1. 4.5 AQUATIC Ecosystems Benchmark:
SC.912.L.17.2 Explain the general distribution of life in aquatic systems as a function of chemistry, geography, light, depth, salinity, and temperature.
Focus on chemical factors in aquatic systems; pH, oxygen, carbon dioxide, nitrogen, phosphorus, and salinity. Focus on geography in aquatic systems; water depth, latitude, temperature, underwater topography, and proximity to land. (not required the identification of oceanic zones)

2. Objectives
Explain how depth, salinity, and temperature affect life in an aquatic system
Explain how chemistry, geography, and light affect life in an aquatic system

3. Essential Question
What are the major differences between freshwater and marine ecosystems?
How do these differences affect the organisms that live there?
All are important…..

4. Aquatic Ecosystems
Salt
Fresh

5. Light in Aquatic Ecosystems
Imagine you are a SCUBA diver, as you go deeper into the ocean, what would you see?
NOT MUCH
As you travel deeper into the ocean, light decreases

6. Light in Aquatic Ecosystems
Divided into 2 zones: photic and aphotic
Anytime we see an “a” in front of a word in biology, it usually means “not”

7. Light in Aquatic Ecosystems
Photic Zone
Aphotic Zone
The photic zone is the region where light is able to penetrate
Producers can live here
Photosynthesis happens here
The aphotic zone is the region where light is NOT able to penetrate
Producers cannot live here because photosynthesis cannot occur
Chemosynthesis occurs instead

8. Check for Understanding
In which of the following marine zone
is light able to penetrate?
a. Benthic Zone
b. Estuary
c. Photic Zone
d. Biosphere.

9. Salinity Salinity is the amount of salt dissolved in a liquid
Does the ocean have more or less salinity than the water from your faucet?

10. Salinity Changes in the Ocean
If there is more evaporation (drying) than precipitation (rain) then the salinity increases
since salt is not evaporated into the atmosphere
If there is more precipitation (rain) than evaporation (drying) then the salinity decreases

11. Salinity Changes
The thawing of large icebergs (made of frozen fresh water and lacking any salt) will decrease the salinity while the actual freezing of seawater will increase the salinity temporarily

12. Temperature in Aquatic Ecosystems
The temperature of seawater varies with the amount of sun that hits that area
Would the temperature be higher in the photic zone or aphotic zone?
PHOTIC ZONE (sun penetrates)

13. Temperature in Aquatic Ecosystems
Do animals prefer warm water or cold water?
Will most organisms be found in the shallow or deep ocean?

14. Gases in Aquatic Ecosystems
The amount of dissolved gases in seawater depends on the types of life forms (plants and animals) that are present
Lots of plants = Lots of oxygen
Few plants = Lots of carbon dioxide

15. Nutrients in Aquatic Ecosystems
Plants need nutrients to live:
Phosphorous
Nitrogen
These nutrients are found in animal feces, which sinks to the bottom of the ocean
The majority of nitrogen and phosphorous nutrients are found in the deep and only come to top during upwelling

16. WE DO: Venn Diagram
Lay out the contents of your envelope and decide which apply to the photic zone and which apply to the aphotic zone. Create a Venn Diagram.