Ecosystems and Energy 3

© 2015 John Wiley & Sons, Inc. All rights reserved. Overview of Chapter 3  What is Ecology?  The Energy of Life  Laws of Thermodynamics  Photosynthesis and Cellular Respiration  Flow of Energy Through Ecosystems  Producers, Consumers and Decomposers  Path of Energy Flow: Who Eats Whom  Ecological Pyramids  Ecosystem Productivity

© 2015 John Wiley & Sons, Inc. All rights reserved. Chesapeake Bay salt marshes  An estuary – semi-enclosed body of water where freshwater drains into ocean  Tidal – gradual changed from fresh to salt water  Cordgrass dominates – brackish  Home to insects and birds, nursery for fish  Very important buffer for coasts against storms

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology  Ecology  “logy” study of, “eco” house – study of one’s house  The study of interactions among and between organisms in their abiotic environment  Biotic - living environment  Includes all organisms  Abiotic - non living or physical environment  Includes living space, sunlight, soil, precipitation, etc.

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology  Organisms interact with biotic components, but also effect many physical and chemical processes  Physical – walking on soil  Chemical – CO 2, O 2, wastes

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology  Ecologists are interested in the levels of life above that of organism

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology Definitions  Species - A group of similar organisms whose members freely interbreed to produce fertile offspring  Population - A group of organisms of the same species that live in the same area at the same time  Community - All the populations of different species that live and interact in the same area at the same time  Ecosystem - A community and its physical (abiotic) environment  Landscape - Several interacting ecosystems (ex: bear hunting for salmon in a river, living in adjacent forest)

© 2015 John Wiley & Sons, Inc. All rights reserved. Part of Earth that contains living organisms Ecology Community and physical environment Individuals Group of same species All populations of species in an area

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology  Coral Reef communities – similar to rainforests for number of species and productivity  Threatened with changing climate  How can communities be protected from warming waters?  What could loss mean?

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology  Biosphere contains earth’s communities, ecosystems and landscapes, and includes:  Atmosphere- gaseous envelope surrounding earth  Hydrosphere- earth’s supply of water  Lithosphere- soil and rock of the earth’s crust

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecology Lithosphere Hydrosphere Atmosphere

© 2015 John Wiley & Sons, Inc. All rights reserved. Energy of Life  The ability or capacity to do work  Chemical, Thermal, Mechanical, Nuclear, Electrical, and Radiant/Solar (below)

© 2015 John Wiley & Sons, Inc. All rights reserved.  Solar radiation is the primary source of energy on planet Energy of Life Plants turn solar radiation into food

© 2015 John Wiley & Sons, Inc. All rights reserved. Energy of Life  Energy exists as:  Potential energy (stored energy)  Kinetic energy (energy of motion)  Potential energy is converted to kinetic energy as arrow is released from bow

© 2015 John Wiley & Sons, Inc. All rights reserved. Thermodynamics  Study of energy and its transformations  System- the object being studied  Closed System- Does not exchange energy with surroundings (rare in nature)  Open System- exchanges energy with surroundings

© 2015 John Wiley & Sons, Inc. All rights reserved. Laws of Thermodynamics  First Law of Thermodynamics  Energy cannot be created or destroyed; it can change from one form to another  Energy is absorbed by water and plate, but not lost

© 2015 John Wiley & Sons, Inc. All rights reserved. Laws of Thermodynamics  Second Law of Thermodynamics  When energy is converted form one form to another, some of it is degraded to heat  Heat is highly entropic (disorganized)  Water in sunlight will get warmer  Engine converts chemical energy of gasoline into mechanical energy inefficiently

© 2015 John Wiley & Sons, Inc. All rights reserved. Photosynthesis  Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules 6 CO H 2 O + radiant energy C 6 H 12 O H 2 O + 6 O 2 Chlorophyll in plants

© 2015 John Wiley & Sons, Inc. All rights reserved. Cellular Respiration  The process where the chemical energy captured in photosynthesis is released within cells of plants and animals  This energy is then used for biological work C 6 H 12 O O H 2 O 6 CO H 2 O + energy

© 2015 John Wiley & Sons, Inc. All rights reserved. Photosynthesis and Cellular Respiration

© 2015 John Wiley & Sons, Inc. All rights reserved. Life without Sun  1970s – discovered hydrothermal vents in deep ocean (200 o C or 392 o F)  Rich ecosystem supported without light  Bacteria perform chemosynthesis  Similar to photosynthesis, but use chemical (H 2 S) not sunlight

© 2015 John Wiley & Sons, Inc. All rights reserved. Energy Flow Through Ecosystems  Passage of energy through an ecosystem

© 2015 John Wiley & Sons, Inc. All rights reserved. Food Chains- The Path of Energy Flow  Energy from food passes from one organism to another based on their Trophic Level  Definition: An organism’s position in a food chain, which is determined by its feeding relationships  First Trophic Level: Producers  Second Trophic Level: Primary Consumers  Third Trophic Level: Secondary Consumers  Decomposers are present at all trophic levels

© 2015 John Wiley & Sons, Inc. All rights reserved. Food chains  Autotrophs = Producers  Auto “self” and tropho “nourishment”  Produce own food from inorganic material  Ex: plants via photosynthesis and hydrothermal vent bacteria via chemosynthesis

© 2015 John Wiley & Sons, Inc. All rights reserved. Food chains  Heterotrophs = Consumers  heter “different” and tropho “nourishment”  Uses bodies of other organisms as food  Omnivores – eat both plants and animals

© 2015 John Wiley & Sons, Inc. All rights reserved. Food chains  Consumers of detritus (detritivores)  Eat dead material such as leaves, carcasses, feces  Ex: crabs, worms, millipedes, snails

© 2015 John Wiley & Sons, Inc. All rights reserved. Food chains  Decomposers or saprotrophs  sapro “rotten” and tropho “nourishment”  Breakdown dead organic material  Release inorganic molecules (CO 2 and nutrients) that producers can use  Ex: fungus, bacteria  Involved in all aspects of food chains

© 2015 John Wiley & Sons, Inc. All rights reserved. Food Web  Food web visualizes feeding relationships within a community  More complex than food chain  Still simplified compared to nature

© 2015 John Wiley & Sons, Inc. All rights reserved. Humans and Antarctic food web  Base of web is algae, which is eaten by krill  Krill are eaten by many larger organisms  Wastes of whales resupply nutrients for algae and krill  Ozone and climate change are warming area

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecological Pyramids  Graphically represent the relative energy value of each trophic level  Important feature - large amount of energy is lost as heat between trophic levels  Three main types  Pyramid of numbers  Pyramid of biomass  Pyramid of energy

© 2015 John Wiley & Sons, Inc. All rights reserved. Pyramid of Numbers  Illustrates the number of organisms at each trophic level  Fewer organisms occupy each successive level  Does not indicate:  biomass of organisms at each level  amount of energy transferred between levels

© 2015 John Wiley & Sons, Inc. All rights reserved. Pyramid of Biomass  Illustrates the total biomass at each successive trophic level  Biomass: measure of the total amount of living material  ~90% reduction in biomass through trophic levels  100 to 10

© 2015 John Wiley & Sons, Inc. All rights reserved. Pyramid of Energy  Illustrates how much energy is present at each trophic level and how much is transferred to the next level  Most energy dissipates between trophic levels  Lost as heat and energy to maintain each level  Explains why there are so few trophic levels

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecosystem Productivity  Gross Primary Productivity (GPP)  Total amount of energy that plants capture and assimilate in a given period of time  Cellular respiration (R)  Plants use some energy of GPP to maintain themselves  Plants respire too  Net Primary Productivity (NPP)  Productivity after respiration losses are subtracted  What is available as food for other organisms

© 2015 John Wiley & Sons, Inc. All rights reserved. Ecosystem Productivity  GPP is similar to gross pay in paycheck  R is similar to taxes  NPP is similar to take home pay Net Primary Productivity (plant growth per area per time) Gross Primary Productivity (total photosynthesis per area per time) Plant Cellular Respiration (per area per time) =-

© 2015 John Wiley & Sons, Inc. All rights reserved. Variation in NPP by Ecosystem  Coral reefs are near tropical rain forests  Humans consume a large amount of global NPP  ~30% but we make up ~0.5% of biomass  This represents a threat to planet’s ability to support both human and non-human inhabitants

© 2015 John Wiley & Sons, Inc. All rights reserved. Energy and Climate Change  Humans use a large portion of global NPP  If we use more biomass as energy rather than fossil fuels, our use of NPP may increase  Corn as fuel, wood for heat  How can we balance our needs with other organisms?

© 2015 John Wiley & Sons, Inc. All rights reserved. ENVIRONEWS  Use of satellite imagery improves biomass estimates of forests  Help protect tropic forests in developing countries  Developed countries pay to keep forests intact  Need to ground truth satellite models with monitoring data from forest