1. IGERT EARS Lacawac Workshop on Lake Sentinels: Craig Williamson Miami University

2. Ganguly, A. R., K. Steinhaeuser, D. J. Erickson III, M. Branstetter, E. S. Parish, N. Singh, J. B. Drake, L. Buja, Higher trends but larger uncertainty and geographic variability in 21st century temperature and heat waves, Proceedings of the National Academy of Sciences of the United States, 10.1073/pnas.0904495106, 2009.

3. Ganguly, A. R., K. Steinhaeuser, D. J. Erickson III, M. Branstetter, E. S. Parish, N. Singh, J. B. Drake, L. Buja, Higher trends but larger uncertainty and geographic variability in 21st century temperature and heat waves, Proceedings of the National Academy of Sciences of the United States, 10.1073/pnas.0904495106, 2009.

6. What will the impacts be on water resources and terrestrial ecosystems? How do we begin to address such daunting challenges of environmental change? Where in the complex landscape should we sample for the best information?

7. Lakes! Lowest point in the landscape Respond to environmental change, and leave signals in the sediments

8. You Need EARS! Environmental Aquatic Resource Sensing You Need GLEON! Global Lake Ecological Observatory Network Advanced sensors to network lakes across continents to look at lake sentinels.

9. Lakes as Sentinels and Integrators of Environmental Change What is a lake sentinel? Any physical, chemical, or biological characteristic of a lake that responds to environmental forcing in an informative and quantifiable way. What is a paleoecological lake integrator? Historical sentinels in the sediments that provide information relevant to climate change over longer time periods

10. Lakes are not Isolated Ecosystems Photosynthesis by phytoplankton, benthic algae, macrophytes – Endogenous C drives lakes towards autotrophy = Autochthonous carbon Integral part of watershed – Receive runoff, streamflow, groundwater – Inputs of fixed C = POM, DOM (measured as DOC) – Exogenous C drives lakes towards heterotrophy = Allochthonous carbon

11. Area Receiving Incident Sunlight

12. DOC Sources to Lakes Roulet & Moore 2006 Nature 444:283

13. Leaching of dissolved organic matter from terrestrial sources feeds fixed C to aquatic ecosystems

14. Allochthonous Sources of Fixed Carbon Vary with plant species

18. Pocono Study Lakes Lake Lacawac 52 hectares Mesotrophic DOC ~ 5 mg/l UV Z 1%320nm ~ 0.5 m Lake Giles 100 hectares Oligotrophic DOC ~ 1.5 mg/l UV Z 1%320nm ~ 3-4 m

19. Light decreases with depth. Why?

20. Usually use a semilog plot for light. The 1% (of surface PAR) depth = Compensation Depth

21. What causes temperature changes with depth? Why do light and temperature profiles differ?

22. Comparing April and September: 1) What are two seasonal changes in temperature? 2) What are the causes of these differences? 3) What are the implications of these differences?

23. What causes these changes with depth and season? Role of abiotic vs biotic factors, auto- vs. allochthony? Where is the compensation depth?

25. What does water transparency tell us? Where is the compensation depth?

26. How did oxygen change since 1990? Not much change early in year (April)

27. How did oxygen change since 1990? 3 major types of change late in year (Sept.)

28. UV Transparency: 14 year trends July data: Lake Giles, N.E. Pennsylvania, USA

29. Increase in Allochthony?

30. Climate Change?

31. Reduced Acid Precipitation?

33. What sentinels of environmental change can you find in Lacawac? Lake sentinel: Any physical, chemical, or biological characteristic of a lake that responds to environmental forcing in an informative and quantifiable way. Environmental Drivers: Energy: - Temperature, wind Mass: -Precipitation, particulates, Dissolved substances.