1. Molles: Ecology 2 nd Ed. Lakes Most of world’s freshwater resides in a few large lakes:  Great Lakes contain 20% of freshwater in world

2. Molles: Ecology 2 nd Ed. Fig 3.37 Structure: Littoral Zone: Shallows Limnetic Zone: Open lake

3. Molles: Ecology 2 nd Ed. Fig 3.37 Lakes Vertical Distribution:  Epilimnion: warm surface layers  Metalimnion: (Thermocline) – temp changes substantially with depth  Hypolimnion: – cold dark waters

4. Molles: Ecology 2 nd Ed. Lakes Color:  Depends on light absorption and bio. activity Stratification:  Become thermally stratified as they warm

5. Molles: Ecology 2 nd Ed. Fig 3.38

6. Molles: Ecology 2 nd Ed. Temperate lake

7. Molles: Ecology 2 nd Ed. Lakes Nutrient Levels Nutrient Levels  Oligotrophic: low biological production, often well oxygenated  Eutrophic: high biological production, may be depleted of oxygen

8. Molles: Ecology 2 nd Ed. Oligotrophic lake = nutrient poor Little plant growth, deeper

9. Molles: Ecology 2 nd Ed. Eutrophic lake = nutrient rich high plant growth, shallow

10. Molles: Ecology 2 nd Ed. Mesotrophic lakes: some plant growth Life cycle of a glacial natural lake  Lake forms from glacial deposits or groundwater filling hole = oligotrophic

11. Molles: Ecology 2 nd Ed. Nutrients wash in from surrounding watershed, lake fills in some = mesotrophic Life cycle of a natural lake

12. Molles: Ecology 2 nd Ed. Lake fills in further, nutrients wash in from surrounding watershed, heavy plant growth = eutrophic Finally lake fills in completely Life cycle of a natural lake

13. Molles: Ecology 2 nd Ed. Lakes Human Populations have had profound, usually negative effects  Municipal and Agricultural Run-off  Eutrophic from nutrients  Toxins  Exotic Species – Zebra Mussels, round goby

14. Molles: Ecology 2 nd Ed.

15. Index of Biotic Integrity IBI score is method to evaluate streams Compare biota to nearby undisturbed stream Fish communities generally used

16. Molles: Ecology 2 nd Ed. IBI 1. Number of species, kinds, tolerances 2. Trophic compositions of species  Omnivores  Insectivores  Piscivores 3. Fish abundance and condition

17. Molles: Ecology 2 nd Ed. Fish IBI Eastern Corn Belt Scoring Classification Metric135 Total Number of Species< 89 - 13> 13 Number of Darter/Madtom/Sculpin Species 0 - 12 - 34 + % Headwater Species< 2020 - 3535 + Number of Minnow Species< 33 - 910 + Number of Sensitive Species< 55 -10> 10 % Tolerant Individuals< 25 %25 – 50 %> 50 % % Omnivore Individuals 1 < 25 %25 – 50 %> 50 % % Insectivore Individuals 1 > 50 %25 – 50 %< 25 % % Pioneer Species Individuals 1 < 25 %25 – 50 %> 50 % Catch per Unit Effort< 100100 – 300> 300 % Simple Lithophil Individuals> 40 %20 – 40 %< 20 % % DELT Individuals 1 < 0.1 %0.1 – 1.3 %> 1.3 %

18. Molles: Ecology 2 nd Ed. East Fork Honey Creek 14 July 2009Actual ObservationIBI Score (no.) 1. Total number of Species61 2. Number of Darter/Madtom/Sculpin Species01 3. Headwaters sp. % of Total0.0001 4. Number of Minnow Species01 5. Number of Sensitive Species01 6. % Tolerant Individuals0.7781 7. % Omnivore Individuals05 8. % Insectivore Individuals01 9. % Pioneer Species Individuals0.7781 10. CPUE1943 11. % Simple Lithophil Individuals0.0001 12. % DELT0.0001 Total IBI18

19. Molles: Ecology 2 nd Ed.

20. Summary Hydrologic Cycle exchanges water among different holding areas. Biology of aquatic largely determined by physical and chemical factors.  Light, temp, salinity, oxygen, etc.

21. Molles: Ecology 2 nd Ed.