BIOMES AND AQUATIC ECOSYSTEMS

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BIOMES AND AQUATIC ECOSYSTEMS

• Chapter 44

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Learning Objectives

• What are biomes?
• What major factors account for their
  distribution?
• What is species diversity?
• Which biomes yield the greatest species
  diversity?
• How are the earths major terrestrial and aquatic
  biomes characterized?

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• A. Biomes
• Major types of terrestrial ecosystems.
• Distribution of biomes largely depends on climate
  (temperature rainfall).
• Climate is determined by the Earths tilt
  uneven heating of Earths surface.

Tilt produces seasons in northern southern
hemispheres.
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We know that altitude and latitude influence the
distribution of biomes .
but how are climatic factors involved?
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How The Sun Heats The Earth By Radiation
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• Unequal heating causes air movements that
  distribute moisture.

Altitude influences climate - conditions usually
become drier colder as altitude increases.
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Dry Air
Precip.
Dry Air
Precip.
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Biomes May be Further Modified By What is Called
the Rain Shadow Effect
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Learning Objectives

• What are biomes?
• What major factors account for their
  distribution?
• What is species diversity?
• Which biomes yield the greatest species
  diversity?
• How are the earths major terrestrial and aquatic
  biomes characterized?

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Species Diversity
What factors contribute to maximum species
diversity?
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Species Diversity
What factors contribute to maximum species
diversity? Heat Sunlight Water Nutrients Environm
ental Stability?
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Species Diversity H, has Two Components

• Evenness E --- addresses the equitability of
  individuals across all species. High evenness
  increases species diversity.
• Richness S --- simply the number of species in
  a community. The greater the number of species,
  the greater the diversity.

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Which Community Has the Greater Diversity, A or B?
Community A Sp. 1 27 individ. Sp. 2 18
Sp. 3 23 Sp. 4 15 Sp. 5 17
__________ Total 100
Community B Sp. 1 79 individ. Sp. 2 3
Sp. 3 8 Sp. 4 6 Sp. 5 4
__________ Total 100
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Which Community Has the Greater Diversity, A or B?
Community A Sp. 1 47 individ. Sp. 2 112
Sp. 3 203 Sp. 4 65 Sp. 5
173 __________ Total 600
Community B Sp. 1 57 individ. Sp. 2 43
Sp. 3 8 Sp. 4 61 Sp. 5 24
Sp. 6 32 Sp. 7 11
__________ Total 236
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Remember that the Diversity Index , H, that you
are calculating in your lab exercise incorporates
both the evenness (equitability) component and
the number of species (richness) component.
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Are patterns of air circulation (called Air
Coils) correlated with species diversity within
major biomes on a global basis? Yes
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Diversity decreases
Diversity decreases
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Learning Objectives

• What are biomes?
• What major factors account for their
  distribution?
• What is species diversity?
• Which biomes yield the greatest species
  diversity?
• How are the earths major terrestrial and aquatic
  biomes characterized?

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Terrestrial Biomes

• Tropical Rain Forest
• Desert
• Temperate Grassland
• Temperate Deciduous Forest
• Taiga or Northern Coniferous Forest
• Tundra

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Tropical Rain Forest Biome
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• Tropical Rain Forest

• warm moist (rainfall 79-157 in/yr)
• nutrients cycle rapidly
• soils are nutrient poor
• plants exhibit vertical stratification
• very high biodiversity

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Desert Biome
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• Desert

• dry (rainfall lt 8 in/yr)
• hot days / cool nights
• plants adapted to obtain store water
• rapid life cycles
• deep roots (mesquite)
• succulent tissues / reduced leaves (cacti)

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• animals adapted to minimize water loss
• tough, waterproof integument
• concentrated urine
• nocturnal habits

Atriplex (saltbush plant) stores salt in outer
cells of leaves.
Red vizcacha rat has adaptation that allows it to
feed on Atriplex.
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• Temperate Grasslands (prairie)

• 1 or 2 dry seasons/year (rainfall 10-40 in/yr)
• lack trees shrubs
• grazing frequent fires maintain grass
• In US, majority of prairie has been replaced by
  farmland.

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• Temperate Forests

rainfall 26-118 in/yr Temperate forests are
either deciduous or coniferous.

• Temperate Deciduous Forest
• oak-hickory or beech-maple predominate
• moist growing season (at least 4 months)
• soil rich in nutrients
• vertical stratification
• organisms adapted to seasonal changes

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• Taiga or Northern Coniferous Forest

• precipitation falls as snow/ice (8-24 in/yr)
• long, cold winters
• soil is thin, moist, acidic nutrient poor
  (subsoil may be frozen)
• biodiversity lower than temperate zone
• conifers predominate

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Tundra Biome A Closer View
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• Tundra

Precipitation 8-24 in/yr

• long, bitterly cold winters
• permafrost begins 18 in. below surface
• low biodiversity
• shallow-rooted shrubs lichens
• plants adapted to short growing season
• animals adapted to cold (small extremities)
  snow (many are camouflaged)

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Aquatic Biomes (Ecosystems)

• Freshwater
• Standing Water lakes, ponds, bogs, swamps
• Running Water streams, rivers
• Marine
• Coastal estuaries, mangrove swamps, intertidal
  zone, coral reefs
• Ocean

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• B. Aquatic Ecosystems
• 1. Freshwater Ecosystems
• Lakes and Ponds (standing water)

• littoral zone
• limnetic zone
• profundal zone
• benthic zone

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Zones Of A Temperate Lake
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Physical/Chemical Factors Important in Lakes

• Radiant Energy
• Permits Photosynthesis
• Produces Heat
• Temperature
• Effects metabolic rates of resident species
• Influences rate of decomposition
• Effects water density

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Physical/Chemical Factors Important in Lakes
Contd.

• Oxygen
• Influences rate of metabolism
• Influences rate of decomposition
• Solubility of O2 in water is effected by
  temperature and exchange with atmosphere
• Water Clarity (inverse of turbidity)
• Effects photosynthesis - and thus food chain
• Effects heating

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Operation of O2/Temp and Light Meters
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Close - Up of Oxygen/Temperature Meter
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Gary, Can you move to the left a bit?
Secchi Disc in action a simple method for
testing water clarity
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Late April Water Quality Data
Surface Waters Starting to Warm Up Turnover Has
Already Occurred
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Mid September Water Quality Data
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The Three Layers of a Lake During Summer
Stratification
Atmosphere
Lake Surface
Epilimnion warm, light water
Thermocline boundary layer
Hypolimnion cold, heavy water
Lake bottom
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Temperate Lakes Go Through an Annual Cycle Based
on Changes in Climate Over the Four Seasons
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Annual Cycle Of A Temperate Lake
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What Are The Consequences of Turnover (i.e. Total
Mixing)?

• O2 gets redistributed throughout the water
  column.
• The gases of decomposition get released to the
  surface of the lake.
• Nutrients (N,P and K) that accumulated at the
  bottom due to organisms dying and sinking are
  released throughout the water column.

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Review and Summary

• Oxygen nutrients (nitrogen/phosphorus) are
  unevenly distributed in lakes.
• O2 level is highest near surface
• nutrient level is highest near bottom
• Oxygen nutrients are redistributed by
• wind (ponds shallow lakes)
• fall spring turnover (deep lakes in temperate
  regions)

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Lake Succession

• Oligotrophic lakes
• young low in nutrients productivity
• clear sparkling blue
• deep water is oxygen-rich
• Eutrophic lakes
• older nutrient rich high in productivity
• green murky
• O2 often depleted in deep water during summer
• Nutrients in sewage agricultural runoff speed
  eutrophication.

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The Process of Eutrophication

• Defined as the enrichment of a body of water and
  subsequent increase in productivity.
• Occurs naturally but at a slow pace over
  geological time
• Human activities greatly accelerate the process
  of eutrophication
• Increased nutrient input from fertilizer
  mismanagement
• Nutrients associated with sewage

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• Rivers and Streams (running water)
• Transport rainwater, groundwater, snowmelt
  sediment from land to ocean or lake.

• At headwaters
• channel is narrow
• water is clear oxygen-rich
• current is swift
• At mouth
• channel widens

• water is murky contains less oxygen
• current slows, depositing sediment

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• 2. Marine Ecosystems
• Coastal Ecosystems
• Include estuaries, mangrove swamps, the
  intertidal zone coral reefs.
• Estuary - area where fresh water of river meets
  salty water of ocean.

• water is brackish
• salinity fluctuates
• very productive
• high biodiversity
• nursery for many ocean animals

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Salinity Gradient in Estuaries
.05 ---------15 ------------ 28 ------------- 32
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Salinity Values in Parts/Thousand (0/00)
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• Mangrove Swamp a type of estuary in which a
  tropical wetland is dominated by salt-tolerant
  plants (mangroves).

• transitional zone between forest ocean
• salinity fluctuates
• plants have aerial roots
• high biodiversity

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• Intertidal Zone - area along coast between high
  low tides.

• organisms adapted to pounding waves varying
  degrees of desiccation
• low productivity

Coral Reef - underwater deposits of calcium
carbonate formed by colonies of animals.

• very productive
• high biodiversity
• very fragile

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• Ocean Ecosystem
• covers 71 of Earths surface
• temperature 35oF - 81oF
• sunlight quickly dissipates with depth
• primary producers are photoautotrophs (found near
  surface) chemoautotrophs (found at deep-sea
  hydrothermal vents)
• highest productivity near upwellings (occurs on
  western side of continents)

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Upwellings

• Warm, light surface water is displaced by strong
  winds
• Then, colder, nutrient-rich water is able to rise
  to the surface from the aphotic zone of the ocean
• Thus, algal productivity and the entire
  epilimnetic food chain is greatly enriched

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Finis