BIOL1007 Lecture Notes - Lecture 24: California Condor, Rachel Carson, Lead Poisoning
Pesticides
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Manufacturing e.g. by-products
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Industrial accidents e.g. Chernobyl
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Chemical spills
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Atmospheric pollution
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Plastics
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Nanoparticles e.g. in face scrubs, shampoos
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Toxic inputs
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1. Review how human activities affect the ecology of natural systems
Chemicals used in food production, accumulating in birds and mammals
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Led to decline in bird pop particularly in raptors
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When these pesticides were banned many pops recovered
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Birds which were poisoned by pesticides -> thinner egg shells -> more prone to breaking -> pop decline
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Silent spring by Rachel Carson
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2. Understand how the ecological impacts of pollution and how it affects the ecology of
natural systems
Can't break down toxins
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Occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost
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Persistent and mobile
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Accumulate in body tissue
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Particularly higher predators
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Diverse group of toxins introduced in various ways esp. pesticides
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2,4-D and 2,4,5-T (herbicides)
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DDT, dieldrin, lindane (organochlorine insecticides)
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PCBs (polychlorinated biphenyls)
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Heavy metals
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Many used because they work short term
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Bioaccumulation
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Pesticides get used -> washed off into sea (land to sea barrier crossed) -> chemicals accumulate in sea life and can't be
removed from system -> inability to excrete/process toxins -> death
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3. Understand how pollutants move into natural systems
PCBs in breast milk of mothers in southern Quebec in mid 80s
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Need for a control ("pristine milk")
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Obtained milk from Inuit mothers which had 5 times the PCBs
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2/3 children had unacceptably high levels of PCBs
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Older people had higher levels
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Eat a lot of whale meat, fish which has PCBs
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Children born to women who ate contaminated fish
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Lower IQ
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Poor memory
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Shortened attention span
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Learning difficulties
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11 year olds exposed to PCBs in the womb had
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Hostility between indigenous people and researchers, inuit had no control over PCBs
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e.g. Inuit of northern Canada - PCBs
No agriculture/manufacturing
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How did it get there?
L24 - The Human Footprint
Thursday, 26 October 2017
9:05 AM
mod 4 - ecology and ecosystems Page 1
No agriculture/manufacturing
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They use almost every bit of the beluga and narwhal whales caught, having a preference for muktuk (fat)
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Toxins accumulate in certain body parts, particularly fat
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The Inuit did not used it - banned in Canada for more than 20 years
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Global distillation and fractionation
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Heavy usage in tropics -> evaporate from soils -> carried on winds -> condense out in cold as toxic snow and rain
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Systematic transfer from warm to cold
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The more toxic components more mobile
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Screen clipping taken: 26/10/2017 9:23 AM
Problem transcends borders and environments
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Global solutions, look at bigger picture
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Regulation
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Hard to automate
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Solutions
Lead poisoning
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HOW? Condors ingest lead when they feed on the carcasses of animals that hunters have shot -> chronic lead poisoning
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High risk of lead contamination
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Many had dangerous levels of lead in their bodies
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Lead poisoning severely damages birds' nervous systems and impair liver and kidney function
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Long term problem
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Recovery of the bird after 30 years on the brink, through intensive capture breeding and medical intervention, detoxify
the animals
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About 20% had lead levels requiring costly treatment
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e.g. California condor
Exxon Valdez 2009
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Long term effects
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Old thinking: acute mortaility through short term toxic exposure to oil deposited on shore accounts for the
important losses of shoreline plants and invertebrates
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Impacts recurring as long as clean up (chemical and physical) continues
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e.g. hoses with high pressure water harmful
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Strong pervasive biological interactions in rocky intertidal and kelp forest communities contribute to
cascades of delayed, indirect impacts expand the scope of injury well beyond the initial direct losses thereby
also delay recoveries
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New: Clean-up attempts can be more damaging than oil
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Impact on coastal communities
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e.g. Oil spills
We want to make an informed prediction which is not harmful!!!
4. Understand how the ecological impacts of habitat fragmentation
Fragmented landscape
mod 4 - ecology and ecosystems Page 2
Document Summary
9:05 am: review how human activities affect the ecology of natural systems. Nanoparticles e. g. in face scrubs, shampoos: understand how the ecological impacts of pollution and how it affects the ecology of natural systems. Chemicals used in food production, accumulating in birds and mammals. Led to decline in bird pop particularly in raptors. When these pesticides were banned many pops recovered. Birds which were poisoned by pesticides -> thinner egg shells -> more prone to breaking -> pop decline: understand how pollutants move into natural systems. Occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. Diverse group of toxins introduced in various ways esp. pesticides. Pesticides get used -> washed off into sea (land to sea barrier crossed) -> chemicals accumulate in sea life and can"t be removed from system -> inability to excrete/process toxins -> death e. g. inuit of northern canada - pcbs.