1. Aquatic Ecology I

2. Question of the Day
Which of the following elements is most likely to limit primary production in freshwater lakes?
oxygen
calcium
phosphorus
carbon
iron

3. Aquatic Ecology Notes

4. Chapter Overview Questions
What are the basic types of aquatic life zones and what factors influence the kinds of life they contain?
What are the major types of freshwater life zones, and how do human activities affect them?

5. Chapter Overview Questions
What do we know about aquatic biodiversity, and what is its economic and ecological importance?
How are human activities affecting aquatic biodiversity?
How can we manage and sustain the world’s marine fisheries?

6. Chapter Overview Questions (cont’d)
How can we protect, sustain, and restore wetlands?
How can we protect, sustain, and restore lakes, rivers, and freshwater fisheries?

7. Chapter Overview Questions
Why is water so important, how much freshwater is available to us, and how much of it are we using?
What causes freshwater shortages, and what can be done about this problem?
What are the advantages and disadvantages of withdrawing groundwater?
What are the advantages and disadvantages of using dams and reservoirs to supply more water?

8. Chapter Overview Questions (cont’d)
What are the advantages and disadvantages of transferring large amounts of water from one place to another?
Can removing salt from seawater solve our water supply problems?
How can we waste less water?
How can we use the earth’s water more sustainably?
What causes flooding, and what can we do about it?

9. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and moves continually through the hydrologic cycle.
Only about 0.02% of the earth’s water supply is available to us as liquid freshwater.

10. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Comparison of population sizes and shares of the world’s freshwater among the continents.
Figure 14-2

11. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Some precipitation infiltrates the ground and is stored in soil and rock (groundwater).
Water that does not sink into the ground or evaporate into the air runs off (surface runoff) into bodies of water.
The land from which the surface water drains into a body of water is called its watershed or drainage basin.

12. Unconfined Aquifer Recharge Area Evaporation and transpiration
Precipitation
Evaporation and transpiration
Evaporation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Figure 14.3
Natural capital: groundwater system. An unconfined aquifer is an aquifer with a permeable water table. A confined aquifer is bounded above and below by less permeable beds of rock where the water is confined under pressure. Some aquifers are replenished by precipitation; others are not.
Infiltration
Water table
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 14-3, p. 308

13. Groundwater plays a key role
Groundwater = any precipitation that does not evaporate, flow into waterways, or get taken up by organisms
Groundwater makes up one fifth of the Earth’s freshwater supply
Aquifers = Porous sponge-like formations of rock, sand, or gravel that hold groundwater
Zone of aeration = pore spaces are partially filled with water
Zone of saturation = spaces are completely filled with water
Water table = boundary between the two zones
Aquifer recharge zone = any area where water infiltrates Earth’s surface and reaches aquifers

14. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
We currently use more than half of the world’s reliable runoff of surface water and could be using 70-90% by 2025.
About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources.
Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%).

15. Salinity
The saltiness.
                                                                                                                    

16. What Kinds of Organisms Live in Aquatic Life Zones?
Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms.
Plankton: important group of weakly swimming, free-floating biota.
Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria)
Necton: fish, turtles, whales.
Benthos: bottom dwellers (barnacles, oysters).
Decomposers: breakdown organic compounds (mostly bacteria).

17. Phytoplankton Description – small drifting plants
Niche – they are producers that support most aquatic food chains
Example – cyanobacteria & many types of algae

18. Zooplankton
Description – herbivores that feed on phytoplankton or other zooplankton
Niche – food stock for larger consumers
Example – krill; small crustaceans

19. Nekton Description – larger, strong-swimming consumers
Niche – top consumers in the aquatic ecosystem
Example – fish, turtles, and whales

20. Benthos Description – bottom-dwelling creatures
Niche – primary consumers, decomposers
Example – barnacles, oysters, and lobsters

21. River Food Chains

22. Freshwater Ecosystems

23. FRESHWATER LIFE ZONES Freshwater life zones include:
Standing (lentic) water such as lakes, ponds, and inland wetlands.
Flowing (lotic) systems such as streams and rivers.
Figure 6-14

24. Flowing Water Ecosystems
Because of different environmental conditions in each zone, a river is a system of different ecosystems.

25. Ecological Services of Rivers
Natural Capital
Ecological Services of Rivers
Deliver nutrients to sea to help sustain coastal fisheries
Deposit silt that maintains deltas
Purify water
Renew and renourish wetlands
Provide habitats for wildlife
Figure 12.11
Natural capital: important ecological services provided by rivers. Currently, the services are given little or no monetary value when the costs and benefits of dam and reservoir projects are assessed. According to environmental economists, attaching even crudely estimated monetary values to these ecosystem services would help sustain them. QUESTIONS: Which two of these services do you think are the most important? Which two of these services do you think we are most likely to decline?
Fig , p. 267

26. Freshwater Streams and Rivers: From the Mountains to the Oceans
Water flowing from mountains to the sea creates different aquatic conditions and habitats.
Figure 6-17

27. Headwater Stream Characteristics
A narrow zone of cold, clear water that rushes over waterfalls and rapids. Large amounts of oxygen are present. Fish are also present. Ex. trout.

28. Downstream Characteristics
Slower-moving water, less oxygen, warmer temperatures, and lots of algae and cyanobacteria.

29. Changes is River Flow

30. Energy Source
Gravity

31. Standing Water Ecosystems
Lakes, ponds, etc.

32. Life in Layers
Life in most aquatic systems is found in surface, middle, and bottom layers.
Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth.
Euphotic zone (upper layer in deep water habitats): sunlight can penetrate.

33. Lakes: Water-Filled Depressions
Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, and groundwater seepage consisting of:
Littoral zone (near shore, shallow, with rooted plants).
Limnetic zone (open, offshore area, sunlit).
Profundal zone (deep, open water, too dark for photosynthesis).
Benthic zone (bottom of lake, nourished by dead matter).

34. Littoral Zone
A shallow area near the shore, to the depth at which rooted plants stop growing. Ex. frogs, snails, insects, fish, cattails, and water lilies.

35. Limnetic Zone
Open, sunlit water that extends to the depth penetrated by sunlight.

36. Profundal Zone
Deep, open water where it is too dark for photosynthesis.

37. Lakes: Water-Filled Depressions
Figure 6-15

38. Zones in Lakes and Ponds

39. Question of the Day
Which of the following is the zone of a pond or lake in which rooted emergent plants such as cattails and rushes are located?
Benthic
Limnetic
Littoral
Profundal
Riparian