 We already discussed that an ecosystem is the combined biotic and abiotic characteristics of a region.  We have grouped ecosystems, looked at the hierarchy of describing ecosystems.  However, the factors that make up an ecosystem are themselves complex systems with structure and relationship.

 Trophic categories is the structure of food sources within an ecosystem.  2 major categories-  Producer  Consumer

 Producers are the intial source of captured energy in an ecosystem.  By definition, producers turn light or inorganic chemical energy into organic chemical energy.  Photoautotroph- captures light energy (photosynthesis) and uses the energy to convert CO2 and H2O into complex organic molecules.  Chemoautotroph- utilizes inorganic chemical energy bonds to convert CO2 and H20 into complex organic molecules.

 All heterotrophs (non-autotrophs) are consumers.  Consuming only plant matter-herbivore.  Consuming only heterotrophs-carnivore.  Consuming both plants and animals-omnivore.  Consuming the remains of organisms-decomposer.  Consuming detritus (organic wastes)-detritivore.

 Because these terms are categories of consumption-the relationship between consumers and producers is intense and specialized.  Think of the examples of camouflage, behavior, and adaptation you saw in the movie; all directly related to eating or being eaten.

 First Trophic Level- all of the producers.  Initial production of organic energy molecules. (energy fixation)  Initial fixation of necessary inorganic molecules. (nutrient concentration)  Second Trophic Level-consumers that feed only on producers.  Primary consumers.  Third Trophic Level-consumers that feed on primary consumers.  Secondary consumers.  Fourth Trophic Level-consumers that feed on secondary consumers.  Tertiary consumers.

 Food chains show a direct linear feeding path.  A food web is the graphic organization of feeding patterns between multiple food chains.

 It turns out that there is a limit of 3-4 levels on land and 4-5 in water ecososytems.  The Law of 10%: Only 10% of the total biomass at a given trophic level is matched by the trophic level above.  This is because approximatly 90% of the energy available at any trophic level is lost in consumption.  Most of the initial biomass is not consumed and goes strait to the detrititus feeders.  And there are limits as to how large a predator can become.  This means that any change at the producer level has an exponential change at each level above.

 Questions 1, 2, 3, 5, 8, 9 on page 53.