Lakes & Rivers

1. Lakes & Rivers

2. Lake Nutrients • 3 categories of MN lakes • Eutrophic- • Mesotrophic (subcategory) • Oligotrophic- • Dystrophic-

3. Eutrophic Lakes • Lakes that are • Usually very • Clarity  • Oxygen levels  • Fish levels 

4. Eutrophic lakes • Weeds and • Good for • Mud holds • Slower • Nutrients from river can

5. Eutrophic lakes • Sibley Lake • High • High levels of • Good • Fish reproduce when • Maybe

6. Eutrophic lakes

7. Oligotrophic Lakes • Lakes that are very • Little • Few • Usually • Clarity  • Oxygen levels  • Fish levels 

8. oligotrophic lakes • Sand and • Not good for • Sand Loses • Filtration • Faster • Nutrients from river get

9. oligotrophic lakes • Pelican Lake • Cleaner • lower in • lower levels of • Poor • Fish reproduce • Maybe

10. Oligotrophic lake

11. Mestrophic Lakes • Lakes that are average in • Some • Some • Usually • Clarity  • Oxygen levels  • Fish levels 

12. Dystrophic Lakes • Shallow lakes that get nutrients from the • Usually • High in hummus and • Organic  • Contains many • Contains

13. Dystrophic lake

14. Lake reproduction • Fish reproduction is tied to

15. Lake reproduction • High nutrient lakes • Fish • Lay • Eggs • Smaller • Usually

16. Lake reproduction • Low nutrient lakes • Fish • Lay • Eggs are • Larger • Usually

17. Invasive species • How many animal invasive species does the DNR list for MN lakes?

18. Invasive species • 16 • http://www.dnr.state.mn.us/invasives/aquaticanimals/index.html

19. currents • Lakes have currents just • They have both • Movement based on

20. Horizontal currents • Seiches • Water moves back and forth from • Surface water can slide across the • Thermocline separates layers of

21. Horizontal currents • Larger seiches can occur • Help • http://www.lakesuperiorstore.com/resources/glinfo.htm

22. Circular currents • Langmuir circulations • Consist of alternating • Traps

25. Vertical currents • Usually based on • Disappearance of the

27. Nutrient mixing • Lakes are grouped by the movement of water from top to bottom that mixes the nutrients. • 4 mixing groups

28. Nutrient mixing • Lake water mixes when the temperature is close to the • Lake temperatures that vary greatly create a • The thermoclines do not allow certain water • If water does not mix oxygen and nutrition can not

29. Thermocline

30. Oligomitic Lakes • Oligomitc lakes  • Surface water never

31. Polymitic Lakes • Polymitic Lakes  • Weather can change rapidly to allow

32. Monomitic Lakes • Monomitic • North • Great Lakes in • Usually short summers so water never

33. Dimitic Lakes • Dimitic Lakes  • Usually mix in • Summer & winter temperatures create

34. Lake Zones • Lakes have different area that are used for . • Not all lakes have • Lakes eco-regions can play a role in the type and • MN has

35. Lake Zones

36. Littoral Zones • Littoral Zone • From the shoreline to • Most important zone for • Larger the littoral zone the

37. Limnetic Zone (open water) • Limnetic Zone Area of lake where there is no influence • This area can be • Long thin Lake with • It can be • Shallow shoreline

38. Benthic Zone • Benthic Zone has • Depth is usually • May depend on • No • No • Depends on

39. Euphotic zone • Euphotic zone is • More of a • Lots of

40. Lake eco-regions • MN has • Eco-region is based on the plants and soil • 98% of MN lakes are in

41. Eco-Regions • 1) Northern MN wetland • 2) Red River Valley • 3) Northern lakes and forest • 4) North central Hardwoods • 5) Northern glaciated plains • 6) Western corn belt plains • 7) Driftless Area