primary production Flashcards
what is primary production?
production of chemical energy in organic compounds by living organisms
- entry point of energy into food webs
- Major biogeochemical transformation of carbon
the importance of primary production
primary production is primarily done by
phytoplankton
is primary production mostly on land or in the ocean ?
the land
microalgae, responsible for >95%
of photosynthesis in the ocean
Phytoplankton
coastal, important in nutrient rich
(often cold) regions
Macroalgae
coastal, highly productive but
restricted to very shallow (often tropical) waters
Seagrasses
small phytoplankton are in what kind of regions?
oligotrophic (low nutrients) regions
large phytoplankton are in what kinds of regions?
eutrophic (high nutrient) regions
describe a diatom
5 – 200 um (human hair ~100 um)
* Silicate Cell‐wall
* ‘Pill‐box’ shape
centric diatoms…
may be circular, triangular, or rectangular and have radial symmetry
penate diatoms…
elongated with surface markings at right angles to the long axis, an arrangement called bilateral symmetry.
Diatoms generally _______the phytoplankton community whenever there are
lots of nutrient inputs
dominate
what are some examples of cyanobacteria
Picoplankton & Trichodesmium
Very Abundant, esp. in Open Ocean
Common in low productivity, nutrient limited regions
Synechococcus, Prochlorococcus
picoplankton
2 flagella (motile)
* 5 – 200 um
* Cell wall of cellulose plates (wood)
* Diverse “life styles”:
Autotrophs, Heterotrophs, Parasites, Symbionts
* Harmful Algal Blooms (HABS)
* Zooxanthellae: symbionts in corals
dinoflagellates
Largest primary producers in the sea (seaweeds, kelp)
* Typically grow on rocky substrates
* Generally restricted to coastal zone
macroalgae
what are some examples of macroalgae ?
kelp and sargassum weed and green algae
sea grasses are
True (flowering) plants
* Shallow, clear habitats (need high light)
what are two examples of seagrass?
eel grass and turtle grass
what are the 2 main factors of controlling primary production?
nutrient availability and light
which has more visible light, the open ocean or coastal water?
COASTAL WATER. This is because coastal areas often contain more suspended particles and phytoplankton, which can reflect and scatter light. In contrast, the open ocean, especially in deeper regions, may absorb more light, leading to lower visibility. However, the specific conditions can vary widely depending on factors like location, time of year, and water clarity.
why are nutrients found at lower concentrations in surface waters than at depth?
Much less abundant in
the ocean than on land
High consumption in the
surface layer
Decaying matter sinks to
depths below the surface
zone
Can only be returned to
sunlit area by upwelling
upwelling = _____ productivity
HIGH
deep mixing = _________ productivity
HIGH
permanently stratified = _______ productivity
LOW
low light or low iron = _______ productivity
LOW
Which organisms are responsible for primary
production in the ocean?
Phytoplankton: Diatoms, Coccolithophores,
Cyanobacteria
Macroalgae and Seagrasses
Why do rates of primary production vary in
the ocean?
Nutrients, Light
How do rates of primary production vary in
the ocean?
Upwelling and Temperate/Subpolar regions
have high primary production, tropics have low
