Ecosystems Chapter 54

Ecosystem Community of organisms plus the abiotic factors that exist in a certain area

Relationships, I Trophic structure / levels ~ feeding relationships in an ecosystem Primary producers ~ the trophic level that supports all others; autotrophs Primary consumers ~ herbivores Secondary and tertiary consumers ~ carnivores Detrivores/detritus ~ special consumers that derive nutrition from non-living organic matter Food chain ~ trophic level food pathway

Energy Flow, I Primary productivity (amount of light energy converted to chemical energy by autotrophs) Gross (GPP): total energy Net (NPP): represents the storage of energy available to consumers Rs: respiration NPP = GPP - Rs Biomass: primary productivity reflected as dry weight of organic material Secondary productivity: the rate at which an ecosystem's consumers convert chemical energy of the food they eat into their own new biomass

Energy Flow, II Ecological efficiency : % of E transferred from one trophic level to the next (5-20%) Pyramid of productivity : multiplicative loss of energy in trophic levels Biomass pyramid : trophic representation of biomass in ecosystems Pyramid of numbers : trophic representation of the number of organisms in an ecosystem

Energy inefficiency incomplete digestion metabolism

Chemical Cycling Biogeochemical cycles: the various nutrient circuits, which involve both abiotic and biotic components of an ecosystem Water Carbon Nitrogen Phosphorus

Carbon cycle CO 2 in atmosphere Diffusion Respiration Photosynthesis Plants and algae Plants Animals Industry and home Combustion of fuels Animals Carbonates in sediment Bicarbonates Deposition of dead material Deposition of dead material Fossil fuels (oil, gas, coal) Dissolved CO2

Birds Herbivores Plants Amino acids Carnivores Atmospheric nitrogen Loss to deep sediments Fish Plankton with nitrogen- fixing bacteria Nitrogen- fixing bacteria (plant roots) Nitrogen- fixing bacteria (soil) Denitrifying bacteria Death, excretion, feces Nitrifying bacteria Soil nitrates Excretion Decomposing bacteria Ammonifying bacteria Nitrogen cycle

Loss to deep sediment Rocks and minerals Soluble soil phosphate Plants and algae Plants Urine Land animals Precipitates Aquatic animals Animal tissue and feces Animal tissue and feces Decomposers (bacteria and fungi) Decomposers (bacteria and fungi) Phosphates in solution Loss in drainage Phosphorus cycle

Nutrient cycling Decomposition connects all trophic levels

What have we done!

Human Impact Biological magnification : trophic process in which retained substances become more concentrated at higher levels Greenhouse effect : warming of planet due to atmospheric accumulation of carbon dioxide Ozone depletion : effect of chlorofluorocarbons (CFC’s) released into the atmosphere Acid Precipitation Cause: Overpopulation?

Impact of ecology as a science Ecology provides a scientific context for evaluating environmental issues – Rachel Carson, in 1962, in her book, Silent Spring, warned that use of pesticides such as DDT was causing population declines in many non-target organisms

Barry Commoner’s Laws of Ecology Everything is connected to everything else Everything must go somewhere  there is no such place as “away” Nature knows best There is no such thing as a free lunch Laws of Unintended Consequences

Acid Precipitation  nitrogen oxides  sulfur dioxide power plants industry transportation

Acid rain

BioMagnification

BioMagnification PCBs – General Electric manufacturing plant on Hudson River – PCBs in sediment – striped bass nesting areas

Carbon Dioxide Global Warming

CO 2 NO x methane

Ozone Depletion protects from UV rays

Ozone Depletion

Bad ozone vs. good ozone

Ozone Depletion Loss of ozone above Antarctica