Aquatic Ecology(BIOL 435)

• Course Introduction• Field Component

• Friday’s Assignment• What is Limnology? (lotic vs lentic)

• Why Care About Water?• Hydrologic Cycle

What is Limnology?• Is it aquatic ecology?

– Marine versus inland waters– Inland waters versus freshwater– Ecology versus biology

• Multi-disciplinary:– Geography– Geology– Physics & Math– Chemistry– Biology

“Limnology is the study of the structural and functional interrelationships of organisms of inland waters as they are affected by their dynamic physical, chemical, and biotic environments.” (Wetzel, 2001)

How Much Water? Where?

(Dodds, 2002; Table 1.1)

These volumes reside in their location (reservoir) for very different time scales. Ice caps for 16,000 y. Oceans for 3100 y. Groundwater for 300 y. Lakes from months to 100s y. Large rivers for 10-20 d. Atmosphere < 10 d.

What is our need for understanding “inland aquatic ecology”

• Global Renewable Supply of Freshwater– 39,000 km3/y– Humans use 54%

• Demotechnic Growth – Population.– Technology.

• Ecosystem Impacts:– Unsustainable

Development– Climate Change

Resource crises in developing nations is increasing with freshwater as a primary concern. These populations are simply not coping with increasing resource limitation. (Wetzel, 2001; Fig 1-1)

Global Distribution of Per Capital Freshwater Consumption

(Dodds, 2002; Table 1.2)

Check out our luxury use compared to other countries with ample water supplies, i.e. Switzerland. (American vanity?)

Our Situation:• Not so much individuals at the tap, although that is increasing.

• Our bigger indirect consumption is for the agriculture, industry and energy we use.

• Per Capita improvement since 1970s (Clean Water Act; EPA).

• What creative technologies are out there to increase supply of improve conservation or reuse? (Dodds, 2002; Fig 1.3)

US water supply sources:

• Situation is has been sustainable managed, for now!

• Surface water (lakes & streams) withdraws are greater.

• Which should we be more concerned about becoming polluted from a human resource perspective?

The Hydrologic Cycle• Hydrodynamics is the variations in the movement of water and changes in its

distribution in time and space. Over large scales, water cycles between oceans, atmosphere, and the terrestrial environment via the processes of evaporation, precipitation, transpiration, and surface and subsurface flows.

The Hydrologic Cycle is driven largely by the energy from solar radiation, Earth’s gravity, the rotation of the Earth (Coriolis Effect), Gravity of Moon and Sun (ocean tides).

Solar energy drives evapotranspiration and winds.

Solar energy and winds drive water movement, via thermal density differences and wave propagation, respectively.

Coliolis Effect influences the direction of wind and ocean circulation.

Earth’s gravity influences precipitation and surface and subsurface flow.