Lecture 3 - Primary Production Flashcards
What percentage of total carbon captured by photosynthesis on the planet occurs in the sea?
50%
What percentage of the Earth’s carbon dioxide is cycled and stored through marine systems?
Over 90%
How can we measure where phytoplankton are located?
Looking at chlorophyll concentration across the planet from satellite images.
What percentage of primary production is produced by phytoplankton?
50%
Describe how carbon flow is linked to photosynthesis in phytoplankton.
- Phytoplankton photosynthesise in the surface layer, using nutrients.
- Organic matter from dying phytoplankton sinks, removing nutrients from surface waters.
- Photosynthesis can then carry on when layers are remixed.
What is primary production?
The fixing of carbon from an inorganic form to an organic form.
What is the term ‘carbon flow’ referring to?
The energy in the open oceans.
Name primary producers that are
a) Pelagic
b) Benthic
a) Pelagic = Phytoplankton
b) Benthic = Microalgae
How big are cyanobacteria?
1 micrometre in diameter
What is a holoplankton?
An organism that spends its whole life as a plankton.
What is a meroplankton?
An organism that spends only a part of its lifecycle as a plankton
What is a picoplankton?
A plankton that is 0.2-2 micrometers in diameter
What is a nanoplankton?
A plankton that is 2-20 micrometers in diameter?
What is a micro plankton?
A plankton that is 20-200 micrometers in diameter.
What is a mesoplankton?
A plankton that is 200-1000 micrometers in diameter.
What is phytoplankton in Greek?
Phyton = plant Planktos = drifter
Describe the structure of diatoms.
Small, single-cellular protists.
Cell wall called a frustule, made up of silica.
Describe the growth of diatoms.
Divide asexually up to 4 times a day - grow fast.
Do diatoms reproduce sexually?
They normally produce asexually, although sexual reproduction has been observed.
Describe algal blooms of diatoms.
Cause harmful algal blooms by producing domoic acid that causes shellfish poisoning.
Describe the structure of dinoflagellates.
Unicellular protists.
Have a flagellum in a groove around the edge of their main body.
What are zooxanthellae?
A type of dinoflagellate that lose their flagella when taken up by a coral host.
How many species of dinoflagellates have been observed?
Over 1,500
What is responsible for the bioluminescence of dinoflagellates?
- Enzyme luciferase
- Substrate luciferin
What are red tides?
Blooms caused by dinoflagellates that are responsible for large die-offs of marine organisms.
Caused by neurotoxins called brevetoxins.
How are coccolithophores distinguished?
They have calcium carbonate plates called coccoliths
What organisms are responsible for carbon storage in the White Cliffs of Dover?
Coccolithophores
What are the three groups of macroalgae?
What determines the group?
- Green macroalgae
- Red macroalgae
- Brown macroalgae
Depends on the pigment they use for photosynthesis and where they can be found on the shore.
What percentage of global marine systems are covered with seagrasses and mangroves?
0.5%
What percentage of carbon storage in marine sediments is from seagrasses and mangroves?
50%
What is compensation depth?
The point at which respiration balances photosynthesis
Where does compensation depth occur?
Just over 200m in depth
Where is the maximum photosynthesis depth?
At approximately 80m below the surface
What is productivity?
The amount of photosynthesis that occurs
What is net primary production?
The difference between production (in photosynthesis) and respiration in the algal community.
What percentage of carbon
a) Is recycled and used in surface waters?
b) Sinks out of surface waters to deeper ocean?
a) 90%
b) 10%
What percentage of organic matter reaches the seabed?
1-3%
What percentage of organic matter is incorporated into benthic sediments?
1%
What is a biological pump?
The carbon that makes it out of the thermocline
What is the most important limiting factor for primary production?
Nitrogen
What is the second most important limiting factor for primary production?
Phosphorous
What needs to happen for nitrogen for it to be usable?
It has to be reduce and turned into nitrate
Describe trichodesmium.
A cyanobacteria that can fix nitrogen into nitrate and make it available.
Give five limiting nutrients for primary production.
- Nitrogen
- Phosphorous
- Sulphur
- Iron
- Silicate
How is iron put into the oceans?
From desert dust blowing into oceans.
95% of organic matter is made up of what six elements?
- Carbon
- Nitrogen
- Hydrogen
- Oxygen
- Phosphorous
- Sulphur
In which zones are there
a) Lots of productivity and nutrients?
b) Low nutrients and productivity?
a) Eutrophic zones
b) Oligotrophic zones
Where does most production occur?
In the North Atlantic or around the coastal areas
What is Deep Chlorophyll Maximum?
The measurement of chlorophyll in water, where phytoplankton are.
Describe seasonal plankton cycles in temperate regions.
- Two phytoplankton blooms.
- One zooplankton bloom in summer.
Describe seasonal plankton cycles in the Arctic.
- One big strong peak in primary production when the sun comes up and melts the sea ice. Zooplankton have a single bloom following the phytoplankton bloom.
Describe seasonal plankton cycles int he topics.
Heat drives a strong thermocline and low in nutrients, no seasonal patterns but small peaks - no high levels of primary production due to low nutrient availability.
Where are there strong algal blooms?
At high altitudes
How are algal blooms generally terminated?
By viruses
What is the name of the project sailing a yacht around the ocean containing a mobile lab?
Tar Oceans Project
How has the abundance changed of
a) Dinoflagellates?
b) Diatoms?
a) Dinoflagellates = declined in abundance.
b) Diatoms = increased in abundance.
