Topic 21 Productivity

1
Topic 21Productivity

• GEOL 2503
• Introduction to Oceanography

2
ECOSYSTEMS The interaction between organisms
and environment

• ORGANISMS
• Primary producers
• Consumers
• Decomposers

• ENVIRONMENT
• Seawater
• Dissolved Gases
• Nutrients
• Sunlight
• etc.

3
Feeding Strategies

• Primary producersmake food
• Photosynthesis
• Chemosynthesis
• Consumersdont make their own food
• Herbivoreseat plants
• Carnivoreseat meat
• Omnivoreseat both
• Decomposersbreak down food by decay

4
Different Feeding Strategies

• Large carnivores like Toothed Whales, Seals
  Sharks feed at top of food web
• Disadvantages collapse of any trophic level
  affects all higher levels. Large prey less
  abundant than small prey.
• Advantage larger prey provide more calories

• Baleen Whales feed low down on food web
• Disadvantage must consume enormous volumes of
  small plankton
• Advantage closer to energy source (less middle
  men)

5
(No Transcript)
6
CHARACTERISTICS OF ECOSYSTEMS

• With progress through an ecosystem
• 1. Biomass decreases
• 2. Size of organisms increases
• 3. Energy decreases
• 4. Entropy (disorder) increases

7
A Simple Food Chain

• Energy
• 1 unit
• 10
• 100 10 efficient
• 1,000 at each level
• 10,000
• 500,000 2 efficient

• Trophic Level
• 5. Killer Whale
• 4. Seal
• 3. Bony Fish
• 2. Zooplankton
• 1. Phytoplankton
• Solar Energy

8
TROPHIC PYRAMID
ENERGY UNITS
TROPHIC LEVEL
1
5
Orca
10
Seal
4
100
Bony Fish
3
2
1000
Zooplankton
1
Phytoplankton
10000
Solar Energy
500,000
9
(No Transcript)
10
Trophic Levels

• Each level represents a link in the food chain
• Primary producers are always the first trophic
  level
• Herbivorous zooplankton are second level, etc.

11
TROPHIC PYRAMIDS

• Trophic levels vary between 2 8 with average of
  5
• Average efficiency about 10 for each level in
  the open ocean
• Efficiency may be 15 near coasts and 20 in
  areas of upwelling

12
(No Transcript)
13
Where does all the energy go?

• If only 10 of energy is harvested at each
  trophic level, where does the other 90 go?
• Energy is lost to
• Excretion
• Metabolism (Respiration)
• When organisms die uneaten

14
Food Chains and Webs

• Food chain implies linear relationship, but it is
  a much more complex interrelationship among
  organisms, called food web
• primary producers ? primary consumers ? secondary
  consumers ? top carnivore
• Example organic molecules ? phytoplankton ?
  zooplankton ? anchovy ? tuna ? killer whale
  (decomposers)

15
(No Transcript)
16
A Food Web
17
(No Transcript)
18
(No Transcript)