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The Biosphere
Chapter 58
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Effects of Sun, Wind, Water
• Biosphere: includes all living communities on Earth
• Global patterns of life on Earth are influenced by
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influenced by
1. The amount of solar radiation that reaches different areas
2. Patterns of global atmospheric circulation which influence oceanic circulation
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Effects of Sun, Wind, Water
• Earth receives energy from the Sun
• Solar radiant energy passes through the atmosphere and its intensity and wavelength composition are modified
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wavelength composition are modified
• About 1/2 of the energy is absorbed within the atmosphere
– UV-B is strongly absorbed by the ozone
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Effects of Sun, Wind, Water
• Some parts of the Earth’s surface receive more energy from the Sun
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from the Sun than others
• This has a great effect on climate
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Effects of Sun, Wind, Water
• Angle of incidence:how the Sun’s rays strike the spherical Earth
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Earth
• Earth’s orbit around the Sun and its daily rotation on its own axis affect climate
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Effects of Sun, Wind, Water
• Global circulation patterns
– Hot air rises relative to cooler air
– Heating at the equator causes air to rise from the surface to high in the atmosphere
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from the surface to high in the atmosphere
– Rising air is rich in water vapor
• Warm air holds more water than cold
• Intense solar radiation at the equator provides the heat needed for water to evaporate
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Effects of Sun, Wind, Water
• After the warm moist air moves from the surface at the equator
– Warm air moves north and south
– Cooler air flows toward the equator from both hemispheres
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from both hemispheres
– Air descends at 30˚ latitude-desert regions of the earth
– At 60˚ latitude air begins to rise again
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Effects of Sun, Wind, Water
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Annual mean temperature varies
with latitude
Global patterns of atmospheric circulation
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Effects of Sun, Wind, Water
• The Coriolis effect: the curvature of the paths of the winds due to Earth’s rotation
– Northern hemisphere: counterclockwise--winds curve to the
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counterclockwise--winds curve to the right of their direction of motion
– Southern hemisphere: clockwise --winds curve to the left; blow westward as well as toward the equator
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Effects of Sun, Wind, Water
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Ocean currents are largely driven by winds
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Effects of Sun, Wind, Water
• Regional and local differences affect terrestrial ecosystems
• Rain shadows:
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• Rain shadows:
– Rain falls as air rises
– Remains dry on the leeward side of the mountain
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• Monsoon winds
– Heating and cooling of continent
– Winds blow off the water into the interior in the summer
– Winds blow off land onto the water in
Effects of Sun, Wind, Water
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– Winds blow off land onto the water in the winter
– Winds affect rainfall patterns
• Duration
• Strength
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• Elevation: temperature and other conditions change with elevation
Effects of Sun, Wind, Water
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elevation
• Air temperature falls about 6˚C for every 1000m increase in elevation
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• Presence of microclimate factors
• Microclimates: highly localized sets of climatic conditions
– Gaps in forest canopy
Effects of Sun, Wind, Water
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• High air temperature and low humidity
– Under a log in the forest
• Low air temperature and high humidity
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Biomes
• Biomes: a major type of ecosystem on land
• Each biome has a characteristic appearance
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– Defined largely by sets of regional climatic conditions
• Biomes are named according to their vegetational structures
• Eight principle biomes
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Biomes
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Predictors of biome distribution Temperature and precipitation
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Biomes
• Tropical rain forests
– 140-450 cm rain/yr
– Richest ecosystems on land
– High temperature and high rainfall
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– High temperature and high rainfall
– Very high diversity: 1200 species of butterflies in a single square mile
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• Savanna
– 50-120 cm rainfall/yr
– Tropical or subtropical grasslands
– Occur as a transition ecosystem
Biomes
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between tropical rainforests and deserts
– Serengeti of East Africa
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• Deserts
– 25-40cm rainfall/yr; unpredictable
• Plants and animals cannot depend on any rainfall
– 30˚N and S latitudes, rainshadows
Biomes
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– 30˚N and S latitudes, rainshadows
– Vegetation sparse, animals adapted to little water availability
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• Temperate grasslands: prairies
– Rich soils
– Grasses with roots that penetrate deep into the soil
Biomes
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– In North America converted to agricultural use
– Adapted to periodic fire
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Biomes
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Freshwater Habitats
• Fresh water covers only 2% of Earth’s surface
• Formation of fresh water
– Evaporation of water into atmosphere
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– Falls back to Earth’s surface as precipitation
• Wetlands: marshes, swamps, bogs
• Rivers, lakes, streams
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• Life depends on oxygen availability
– Oxygen per liter is only 5% of that in the atmosphere
• Oxygen added by photosynthesis and
Freshwater Habitats
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aeration from the atmosphere
• Oxygen is removed by animal and detritivores respiration, and through decaying organic matter
• Warm water holds less O2 than cooler water
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• Lake and pond habitats change with water depth
– Intensity of light decreases with water depth
– Photic zone: area where light
Freshwater Habitats
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– Photic zone: area where light penetrates and photosynthesis is possible
– Littoral zone: shallows at edge of lake
– Aphotic (benthic) zone: below light penetration level
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Freshwater Habitats
26Lake Zones and Productivity
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• Thermal stratification: warm water is less dense than cold water and tends to float on top. Layering is stratification.
• Thermocline: a transition layer between warm and cold waters
Freshwater Habitats
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between warm and cold waters
• Water is most dense at 4˚C and least dense at 0˚C
• Thermal stratification tends to cut off the oxygen supply to bottom waters
• Anoxia: oxygen depleted waters
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Freshwater Habitats
• Wind can force the
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Annual cycle of thermal stratification in a temperate-zone lake
force the layers to mix
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• Oligotrophic water: low in nutrients, usually high in oxygen
• Crystal clear conditions because of the low amount of organic matter
Freshwater Habitats
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• Light penetrates deep in the water column
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• Eutrophic water: high in nutrients, densely populated with algae and plant material
• Low in dissolved oxygen in summer
Freshwater Habitats
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• Light does not penetrate the water column
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Marine Habitats
• 71% of the Earth’s surface is covered by ocean
• Continental shelves: near coastlines, water is not especially deep
– ~ 80km wide and 1m to 130m deep
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– ~ 80km wide and 1m to 130m deep
• Average depth of the open ocean is 4,000 - 5,000m deep
– Trenches: 11,000m deep
• Principle primary producers are phytoplankton (single cell or colonial)
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Marine Habitats
• Oceanic Zones
• Open oceans have low primary
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low primary productivity
• Oligotrophic ocean: Low nutrient levels “biological deserts”
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Marine Habitats
• Continental shelf ecosystems provide abundant resources
• Neritic waters: waters over the shelves
– High concentrations of nitrates and other nutrient
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nutrient
– Shallow, up welling occurs here
• 99% of ocean food supply comes from neritic waters
• Petroleum comes almost exclusively from shelves
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Marine Habitats
• Estuaries: shelf ecosystem where fresh water from streams or rivers mix with ocean water
– Intertidal habitat: area that is exposed to air at low tide but under
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exposed to air at low tide but under water at high tide
– Salt marshes: in the intertidal zone
– Mangrove swamps: occur in tropical and subtropical intertidal zones
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Marine Habitats
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Mangrove Swamp Louisiana Marsh
Coral Reef
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Marine Habitats
• Banks and coral reefs
– Banks are local shallow areas on the shelves
• Fishing grounds
– Coral reefs occur in subtropical and
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– Coral reefs occur in subtropical and tropical latitudes
– Defining feature is stony corals
• Algal symbioses: cnidarians and dinoflagellates
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Marine Habitats
Green areas are upwelling regions
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Upwelling regions: localized places where deep water is drawn consistently
to the surface
Dark blue are oligotrophic
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Marine Habitats
• El Niño Southern Oscillation
– 2-7 years on an irregular and unpredictable basis
– Coastline waters become waters become profoundly warm
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profoundly warm
– Primary productivity unusually low
– Weakening of the east-to-west Trade Winds
– Upwelling continues, but only recirculates the thick warm surface layer
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Marine Habitats
• El Niño can wreak havoc on ecosystems
– Plankton abundance can drop to 1/20th normal levels
– Fish stocks disappear
– Seabirds and sea lion populations crash
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– Seabirds and sea lion populations crash
• On land:
– Heavy rains produce abundant seeds and land birds flourish
– Increase rodent population
– Increase predator population
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Marine Habitats
El Niño winter
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Marine Habitats
• Deep sea: cold, dark place with fascinating communities
– Seasonless, 2-5˚C, pressure: 400-500 atms
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• Food originates from photosynthesis in the sunlit waters
• 99% eaten as it drifts down through the water column
• Animals: small-bodied, thinly distributed
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Marine HabitatsHydrothermal vent communities: thick with life
• Large bodied animals
• Do not depend on the Sun’s energy for primary
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Sun’s energy for primary production
• Depend on sulfur-oxidizing bacteria
• Water temperature up to 350˚C
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Marine Habitats
• Once Trade Winds weaken a bit, the pressure difference that makes them blow is lessened, weakening the Trade Winds even more
– Shift the weather systems of the
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– Shift the weather systems of the western Pacific Ocean 6,000km eastward
– Tropical rainstorms fall on Peru and Ecuador
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Human Impacts: Pollution
• Human impacts can cause adverse changes in ecosystems
• DDT: highly effective insecticide, sprayed in United States after WWII
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• DDT is oil soluble and biomagnifies in the food chain
• Result of use:
– Populations of ospreys, bald eagles, and brown pelicans plummeted
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• Biomagnification of DDT concentrations in the food chain. Predatory bird species were
Human Impacts: Pollution
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species were affected because it made their eggshells so thin that the shells broke during incubation
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• Freshwater habitats are threatened by pollution and resource use
• Point source pollution: comes from an identifiable location
Human Impacts: Pollution
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– Factories
– Sewage-treatment plants
• Laws and technologies can be applied because the source is known
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• Diffuse pollution: is exemplified by eutrophication caused by excessive run-off of nitrates and phosphates
– Dissolved oxygen declines
– Fish species change, carp take the
Human Impacts: Pollution
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– Fish species change, carp take the place of more desirable species
• Can originate from thousands of lawns, farms, golf clubs…
• Solutions depend on public education and political action
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• Pollution from coal burning: acid precipitation
– When coal is burned sulfur oxide is released
– Sulfur oxide combines with water in the
Human Impacts: Pollution
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– Sulfur oxide combines with water in the atmosphere to create sulfuric acid
• Mercury emitted in stack smoke is a second potential problem
– Mercury biomagnifies: causes brain damage in humans
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• Acid precipitation and mercury pollution affect freshwater ecosystems
– pH levels below 5.0, many fish
Human Impacts: Pollution
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– pH levels below 5.0, many fish species and other aquatic animals die or are unable to reproduce
– Mercury accumulates in the tissues of food fish: dangerous to public health
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• Terrestrial ecosystems are threatened by deforestation
– Single greatest problem is deforestation by cutting or burning
Human Impacts: Pollution
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• Deforestation consequences
– Loss of habitat
– Major contributing factor in increased desertification
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– Loss of nutrients from soils
– Eutrophication of lakes, streams, and rivers
– Disruption of the water cycle
– Loss of topsoil
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• Overfishing of the ocean
– Crisis proportions -- single greatest problem in the ocean realm
Poaching on
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Poaching on terrestrial animals increases when fish populations decline
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• Aquaculture is only a quick fix
– Dietary protein needs of many aquacultured fish are met with wild-caught fish
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– Often damage natural ocean ecosystems: clearing of mangrove swamps for aquaculture area
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• Pollution effects in the ocean
– Plastic found washed up on beaches in remote areas
– Waters are laced with toxic chemicals
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– Biopsy of tissue from Arctic killer whales reveal high levels of pesticides and flame-retardant chemicals
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• Destruction of coastal ecosystems
– Estuaries subjected to severe eutrophication
– Destruction of salt marshes
• Major contributing factor to hurricane
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• Major contributing factor to hurricane destruction along the coast of Louisiana
• Had marshes been present, Katrina might not have caused so much damage
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• Stratospheric ozone depletion
– Ozone hole: over Antarctica between 1/2 to 1/3 of original ozone concentrations are present
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• Over United States
– Ozone concentration has been reduced by about 4%
• Stratospheric ozone is important because it absorbs UV radiation (UV-B)
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absorbs UV radiation (UV-B)
• UV-B damages tissue increases risks for
– Cataracts
– Skin cancer: 1% drop in ozone leads to a 6% increase in skin cancer
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• Ozone depletion and CFCs: Major cause of ozone depletion are chlorine and bromine containing compounds in the atmosphere
• Use of CFCs are being phased out in
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• Use of CFCs are being phased out in many countries
• CFC are chemically stable in the atmosphere for many years
• Ozone depletion will continue to occur until all of the CFCs are broken down
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• CO2 and other gases in the atmosphere maintain the Earth’s average temperature at 25˚C
• Human activities are now changing the composition of the atmosphere;
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composition of the atmosphere; increasing the CO2 and other gas levels
• Because of the increase, global temperatures are increasing, causing global warming
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Global Warming
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2005 was the warmest year on record
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Global Warming
• Based on the outputs of all four models
– Temperature in Europe is predicted to increase by 2˚C-4˚C by 2080
– Increases in temperature will be disruptive
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disruptive
• Snow cover in the Swiss Alps: 300 m higher than today
• Parts of southern Europe will receive 20% less precipitation
• Cause major economic upheavals
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Global Warming
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Concentrations of CO2 since 1958
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Global Warming
• Cause of global warming?
– Greenhouse effect: which is good in that it keeps the Earth warm enough for life
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– But increase in CO2 emissions through burning of fossil fuels will continue to increase temperatures on Earth
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Global Warming
• How CO2 affects temperature
– CO2 absorbs electromagnetic radiant energy
– Earth receives radiant energy from
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the Sun
– Earth also emits radiant energy
– The Earth’s temperature will be constant only if the rates of these two processes are equal
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Global Warming
• The atmosphere allows in short wave radiant energy from the Sun, but does not allow the long wave radiant energy from the Earth to escape
• This is the same principle as a
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• This is the same principle as a Greenhouse
Short wave- in, long wave -cannot get out, increase in
temperature in the greenhouse
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Global Warming
• Other greenhouse gases
– Methane: 20 xs the heat trapping properties of CO2, less concentration in the atmosphere, less long-lived
– Methane is produced globally in
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– Methane is produced globally in anaerobic soils and fermentation reactions of ruminant mammals
– Methane is locked up in permafrost
• Sudden release will cause large perturbation in global temperature
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Global Warming
• Other greenhouse gases
– Nitrous oxide: agricultural use of fertilizers is the largest source
– Energy consumption
– Industrial use
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– Industrial use
• Evidence confirms global warming
– Ice free seasons 2.5 wks longer
– Ice at the North Pole decreased
– Glaciers decreasing in size
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Global Warming
68Disappearing glaciers
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Global Warming
• Global temperature change has affected ecosystems in the past and is doing so now
– Shift in species geographic ranges
– Migratory birds arrive earlier at their
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summer breeding grounds
– Insects and amphibians breed earlier
– Wild fruit fly populations-changes in gene frequency
– “bleaching” of reef building corals
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Global Warming
• Problems
– Rate of warming today is rapid
– Evolutionary adaptations for species survival may not have time to occur
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– Natural areas no longer cover the whole landscape
– Species that shift to higher altitudes may have reached the peak of the mountain
– Species’ habitat disappears entirely
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• Possible effects on human species
– Rising sea levels: 200 million people would be affected by increased flooding
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• Coastal cities and entire islands could be submerged
– Frequency or severity of extreme events will increase (hurricanes, El Niño)
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• Effects on agriculture
– Positive: more CO2 tends to increase growth of some crops
– Increase pollen production causing
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more severe allergies
– More droughts in some regions
– Decrease in crop production in tropical areas
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• Human health
– Frequent flooding = loss of safe drinking water
• Cholera and other epidemics may occur more often
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occur more often
– Tropical diseases may invade nontropical countries
• Malaria
• Dengue fever