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

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 60-300 years lakes 0.016 (2/10,000) 1-5 years atmosphere 0.001 (1/100,000) 7-11 days rivers 0.0001 (1/1,000,000) 7 days

Answer depends a lot on small ponds- ~3% How much of the earth’s surface is covered by lakes? Downing et al. 2006 Limnology and Oceanography 51:2388 Answer depends a lot on small ponds- ~3%

Quetico (Ontario) canoe area Canada is very lake-y Quetico (Ontario) canoe area

Water is unevenly distributed

Water limits productivity

Water limits human population

Future of water use Tilman et al. 2001 Science 292: 281

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

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

What are we doing to freshwater ecosystems? chemical pollution biological pollution water cycle alteration

Human pollution in prehistoric freshwater ecosystems

Inuit whalers and freshwater ponds Smol et al. 2007 PNAS 104:12395

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

Three gorges dam Yangtze River, China

dam is 2.4 km long raised water level 175m displaced 1.5 million people

Itaipú Dam, Brazil

Chemical pollution Nitrogen fertilization

Lakes and the global carbon cycle Cole et al. 2007 Bioscience 10: 171-184

Freshwater organisms: too many…

Freshwater organisms: too few…

Freshwater organisms: the wrong ones

Algae as a source of fuel!

Important course details No required text, two on reserve in Woodward Slides posted at http://www.zoology.ubc.ca/~shurin/402.html 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%