Transcript Ecosystems
Ecosystems Food of the Sea In The News Ecosystem • Includes abiotic environment & community • Types of organisms of an ecosystem – Producers – Consumers – Decomposers Producers • Make their own food • Base of the food chain • Plants & photosynthetic protists Consumers • Heterotrophs – feed on other organisms • Kill & eat their food Decomposers • Special group of consumers • Nourishment from dead matter • Recyclers An Ecosystem Ecosystem Boundaries • May or may not be distinct Transfer of Nutrients • Ultimate source of most energy is the sun • Green plants capture energy from the sun • Consumers eat producers & other consumers • Detritivores convert organic materials to nutrients usable by plants Trophic Levels • Feeding levels & transfer of energy – Producer – Primary consumer – feed on producer – Secondary consumer – eat primary consumer – Tertiary consumer – eat secondary consumer Food Chain Food Web • Many species do not strictly feed on one trophic level • Interactions become more complicated • Food web – group of interwoven food chains Energy Flow Through Ecosystems • Most energy is lost & does not transfer to the next trophic level • Higher trophic levels must have fewer individuals – Next highest trophic level has about 1/10th the number of individuals, biomass & energy Flow of Energy Numbers in Trophic Levels Biomass in Trophic Levels Energy in Trophic Levels Obtaining Substances for Life • Materials cycle through ecosystems • Reservoir –area with most of a material • Examples of ecosystem cycles – Water (hydrologic cycle) – Nitrogen – Phosphorus – Oxygen – Carbon Water Cycle • Most living things are primarily water • Life’s chemical reactions require water • 90% of water that reaches atmosphere comes from plant transpiration • Atmospheric water condenses Water Cycle • Plants take up about 1000 kg of water to produce 1 kg of biomass • Groundwater provides ¼ of water used by humans in U.S. • 2% of U.S. groundwater is polluted – Industry – Pesticides Carbon Cycle • CO2 found in atmosphere & oceans • Producers & some consumers incorporate carbon into organic molecules • Animals & combustion return carbon to atmosphere Oxygen Cycling • Plants use CO2, release O2 • Consumers use O2, release CO2 • Some CO2 is liberated by decomposition Nitrogen Cycle • Important plant nutrient • Atmosphere is reservoir • Nitrogen fixing bacteria convert N2 to ammonia Phosphorus Cycle • Required plant nutrient • Soil has only small amounts • Animals obtain phosphorus by eating plants End chapter 40