9/6/2013. Ecosystem Ecology. Orgnaisms (biotic factors) interact with abiotic factors

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1 Ecosystem Ecology Orgnaisms (biotic factors) interact with abiotic factors 1

2 Matter and Energy Matter has mass and occupies space: it is the stuff you and everything else is made of. Energy is what you and all living things use to move matter around and to change matter from one form to another. Organization of matter in an organism Atoms of different elements Matter in living things is organized: Cells are made of Which are made of Bonded together to form molecules These bonds store chemical energy Organisms are made of organic molecules 2

3 Life obeys physical laws Life follows the law of conservation of matter: Matter can not be created nor destroyed only transformed Where did the matter that you are made of come from? Life obeys physical laws Life follows the laws of thermodynamics : Energy can not be created nor destroyed only transformed Every time energy is transformed into a usable form, Some of it is transformed as heat (unusable form) Where did the energy To move your arm come from? 3

4 Food is the immediate source of energy and matter for living things What abiotic factors do organisms interact with? Energy it is needed by organisms to do the processes to keep alive Forms: light, chemical, heat Type of energy used by living things: Chemical elements carbon, nitrogen, phosphorous, oxygen They are what organisms are made of (matter) 4

5 All living things need organic molecules for growth and for energy Cellular Respiration is the process in every cell that extracts usable energy out of food feces FOOD energy growth Transforms chemical energy (in the bonds of organic molecules) into usable energy by living things (can be used for running, working) E And also Converts organic molecule into inorganic molecule Where did the organic molecules in food come from? Plants are able to make their own organic molecules for growth or energy Photosynthesis transforms light energy from the sun into chemical energy in organic molecules And Converts inorganic molecules into organic molecule What can sugar be used for? 5

6 Two processes that transform energy and matter Photosynthesis Energy transformation Matter transformation Autotrophic organisms (producers) are the ONLY ones that can do photosynthesis Heterotrophic organisms (consumers) can not do photosynthesis in plants Cellular Respiration Energy transformation Matter transformation This occurs in autotrophs AND in the heterotrophs that eat them in plants and animals These processes allow for the movement of energy and chemicals in an ecosystem Movement of energy and chemicals in an ecosystem 6

7 Movement of energy and chemicals Movement of energy and chemicals in an ecosystem is different Energy flows - not recyclable - energy as heat can t be used again - Ecosystem always needs an external input of energy Chemicals cycle - recyclable - e.g. carbon dioxide can be used again - Ecosystem does not need external input of chemicals if cycling is complete Their movement is linked because both depend on transfer of food. We can represent their movement Via a food chain: Simplified linear diagram of who eats whom In an ecosystem, food chains interconnect forming Food Web Complex network of who eats whom We can group organisms by the level at which they feed 7

8 Trophic structure: The different feeding relationships in an ecosystem Detritivores and decomposers eat nonliving organic matter; they recycle chemicals. Animals that eat herbivores are secondary consumers, at the third trophic level. Animals that eat plants are primary consumers, or herbivores, and are at the second trophic level. Plants and other photosynthetic organisms are producers. What trophic level are you if you eat an apple? What trophic level are you if you eat a steak? Amount of energy and Trophic structure What happens to the energy at each trophic level? Which energy is available to the next trophic level? Energy available to all the consumers and decomposers in an ecosystem comes from the energy in the producers 8

9 Energy pyramid shows the available energy to the next trophic level The higher the trophic level a species is at, the less available energy that it has from the original energy stored as photosynthesis Implication: Animals at higher trophic levels require more vegetation to provide for their food than animals at lower trophic levels We can apply this information to the human diet! Meat eaters vs. Plant eaters 3,000 lbs of corn and soybeans is capable of supporting ONE person if converted to beef, however, the same amount of soybeans and corn utilized directly without converting to beef will support 22 people! If the world population ate like in the US, ONLY less than ½ of the population could be fed. If the world population ate strict vegetarian diets we could feed 1 billion MORE than present 9

10 BIOMASS PYRAMID shows that amount of mass is reduced in higher trophic levels We can use a biomass pyramid to understand why organisms at higher trophic levels have higher concentration of toxic chemicals than lower ones 10

11 What happens to these toxics in the food chain? As biomass is consumed through food chain The amount of biomass is reduced But The amount of toxic does not (due to persistence) RESULT: The concentration of the toxic increases Having a greater impact on top predators Biological Magnification or Biomagnification: accumulation of toxics in tissues of consumers in food chains Coal-burning power plants are the most common source of mercury pollution. Coal contains mercury naturally, and when it is burned, the mercury travels up the smokestack and is released into the air. 11

12 Mercury Methylation Bacteria convert inorganic mercury (Hg) to the organic form methylmercury (MeHg) Hg in emissions (smoke) Hg - Deposited on land and into water 50-75% from anthropogenic (human) sources Bacteria Methyl-mercury (MeHg) Methylmercury (MeHg) Highly toxic Gets into the food web Snail Phytoplankton (algae) Herbivorous fish Largemouth bass Zooplankton Small fish 12

13 Hg in emissions (smoke) Hg - Deposited on land and into water 50-75% from anthropogenic (human) sources Bacteria Methyl-mercury (MeHg) Large fish MeHg MeHg Zooplankton MeHg Small fish MeHg Phytoplankton (algae) Hg concentrations in fish were several orders of magnitude higher than in stream water. Bioaccumulation: the buildup of substances, such as pesticides or heavy metals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it excretes it. Bioaccumulation results in the organism having a higher concentration than the surrounding environment. Mercury in Mercury out 13

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