lecture 14 (phytoplankton eco-physiology) Flashcards
why are phytoplankton so important on earth?
they form large blooms,
influence atmospheric chemistry and biogeochemistry of nutrient cycling,
fix about 1/2 of total carbon fixed by photosynthesis,
represent the base of food chains supporting marine mammals, birds, and fisheries,
form oil and siliceous and limestone deposits
describe the biological carbon pump:
CO2 is reduced in surface waters and fixed into organic matter by photosynthesis,
organic matter passes from producers to consumers through respiration and bacterial decomposition of organic matter
ultimate deposition locks the C away in sediments (carbon sequestration)
atmospheric CO2 -> algae -> consumers -> sink -> deposition/remineralization -> sequestration
what is the difference between PP and phytoplankton biomass? how do you measure them?
primary productivity: the rate at which food is incorporated, yields biomass eg. g O2 produced/L, gC/m2/d (measured with fluorescence, satellites etc.)
phytoplankton biomass: standing stock (set number, not rate) eg. cells/L or chla/L
what is NPP
net primary productivity (GPP-respiration)
what is GPP
the total PP
what is a phytoplankton bloom
an accumulation of phytoplankton biomass in a particular area
how is size relevant to phytoplankton eco physiology?
as they grow larger, the SA:V ratio decreases, since SA increases to radius squared and thus it increases slower than volume. This is relevant since a high SA/V ratio allows for faster nutrient exchange
why is a smaller size beneficial?
because it corresponds to a high SA/V ratio, allowing for faster and more nutrient exchange, and faster growth rates
how does SA to volume ratio change with algal size
smaller size has a higher SA/V ratio
larger size has a smaller SA/V ratio
this is because Volume changes with radius cubed, and SA changes with radius Square
how does size affect sinking?
larger cells sink faster, smaller cells are more buoyant
what are adaptations to avoid sinking (5)
gas bubbles, lipids, oils, spines, chains
explain the importance of considering spatial and temporal scales in phytoplankton ecology
different parts of phytoplankton ecology occur at different scales of time and space.
abundance of phytoplankton depends on time and space
spatial scale
what volume or area (eg. how much volume)
temporal scale
how often a bloom occurs (eg. what season)
describe how certain aspects of the aquatic physical environment affects phytoplankton
density changes with temperature and salinity
increasing salinity increases density and lowers freezing point, keeping phytoplankton more buoyant
temperature increases lower density, causing phytoplankton to sink faster
give four examples of nutrients essential for phytoplankton and their roles in physiology
Nitrogen -> amino acids, chlorophyll, nucleotides
Mg -> chlorophyll
Si -> diatom frustules, scales, stomatocyst walls,
S some amino acids, nitrogenase, thylakoid lipids, carrageenan, agar, DMSP, biotin
how much light makes it to the surface
50% of light
what wavelength penetrates deepest? shallowest?
blue penetrates deepest in water column
red is shallowest
what impacts the depth that light reaches in the water column
clarity of the water (particulate/dissolved matter scatters light more quickly)
location (deeper in offshore, shallower in coastal)
what is radience
the light that is visible
what is the base of the euphotic zone
depth with 1% of incident light remaining
draw a temperature profile, and a chlorophyll profile
both are straight down at surface (mixed layer), temperature decreases from then.
chlorophyll increases slightly below the surface, then decreases to 0 (too bright/no nutrients at surface, too dark further down)
what is a langmuir cell
water with streaks of white lines parallel to one another
water masses spinning in localized area, upwelling and downwelling cells beside one another
how does water motion impact phytoplankton
horizontal water motions concentrate/disperse phytoplankton patches
vertical motion affects sinking and nutrient supply
turbulence has species dependent effects