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Exploring oceans - Coggle Diagram

- - - - Sunlight rarelly pentrates past this point and so this is where all of the photosynthesis occurs.
    - - Sunlight deacrease rapiddly with depth in this zone and photoynthesis is not possible.
    - - There is no sunlight here and animals must be bioluminscencent to be able to see.
      - Despite a lack of sunlight there are areas of intense life found around hydrothermal vents and cold seeps due to the process of chemosynthesis (using chemicals instead of sunlight to produce energy).
        
        Hydrothermal vents are very hot (over 350oc) mineral-laden cracks in the crust which form what are effectively underwater volcanoes (lava is not released).
        
        Cold seeps are places on the sea floor where chemicals such as methane and hydrogen sulfide leak to the surface and are capable of sustaining large amounts of biodiverse life.
  - - - This is where nutrients sinks from the surface down to the lower depths of the oceans.
    - - This is where nutirents returns to the surface through cold ocean currents.
  - - - Despite low tempretures these are some of the most productive seas in the world.
        
        Cold water means that more oxygen disolves into the water whcih helps sustain marine life.
        
        Phytoplankton productivity is high durring the summers when there is never fewer then 12 hours of sun light.
      - The waters are so rich because:
        
        Sea ice forms in the winter releasing salt into the oceans.
        
        Saline water is more dense, this water is cooled to 0oc and it sinks.
        
        Less saline water rises with nutrients such as nitrogen and silica.
        
        Phytoplankton uses these nutrients to grow and reproduce.
        
        The rest of the food web then benefits from more phytoplanton.
    - - Sediment is trapped by plants and accumalted which enables the development of a salt marsh.
      - These are nutrient rich water because:
        
        They are usally fed by rivers inputing nutrients.
        
        Regular tidal movements enable water and nutrients to mix.
        
        Alhtough light levels are seasonal they are only a liminting factor durring winter.
      - Salt marshes are split into different zones depending on their proximity to the sea and thus the types of organisms living in them.
        
        The changes in vegitation between the different zones in a salt marsh is know as plant succession.
- - - - The drop in salinity could mean a drop in density. If this happens this could prevent water sinking in the Arctic oceans and thus disrupting the entire ocean conveyor system.
        
        This could lead to the North Atlanatic Drift stopping and tempretures in Northern Europe mirroring that of Canada.
- - - - Although warm the equator has a high level of precipitation and this means that the salinity is lower then it is as the tropics.
    - - This is the rapid change in salinity of the oceans close to the surface (surface water has a higher salinity as there is a higher level of evaportation meaning salinity at the surface is 35.5% and below 2km salinity is 34.7%).
  - - - This is the rapid change of tempreture near the surface.
      - Tempretures drop rapidly below the surface. At the surface tempretures are on average 22oc and after you drop from 500m to 1km tempretures are as low as 4oc.
- - - - These cover the top 10% of the oceans.
      - These are warm ocean currents that are moving away from the tropics towards the high lattitude seas.
      - They play an important role in regulating global climate by moving warm water around, this can best be seen in Northern Europe where because of the North Atlantic Gulf Stream it is warmer then it should be (Northern Europe should have a climate similar to Canada).
      - The wind (trade winds) is key to move these surface currents.
    - - These make up 90% of the oceans and are located below the surface.
      - These move from the poles towards the tropics.
      - These are moved through changes in water density throughout the oceans.
    - - This is the circulation of surface water in a circular motion.