1. 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

2. Why study freshwater? Global Water Budget Pool % Residence time Oceans97
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

3. 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%

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

5. Water is unevenly distributed

6. Water limits productivity

7. Water limits human population

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

9. 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

10. 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

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

12. Human pollution in prehistoric freshwater ecosystems

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

14. 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

16. Three gorges dam
Yangtze River, China

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

20. Itaipú Dam,
Brazil

21. Chemical pollution
Nitrogen fertilization

24. Lakes and the global carbon cycle
Cole et al Bioscience 10:

25. Freshwater organisms: too many…

26. Freshwater organisms: too few…

27. Freshwater organisms: the wrong ones

28. Algae as a source of fuel!

29. 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%