1. Biotic/Abiotic Factors, Food Webs, and Chains Environmental Science

2. I. Ecology Ecology- the scientific study of interactions between organisms and their environments, focusing on energy transfer It is a science of relationships.

3. A. Ecological Organization

5. What is an ecosystem? System = regularly interacting and interdependent components forming a unified whole Ecosystem = an ecological system; = a community and its physical environment treated together as a functional system

6. OR, MORE SIMPLY an ecosystem is composed of the organisms and physical environment of a specified area. SIZE: micro to MACRO

7. THE RULES OF ECOLOGY 1. Everything is connected to everything else. 2. Everything must go somewhere. 3. There is no such thing as a free lunch.

8. Attributes of Ecosystems Order Development Metabolism (energy flow) Material cycles Response to the environment Porous boundaries Emphasis on function, not species

9. Ecological communities Community = an assemblage of populations of organisms living in the same place at the same time Members interact with each other Interactions determine the structure, function, and species composition of the community Community ecologists are people interested in how: Species coexist and relate to one another Communities change, and why patterns exist

10. B. An ecosystem has abiotic and biotic components: ABIOTIC components: Non-living factors of an ecosystem Solar energy provides practically all the energy for ecosystems. Inorganic substances, e.g., sulfur, boron, tend to cycle through ecosystems. Organic compounds, such as proteins, carbohydrates, lipids, and other complex molecules, form a link between biotic and abiotic components of the system.

11. C. Biotic Factors BIOTIC components: Living organisms in an ecosystem The biotic components of an ecosystem can be classified according to their mode of energy acquisition. In this type of classification, there are: Autotrophs and Heterotrophs

12. 1. Nutritional Relationships

13. Producers  Organisms that produce their own food (autotrophs)

14. Autotrophs Autotrophs (=self-nourishing) are called primary producers. Photoautotrophs fix energy from the sun and store it in complex organic compounds (= green plants, algae, some bacteria) photoautotrophs simple inorganic compounds complex organic compounds light

16. Chemoautotrophs (chemosynthesizers) are bacteria that oxidize reduced inorganic substances (typically sulfur and ammonia compounds) and produce complex organic compounds. chemoautotrophs reduced inorganic compounds complex organic compounds oxygen

17. Chemosynthesis near hydrothermal vents

18. Other chemoautotrophs: Nitrifying bacteria in the soil under our feet!

19. Heterotrophs Heterotrophs (=other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds. They require energy previously stored in complex molecules. heterotrophs simple inorganic compounds complex organic compounds (this may include several steps, with several different types of organisms) heat

20. Heterotrophs can be grouped as: consumers decomposers

21. Consumers  Organisms that cannot make their own food (heterotrophs) so they eat!

26. Herbivore A plant eating organism

27. Carnivore  A flesh eating organism  Predators- hunt and kill prey for food  Scavengers- eat dead animals

28. Omnivore An organism that eats both plants and animals

29. Decomposer Organisms that use dead organisms as food and return elements to the earth.

30. Consumers feed on organisms or particulate organic matter. Decomposers utilize complex compounds in dead protoplasm. Bacteria and fungi are the main groups of decomposers. Bacteria are the main feeders on animal material. Fungi feed primarily on plants, although bacteria also are important in some plant decomposition processes.

32. Energy flow Simplistically: This pattern of energy flow among different organisms is the TROPHIC STRUCTURE of an ecosystem. heat Producers Consumers Decomposers heat

33. It is useful to distinguish different types of organisms within these major groups, particularly within the consumer group. Consumers

34. a. Food Chains and Food Webs: What’s the Difference?

35. Food Chain vs. Food Web Food Chain = Flow of energy through organisms organized by trophic levels. Trophic Level = Position on a food chain based on how an organism gets energy..

37. All organisms have a role in their environment, also know as their Niche. Producers Consumers Carnivore Scavenger Predator Herbivore Omnivore Parasite

38. Terminology of trophic levels We can further separate the TROPHIC LEVELS, particularly the Consumers: Producers (Plants, algae, cyanobacteria; some chemotrophs)-- capture energy, produce complex organic compounds Primary consumers--feed on producers Secondary consumers--feed on primary consumers Tertiary consumers--feed on secondary consumers

39. More trophic levels: Detritivores--invertebrates that feed on organic wastes and dead organisms (detritus) from all trophic levels Decomposers--bacteria and fungi that break down dead material into inorganic materials

40. Food chains

41. Problems Too simplistic No detritivores Chains too long

42. Rarely are things as simple as grass, rabbit, hawk, or indeed any simple linear sequence of organisms. More typically, there are multiple interactions, so that we end up with a FOOD WEB.

43. Food Web = Complex interactions represented by arrows. Shows several intertwined food chains

45. Energy Pyramids An energy pyramid shows the amount of energy that moves from one trophic level to another in a food chain. The most energy is available at the producer level of the pyramid. The availability of energy decreases as it moves up the energy pyramid.