1. Warm Up 2/19-20 Most ocean water is located in which zone?
a. mixed zone c. surface zone
b. transition zone d. deep zone
Which ocean zone does sunlight penetrate?
a. aphotic zone c. neritic zone
b. photic zone d. abyssal zone
Which of the following best describes the ocean bottom?
a. quiet c. cold
b. dark d. all of the above
Answers: 1) d. 2) b. 3) d.

2. Oceanic Productivity
Chapter 15, Section 3

3. Primary Productivity
Primary Productivity – the production of organic compounds from inorganic substances through photosynthesis or chemosynthesis
Photosynthesis – the use of light energy to convert water and carbon dioxide into energy-rich glucose molecules
Chemosynthesis – the process by which certain microorganisms create organic molecules from inorganic nutrients using chemical energy
Two factors influence a region’s photosynthetic productivity: the availability of nutrients and the amount of solar radiation, or sunlight

4. Photosynthesis

5. Concept Check
What factors influence a region’s photosynthetic productivity?
Sunlight and nutrient availability

6. Productivity in Polar Oceans
Polar regions experience continuous darkness for about three months of winter and continuous illumination for about three months of during summer
Productivity of phytoplankton, mostly single-celled algae, peaks in May
As soon as the phytoplankton develop, zooplankton come in to eat them
In summer, melting ice creates a low-salinity, low-density region on the surface that will not readily mix with the deeper waters; helping the phytoplankton to continue producing
The availability of solar energy is what limits photosynthetic productivity in polar areas

7. Productivity in Polar Oceans

8. Productivity in Tropical Oceans
Productivity is low in tropical regions of the open ocean
Light penetrates much deeper into tropical oceans than in temperate and polar waters
Solar energy is available year-round
A permanent thermocline prevents mixing between surface waters and nutrient-rich deeper waters; it is a barrier that cuts off the supply of nutrients from deeper waters
Productivity in tropical regions is limited by the lack of nutrients

9. Water Layers in the Tropics

10. Productivity in Temperate Oceans
In temperate regions, which are found at mid-latitudes, a combination of these two limiting factors, sunlight and nutrient supply, controls productivity
Winter: productivity is low, due to the low angle of the sun and shallower sunlight penetration
Spring: phytoplankton bloom due to an increase in nutrients and sunlight, nutrient supply is in greater demand and limits production
Summer: nutrients depleted from spring “bloom” are not able to be replenished from deep waters due to a sharp thermocline, phytoplankton population will remain low
Fall: nutrients return to the surface, as the summer thermocline breaks down, and another “bloom” of phytoplankton occurs (short-lived due to decreasing sunlight)

11. Productivity in Temperate Oceans

12. Comparing Productivities

13. Concept Check
What limits primary productivity in tropical oceans? Why?
The availability of nutrients; solar energy is available year round but nutrient are trapped in deeper waters because the permanent thermocline prevents mixing between surface water and deeper water.

14. Oceanic Feeding Relationships
As producers make food available to the consuming animals of the ocean, energy passes from one feeding population to the next
Trophic Level – a nourishment level in a food chain; plant and algae → herbivores → carnivores
The transfer of energy between trophic levels is very inefficient
Food Chain – sequence of organisms through which energy is transferred, starting with the primary producer
Food Web – a group of interrelated food chains
Animals that feed through a food web rather than a food chain are more likely to survive because they have alternative foods to eat should one of their food sources diminish or disappear

15. Ecosystem Energy Flow

16. Food Chain Vs. Food Web

17. Concept Check
What advantage do organisms in a food web have over those in a food chain?
Organisms in a food web have alternative foods to eat if one of their food sources diminishes or disappears.

18. Assignment (Due 2/21) Read Chapter 15 (pg. 422-437)
Do the Chapter 15 Assessment #1-32 (pg )
Study for Chapter 15 Quiz!!!

19. Cool Down Describe the transfer efficiency between trophic levels.
Very inefficient; as little as 2%
Explain why producers are always the first trophic level in a food chain or food web.
Producers are organisms that are able to use light or chemical energy to produce glucose. Consumers cannot produce their own food and rely on producers as a food source.
What is one thing you learned today that you never knew? Explain.