Humans in the Biosphere

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Humans in the Biosphere

• Honors Biology Chapter 6

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The Tragedy of the Commons

• Areas used by everyone are no ones
  responsibility
• Leads to misuse loss of resources

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Renewable Resources

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

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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

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Nonrenewable Resources

• Cannot be replenished by natural processes.
• Examples
• Fossil fuels

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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.

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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

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Sustainable Development Strategy - Example

• Using insects instead pesticides to control pests

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Land Resources - Soil

• Renewable or not?
• Renewable if managed properly

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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

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Mismanagement of Soil Resources

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

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Forest Resources

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

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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

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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.

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Old Growth Forest
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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.

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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

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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

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Menhaden Fishery in Virginia
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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

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Air Resources

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

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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

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What are particulates

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

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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

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Freshwater Resources

• People use freshwater for
• Drinking
• Washing
• Watering crops
• Industry
• Recreation

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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.

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Protection of Wetlands and the sustainable use of
water

• Wetlands act to purify water that passes through
  them
• Saving wetlands means cleaner water

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Primary use of water in the U.S.

• Agriculture
• Uses ¾ of freshwater

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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

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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???

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Threats to Biodiversity Human Impacts

• Altering habitats
• Hunting species to extinction
• Introducing toxins into the environment
• Introducing foreign species into a new environment

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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.

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Habitat fragmentation
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Demand for Wildlife Products

• Demand for animal species products has caused
  extinction by hunting
• Carolina parakeet
• Passenger pigeon

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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.

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Biological Magnification

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

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Famous Incidents of Biological Magnification

• DDT

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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

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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

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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

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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

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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

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Invasive species
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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

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Kudzu
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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.

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Northern snakehead
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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

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Phragmites

• Highly invasive
• Threatens native marsh plants

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Veined Rapa Whelk

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

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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

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Conserving Biodiversity

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

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Conservation Strategies

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

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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

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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

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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?

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Ozone depletion

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

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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.

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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

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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

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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.

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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

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Is Global Warming REALLY occurring

• YES

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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?

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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

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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