Ecology Test #3

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Water pollution
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Terms in this set (27)
-Thermometers, fluorescent lights
-Coal burning power plants
•Just 1/70th of a teaspoon could contaminate a 25 acre lake
•More than ½ of US, including 1000s of rivers and lakes have had to set restrictions on fish consumption
•Concentrations of Hg in game fish can be...
-1 million times greater than surrounding water
point-sourcePollutants discharged from a single identifiable location (e.g., pipes, ditches, channels, sewers, tunnels, containers of various types).nonpoint-sourcepollution that comes from many sources rather than from a single, specific sitepollution - cows and corn• Bank erosion • Sedimentation • Nutrient loading Limit cows access to streams!! Allow vegetative buffer to developBiodiversity•Most often our concern is the rate of extinction that is caused by humans •Need to how many species there are •Rate at which these are going extinct •How that rate compares with pre human times________ known species ________ species not yet identified1.8 million 3-30 million species not yet identifiedUnknown areas for species diversity•Tropics -Estimated 6-30 million invertebrate species in tropics, only small fraction so far described •Soils •Ocean... especially deep sea -Ex. Deep sea vents - entirely new communities discovered only in last 20 yrs.-- > 20 families, 20 genera, 100 spp.Extinction•Average species persisted for 1-10 million years •Conservatively estimate 10 million species globally •Predict that 100 to 1000 would go extinct each century on average •Current rate for birds and mammals alone is 100 to 1000 times that background rateWhy 99% of species have gone extinct•Natural process -Natural selection -Competitive exclusion •probably the #1 cause of extinction -Predation/herbivory -Other reasons •loss of habitat, climate change, overhunting, etcThreat of extinctionsome taxa more susceptible than othersthreatened species10%b prob in next 100 yearsendangered20% prob in next 20 yearscritical species>50% chance in next 5 yearsWhat it means to be rare: and example1.Small geographic range 2.Narrow range of tolerances 3.Small local population •At risk when habitats altered •Giant panda - all threeValue of biodiversity:Economical (Direct and Indirect) and Ethical •Aesthetics and economics •Sources of food, fiber, raw materials •Pharmaceuticals •Ethics/ Scientific information •Ecosystem services ... many, many more...Causes of Extinction•Natural selection, competition, predation •Habitat destruction and fragmentation •Introduction of exotic species •Overexploitation - harvesting above MSY •Low genetic diversityEspecially vulnerablespecies with long generation times, slow reproductive cycles, low fecundities.Exotic Species•Most introduced species do not survive •Most that survive are incorporated into community •Some... become nuisance and can exclude native species. -Ex. Zebra mussel -Ex. Purple loosestrife