Environmental cues Flashcards
What are key environmental factors
Light regime (specral properties, attenuation)
Temperature
CO2 system (buffer)
Nutrients (N, P, Si, trace metals)
Salinity (osmotic pressure)
Phytoplankton (buoyancy control, critical depth)
Which color does 400nm correspond to
Blue
Which factors cause the spectral irradiance to vary
Sun angle Cloud cover Aerosol Depth and ice thickness Phytoplankton and ice algae cover Zooplankton and detritus Inorganic particles Yellow substance
What are the inherent optical properties
Depend only on the medium, absorption and scattering, easy to interpret, difficult to measure
What are the bio-optical properties of phyto-cells
Scatterin of light by the cell wall
Absorption by PS and photoprotective pigments
Fluorescence
Why is temperature so important
Slows down respiration and enzymatic steps of PS (lowers growth rate)
No effect on light reaction of PS
What is the CO2 system and why is it important
Feeds primary producers C during PS Very efficient buffer Keeps the pH at a constant 8.2 90% is as HCO3 Seawater with full salinity (35psu) has partial CO2 pressure of 0.03%
What are the most important characteristics of nutrients
Vary as function of time and space
N is a building block of proteins and nucleic acids
N is found as Nitrate (NO3) or ammonia (NH4)
Phytoplankton needs 16 N for 1 P (Redfield ratio)
Phytoplankton cannot synthesize all vitamins
Tracemetals are needed
What is the ice edge effect
Ice is melting northwards New nutrients are exposed Favorable light for PS Water masses stabilize Termocline and nutricline Seeding stock for ice algae All this leads to phytoplankton bloom
What are important factors of salinity
Full salinity is 35psu Osmotic regulation mechanisms Big differences in salinity inside and under ice One year sea ice = high salt content Multi year old ice = low salt content
What are important factors of buoyancy in phytoplankton
Buoyancy control (small particles sink slower than big ones)
Oil droplets for buoyancy control
Shape of cells helps with buoyancy control
Critical depth = PS and respiration are even when integrated over the whole water column
When can a phytoplankton bloom develop
Total integrated PS must be higher than total respiration
Vertical mixing is lower than the critical depth
