The Balance of the Living World

 Ecology is the study of the distribution and interactions of living communities with each other and the abiotic habitat.  It is an objective science based on the collection of field observations and experimental data.

 Environmentalism is a way of thinking that places maintaining the richness and balance of nature as a top priority.  It is a subjective belief system based on an emotional response to information provided by ecology

Biosphere Ecosystem Community Population Individual

A single of member of a species Chimpanzee, Pan troglodytes

A group of individuals that belong to the same species, live in the same area, and breed with others in the same group. Scalloped hammerhead, Sphyrna lewini

 The many different species that live together in a given area.  A collection of populations in a habitat.

An ecological system encompassing a community and all the physical aspects of its habitat.

The sum total of all ecosystems

 autotroph  Self-feeder, uses environmental energy to create organic molecules  ex. plant, algae, cyanobacteria  Common name: producer  chemoautotroph  Self-feeder, uses non-organic chemicals (H2S) as energy source  ex. bacteria surrounding ocean vents  Common name: producer

 heterotroph  Other-feeder, consumes living organisms for energy needs  Ex. Insects, zooplankton, mammals, etc.  Common name: consumer  saprotroph  obtains energy by secreting enzymes outside body and absorbing digested remains of once living organisms  Ex. Fungi and bacteria  Common name: decomposer

The trophic level of an organism is its position in the food chain  Primary Producer  The foundation of the trophic pyramid (food chain)  Primary Consumer  Heterotrophic feeders of producers  Typically herbivores (eat photosynthetic organisms)  Secondary Consumer  Obtains energy from the primary consumer  Typically carnivores or omnivores.  Tertiary Consumer, etc.

 The collection of all the food chains in a given area  A food web describes the predator-prey relationships of a given community  It is a model of the energy flow through a living system  Very rarely does the model accurately represent the full collection of organisms

 First Law of Thermodynamics:  Energy can be transferred and transformed, but it cannot be created or destroyed.  Second Law of Thermodynamics  Every energy transfer or transformation increases the entropy of the universe  Ordered forms of energy are at least partly converted to heat.

Microorganisms and other detritivores Tertiary consumers Secondary consumers Detritus Primary consumers Sun Primary producers Heat Key Chemical cycling Energy flow Nutrient Cycling

chemical  Defined as the amount of light energy converted to chemical energy, i.e., the total amount of organic matter made by producers, during any given time period. 10 billion tons of organic materials  Globally, primary producers create approximately 10 billion tons of organic materials per year.

 Gross Primary Production (GPP) is the total primary production in an ecosystem  Net Primary Production (NPP) is the GPP minus the energy used by primary producers for respiration (R) NPP = GPP - R

 NPP represents the storage of chemical energy that will be available to consumers in the ecosystem.  NPP can be expressed as:  Energy per unit area per unit time (J/m 2 /yr)  Biomass (weight; usually dry weight) of vegetation added per unit area per unit time (g/m 2 /yr)

 Standing crop: total mass of photosynthetic organisms present at a given time  NPP: amount of new biomass added in a given time period

Open ocean Continental shelf Upwelling zones Extreme desert, rock, sand, ice Swamp and marsh Lake and stream Desert and semidesert scrub Tropical rain forest Temperate deciduous forest Temperate evergreen forest Tropical seasonal forest Savanna Cultivated land Estuary Algal beds and reefs Boreal forest (taiga) Temperate grassland Woodland and shrubland Tundra Freshwater (on continents) Terrestrial Marine Key Percentage of Earth’s surface area Average net primary production (g/m 2 /yr) ,500 2,0001,500 1, Percentage of Earth’s net primary production , , , ,600 1,200 1,300 2,

North Pole 60°N 30°N South Pole Equator 60°S 30°S 60°W 60°E 120°E 120°W 180° 0° 180° High R O Y G B I V Low

 How much energy is passed to the next level of a food chain relative to what is available.  Energy transfer between trophic levels is usually < 20% efficient

 Defined as: amount of chemical energy in consumer’s food that is converted to their own biomass during a given time period  How much mass is gained compared to how much food is eaten.

NET SECONDARY PRODUCTION = 33J Growth (new biomass) Cellular respiration Feces 100 J 33 J 67 J 200 J Plant material eaten by caterpillar

Production Efficiency = Net Secondary Production Assimilation of Primary Production 33J 100J = 33% Note that energy lost as undigestible material does not count toward assimilation. Growth (new biomass) Cellular respiration Feces 100 J 33 J 67 J 200 J Plant material eaten by caterpillar

The percentage of food intake (energy) that is converted to new biomass  Birds & Mammals (endotherms) ~ 1-3%  Fish ~ 10%  Insects ~ 40%

Trophic Efficiency = Y/X x 100 Usually ranges from 10% – 20%. i.e., 80% – 90% energy available at one trophic level is not transferred to the next trophic level. This loss is multiplied over the length of the food chain.

1,000,000 J of sunlight 10,000 J 1,000 J 100 J 10 J Tertiary consumers Secondary consumers Primary consumers Primary producers Size of each block is proportional to the net production, expressed in energy units.

Trophic level Dry weight (g/m 2 ) Tertiary consumers Secondary consumers Primary consumers Primary producers Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida. Size of each block is proportional to the standing crop (total dry weight of all organisms) at each trophic level.

Carbon, Nitrogen, Potassium, Water, Phosphorous

 Energy is used to maintain highly ordered homeostasis with organisms  Basic materials of living organisms:  Carbon  Nitrogen  Oxygen  Phosphorus

CO 2 + H 2 O C 6 H 12 O 6 + O 2 sunlight Only occurs in autotrophs (animals that make their own food)

CO 2 + H 2 O + ATP C 6 H 12 O 6 + O 2 Happens in all eukaryotic cells (everything but bacteria) Yes, that means both animals and plants sugar

 Carbon Dioxide required for photosynthesis  Plants take CO 2 from the air.  Carbon can be found… 1. in atmosphere, 2. dissolved in water, 3. in living organisms, 4. or deposited at CaCO 3 (limestone) or fossil fuels  Decomposition, combustion, and respiration returns C to atmosphere as CO 2

Atmospheric and Ocean CO 2 Plants Animals Fossil Fuels photosynthesis respirationcombustion Limestone (plankton) erosion

 N is a major component of proteins, the basic functional unit of the cell.  Most N is found in atmosphere as N 2  Only a few bacteria can use N 2 and turn it into forms of N that plants can use.  Animals get their N from the food they eat.  Other bacteria turn organic N from urea and dead organisms back into N 2

N 2 (79% of atmosphere) AnimalsPlants Urea Death Bacteria, soil Bacteria N2N2 NH 3 NO 3 N2N2 NH 3 NO 3