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Why study freshwater? Why not to
Small but important part of global ecosystem Ecosystems at your service What we’re doing to them Why we should care
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Why study freshwater? Global Water Budget Pool % Residence time Oceans
97 300-11,000 years ice caps 2.2 12,000 years groundwater 0.16 years lakes 0.016 (2/10,000) 1-5 years atmosphere 0.001 (1/100,000) 7-11 days rivers (1/1,000,000) 7 days
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Answer depends a lot on small ponds- ~3%
How much of the earth’s surface is covered by lakes? Downing et al Limnology and Oceanography 51:2388 Answer depends a lot on small ponds- ~3%
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Quetico (Ontario) canoe area
Canada is very lake-y Quetico (Ontario) canoe area
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Water is unevenly distributed
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Water limits productivity
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Water limits human population
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Future of water use Tilman et al. 2001 Science 292: 281
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Ecosystem services economic value derived from natural processes
fisheries clean water it’s valuable but you don’t pay for it hard to assess often under-valued
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Robert Costanza et al., 1997. The value of the world’s
ecosystem services and natural capital. Nature 387:253 System Area (ha x 106) Value per ha (USB$/ha) Total value (USB$/y) Marine 36,302 577 20,949 Open ocean 33,200 252 8,381 Coastal 3,102 4,052 12,568 Terrestrial 15,323 804 12,319 forests 4,855 969 4,706 grasslands 3,898 232 906 Wetlands 330 14,785 4,879 Lakes + rivers 200 8,498 1,700 Value in terms of gas regulation climate regulation disturbance regulation*** water regulation*** water supply*** erosion control soil formation nutrient cycling waste treatment*** pollination biological control habitat/refugia food production raw materials genetic resources recreation cultural TOTAL = US$33,000,000,000,000/year (Canadian = $34,650,000,000,000) Global GDP = US$18,000,000,000,000
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What are we doing to freshwater ecosystems?
chemical pollution biological pollution water cycle alteration
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Human pollution in prehistoric freshwater ecosystems
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Inuit whalers and freshwater ponds Smol et al. 2007 PNAS 104:12395
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Aral Sea was world’s 4th biggest lake river flow reduced by irrigation
43,000km2 of lake bed exposed salinity increased 3X fish extinctions made surrounding area drier and saltier
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Three gorges dam Yangtze River, China
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dam is 2.4 km long raised water level 175m displaced 1.5 million people
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Itaipú Dam, Brazil
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Chemical pollution Nitrogen fertilization
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Lakes and the global carbon cycle
Cole et al Bioscience 10:
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Freshwater organisms: too many…
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Freshwater organisms: too few…
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Freshwater organisms: the wrong ones
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Algae as a source of fuel!
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Important course details
No required text, two on reserve in Woodward Slides posted at Penalty for lateness REQUIRED field trip Sept 26-27 bring rain gear, sleeping bag food, housing, transport provided Grading midterm and final, 20% each lake paper, 30% paper presentation, 20% stream write-up, 10%
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