Biology 1B, Ecology Lecture 9, Page 1 Professor Resh • Spring 2007*Assigned readings, 7th Edition pp. 1154-12066th Edition pp. 1198-1214EcosystemsOutline of Lecture 9A. EcosystemB. Water cycleC. Carbon cycleD. Nitrogen cycleE. Phosphorous cycleF. Succession in ecosystemsG. Ecosystems and diseases – SchistosomaA. Ecosystem: an interacting system thatinvolves both the organisms and theirnon-living environment. The flow ofenergy and nutrients is regulated.1. “Cycling” because substancesoriginated from the atmosphere orweathered rock, then becameincorporate into various organisms,and ultimately (throughdecomposition) are returned to thenon-living world.B. Water cycle involves evaporation,precipitation, and transpiration…• Aquafer: permeable, saturatedundergound layers of rock, sand andgravel• point vs. non-point sources ofpollution; what is biomonitoring?C. Carbon cycle involves atmosphere,autotrophic organisms, heterotrophicorganisms, and decompositionBiology 1B, Ecology Lecture 9, Page 2 Professor Resh • Spring 2007*Assigned readings, 7th Edition pp. 1154-12066th Edition pp. 1198-1214EcosystemsD. Nitrogen cycle involves nitrogenbecoming available through metabolicactivities of a few types of bacteria (somefree-living, other symbiotic).E. Phosphorous cycle involves soil leaching,erosion, uplifting, guano, andmycorrhizae (symbiotic associationsbetween plants and fungi); a mineral-based cycle.F. Succession in ecosystems1. As ecosystems mature, there is anincrease in biomass but a decrease innet productivity.2. Earlier successional stages are moreproductive than later ones.3. Disturbance keeps some systems inearlier successional stages and athigher productivities.4. Mature ecosystems have morespecies than immature ones (becauseof an increase in heterotrophicorganisms).5. Plants and animals in latersuccessional stages are morespecialized, and often have narrowerecological tolerances.Biology 1B, Ecology Lecture 9, Page 3 Professor Resh • Spring 2007*Assigned readings, 7th Edition pp. 1154-12066th Edition pp. 1198-1214EcosystemsG. Ecosystems and disease- Schistosomiasis1. Disease caused by Schistosomablood flukes; >800,000 humans dieper year.2. Eggs leave human body, and if theyreach water hatch into larvae; larvaemust find a certain type of snail toinvade. Infected snails may release100,000 sporocysts a day. Cercariaburrow into human skin tobloodstream, lungs, and to the liver.3. Effects of human activities: NileDelta population has Schistosomiasisbut after construction of Aswan Damupper Nile infected as well.4. Control approaches: sanitation,chemicals, “People’s war against
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