Equilibrium in the Biosphere

Week 2 Bio 20 Cyber High

Ecology  Study of the interactions between organisms and their physical environment and with each other.

 Biosphere  the part of the earth that is inhabited by organisms. 3 parts: 1Lithosphere  Land 2Hydrosphere  water 3Atmosphere  The gasses that surround the Earth.

Living vs. Non-living  There are two factors which make up the biosphere.  Biotic Factors  Living components of the biosphere  plants and animals…  Abiotic Factors  Non-living components of the biosphere  minerals, water, weather...

Interactions Within the Biosphere  Abiotic vs Biotic  When a non-living factor affects a living factor.  i.e. The weather affecting a living organism  Biotic vs. Biotic  When a living factor affects another living factor.  i.e. Two organisms fighting for the same food.  Biotic vs. Abiotic  Abiotic vs. Abiotic

Levels of Organization

Levels of organization Cell Tissue Organ System Organism Population Community Ecosystem Biosphere Biome

Hierarchical Levels within the Biosphere Biosphere Ecosystem Community Population Organism World Lake or River Lots of different species of organisms Lots of same species of fish Fish

Important Definitions  Population: group of individuals of the same: species, place & time  Community : populations of all species in an area  Ecosystem : community and its biotic and abiotic factors  Interactions  Biome : large scale ecosystems  Can be found around the world  tundra, grassland

General Terms  Autotroph  Producer  Photosynthesis  Light energy used to make organic compounds (glucose)  Done by chloroplast containing organisms (plants, algae)  Chemosynthesis  Energy released by chemical reactions to make a sugar  Oxidizing hydrogen sulfide or methane  Done by bacteria in extreme environments (deep sea vents, hot springs)

 Heterotroph  Consumer  A Primary consumer eats a producer  A Secondary consumer eats a primary consumer  A Tertiary consumer eats a secondary consumer… More General Terms

 Herbivore  An organism that only eats plants.  Rabbit, squirrel  Carnivore  An organism that only eats animals.  Wolf, Lion, Tyrannosaurus Rex  Omnivore  An organism that eats both plants and animals.  Bear, Human More General Terms

 Scavenger  An organism that feeds on dead organisms or the wastes of organisms.  Vulture, Seagull,  Decomposer  An organism that breaks down organic wastes and the remains of dead organisms into simpler compounds such as:  carbon dioxide  ammonia  Water

Input energy Biogeochemical Cycles Energy Lost Ecosystems are OPEN SYSTEMS. Energy and matter can flow in and out of system

Food chains  Food Chain  A linear illustration that represents the step sequence of who eats whom in the biosphere.  used to show:  energy transfers  Two Types  Grazer: plant, herbivore, carnivore  Detritus: organic waste, scavengers, decomposers

Food chains  Characteristics:  Energy is transferred from organism to organism  Each time energy is transferred about 90% is lost as heat or used for life processes  Lost as heat during cellular respiration, stored in an unusable form, metabolized by the organism itself for ATP to live

Food Chain  Note that:  the arrow points at the eater  the arrows separate trophic (eating) levels

Trophic Levels  Trophic level: how far an organism is from the original energy source  Plants – first trophic level  Original energy is from the sun  When an organism is ingested by another, energy is transferred  Plant – mouse – owl  Producer – primary consumer – secondary consumer (top carnivore)  T1 – T2 – T3

Food Webs  What would happen if we relied on deer for our food?  In reality, a consumer relies on more than one food source  If one source is scarce, consumer can eat more of something else  Food web:  a series of interlocking food chains  more accurately represents energy pathways  who eats whom… really

Food Web  ABCD represent different trophic levels.  Level D represents the decomposers

Laws of Thermodynamics  Biosphere requires a constant flow of energy  Energy flows one way through the biosphere following basic scientific principles called the laws of thermodynamics

Laws of Thermodynamics Energy can be changed in form, but not created or destroyed. (Law of conservation of energy) Energy input = Energy Output First Law

Second Law Any energy change results in loss of energy as heat Energy input  desired energy + waste energy

Energy Flow  About 10% of the energy is transferred from one trophic level to the next.

 During any change, some of the energy is lost as waste energy or heat.  Applied to an ecosystem, as energy flows through the community there is energy loss at each trophic level.  Much of this loss is in the form of heat which is lost when food molecules are broken down in the cells.  There would be less energy loss in the community if consumers only fed on producers

Ecological Pyramids  Ecological pyramids illustrate the energy loss through the trophic levels  Solar radiation transformed in plants  Plants create chemical energy  Plant eaten by consumer  Energy lost at each transformation  Higher trophic level = less energy available  Number of trophic levels limited b/c of loss of energy

Ecological Pyramids  In ecological pyramids,  Base -the producer populations  Next Level - the primary consumers  Higher levels and above -the secondary, tertiary etc.

Ecological Pyramids  Three types:  Numbers: total number of organisms in each trophic levels  Biomass: mass of dry tissue of organisms at each trophic level  shows how mass decreases as you move up the food chain  Energy: based on energy produced at each trophic level

Energy Pyramids

Pyramid of Numbers

Pyramid of Biomass

Human Interference in the Ecosystem  Pesticides  used to kill pests  mosquitoes - malaria  pesticides in food chain accumulate at each level  causes loss of diversity.

 Example  DDT: dichloro diphenyl trichloroethane  developed as a biological weapon in WWII  1950’s - used as a pesticide for insects

 DDT also affects human populations  found in breast milk  came from sprayed crops  animals that ate crops  Banned in Canada and US in 1970’s  Not banned in other areas - Mexico, Central America  Continues to be produced as a cheap pesticide in poorer nations

Biological amplification  Pesticide concentration builds up at the top level of the pyramid  toxins accumulate in fatty tissue  not released in wastes  Magnifies each time you move up  higher trophic level - higher concentration