Marine productivity Flashcards
What % of earth is covered by Oceans?
70
Why aren’t all of the oceans productive?
as limiting factors restrict the growth of the most important photosynthetic organism algae
What are the 3 layers of light penetration in the ocean?
Sunlight (euphotic)
Twilight (Dysphotic)
Midnight (aphotic)
At what water depth does very little light penetrate?
100m (shallower if turbid)
What does the short light penetration depth mean for photosynthesis in the oceans?
photosynthesis is limited to the surface or photic layer of the ocean
What does most life in the darker parts of the ocean rely on for food?
rely on food produced near the surface (bodies of dead organisms or planktonic organism carried by the currents)
How do algae absorb nutrients?
directly from the water because there is no soil and they don’t have roots
What nutrient is readily available to the photosynthetic algae?
Carbon dioxide
What sort of nutrients are limiting factors for photosynthetic algae?
Phosphates as they aren’t as readily available due to their low solubility
How can phophate levels in the sunlight zone be increased?
Run-off from rivers
Upwelling ( deep cold nutrient water rises towards the ocean surface)
What can increased nutrient availability of nutrients in the ocean cause?
an algal bloom (eutrophication)
What is upwelling?
when cold water is forced/ pushed to the surface bringing nutrient rich water form the sea bed
Why is deep ocean water so nutrient rich?
organisms die and sink to the bottom as does excrement
