Biology 1B Ecology Lecture 9 Page 1 Assigned readings 7th Edition pp 1154 1206 6th Edition pp 1198 1214 Ecosystems Outline of Lecture 9 A B C D E F G Ecosystem Water cycle Carbon cycle Nitrogen cycle Phosphorous cycle Succession in ecosystems Ecosystems and diseases Schistosoma A Ecosystem an interacting system that involves both the organisms and their non living environment The flow of energy and nutrients is regulated 1 Cycling because substances originated from the atmosphere or weathered rock then became incorporate into various organisms and ultimately through decomposition are returned to the non living world B Water cycle involves evaporation precipitation and transpiration Aquafer permeable saturated undergound layers of rock sand and gravel point vs non point sources of pollution what is biomonitoring C Carbon cycle involves atmosphere autotrophic organisms heterotrophic organisms and decomposition Professor Resh Spring 2007 Biology 1B Ecology Lecture 9 Page 2 Assigned readings 7th Edition pp 1154 1206 6th Edition pp 1198 1214 Ecosystems D Nitrogen cycle involves nitrogen becoming available through metabolic activities of a few types of bacteria some free living other symbiotic E Phosphorous cycle involves soil leaching erosion uplifting guano and mycorrhizae symbiotic associations between plants and fungi a mineralbased cycle F Succession in ecosystems 1 As ecosystems mature there is an increase in biomass but a decrease in net productivity 2 Earlier successional stages are more productive than later ones 3 Disturbance keeps some systems in earlier successional stages and at higher productivities 4 Mature ecosystems have more species than immature ones because of an increase in heterotrophic organisms 5 Plants and animals in later successional stages are more specialized and often have narrower ecological tolerances Professor Resh Spring 2007 Biology 1B Ecology Lecture 9 Page 3 Assigned readings 7th Edition pp 1154 1206 6th Edition pp 1198 1214 Ecosystems G Ecosystems and disease Schistosomiasis 1 Disease caused by Schistosoma blood flukes 800 000 humans die per year 2 Eggs leave human body and if they reach water hatch into larvae larvae must find a certain type of snail to invade Infected snails may release 100 000 sporocysts a day Cercaria burrow into human skin to bloodstream lungs and to the liver 3 Effects of human activities Nile Delta population has Schistosomiasis but after construction of Aswan Dam upper Nile infected as well 4 Control approaches sanitation chemicals People s war against the snail Professor Resh Spring 2007
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