Lecture #7 - Pelagic Environment Flashcards
Light attenuation
water absorbs or scatters light strongly enough to limit the depth of sunlight
5 pelagic zones
epipelagic, mesopelagic, bathypelagic, abyssopelagic, hadalpelagic
epipelagic zone
first 200 m; abundance of light allows for photosynthesis and high nutrient levels
mesopelagic zone
200 to 1,000 meters; Twilight Zone, has some light but not enough to support photosynthesis
bathypelagic zone
1,000 to 4,000 meters; contains the infrequent bioluminescent organisms that survive mostly on the detritus that drifts down from the epipelagic
abyssopelagic zone
> 4,000 meters to the ocean floor, completely dark; home to colorless and blind organisms
hadalpelagic zone
submarine trenches, deepest points
what % of Earth’s primary production does the epipelagic provide?
nearly 50%
Oxygen Minimum Zone
OMZ; occurs at 500 to about 1,000 meters; an ocean layer with little oxygen
what makes the OMZ so oxygen-poor?
at this depth, oxygen is being metabolized (consumed by organisms for energy production), so there is less of it present
advantages of living in OMZ
fewer predators and reduced competition
where is species richness greatest?
tropical waters
Match vs. Mismatch
good year or poor year
good year
match of increases in plankton pairs with increases in upper-trophic level to allow for high breeding success
poor year
mismatch in the timing of the plankton increase and the reproductive output of upper-trophic level, causing low breeding success
what are the primary producers in a deep-sea hydrothermal vent system?
chemoautotrophic sulfur-oxidizing bacteria
what do chemoautotrophic sulfur-oxidizing bacteria do?
oxidize inorganic sulfide to obtain energy to synthesize organic molecules
how to colonize new vent communities
Produce large numbers of larvae
May use carcasses as intermediate habitat
Methane hydrate communities
“cold seeps” that have a flow of methane gas
what organisms are supported by methane hydrate communities?
tube worms, clams, mussels, sulfur-oxidizing bacteria
oceanic gyre primary production
very low due to lack of nutrients; like a desert
5 major oceanic gyres
North Pacific, North Atlantic, South Pacific, South Atlantic, Indian Ocean
coriolis effect
Northern hemisphere everything bends to the right
Southern hemisphere everything bends to the left
productivity in open ocean
low
productivity in continental shelves
moderate
productivity in upwelling zones
high
where is most of the ocean’s biomass concentrated?
in thin layers at ~100 m depth where there is sufficient light and nutrients
