Ocean Biology Flashcards
What is the primary long term removal pathway for volcanic CO2?
Production and burial of organic carbon and calcium carbonate shells/skeletons
Give an example of a tertiary, secondary and primary producer in the ocean.
Tertiary - fish, dolphins, squids, sharks and whales
Secondary - zooplankton, shrimps, krills.
Primary - phytoplankton
Photosynthesis uses energy from sunlight. Where do algae get this from in the ocean? show this in the overall equation.
Light energy from chlorophyll in algae. CO2+H20 —> chlorophyll —-> O2 and Organic matter
Coccolithophores are large phytoplankton. What is their defining feature and what is it used for?
CaCO3 shell to protect from viruses and grazing.
How big are Coccolithophores?
Unicellular 5-100 µm (micro meters).
What do coccolithophores contribute to the ocean?
After death, their shells sink to the bottom of the ocean, forming chalky sediments.
Diatoms are also large phytoplankton. How big are they and what is their defining feature?
Form Silicate (SiO2) shell. 2 - 200µm.
Name the other two smaller, unicellular phytoplankton abundant in the ocean. Where do they live and how do they differ in size?
Prochlorococcus 0.5-0.7µm and Synedococcus 0.8-1.5µm occupy the tropics and sub tropics.
What is the distribution of Coccolithophores and diatoms in the ocean?
Coccolithophores - 30-60 degrees north
Diatoms - 40-80 degrees south
Where is total biomass in the oceans highest and why?
At the coast nutrients are brought to the surface waters by tidal and wave turbulence as well as freshwater runoff from the land. Freshwater runoff also creates a low-density surface water layer that keeps phytoplankton near the surface.
Why does primary production occur at the ocean surface?
Sunlight is strongly attenuated in water - only 25% reaches 10m depth in clear water.
What is the assimilation number for phytoplankton photosynthesis and what two properties of phytoplankton is this related to?
assimilation number - the rate of photosynthetic carbon assimilation per weight of chlorophyll, determined by the carbon/chlorophyll ratio and growth rate of the phytoplankton.
Why do tropical seas and temperate waters show low summer assimilation rates, whilst coastal estuaries show seasonal variation?
Low summer assimilation = low ambient nutrient concentrations. Seasonal variation is due to temperature, as nutrients constantly supplied from freshwater of rivers.
Where do the C, N and P required for phytoplankton in the ocean come from.
C from DIC (rarely limiting)
N from No3- and NH4+
P from PO43-
Which phytoplankton type does not get nitrogen from NO3-?
Prochlorococcus
Where is nitrate concentration highest, andhow does this relate to phosphate and chlorophyll concentrations?
Highest in polar south, with concentrations in N high latitudes, particularly in the Pacific, and off the western coast of S America - both phosphate and chlorophyll presence reflect this.
What is the redfield ratio including Fe?
P : N : C : Fe
1 : 16 : 106 : 5x10-4
What is the condition for nitrogen limitation, and where do nitrogen fixers grow in response to this?
[NO3- + NH4+] < 16x[PO43-]
Nitrogen fixers found in tropics and sub-tropics (of the atlantic and indian oceans - less so in the pacific)
What does the distribution of diatoms in the ocean correspond to?
High Silicate levels (Si04)
Where is average dissolved total iron lowest in the surface ocean?
Southern and Pacific oceans
What are HNLC regions and where are they found?
High Nitrate, Low Chlorophyll regions, where biomass of phytoplankton is low despite high nutrient levels - caused by iron limitation. Found in equatorial east pacific and southern oceans.
Sediment burial is a sink which nutrients? what are the two ‘exceptions’?
Sink for Phosphorus, Carbon, Nitrogen and Silica. However, nitrogen also ‘sunk’ by denitrification whilst decomposition is the sink for Oxygen.
Rivers are a source of which 4 nutrients? in what form?
Phosphorus (PO43-)
Carbon (DIC, DOC)
Nitrogen (DIN, ON)
Silica (SiO4)
Which two nutrients can be obtained by air-sea gas exchange?
Carbon and Oxygen
