1. Ecology and Energy in Ecosystems

2. WHAT IS ECOLOGY? *Ecology is the study of interactions that take place between organisms and their environment. *Living things are affected by both the physical or nonliving environment (abiotic factors) and by other living things (biotic factors). *Ecologists study: 1. Individual organisms 2. Interactions among organisms of the same species. 3. Interactions among organisms of different species. 4. The effects of abiotic factors on interacting species.

3. Abiotic Factors in an Ecosystem *Ecology includes the study of features of the environment that are abiotic because these features are part of an organism’s life. *Examples of abiotic factors include: air currents, temperature, moisture, light, nutrient availability, pH, oxygen levels, carbon dioxide levels and soil/ soil type. Food Production in Salt Bush Food production (mg of glucose/hr Temperature (°C)

4. Levels of Organization *Ecologists have organized the living world into levels—the organism by itself, populations, communities, ecosystems, and the biosphere. ORGANISM: *An individual living thing that is made of cells, uses energy, reproduces, responds, adapts, develops, maintains homeostasis. Each organism has its own: 1. Habitat – the place where an organism lives 2. Niche – the role, or job, an organism has in its community

5. POPULATION: *A group of organisms of the same species, which interbreed and live in the same place at the same time. *Members of the same population may compete with each other for food, water, mates, and/or other resources. *Competition occurs depending upon whether resources are in short supply or not. Competition is the struggle between organisms for resources, such as food, mates, shelter, space, and water

6. COMMUNITIES * Many different populations of organisms living and interacting in the same place at the same time. *A change in one population in a community may cause changes in the other populations. MINOR CHANGES? MAJOR CHANGES?

7. ECOSYSTEMS *A community AND its abiotic components. *There are two major types of ecosystems—terrestrial (land) ecosystems and aquatic (water) ecosystems.

8. Human body Skin Intestine Mouth Buildings Mold in walls Basement Ventilation systems Bathrooms Food Any moldy food Refrigerator Freshwater Pond Lake Stream Estuary Salt water Ocean Estuary Aquarium Forest Old farm field Meadow Yard Garden plot Empty lot Compost heap Volcano site Rotting log Terrestrial Ecosystems Other Sites for Ecosystems Aquatic Ecosystems Examples of Aquatic and Terrestrial Ecosystems

9. HOW ORGANISMS OBTAIN ENERGY AND NUTRIENTS *Ecologists trace the flow of energy and nutrients through communities to understand feeding relationships between organisms. Ecologists categorize organisms based on HOW they obtain energy and nutrients! All organisms are categorized as autotrophs OR heterotrophs *1. Autotrophs (auto = self, troph = feeding) - also called Producers *Plants use the sun’s energy to “produce” their own food (glucose) in a process called photosynthesis. CO 2 + H 2 O + sunlight → glucose (sugar) + O 2 (in the presence of chlorophyll)

10. Energy Conversion in Photosynthesis The energy Conversion: Light + 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 (energy) + (carbon dioxide) + (water)  (glucose) + (oxygen) Light (radiant) energy  chemical energy photons of light chemical energy in bonds

11. It takes a LOT of autotrophs to make food for the entire ecosystem!

12. *2. Heterotrophs (hetero = other, troph = feeding) - also called Consumers --An organism that feeds on (consumes) other organisms to obtain energy and nutrients. There are 5 different types of heterotrophs/ consumers: 1. Herbivores (plant eaters – organisms that eat producers) 2. Carnivores (meat eaters – organisms that eat other consumers) 3. Omnivores (eat both producers and consumers) 4. Scavengers (eat consumers that have already died) 5. Decomposers (break down the complex compounds of dead and decaying plants and animals into simpler molecules)

13. Organisms Interact Through Feeding Relationships 1. Food Chains and Food Webs: Organisms rely on different parts of the ecosystem for energy and nutrients. Energy and nutrients travel from one part of the ecosystem to the next through the feeding interactions of organisms (through food chains and food webs)

14. Food Chains *Simple, linear (straight line) diagram that scientists use to show how energy and nutrients move from one organism to the next. sun berry plants → mice → fox decomposers *Nutrients and energy move from autotrophs to heterotrophs and, eventually, to decomposers. *Arrows indicate where energy and nutrients are traveling to. *A complete food chain ALWAYS starts with the sun. WHY? *A complete food chain ALWAYS ends with decomposers. WHY? *When organisms use energy they produce heat. Therefore, a portion of the energy transferred to each organism is given off as heat as it is used. Food chains and food webs contain plants (producers/ autotrophs), predators (organisms that hunt and kill others for food), and prey (organisms eaten by others for food).

15. Trophic (“Feeding”) Levels * Each organism in a food chain represents a feeding step/ level. * A primary producer is an organism that uses the sun’s energy to make its own food (plants and other organisms - using photosynthesis) *A primary (first level) consumer is an organism that feeds on plants, such as a grasshopper. (a herbivore) *A secondary (second level) consumer is an organism that feeds on a primary consumer. (a carnivore) *A tertiary (third level) consumer is an organism that feeds on a secondary consumer (a top predator)

16. Food Web A food web is a method for organizing the food connections in an ecosystem. Food webs are made of many food chains.

17. Food Web *A diagram that shows ALL of the food chains that exist in a given community –because organisms generally eat MORE than just one thing.

18. Energy Pyramids and Trophic Levels Energy pyramids show the feeding order of trophic levels. The size each level represents: Number of organisms Amount of biomass (mass of living organisms) Amount of energy within living organisms

19. Ecological/ Energy Pyramids *Diagrams that show how energy flows through an ecosystem. *The base of the ecological pyramid represents the autotrophs, or first trophic level (the primary producers – the plants!). *The ecological pyramid of energy illustrates that the amount of available energy decreases at each successive trophic level. WHY??? ***Organisms USE most of the energy they obtain for themselves – for their own growth and cellular processes (when they do this, some of the energy is given off/ lost as heat) Note: Parasites, scavengers, and decomposers feed at each level. Heat

20. How much energy is transferred? 1% of the sun’s energy reaching Earth is used by producers *10% of energy in each trophic level is passed on to next trophic level *90% of the energy is used/ released as heat due to functions of the organism

21. Energy available at each trophic level---The 10% rule: The amount of energy available to each successive trophic level is only 10% of the available energy at the trophic level before/ below it. WHY? Producers Example: If herbivores have 256g of energy, how much is passed on to the first order consumers that eat them? (Hint: What percent of the energy is passed on to the next trophic level?)