Biological Productivity

1
Biological Productivity
2
Basic Ecology

• physical and chemical parameters affecting
  distribution and abundance
• An ecosystem includes both the living (biotic)
  and non-living (abiotic) portions of the
  environment.
• Examples include salt marshes, estuaries, coral
  reefs, the North Pacific Gyre.

3
Classification of Organisms by Environment

• horizontal neritic oceanic
• vertical
• epipelagic (top) / euphotic (good)
• mesopelagic (middle) / disphotic (low)
• bathypelagic (deep) / aphotic (without)
• abyssopelagic (bottomless)

4
Divisions of the Marine EnvironmentFigure 9-1
5
Classification of Organismsby Lifestyle

• Scientists have established another
  classification scheme to categorize biota on the
  basis of lifestyle. The major groups are
• plankton (floaters)
• nekton (swimmers)
• benthos (bottom dwellers)

6
Plankton

• weak swimmers, drifters, unable to counteract
  currents.
• Phytoplankton (plants)
• Zooplankton (animals)

7
Nekton

• active swimmers capable of counteracting
  currents.
• Fish
• Squids
• Reptiles
• Birds
• Mammals

8
Conditions for Life in the Sea

• Consider the main biochemical reaction for life
  in the sea, and on earth in general
• 6H2O 6CO2 energy nutrients C6H12O6 6O2
• Focus on left side of equation
• What is in short supply in the sea and thus
  limits the amount of life in the ocean??

9
Absorbing Nutrients 6H2O 6CO2 energy
nutrients C6H12O6 6O2

• Phytoplankton are base of the food chain
• Most important primary producers of complex
  sugars and oxygen

Lauderia sp.
10
Open Ocean Food Webs
Coccolithophores
ARCOD_at_ims.uaf.edu
Copepods
Barrie Kovish
Pacific Salmon
Vicki Fabry
Pteropods
11
Present Ocean Food Web Complex ecosystem
interactions based on a low CO2 ocean
Ocean Food Web
Primary Producers
Upper Trophic Levels
Zooplankton Food Web
Sinking Organic Debris
Provided by James Barry MBARI
Microbial Remineralization
Seafloor community
12
Absorbing Nutrients

• Nutrients absorbed by plants through diffusion
  across a semi-permeable membrane

Lauderia sp.
13
Diffusionmolecules move from high to low
concentrations
14
Which Nutrients are in Short Supply?

• Nitrogen (N) as Nitrate NO3 (-2)
• Phosphorus (P) as Phosphate PO4 (-2)
• Silicon (Si) as Silicate SiO4 (-2)

15
Phosphate and Nitrate in the Pacific
16
Silicate in the Pacific
17
Biolimiting Nutrients

• N, P, and Si are exhausted first in surface
  waters during photosynthesis
• Essential to the growth of phytoplankton
• If these biolimiting nutrients increase in sea
  water, life increases
• If these biolimiting nutrients decrease in sea
  water, life decreases
• Where would you expect to find the highest
  biomass in the Pacific??

18
How Does Nutrient Distribution Compare
w/Dissolved Oxygen?
6H2O 6CO2 energy nutrients C6H12O6 6O2

• O2 is high in the surface and mixed layer
• O2 decreases to a minimum at base of thermocline

19
Dissolved O2 Reverse of Nutrients
20
Why is the Concentration of Oxygen High in the
Mixed Layer??

• Hint 1 How and where is oxygen produced in the
  sea???
• 6H2O 6CO2 energy nutrients C6H12O6 6O2
• Hint 2 How can oxygen be mixed downward from
  the atmosphere into the ocean?

21
How is Oxygen Removed from the Thermocline
Slightly Below??
22
Dead and decaying organic matter sinks downward
from surface waters

• Rate of sinking decreases as it encounters the
  cold, dense water of the thermocline
• Material decays (oxidizes) at the thermocline,
  which strips O2 out of the water and returns
  nutrients to the sea
• Cold, nutrient-rich water of the thermocline is
  returned to sunlit surface waters by way of
  upwelling

23
CZCS Global Primary Production