferA typical aquifer

Groundwater ProblemsGroundwater Problems

These include pollution, These include pollution, salt, and draining too much.salt, and draining too much.

Other Effects of Groundwater Other Effects of Groundwater OverpumpingOverpumping

Sinkholes form Sinkholes form when the roof of when the roof of an underground an underground cavern collapses cavern collapses after being after being drained of drained of groundwater.groundwater.


Groundwater Depletion: Groundwater Depletion: A Growing ProblemA Growing Problem

The Ogallala, the worldThe Ogallala, the world’’s largest aquifer, s largest aquifer, is most of the red area in the center is most of the red area in the center (Midwest).(Midwest).

Areas of Areas of greatest greatest aquifer aquifer depletion depletion from from groundwater groundwater overdraft in overdraft in the the continental continental U.S.U.S.


Ogallala AquiferOgallala Aquifer

This is the worldThis is the world’’s largest known aquifer, s largest known aquifer, and fuels agricultural regions in the U.S. It and fuels agricultural regions in the U.S. It extends from South Dakota to Texas. Itextends from South Dakota to Texas. It’’s s essentially a non-renewable aquifer from essentially a non-renewable aquifer from the last ice age with an extremely slow the last ice age with an extremely slow recharge rate. In some cases, water is recharge rate. In some cases, water is pumped out 8 to 10 times faster than it is pumped out 8 to 10 times faster than it is renewed. Northern states will still have renewed. Northern states will still have ample supplies, but for the south itample supplies, but for the south it’’s s getting thinner. It is estimated that ¼ of getting thinner. It is estimated that ¼ of the aquifer will be depleted by 2020. the aquifer will be depleted by 2020.

Water Use & Water Use & Water Water ManagmentManagment

Water UsageWater Usage Irrigation – watering cropsIrrigation – watering crops Industry – coolant (power plant)Industry – coolant (power plant) Domestic and Municipal – drinking, Domestic and Municipal – drinking,

sewage, bathwater, dishwater & sewage, bathwater, dishwater & laundrylaundry

Water supplies houses, Water supplies houses, agriculture, and industryagriculture, and industry

Proportions of these three types of Proportions of these three types of use vary dramatically among nationsuse vary dramatically among nations Arid countries use water for agricultureArid countries use water for agriculture Developed countries use water for Developed countries use water for

industryindustry

Different types of water Different types of water useuse

Consumptive use Consumptive use == water is removed from an aquifer water is removed from an aquifer or surface water body, and is not returned or surface water body, and is not returned

Non-consumptive useNon-consumptive use = does not remove, or only = does not remove, or only temporarily removes, water from an aquifer or surface temporarily removes, water from an aquifer or surface waterwater Electricity generation at hydroelectric damsElectricity generation at hydroelectric dams

Dams and ReservoirsDams 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.

USING DAMS AND USING DAMS AND RESERVOIRS TO SUPPLY RESERVOIRS TO SUPPLY MORE WATERMORE WATER

Large dams and reservoirs can Large dams and reservoirs can produce cheap electricity, reduce produce cheap electricity, reduce downstream flooding, and provide downstream flooding, and provide year-round water for irrigating year-round water for irrigating cropland, but they also displace cropland, but they also displace people and disrupt aquatic systems.people and disrupt aquatic systems.

Fig. 14-13b, p. 317

Powerlines

Reservoir

Dam

PowerhouseIntake

Turbine

Benefits and drawbacks of Benefits and drawbacks of damsdams Benefits:Benefits:

Power generationPower generation Emission reductionEmission reduction Crop irrigationCrop irrigation Drinking waterDrinking water Flood controlFlood control ShippingShipping New recreational New recreational

opportunitiesopportunities

Drawbacks:Drawbacks: Habitat alterationHabitat alteration Fisheries declinesFisheries declines Population Population

displacementdisplacement Sediment captureSediment capture Disruption of Disruption of

floodingflooding Risk of failureRisk of failure Lost recreational Lost recreational

opportunitiesopportunities

Case Study: Case Study: ChinaChina’’s Three Gorges Dams Three Gorges Dam

There is a debate over whether the advantages of There is a debate over whether the advantages of the worldthe world’’s largest dam and reservoir will outweigh s largest dam and reservoir will outweigh its disadvantages.its disadvantages. The dam will be 2 kilometers long.The dam will be 2 kilometers long. The electric output will be that of 18 large coal-burning The electric output will be that of 18 large coal-burning

or nuclear power plants.or nuclear power plants. It will facilitate ship travel reducing transportation costs.It will facilitate ship travel reducing transportation costs. Dam will displace 1.2 million people.Dam will displace 1.2 million people. Dam is built over seismatic fault and already has small Dam is built over seismatic fault and already has small

cracks. cracks.

Dam RemovalDam Removal

Some dams are being removed for ecological Some dams are being removed for ecological reasons and because they have outlived their reasons and because they have outlived their usefulness.usefulness. In 1998 the U.S. Army Corps of Engineers announced In 1998 the U.S. Army Corps of Engineers announced

that it would no longer build large dams and diversion that it would no longer build large dams and diversion projects in the U.S.projects in the U.S.

The Federal Energy Regulatory Commission has The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams.approved the removal of nearly 500 dams.

Removing dams can reestablish ecosystems, but can Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.also re-release toxicants into the environment.

Water DiversionWater Diversion

•Description: Damming a river to control where the water flows

•Benefits: Keeps water where we want it- cities!

•Problems: Drains wetlands, destroys land

Case Study: The Colorado Case Study: The Colorado Basin – an Overtapped Basin – an Overtapped ResourceResource

The Colorado River has so many dams The Colorado River has so many dams and withdrawals that it often does not and withdrawals that it often does not reach the ocean.reach the ocean. 14 major dams and reservoirs, and canals.14 major dams and reservoirs, and canals. Water is mostly used in desert area of the Water is mostly used in desert area of the

U.S.U.S. Provides electricity from hydroelectric plants Provides electricity from hydroelectric plants

for 30 million people (1/10for 30 million people (1/10thth of the U.S. of the U.S. population).population).

Case Study: The Colorado Case Study: The Colorado Basin – an Overtapped Basin – an Overtapped ResourceResource

Lake Powell, is Lake Powell, is the second the second largest reservoir largest reservoir in the U.S.in the U.S.

It hosts one of It hosts one of the hydroelectric the hydroelectric plants located plants located on the Colorado on the Colorado River.River.


Case Study: The Aral Sea Case Study: The Aral Sea DisasterDisaster

Diverting water from the Aral Sea and Diverting water from the Aral Sea and its two feeder rivers mostly for irrigation its two feeder rivers mostly for irrigation has created a major ecological, has created a major ecological, economic, and health disaster.economic, and health disaster. About 85% of the wetlands have been About 85% of the wetlands have been

eliminated and roughly 50% of the local bird eliminated and roughly 50% of the local bird and mammal species have disappeared.and mammal species have disappeared.

Since 1961, the seaSince 1961, the sea’’s salinity has tripled s salinity has tripled and the water has dropped by 22 meters and the water has dropped by 22 meters most likely causing 20 of the 24 native fish most likely causing 20 of the 24 native fish species to go extinct.species to go extinct.

Modern Marvels: DamsModern Marvels: Dams

https://www.youtube.com/watch?v=eoTKcsgUEj0&feature=share&list=PL7WxmjMiAYikNGKPUWeZxBNOhKsd8LxSo

Impact of Human Impact of Human Actions on WaterActions on Water


Negative environmental impacts Negative environmental impacts associated with large scale associated with large scale hydroelectric projects has been hydroelectric projects has been demonstrated in which areas?demonstrated in which areas?

James Bay, QuebecJames Bay, Quebec Three Mile Island, PennsylvaniaThree Mile Island, Pennsylvania Kissimmee River, FloridaKissimmee River, Florida Aral Seas, Former USSRAral Seas, Former USSR

Too Little WaterToo Little Water

ExamplesExamples

Examples include drought Examples include drought and expanding deserts.and expanding deserts.

Overdrawing Surface Overdrawing Surface WaterWater Lake levels drop, recreation use Lake levels drop, recreation use

drops, fisheries drop, and salinization drops, fisheries drop, and salinization occurs. Ex. Soviet Union (Aral Sea); occurs. Ex. Soviet Union (Aral Sea); the inland sea drained the river that the inland sea drained the river that fed into it. Now itfed into it. Now it’’s a huge disaster s a huge disaster (read pg. 322 in text).(read pg. 322 in text).1964 1997

Aquifer DepletionAquifer Depletion

This harms endangered This harms endangered species, and salt water can species, and salt water can seep in.seep in.

Salinization of Irrigated Salinization of Irrigated SoilSoilWater is poured onto soil and Water is poured onto soil and

evaporates. Over time, as this evaporates. Over time, as this is repeated, nothing will grow is repeated, nothing will grow there anymore.there anymore.

Point and nonpoint source Point and nonpoint source water pollutionwater pollution

Point source water pollutionPoint source water pollution = discrete locations of = discrete locations of pollutionpollution Factory or sewer pipesFactory or sewer pipes

Nonpoint source water pollutionNonpoint source water pollution = pollution from multiple = pollution from multiple cumulative inputs over a large areacumulative inputs over a large area Farms, cities, streets, neighborhoodsFarms, cities, streets, neighborhoods

The U.S. Clean Water ActThe U.S. Clean Water Act Addressed point sources Addressed point sources Targeted industrial dischargeTargeted industrial discharge

In the U.S., nonpoint sources have a greater impact on qualityIn the U.S., nonpoint sources have a greater impact on quality Limit development on watershed land surrounding Limit development on watershed land surrounding

reservoirsreservoirs

Freshwater pollution Freshwater pollution sourcessources

Indicators of water qualityIndicators of water quality Scientists measure properties Scientists measure properties

of water to characterize its of water to characterize its qualityquality Biological indicatorsBiological indicators: presence : presence

of fecal coliform bacteria and of fecal coliform bacteria and other disease-causing organismsother disease-causing organisms

Chemical indicators: Chemical indicators: pH, pH, nutrient concentration, taste, nutrient concentration, taste, odor, hardness, dissolved oxygenodor, hardness, dissolved oxygen

Physical indicators: Physical indicators: turbidity, turbidity, color, temperaturecolor, temperature

Surface Water ProblemsSurface Water Problems

The polluted Mississippi River (non-source The polluted Mississippi River (non-source point pollution) has too much point pollution) has too much phosphorus. phosphorus.

In the Eerie Canal, which connects the In the Eerie Canal, which connects the ocean to the Great Lakes, lampreys came ocean to the Great Lakes, lampreys came in and depleted the fish. The zebra in and depleted the fish. The zebra mollusk is also a problem in the Great mollusk is also a problem in the Great Lakes.Lakes.

Effects of Plant Nutrients on Effects of Plant Nutrients on Lakes:Lakes:Too Much of a Good ThingToo Much of a Good Thing

Plant nutrients from a lakePlant nutrients from a lake’’s s environment affect the types and environment affect the types and numbers of organisms it can support.numbers of organisms it can support.


Effects of Plant Nutrients on Effects of Plant Nutrients on Lakes:Lakes:Too Much of a Good ThingToo Much of a Good Thing Plant nutrients from a lakePlant nutrients from a lake’’s s

environment affect the types and environment affect the types and numbers of organisms it can support.numbers of organisms it can support. OligotrophicOligotrophic (poorly nourished) lake: (poorly nourished) lake:

Usually newly formed lake with small Usually newly formed lake with small supply of plant nutrient input.supply of plant nutrient input.

EutrophicEutrophic (well nourished) lake: Over time, (well nourished) lake: Over time, sediment, organic material, and inorganic sediment, organic material, and inorganic nutrients wash into lakes causing excessive nutrients wash into lakes causing excessive plant growth.plant growth.

Effects of Plant Nutrients on Effects of Plant Nutrients on Lakes:Lakes:Too Much of a Good ThingToo Much of a Good Thing

Cultural eutrophicationCultural eutrophication:: Human inputs of nutrients from the Human inputs of nutrients from the

atmosphere and urban and atmosphere and urban and agricultural areas can accelerate the agricultural areas can accelerate the eutrophication process.eutrophication process.

Mono LakeMono Lake(like the Dead Sea) This has a (like the Dead Sea) This has a

huge salt concentration due to huge salt concentration due to manman’’s draining.s draining.

Impacts of Human Activities Impacts of Human Activities on Freshwater Systemson Freshwater Systems Dams, cities, farmlands, and filled-in wetlands Dams, cities, farmlands, and filled-in wetlands

alter and degrade freshwater habitats.alter and degrade freshwater habitats. Dams, diversions and canals have Dams, diversions and canals have

fragmented about 40% of the worldfragmented about 40% of the world’’s 237 s 237 large rivers.large rivers.

Flood control levees and dikes alter and Flood control levees and dikes alter and destroy aquatic habitats.destroy aquatic habitats.

Cities and farmlands add pollutants and Cities and farmlands add pollutants and excess plant nutrients to streams and rivers.excess plant nutrients to streams and rivers.

Many inland wetlands have been drained or Many inland wetlands have been drained or filled for agriculture or (sub)urban filled for agriculture or (sub)urban development.development.

Stable RunoffStable Runoff As water runs off from rain, itAs water runs off from rain, it’’s supposed s supposed

to get into rivers, and finally off to the to get into rivers, and finally off to the sea. But when we dam rivers, less goes sea. But when we dam rivers, less goes to the ocean, meaning the brackish water to the ocean, meaning the brackish water (where the river hits the ocean) becomes (where the river hits the ocean) becomes more salty. This is the breeding ground more salty. This is the breeding ground for many fish and invertebrates. This for many fish and invertebrates. This harms the ecology of the area.harms the ecology of the area.

Inefficient irrigation Inefficient irrigation wastes waterwastes water Today, 70% more water is withdrawn Today, 70% more water is withdrawn

for irrigation than in 1960for irrigation than in 1960 The amount of irrigated land has doubledThe amount of irrigated land has doubled Crop yields can doubleCrop yields can double

Most irrigation is highly Most irrigation is highly inefficientinefficient Only 45% of water is absorbed by crops Only 45% of water is absorbed by crops

via via ““flood and furrowflood and furrow”” irrigation irrigation Overirrigation leads to waterlogging, Overirrigation leads to waterlogging,

salinization, and lost farming incomesalinization, and lost farming income Most national governments subsidize Most national governments subsidize

irrigationirrigation Water miningWater mining = withdrawing water = withdrawing water

faster than it can be replenishedfaster than it can be replenished

Your Yard Is EvilYour Yard Is Evil

https://www.youtube.com/watch?v=-enGOMQgdvg&feature=share&list=PL7WxmjMiAYikNGKPUWeZxBNOhKsd8LxSo

Question of the DayQuestion of the Day All of the following are commonly used to deal with

the side effects of eutrophication in lakes EXCEPT

applying herbicides to kill nuisance plants dredging out lakes to deepen them pumping oxygen into the lowest layers of water introducing insects that eat certain nuisance

plants adding nitrates

Drinking Water Drinking Water ProblemsProblems

Coliform BacteriaColiform Bacteria

The W.H.O. recommends there The W.H.O. recommends there be zero colonies of bacteria per be zero colonies of bacteria per 100ml of drinking water and 200 100ml of drinking water and 200 colonies per 100ml of swimming colonies per 100ml of swimming water. The average human water. The average human excretes 2 billion organisms per excretes 2 billion organisms per day (see how easily untreated day (see how easily untreated sewage can contaminate sewage can contaminate water?).water?).

Water-Soluble Inorganic Water-Soluble Inorganic ChemicalsChemicals

These include acids, salts, These include acids, salts, mercury, and lead. They make mercury, and lead. They make water unfit to drink.water unfit to drink.

Organic MaterialOrganic Material

These include oil, gas, These include oil, gas, plastics, pesticides, and plastics, pesticides, and detergents.detergents.

Population GrowthPopulation GrowthProblems include over-Problems include over-

drawing fresh water, drawing fresh water, pollution, and over-building pollution, and over-building so that water canso that water can’’t seep t seep into the ground.into the ground.

Possible Possible Solutions for Solutions for Water UseWater Use

Sharing Water ResourcesSharing Water Resources

There are water wars out west. There are water wars out west. California bought the water from California bought the water from the Colorado River, but Arizona the Colorado River, but Arizona wants it. Who owns it? The same wants it. Who owns it? The same thing is happening in Texas. More thing is happening in Texas. More water rights are sold than the water rights are sold than the actual amount of water. How do actual amount of water. How do you share water? This is a you share water? This is a problem all over the world.problem all over the world.

DesalinizationDesalinization

•Description: Removing salt from salt water

•Benefits: Freshwater

•Problems: Uses lots of energy; costs 3-5X’s more money; what do we do with the salt?

DESALTING SEAWATER, DESALTING SEAWATER, SEEDING CLOUDS, AND SEEDING CLOUDS, AND TOWING ICEBERGS AND TOWING ICEBERGS AND GIANT BAGGIESGIANT BAGGIES

Removing salt from seawater by current Removing salt from seawater by current methods is expensive and produces large methods is expensive and produces large amounts of salty wastewater that must be amounts of salty wastewater that must be disposed of safely.disposed of safely. DistillationDistillation: heating saltwater until it evaporates, : heating saltwater until it evaporates,

leaves behind water in solid form.leaves behind water in solid form. Reverse osmosisReverse osmosis: uses high pressure to force : uses high pressure to force

saltwater through a membrane filter.saltwater through a membrane filter.

DESALTING SEAWATER, DESALTING SEAWATER, SEEDING CLOUDS, AND SEEDING CLOUDS, AND TOWING ICEBERGS AND TOWING ICEBERGS AND GIANT BAGGIESGIANT BAGGIES

Seeding clouds Seeding clouds with tiny particles of with tiny particles of chemicals to increase rainfall, chemicals to increase rainfall, towing towing icebergsicebergs or or transporting huge bags transporting huge bags filled with freshwater to dry coastal filled with freshwater to dry coastal areas have all been proposed but are areas have all been proposed but are unlikely to provide significant unlikely to provide significant amounts of freshwater.amounts of freshwater.

INCREASING WATER SUPPLIES INCREASING WATER SUPPLIES BY WASTING LESS WATERBY WASTING LESS WATER

Sixty percent of the worldSixty percent of the world’’s irrigation s irrigation water is currently wasted, but improved water is currently wasted, but improved irrigation techniques could cut this waste irrigation techniques could cut this waste to 5-20%.to 5-20%.

Center-pivot, low pressure sprinklers Center-pivot, low pressure sprinklers sprays water directly onto crop.sprays water directly onto crop. It allows 80% of water to reach crop.It allows 80% of water to reach crop. Has reduced depletion of Ogallala aquifer in Has reduced depletion of Ogallala aquifer in

Texas High Plains by 30%.Texas High Plains by 30%.

Fig. 14-18, p. 325

Center pivotCenter pivot

Drip irrigationDrip irrigation

Gravity flowGravity flow(efficiency 60% and

80% with surge valves)

Above- or below-ground pipes or tubes deliver water to individual plant roots.

Water usually comes from an aqueduct system or a nearby river.

(efficiency 90–95%)

(efficiency 80%–95%)

Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Legislative efforts reduce Legislative efforts reduce pollutionpollution Federal Water Pollution Control Act (1972)Federal Water Pollution Control Act (1972)

Renamed the Clean Water Act in 1977Renamed the Clean Water Act in 1977 Illegal to discharge pollution without a permitIllegal to discharge pollution without a permit Standards for industrial wastewaterStandards for industrial wastewater Funded sewage treatment plantsFunded sewage treatment plants

Because of legislation, the situation is Because of legislation, the situation is much better than it wasmuch better than it was

Other nations have also reduced pollutionOther nations have also reduced pollution

Water ConservationWater 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

Treating wastewaterTreating wastewater WastewaterWastewater = water that has been used by = water that has been used by

people in some waypeople in some way Sewage, showers, sinks, manufacturing, storm Sewage, showers, sinks, manufacturing, storm

water runoffwater runoff Septic systemsSeptic systems = the most popular method = the most popular method

of wastewater disposal in rural areasof wastewater disposal in rural areas Underground septic tanks separate solids and Underground septic tanks separate solids and

oils from wastewateroils from wastewater The water drains into a drain field, where The water drains into a drain field, where

microbes decompose the watermicrobes decompose the water Solid waste needs to be periodically pumped and Solid waste needs to be periodically pumped and

landfilledlandfilled

Dirty Jobs: The Honey PotDirty Jobs: The Honey Pot

https://www.youtube.com/watch?v=NXgoUpbgo68&feature=share&list=PL7WxmjMiAYikNGKPUWeZxBNOhKsd8LxSo

Municipal sewer systemsMunicipal sewer systems In populated areas, sewer systems carry In populated areas, sewer systems carry

wastewater wastewater Physical, chemical, and biological water treatmentPhysical, chemical, and biological water treatment

Primary treatmentPrimary treatment = the physical removal = the physical removal of contaminants in settling tanks (clarifiers)of contaminants in settling tanks (clarifiers)

Secondary treatmentSecondary treatment = water is stirred and = water is stirred and aerated so aerobic bacteria degrade organic aerated so aerobic bacteria degrade organic pollutantspollutants Water treated with chlorine is piped into rivers or Water treated with chlorine is piped into rivers or

the oceanthe ocean Some reclaimed water is used for irrigation, lawns, Some reclaimed water is used for irrigation, lawns,

or industryor industry

A typical wastewater A typical wastewater treatment facility treatment facility

ENDEND

Marine Marine EcosystemsEcosystems

Overfishing and Extinction: Overfishing and Extinction: Gone Fishing, Fish GoneGone Fishing, Fish Gone

About 75% of the worldAbout 75% of the world’’s commercially s commercially valuable marine fish species are over valuable marine fish species are over fished or fished near their sustainable fished or fished near their sustainable limits.limits. Big fish are becoming scarce.Big fish are becoming scarce. Smaller fish are next.Smaller fish are next. We throw away 30% of the fish we catch.We throw away 30% of the fish we catch. We needlessly kill sea mammals and birds.We needlessly kill sea mammals and birds.

Fishing Problems & Fishing Problems & TechniquesTechniques

The major decline in the worldwide The major decline in the worldwide catch of fish since 1990 is because catch of fish since 1990 is because of over-fishing.of over-fishing.

By-catch- fish or animals that were By-catch- fish or animals that were not meant to be caught.not meant to be caught.

Fig. 12-A, p. 255

Fish farming in cage

Trawler fishing

Spotter airplane

Sonar

Trawl flap

Trawl lines

Purse-seine fishing

Trawl bagFish school

Drift-net fishingLong line fishing

Lines with hooks

Fish caught by gills

Deep sea aquaculture cage

Float Buoy

Purse SeinesPurse Seines

A large purse-like net is put into A large purse-like net is put into the ocean and is then closed like a the ocean and is then closed like a drawstring purse to trap the fish. drawstring purse to trap the fish.

Tuna is a fish typically caught in Tuna is a fish typically caught in purse seinespurse seines

Dolphins are a by-catch of purse Dolphins are a by-catch of purse seinesseines

Long-line fishingLong-line fishing

Lines are put out that can be up to Lines are put out that can be up to 80 miles long w/ thousands of baited 80 miles long w/ thousands of baited hooks on them. These are left out hooks on them. These are left out free-floating for days and then the free-floating for days and then the boat comes back and picks them up. boat comes back and picks them up.

Pilot whales, dolphins, sea turtles, Pilot whales, dolphins, sea turtles, and birds are by-catch of this and birds are by-catch of this technique.technique.

Drift-net fishingDrift-net fishing

Each net hangs as much as 50 feet below Each net hangs as much as 50 feet below the surface and up to 34 miles long. the surface and up to 34 miles long.

Anything that comes into contact w/ these Anything that comes into contact w/ these nearly invisible nets are entangled. nearly invisible nets are entangled.

This leads to overfishingThis leads to overfishing Many unwanted fish and marine Many unwanted fish and marine

mammals, turtles and seabirds are caught.mammals, turtles and seabirds are caught.

HUMAN IMPACTS ON AQUATIC HUMAN IMPACTS ON AQUATIC BIODIVERSITYBIODIVERSITY

Area of ocean before and after a trawler Area of ocean before and after a trawler net, acting like a giant plow, scraped it.net, acting like a giant plow, scraped it.


Population Growth and Population Growth and PollutionPollution

Each year Each year plastic items plastic items dumped from dumped from ships and left ships and left as litter on as litter on beaches beaches threaten threaten marine life.marine life.


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