Water Circulation-Primary Productivity Flashcards
thermocline variation in relation to latitude
Temperature at the top layer is the highest (tropics)
- wider thermoclines
strong summer thermocline
No vertical mixing
relatively difficult mixing and diffusion
thermocline variation in relation to season
Stronger in summer, weaker in winter
Weak winter thermocline
Full vertical mixing
- Has implications for ocean productivity and upwelling
Upwelling
The movement of deep, cold, and nutrient-rich water to the surface
What does upwelling cause?
Nutrients + light near surface = photosynthesis
- surface currents, more plants, animals, fisheries
Why does upwelling matter?
Permanent upwelling areas support the richest fisheries
- 1% sea surface
- 50% of world fisheries
ENSO
El Nino Southern Oscillation
- Starts ~December
- Periodic (irregular) phenomenon
- Influences weather; large scale
continental margin
Made up of continental shelf, continental slope and continental rise
pelagic zone
open water above the ocean floor
neritic zone (ocean)
Everything that is on top of the continental shelf
oceanic zone (ocean)
Everything beyond the continental shelf
water column
Vertical Zones of the ocean with changing conditions as depth increases.
layers of the water column
- Epipelagic (200 m)
- Mesopelagic (1,000m)
- Bathypelagic (4,000m)
- Hadal-pelagic (>6,000 m)
depth & conditions of epipelagic zone
0-200m; Photosynthesis
depth & conditions of mesopelagic zone
1,000m; Some light but no photosynthesis
depth & conditions of bathypelagic zone
4,000 m; no light
Depth & Conditions of Hadalpelagic zone
> 6,000 m; no light
Benthos
Seafloor creatures
Pelagos
Water column creatures
Two groups of pelagos organisms
- Nekton; swim against currents
- secondary producers - Plankton; drifting
- primary producers
What are the limiting factors for phytoplankton photosynthesis?
- Light
- Nutrients (phosphate, nitrate, iron and silicon)
Gross primary productivity
Total organic carbon produced by photosynthesis
Net primary productivity
Total organic carbon minus the carbon used for respiration
Compensation depth
Depth where photosynthesis = respiration meaning net productivity = 0
What type of growth do phytoplankton show?
Exponential growth
- due to asexual reproduction
temperate latitude and phytoplankton growth
- two phytoplankton blooms (more intense in spring)
- limited by availability of light or nutrients (never both)
Polar latitudes and phytoplankton growth
- one bloom
- limiting factor is sunlight
- lots of nutrients because of upwelling
- vertical mixing ( weak thermoclines)
Tropical latitudes and phytoplankton growth
- permanent thermocline as a barrier for vertical mixing
- nutrients are limiting factor
Micro plankton size
20-200 um
Nano plankton size
2-20 um
Three groups of phytoplankton
- Diatoms
- Dinoflagellates
- coccolithophores
Diatoms
- microplankton; unicellular usually forming chains
- cell wall made of silica
- benthic habitat
Dinoflagellates
- microplankton With two flagella
- thick cellulose theca
Coccolithophores
nanoplankton
- highly reflective
- removes co2 from atmosphere
Describe the halocline
quiz question
Areas of water with a sharp change in salinity
If you are on the coast of Peru, what happens to the thermocline during ENSO in comparison to La Nina? Any differences?
(Quiz question)
Thermocline during ENSO affects weather patterns and upwelling (regional) and La Nina returns conditions back to normal
