Download Nutrient Cycles in Marine Ecosystems Part I

Nutrient Cycles in Marine
Ecosystems Part I
Section 4
Surface Layer of Ocean
• Dissolved nutrients
• Recall: algae require light for
photosynthesis
• Intensity of light
as depth
• Restricted to surface layer (photic zone)
• Depth 30 m to 150 m
• Obviously less in turbid water (high turbidity)
What is an ion?
• atom or molecule in which the total
number of electrons is not equal to the
total number of protons, giving the atom
a net positive (+) or negative (-)
electrical charge.
SOME Surface Layer Ions
1. Copy this table on the next page of your notebook.
2. Create a legible bar graph from the information above
Surface Ions
• Those ions, together with nitrate and
phosphate ions form nutrients for
growth of algae and other producers
• RECALL: ppm
• Nitrate and phosphate ions occur in low
concentrations in seawater
• Nitrate = 0.5 ppm
• Phosphate = 0.07 ppm
Replenishment of dissolved nutrients (3)
• 1. Upwelling –
movement of
water from deep
in the ocean to
the surface layer,
where nutrients
become available
to primary
producers
Causes of Upwelling
• Deflection of deep water currents
upwards
• Nutrients sunk to sea floor brought back up
to surface of ocean
• Movement of water away from the coast
by wind
2. Run-off from land
• Part of hydrological cycle
• Water leach nutrients (including nitrates
and phosphates) from soil
3. Atmospheric Gases
• CO2 dissolved in seawater forming
hydrogencarbonate ions (HCO3-)
• AKA bicarbonate
• Makes CO2 available for fixation in
photosynthesis for primary producers
• N gas is fixed by blue-green algae in intertidal
zones
• Forms nitrogen-containing organic compounds
• How nitrogen enters marine ecosystems
Intertidal Zone
Area above water during low tide but underwater during high tide
Nitrogen Cycle
Recycled
• Nutrients like nitrates and phosphates
are recycled at the ocean surface by
excretion from zooplankton
Depletion of dissolved nutrients
• Uptake by primary producers like
phytoplankton
• Synthesis of organic substances
• Example: nitrate ions used for synthesis
of amino acids and proteins
• Phytoplankton  zooplankton  small fish
• Proteins passed to next trophic level and so
forth
Recall