1. Spring 2008

2. Lentic is describe as standing water habitats Inland depressions that hold water Range from 1 meter to 2000 meters Formation Glacial Retreat Cutting of the valley Oxbow Lakes Building of dams Volcanic Crater

3. Lentic systems may be formed by two mammals Beavers Dammed streams to make shallow but extensive ponds Humans Create artificial lakes by damming rivers and streams Used for power, irrigation, and water storage Can also be used for water, fishing and wildlife Union Canal (Stovers, Lions Lake, Strikes Dam) Quarries to fill in

4. Because of high specific heat, lentic ecosystems do not experience sharp daily temperature changes Results in seasonal stratification of the system Each season change brings about changes in the system

5. Epilimnion - upper, warm layer Greek for “upper layer” Metalimnion - middle layer - layer of change Also known as Thermocline Rapid decrease in temperature as descending in depth 1°C per meter in depth Hypolimnion - bottom later Coldest layer (4°C) Cut off from air above Stratification breaks down during fall and spring called overturn

7. When fall begins, upper layer become cooler When it gets cooler than lower level, it falls Due to increase density of the water Lower level is lifted up Brings nutrients from benthic (bottom) Nutrients are evenly distributed in the system, creating high productivity

8. As water becomes cooler than 4° C, water becomes lighter In the spring… water heats above 4°C, and become dense Falls to bottom surface Slightest winds can cause circulation

11. Overturn creates uniform dispersal of nutrients Increase plant growth Increases productivity of a system Why would fish spawn in the spring, and fatten up for winter in the fall?

12. In air, oxygen is rarely limited In water, oxygen is limited or excessive At saturation, dissolved oxygen becomes problematic and meager Organisms are dependent on oxygen levels Trout must have high oxygen, which is a correlation with temperature

13. Absorption from atmosphere Photosynthesis - produces 7x amount of oxygen need for respiration of plants At night, plants respire! Amount of oxygen is dependent on: Temperature - lower temperature, increase oxygen Pressure - more force to keep oxygen in solution Salinity - increase salinity decreases oxygen levels Hence why marine organisms breed in brackish water (mixing of fresh and salt water) because of higher oxygen concentration for mating and nursery Also nutrients

14. Oxygen levels are stratified based on temperature and photosynthetic levels In the summer, increase of oxygen near the surface due to increase photosynthesis Oxygen reaches lower level during turn over or if light penetrates

15. Carbon dioxide dissolved in water creates Carbonic Acid Low concentration is held as an acid due to gas laws Other Forms: carbonate and bicarbonates Formation of Carbonic Acid CO 2 + H 2 H 2 CO 3 H 2 CO 3 HCO 3 - + H + HCO 3 H + + CO 3 2-

16. Amount of acid need to free CO 2 Gauge of buffering capacity of the carbonate - CO 2 equilibrium Seawater and hard water (increase and high pH) are high buffers pH levels Freshwater varies = 3 to 10 Rainwater = 5-6 Usual Range - 6.5-8.5 Low as 3.5 in seasonal (later summer) Calcium Carbonate helps with buffering high pH Lebanon Valley is a limestone valley with a pH around 8.0 to 8.5