BIOMES AND AQUATIC ECOSYSTEMS

							BIOMES AND AQUATIC
    ECOSYSTEMS



            Chapter 44
      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 earth’s major
  terrestrial and aquatic biomes
  characterized?
A. Biomes
  Major types of terrestrial ecosystems.
Distribution of biomes largely depends on
 climate (temperature & rainfall).
Climate is determined by the Earth’s tilt
  & uneven heating of Earth’s surface.
                              Tilt produces
                              seasons in
                              northern &
                              southern
                              hemispheres.
We know that altitude and
  latitude influence the
distribution of biomes ….


   but how are climatic
    factors involved?
How The Sun Heats The Earth By
          Radiation
Unequal heating causes air movements
 that distribute moisture.




Altitude influences climate - conditions usually
  become drier & colder as altitude increases.
Dry Air


Precip.


Dry Air

Precip.
 Biomes May be Further Modified By
What is Called the “Rain Shadow Effect”
      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 earth’s major
  terrestrial and aquatic biomes
  characterized?
     Species Diversity



What factors contribute to maximum
        species diversity?
     Species Diversity


What factors contribute to maximum
        species diversity?

              Heat
             Sunlight
              Water
            Nutrients
     Environmental Stability?
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.
Which Community Has the Greater
       Diversity, A or B?
Community A           Community B
Sp. 1 – 27 individ.   Sp. 1 – 79 individ.
Sp. 2 – 18    “       Sp. 2 – 3    “
Sp. 3 – 23    “       Sp. 3 – 8    “
Sp. 4 – 15    “       Sp. 4 – 6    “
Sp. 5 – 17    “       Sp. 5 – 4    “
__________            __________
Total 100             Total 100
Which Community Has the Greater Diversity, A or B?
   Community A              Community B
   Sp. 1 – 47 individ.      Sp. 1 – 57 individ.
   Sp. 2 – 112       “      Sp. 2 – 43       “
   Sp. 3 – 203       “      Sp. 3 – 8    “
   Sp. 4 – 65    “          Sp. 4 – 61       “
   Sp. 5 – 173              Sp. 5 – 24       “
   __________               Sp. 6 – 32   “
   Total 600                Sp. 7 – 11   “
                            __________
                            Total 236
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.
Are patterns of air circulation (called
“Air Coils”) correlated with species
 diversity within major biomes on a
            global basis?


               Yes ……
      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 earth’s major
  terrestrial and aquatic biomes
  characterized?
           Terrestrial Biomes

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




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



 dry (rainfall: < 8 in/yr)
 hot days / cool nights
 plants adapted to obtain & store water
   rapid life cycles
   deep roots (mesquite)

   succulent tissues / reduced leaves (cacti)
 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.
     Temperate Grasslands (prairie)




1   or 2 dry seasons/year (rainfall: 10-40
  in/yr)
 lacktrees & shrubs
 grazing & frequent fires maintain grass
In US, majority of prairie has been replaced
  by farmland.
         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
    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
Tundra Biome – A Closer View
  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)
    Aquatic Biomes (Ecosystems)
   Freshwater
     Standing Water – lakes, ponds,
      bogs, swamps
     Running Water – streams, rivers



 Marine
            – estuaries, mangrove
     Coastal
      swamps, intertidal zone, coral reefs
     Ocean
B. Aquatic Ecosystems
1. Freshwater Ecosystems
 Lakes   and Ponds (standing water)
   littoralzone
   limnetic zone

   profundal zone

   benthic zone
Zones Of A Temperate Lake
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
Physical/Chemical Factors Important
          in Lakes – Cont’d.
  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
Operation of O2/Temp and Light
            Meters
Close - Up of Oxygen/Temperature
               Meter
Gary, Can you
 move to the
 left a bit?


Secchi Disc in
  action … a
simple method
  for testing
 water clarity
   Late April Water Quality Data




Surface Waters Starting to Warm Up – Turnover Has
                Already Occurred
Mid September Water Quality Data
                The Three Layers of a Lake
               During Summer Stratification
Lake Surface                                      Atmosphere


               Epilimnion –   warm, light water


               Thermocline –   boundary layer


               Hypolimnion –   cold, heavy water


 Lake bottom
   Temperate Lakes Go
 Through an Annual Cycle
Based on Changes in Climate
  Over the Four Seasons
Annual Cycle Of A Temperate Lake
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.
       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)
           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.
 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
 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
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
Salinity Gradient in Estuaries




.05 ---------15 ------------ 28 ------------- 32 -----------35
Salinity Values in Parts/Thousand (0/00)
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
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
 Ocean  Ecosystem
   covers 71% of Earth’s 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)
            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
Finis