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Humans in the Biosphere

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Humans in the Biosphere Honors Biology Chapter 6 – PowerPoint PPT presentation

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Title: Humans in the Biosphere


1
Humans in the Biosphere
  • Honors Biology Chapter 6

2
The Tragedy of the Commons
  • Areas used by everyone are no ones
    responsibility
  • Leads to misuse loss of resources

3
Renewable Resources
  • Resources can regenerate (living) or
  • Resources that can be recycled through
    biogeochemical cycles
  • Examples
  • Trees
  • Water

4
Renewable resources are NOT necessarily UNLIMITED.
  • Freshwater is a renewable resource, BUT there are
    events that CAN make it very limited. For
    example
  • Drought
  • Pollution

5
Nonrenewable Resources
  • Cannot be replenished by natural processes.
  • Examples
  • Fossil fuels

6
Is a tree population renewable or nonrenewable?
  • Individual trees are renewable
  • A population of trees may not be, because the
    ecosystem they were in may change forever once
    the trees are gone.

7
Sustainable Development
  • Using resources without depleting them
  • Providing for human needs without causing
    long-term damage to the environment
  • Must take into account
  • Functioning of ecosystems
  • Human economic systems

8
Sustainable Development Strategy - Example
  • Using insects instead pesticides to control pests

9
Land Resources - Soil
  • Renewable or not?
  • Renewable if managed properly

10
Mismanagement of Soil Resources
  • Soil Erosion
  • Wearing away of surface soil by water and wind
  • Results when land is plowed, and roots that hold
    soil in place are removed

11
Mismanagement of Soil Resources
  • Desertification
  • Misuse of soil causes once productive areas to
    become deserts
  • Dry climate
  • Farming
  • Overgrazing
  • Drought

12
Forest Resources
  • Ways in which forest resources are used by people
  • Building
  • Burning

13
Forest Resources
  • Ways in which forests provide ecological services
  • Forests as lungs of the Earth
  • Absorb CO2 and release O2
  • Store nutrients
  • Provide habitat and food for organisms
  • Moderate climate
  • Limit soil erosion
  • Protect freshwater supplies

14
Are Forests Renewable Resources?
  • Maybe it depends on the forest
  • Our temperate deciduous forests seem to come back
    pretty well after cutting, though not always
    exactly as they were
  • Old Growth Forests are NOT renewable
  • Ancient trees and ecosystems
  • Will not be replaced by a similar ecosystem if
    cut
  • The plants and animals dependent on the anceint
    trees in the system would die
  • Even if allowed to come back, the ecosystem would
    never return to its present state.

15
Old Growth Forest
16
Deforestation
  • Definition The loss of forests
  • Deforestation can lead to
  • Severe soil erosion
  • Erosion can wash nutrients out of the soil
  • Grazing or plowing after deforestation can cause
    permanent changes in the soils that prevent
    regrowth of trees.

17
Fishery Resources
  • Overfishing
  • Harvesting fish at a rate greater than they can
    replace themselves by reproduction
  • 1950 1990
  • Fish harvest dramatically increased
  • Fish populations dramatically declined
  • Tragedy of the Commons
  • Fishing of certain species banned
  • Some populations have seen recovery

18
Virginia Example
  • Menhaden
  • breadbasket of the Bay
  • favorite foods of striped bass, bluefish, sea
    trout, tuna and sharks
  • Menhaden Fishery
  • one of the most important and productive on the
    Atlantic coast
  • providing fish meal, fish oil and fish solubles
    and bait for other fisheries
  • More pounds of menhaden are landed each year than
    any other fish in the United States
  • Fishery is considered stable along Atlantic
    coast, BUT may be causing damage in the Bay
  • Menhaden play a key ecological role in the Bay as
    an important prey species for top predators such
    as striped bass, and for their ability to filter
    the water
  • the number of juvenile menhaden in the Bay
    population has been low
  • A proposal to cap the harvest in Chesapeake Bay
    is under discussion

19
Menhaden Fishery in Virginia
20
Aquaculture
  • Raising aquatic animals for human consumptions
  • Good provides food for people without drawing
    from natural populations
  • Disposal of wastes from the aquatic animals can
    be a source of pollution

21
Air Resources
  • Smog
  • Mixture of chemicals that results in a brown/gray
    haze in the atmosphere.
  • Mostly due to
  • Automobile exhaust
  • Industrial emissions

22
Pollutant
  • A harmful material that can enter the biosphere
    through the land, air or water.
  • Pollutants released from burning fossil fuels
    include
  • Carbon dioxide
  • Nitrates and Sulfates
  • Particulates

23
What are particulates
  • Microscopic particles of ash and dust that can
    enter the nose mouth and lungs causing health
    problems

24
Nitrates and Sulfates
  • Combine with water vapor in the air
  • Create Acid Rain
  • Kills plants by damaging leaves
  • Change soil chemistry
  • Change chemistry of standing water ecosystems
  • Dissolves and releases toxic elements that may be
    bound up in soil
  • mercury

25
Freshwater Resources
  • People use freshwater for
  • Drinking
  • Washing
  • Watering crops
  • Industry
  • Recreation

26
Pollution Threatens Freshwater Supplies
  • Improperly discarded chemicals can enter streams
    and rivers
  • Wastes discarded on land can seep through soil
    into groundwater supplies
  • Sewage containing phosphorus and nitrogen
    encourages algae growth
  • Sewage can also spread disease
  • Though most cities due try to treat sewage before
    it enters water ways
  • Still, animal waste runs off cow pastures, etc.

27
Protection of Wetlands and the sustainable use of
water
  • Wetlands act to purify water that passes through
    them
  • Saving wetlands means cleaner water

28
Primary use of water in the U.S.
  • Agriculture
  • Uses ¾ of freshwater

29
The Value of Biodiversity - Terms
  • Biodiversity
  • Sum total of the genetically based variety of all
    organisms in the biosphere
  • Ecosystem diversity
  • the variety of habitats, communities and
    ecological processes in the living world
  • Species diversity
  • number of different species in the biosphere
  • Genetic diversity
  • sum total of all the different forms of genetic
    information carried by organisms living on Earth

30
Why is biodiversity of practical value to humans?
  • Species of many kinds have provided us with
    foods, industrial products and medicines
  • Inherent value just of its own merit???

31
Threats to Biodiversity Human Impacts
  • Altering habitats
  • Hunting species to extinction
  • Introducing toxins into the environment
  • Introducing foreign species into a new environment

32
Habitat Alteration
  • Natural habitats may be destroyed when land is
    developed
  • As habitats disappear, the species that live in
    them vanish
  • Habitat fragmentation
  • The splitting up of ecosystems as developments
    take up land area
  • Habitats become biological islands isolated
  • The smaller the island, the smaller the number of
    species and population sizes the more
    vulnerable they are.

33
Habitat fragmentation
34
Demand for Wildlife Products
  • Demand for animal species products has caused
    extinction by hunting
  • Carolina parakeet
  • Passenger pigeon

35
Pollution Biological Magnification
  • Certain polluntants are NONbiodegradable
  • When producers take chemicals these into their
    bodies, they are stored in tissues rather than
    altered and excreted.
  • When consumers eat the producers, they consume
    more concentrated amounts of the chemical
  • This pattern repeats itself as you move up the
    food chain and the toxin gets more an more
    concentrated.

36
Biological Magnification
  • Definition phenomenon in which the
    concentration of certain compounds in each
    organism in a food chain increases

37
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38
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39
Famous Incidents of Biological Magnification
  • DDT

40
DDT and Biological Magnification
  • Decade After WWII
  • Pesticide industry propmoted the benefits of DDT
    before the consequences of its use were
    understood.
  • By the 1950s scientists learned that
  • DDT persists in the environment
  • DDT is transported by water to areas far from
    where it is applied
  • By this time, DDT was already a global problem

41
DDT and Biological Magnification
  • Who was affected
  • Pelicans, ospreys, eagles
  • Top of the food chain
  • Affected calcium deposition in eggs made them
    weak and easy to crush
  • Weight of parent while incubating eggs crushed
    eggs

42
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43
Other pollutants and biological magnification
  • PCBs
  • Great Lakes
  • Endocrine system problems in lots of animals
    including humans
  • Concentration in Herring Gull eggs is 5,000 times
    greater than in phytoplankton at base of food web

44
Other Pollutants and Biological Magnification
  • Mercury
  • By-product of plastic production
  • Plastic production and coal power plants
  • Expelled into rivers/oceans
  • Bacteria at the bottom mud convert to a more
    harmful substance
  • Methyl mercury
  • Accumulates in tissues of organisms including
    humans

45
Introduced / Invasive Species
  • Species that are introduced into a new
    environment
  • May be no natural predators
  • Reproduce rapidly
  • Take over habitat
  • Crowd out native species
  • Reduce biodiversity in native ecosystems

46
Invasive species
47
Zebra mussels
  • Native to freshwater lakes of southeast Russia
  • Spread began in 1700s
  • First discovered in this country in Great Lakes
    in 1988
  • Ballast water from ships probably responsible for
    introduction

48
Kudzu
49
Kudzu
  • Introduced intentionally in 1876 as a forage crop
    and ornamental plant
  • From 1935 to 1950 farmers were encouraged to
    plant it to prevent erosion
  • The southern U.S. has near perfect conditions for
    this plant to grow out of control, which it has
    done.

50
Northern snakehead
51
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52
Northern Snakehead
  • Native to China, Russia, Korea
  • Top level predator
  • First reported in U.S. in 2000 in pond in
    Maryland
  • Found in pond in Chesapeake Bay watershed pond
    was drained and the fish were destroyed
  • A man admitted releasing two snakeheads into the
    pond after purchasing them in NY
  • 19 found in Potomac River in 2004
  • Found in other states now

53
Phragmites
  • Highly invasive
  • Threatens native marsh plants

54
Veined Rapa Whelk
  • Our Knobbed whelk at left
  • Rapa Whelk on right w/ egg masses on far right

55
Nutria
  • Native to S. America (Brazil, etc)
  • 1899 - Intentionally introduced to N. America for
    their fur
  • 1940 nutria fur market collapsed
  • Farmers released them or did not recapture those
    that escaped
  • Aggressive nature and habitat needs put it in
    competition with native muskrat
  • Feeding style very damaging to native wetlands
  • Young are food for foxes, etc., but no predators
    for adults except humans

56
Conserving Biodiversity
  • Conservation
  • Wise management of natural resources, including
    the preservation of habitats and wildlife
  • Conservation seeks to protect biodiversity

57
Conservation Strategies
  • Preventing single species extinction
  • Example Zoos
  • Establish captive breeding programs
  • Raise and protect animals until population is
    stable then return to wild.

58
Conservation Strategies
  • Now more focused on protecting entire ecosystems
  • Ensures that natural habitats and interactions of
    many different species are preserved at the same
    time
  • Much bigger challenge
  • Governments and conservation groups must work
    together to set aside land, etc.
  • Even though the U.S. has lots of national parks,
    etc., this is not nearly enough to protect
    biodiversity

59
Hot Spots
  • Places where large numbers of habitats and
    species are in immediate danger of extinction as
    a result of human activity
  • Hot spot strategy MAY help to focus efforts

60
Effects of Ecosystem Protection on People
  • Regulations to reduce hunting/fishing may place
    financial hardships on people for several years
  • But what will consequences be if nothing is done?

61
Ozone depletion
  • Ozone layer
  • 20 50 km above Earths surface
  • Made of O3
  • A pollutant at Earths surface
  • Protects people from UV radiation

62
Ozone depletion
  • Hole in ozone was discovered in 1970s
  • Image is from 2006
  • Over Antarctica
  • Continued to grow larger and last longer
  • 1974 Cause of ozone hole determined
  • Chlorofluorocarbons (CFCs)
  • Propellants in aerosol cans
  • Coolant in refrigerators, air conditioners, etc.

63
Ozone depletion
  • 1987, US and many other nations began reducing
    use of CFCs
  • Today they are mostly banned
  • Effects of ban will not be seen right away
  • CFCs linger for years in the atmosphere
  • Ozone hole should shrink and disappear in 50 years

64
Global Climate Change
  • Greenhouse Effect
  • CO2 in atmosphere allows high energy UV radiation
  • Warms Earth
  • Earth radiates heat back towards space as low
    energy infrared radiation
  • Not strong enough to penetrate CO2
  • Heat remains to keep climate on Earth moderate
  • Greenhouse Effect is GOOD and NEEDED
  • Without it Earth would be MUCH colder

65
Problem
  • Too much CO2 traps too much heat
  • Result is global warming
  • Too much CO2 in atmosphere due to
  • Burning of fossil fuels
  • Reduction in forests, etc.

66
Global Warming
  • Definition increase of average temperature of
    the biosphere
  • Records show
  • Since 1900 temp has risen .6 C
  • Since 1980 temp has risen .2 to .3 C
  • 1990s were warmest decade on record
  • 1998 was warmest year on record

67
Is Global Warming REALLY occurring
  • YES

68
Is global warming due to human activity?
  • Earths climate does fluctuate naturally
  • Remember, there was once an ice age
  • Glaciers have advanced and retreated over
    geologic history
  • Couldnt the rise in temperatures were observing
    be part of this natural fluctuation?

69
Evidence for global warming being caused by human
activity
  • The current temperature increases are unlike
    anything ever observed in history
  • They directly coincide with humans increased
    burning of fossil fuels
  • The vast majority of scientists agree that the
    evidence shows humans are impacting global
    warming
  • Still there is controversy among some
  • Careful to consider the sources

70
Possible Effects of Global Warming
  • Average global temperatures will increase by 1-2
    degrees C by 2050
  • Sea level rise due to melting ice caps
  • Coastal ecosystems
  • Coastal human communities
  • N. America more droughts?
  • Entire ecosystems change as climates change
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