nutrient cycles in marine ecosystems part ii section 4
TRANSCRIPT
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 levelsExample: upwelling – high productivity
Benguela upwelling system
Removal of Nutrients1. 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 Nutrients3. Removed by harvesting
• Removing/eating fish and other marine organisms
Nutrient Biological UsesNutrient Biological Use
Nitrogen Make proteins; synthesis of amino acids
Carbon Synthesis of all organic materials (ex: carbohydrates, proteins)
Magnesium Make chlorophyll for plants
Calcium Production of bones, corals and shells
Phosphorus Production of bones and synthesis of DNA
• Summary of ways in nutrients are cycled in marine systems
Nutrients derived from both
Removal (3)
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/seawater.htm#composition
• http://www.marinebio.net/marinescience/02ocean/swcomposition.htm