Biological Oceanography Flashcards
What factors affect life in the ocean?
Light, nutrients, temperature, salinity, dissolved gases, pH, pressure
Why is light necessary in marine/aquatic ecosystems?
For photosynthesis of phytoplankton
What is the depth of the Photic zone equivalent to?
The depth in which the photosynthetic active radiation (PAR) is 1% of the surface PAR
What is PAR?
Photosynthetic Active Radiation - the portion of the light spectrum which can be used for photosynthesis
In the open ocean (clear water), what is the limit of the photic zone?
100-200m
At the continental margin, what is the limit of the photic zone?
50-100m
At the mouths of rivers, what is the limit of the photic zone?
Can be less than 50m
What are nutrients needed for in marine/aquatic ecosystems?
Nutrients are required for the production of organic (carbon-based) matter
How does nutrient replenishment occur in coastal areas?
Upwelling and terrestrial runoff
What are the issues with nutrient replenishment in coastal areas?
Eutrophication and harmful algal blooms (HABs)
What is the redfield ratio?
The elemental composition of marine organic matter
C:N:P = 106:16:1
What is often the limiting micronutrient in the ocean?
Iron
Which element had an unlimited supply and can be recycled fast?
Carbon
Which element is abundant but has a large demand and is recycled slowly?
Nitrogen
Which element is in less demand and can be recycled more quickly?
Phosphorous
What is the meaning of a limiting nutrient in marine/aquatic ecycosystems?
A nutrient which is not in the required proportion needed for phytoplankton to grow
Where does iron limit the growth of primary producers?
In the Southern Ocean around Antarctica and elsewhere
What caused an algal bloom in the Gulf of Alaska in 2008
In 2008, Mount Kasatoshi in Alaska erupted, spreading iron dust from volcanic ash far into sea and prompting plankton blooms
What is the mixed temperature layer?
Near the surface where the temperature is roughly that of surface water
What is the thermocline?
Area of rapid temperature transition from upper to deep layer