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First Exam Review Notes - Geography 2011.docx

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Geography 2011A/B
Wendy Dickinson

Notes from A Late Great LakeThere is a dead zone out there somewhere Lake EriePort Dover Ont a vast mound of zebra mussels quagga mussels and other organisms much of it new to the region much of it laced with harmful bacteria that recurs every summer and sucks so much oxygen from the bottom waters that nothing else can live thereo Biological Oxygen Demand BOD Problem Depletion of oxygen via decomposition of organic materialNo usual evidence of this but in 1999o Enormous kill of birds and fish washed up on the beaches in windrows Loons laced with toxins lost the ability to hold up their heads drowned by the hundreds and floated ashore to mix with other dead specieso Happens every year nowo Botulism claimed 50000 birds and an undetermined number of aquatic species but researchers remain uncertain about the outbreaks causes and why the outbreak has lasted so long Professor Henry Regier at U of To There is a dead zone occupying perhaps onequarter of the central basin of the lake This area is not really dead We just use the term because the things there are not the things we want there bacteria and decomposing organisms In early summer the top 15 meters of Eries water heats upit can reach 26 degrees Cwhile the bottom stays at about 68 degrees C The result is that the lake becomes stratified with the lower layer blocked from the atmosphere and thus cut off from oxygen Because Erie has such a shallow basin the stratification is causing many problems plankton dies sinks and in rotting uses up what little oxygen is lefto The vast area of the lake bottom becomes anoxic with less than 05 milligrams of oxygen per liter o Most life cannot survive in these conditions but zebra and quagga muscles can for 2448 hours Their mucus and feces add to the mess and the end result is the production of deadly gases in which toxic organisms such as botulinum a sporeforming bacterium that causes botulism can survive End of 1960s Eries waters were a grey sludge Not only the great five but many of the 80000 lesser lakes within the region were damaged through human impacts vast stew of human waste industrial garbage agricultural runoff and chemicals with high toxicity levels Symptoms were everywhereo Bald eagles ceased to reproduce beaches were closed due to unsafe swimming conditions fish eating birds and animals at the top of the food chain suffered reproductive problems and populations declined Many species of fish could no longer survive in the lakesIn 1972 Canada and the USA got together to pass the Great Lakes Water Quality Agreement GLWQA binding ourselves to clean up the Great Lakes and do it nowMost work to be done by US Environmental protection agency and Environment Canada Main problem behind lake eutrophicationo Excessive phosphorus from phosphates in detergents and agricultural fertilizers along with industrial pollutantso The phosphorus was promoting algae bloom and absorbing oxygen New sewage treatment plants installed in US and Ontario Phosphate were regulated in detergents Rules were established to block pollutants Between 1978 and 1988 10 Billion spent Within that decade the water was clearer beaches were safer and the fish catch was climbing again After it was cleaned up bureaucracy eased back on regulatory oversight neglected to pursue the polluters and decided to let the environment take care of itself Massive cuts in staffingdown to less than 40 of the staff levels in 1994 No measurement of phosphates anymore Human reproductive levels sufferingo One worryOther worry is Invasive specieso New varieties of plants and animals brought into the Great Lakes system mostly in the ballast of oceangoing ships that come up the St Lawrence Seawayo Their populations explode and compete with other predators changing the ecosystemo Sea Lamprey have nearly destroyed the laketrout populationo Brought it under control using poisons dont even know if this was a good or bad idea Zebra and Quagga mussels clog water intake pipes of power plants and industrieso The current theory is these mussels pick up harmful bacteria which dont hurt them but are passed on to the birds and fish that feed on them The toxins become more potent as they bioaccumulate up the food chain and you get these massive kills US estimates costs of fighting invasive species come to about 135 billion annually Scientists have identified over 360 chemical compounds in the great lakes Various species of fish now suffer from tumors and lesions and their reproductive capacities are decreasingo Populations of fishconsuming birds and mammals also seem to be on the declineo 710 most valuable fish in Lake Ontario have vanished One of newest threats Asian Carp
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