1. Early Limnology: Temperature Profiles

2. Lake Zones Zones are dynamic! Input of heat  Mixing forces

3. The stratification and mixing cycle of an average-sized, temperate lake

4. Stratification and Mixing

9. The Whole Cycle in One Confusing Figure!

10. Factors that influence stratification pattern Heating / Density  Wind / Waves Depth Surface Area Topography / Location / Exposure

11. The Family of Lake Cycles Temperature Incident Solar Radiation

12. The Family of Lake Cycles

13. Amictic Perennially ice-covered Inversely stratified

14. The Family of Lake Cycles

15. Cold Monomictic Water temperature never exceeds 4  C Ice-covered for most of the year = inversely stratified One period of free circulation in summer at or below 4  C

16. The Family of Lake Cycles

17. Dimictic

18. The Family of Lake Cycles

19. Warm Monomictic Circulates once in winter at or above 4  C Directly stratified for the rest of the year Not ice covered

20. The Family of Lake Cycles

21. Oligomictic Stable, direct stratification most of the year Circulation at irregular intervals (scale of years) during cool periods

22. The Family of Lake Cycles

23. Polymictic Frequent periods of mixing per year Not ice-covered

24. Cold Polymictic Equatorial, high elevation Hovering around 4  C Intense heat during day (stratification) Intense cooling at night (mixing)

25. Warm Polymictic Warm throughout (i.e., well above 4  C) Sometimes get intense heating of epilimnion = development of weak stratification.

26. 4  C is IMPORTANT

27. Holomixis: Circulation occurs throughout the entire water column. Meromixis: Primary water mass never mixes with the lower portion.

28. Stratification in meromictic lakes Monimolimnion: deep stratum, high salinity Chemolimnion: strong salinity gradient Mixolimnion: upper stratum (i.e., epi-, meta-, and hypolimnion)

29. How does the salt get there? Ectogenic meromixis Crenogenic meromixis Biogenic meromixis

30. Consequences of meromixis Monimolimnion = Dead Zone Chemolimnion = Heat Trap

31. More Blue More Red Frequency Wavelength

32. Consequences of meromixis Hot Lake, north-central WA On top of epsom salt excavation High MgSO 4 in monimolimnion Temperature in monimolimnion can get to 50  C!

33. Why Lake Circulation Matters: Lake Nyos Gas Disaster

34. Lake Nyos Degassing Project Pipe is 203 m long and 14.5 cm in diameter. Upper end attached to raft and supported by lines to shore.

35. Oxygen Light Temperature

36. Patterns along the “river continuum” Oxygen Light Temperature

37. Temperature along streams

38. Temperature fluctuations along the streams

39. Effect of Groundwater on Stream Temperature: Nyack Floodplain, MT

40. Oxygen along streams DO in unpolluted, flowing water usually at or near saturation, and concentrations are of little biological significance.