Geography and Oceanography - Chapter 23 pps

Biological Productivity
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??
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.
Open Ocean Food Webs
Barrie Kovish
Vicki Fabry

Pacific Salmon
Copepods
Coccolithophores
Pteropods
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Present Ocean Food Web – Complex ecosystem interactions based on a low CO
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ocean
Microbial
Remineralization
Primary Producers
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Seafloor community
Provided by James Barry MBARI
Ocean Food Web
Absorbing Nutrients

Nutrients absorbed by
plants through
diffusion across a
semi-permeable
membrane
Lauderia sp.
Diffusion:
molecules move from high to low concentrations
Which Nutrients are in Short
Supply?

Nitrogen (N) as Nitrate NO3 (-2)

Phosphorus (P) as Phosphate PO4 (-2)

Silicon (Si) as Silicate SiO4 (-2)
Phosphate and Nitrate in the Pacific
Silicate in the Pacific
Biolimiting Nutrients

N, P, and Si are exhausted first in Eq.

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??
CZCS Global Primary Production

O2 is high in the
surface and mixed
layer

O2 decreases to a
minimum at base of
thermocline

O2 then steadily
increases with depth
How Does Nutrient Distribution Compare w/
Dissolved Oxygen?
6H2O + 6CO2 + energy + nutrients = C6H12O6 + 6O2
Dissolved O2 Reverse of
Nutrients
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?
How is Oxygen Removed from the
Thermocline & Slightly Below??
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
CZCS Global Primary Production
Marine Ecology

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.
Classification of Organisms
by Environment

horizontal: neritic | oceanic

vertical:
–
epipelagic (top) / euphotic (good)
–
mesopelagic (middle) / disphotic (low)
–
bathypelagic (deep) / aphotic (without)
–
abyssopelagic (“bottomless”)
Divisions of the Marine Environment
Figure 9-1
Classification of Organisms
by 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)
Plankton

weak swimmers, drifters, unable to
counteract currents.
–
Phytoplankton (plants)
–
Zooplankton (animals)
Nekton

active swimmers capable of counteracting
currents.
–
Fish
–
Squids
–
Reptiles
–
Birds

–
Mammals