Transcript Nutrient Cycles in Marine Ecosystems Part II

Nutrient Cycles in Marine
Ecosystems Part II
Section 4
Limited Productivity
• Inorganic nutrients (ex: nitrate and phosphate
ions) are essential for growth of primary
producers
• Productivity of
primary producers
will affect
productivity of
higher trophic
levels
Example: upwelling
– high productivity
Benguela upwelling system
Removal of Nutrients
1. Sink to sea floor
•
•
In feces
Detritus (decaying organic
materials); organisms die
Loss of nutrients from surface
water
•
•
•
Will only return to surface by
upwelling
Slow decomposition on sea bed
(floor) due to cold/lack of
oxygen
Removal of Nutrients
2. Incorporated into coral reefs
•
Deposition of calcium carbonate for
growth of corals
Removal of Nutrients
3. Removed by harvesting
•
Removing/eating fish and other marine
organisms
Nutrient Biological Uses
Nutrient
Biological Use
Nitrogen
Make proteins; synthesis of
amino acids
Carbon
Synthesis of all organic
materials (ex: carbohydrates,
proteins)
Make chlorophyll for plants
Magnesium
Calcium
Production of bones, corals
and shells
Phosphorus
Production of bones and
synthesis of DNA
Nutrients derived from both
Removal (3)
• Summary of ways in nutrients are
cycled in marine systems
In Summary
• Fertilizers, like nitrogen (N), phosphorous (P), and potassium
(K), are important for plant growth and are called 'nutrients.'
The level of dissolved nutrients increases from animal feces
and decomposition (bacteria, fungi). Surface water often may
be lacking in nutrients because feces and dead matter tend to
settle to the bottom of the ocean. Most decomposition is thus at
the bottom of the ocean. In the oceans most surface water is
separated from bottom water by a thermocline (seasonal in
temperature and marginal polar regions, constant in tropics)
which means that once surface nutrients get used up (by the
plants there) they become a limiting factor for the growth of new
plants. Plants must be at the surface for the light. Nutrients are
returned to surface waters by a special type of current called
'upwelling' and it is in these areas of upwelling that we find the
highest productivity of marine life.
Website References
• http://www.seafriends.org.nz/oceano/se
awater.htm#composition
• http://www.marinebio.net/marinescience
/02ocean/swcomposition.htm