Lecture 10 Flashcards
What is one of the greatest threats to estuaries globally?
Rising sea levels
Why do greater temperatures cause sea level rise?
Through thermal expansion and the melting of polar glaciers
What would happen to sea level if you fully melted the Greenland, west Antarctic ice sheets and the entirety of Antarctica?
- 7m sea level rise for Greenland
- 6m sea level rise for west Antarctic
- 61m sea level rise for full Antarctic
What are the five global ocean?
Pacific, Atlantic, Indian, arctic
Whist is special about the Arctic Ocean?
Waters are most uniform and in terms of physical features and they are highly productive
What is the mixing regime in oceans?
Horizontal cane vertical currents
How does the Coriolanus effect influence currents in oceans?
The horizontal currents form via the Coriolanus effect.
In the norther hemisphere currents move clockwise
In the Southern Hemisphere currents move anti clockwise
Which current rotates around 5e South Pole? Give details of it
The Antarctic circumpolar current . Rotates at a rate of 0.4-0.5 m/s
Which causes upwelling ,divergence or convergence?
Divergent
In which global region does lots of upwelling occur?
At the equator, diverging currents cause lots of mixing. This essentially disturbs the deep water, causing upwelling
In which regions is food web productivity high in the global oceans? Why?
Regions of upwelling, as the high influx of nutrients supports many algae (primary producers) and a stable food web
At continental shelves, as the shallow depth of the oceans means that mixing is more likely to occur
Why does all the oceans deep water originate at polar regions?
Salt dissolves out of melting ice, increasing the salt content of oceans. This then causes the water to be highly saline, and dense.
This and the coldness of the poles causes it to sink, forming deep water that slowly disperse at depth to the other oceans (in a slow process)
Where does all the worlds deep water come from?
Polar regions
What is the stratified status of all oceans?
They are meromictic (permanently stratified)
What are the depths for the temperature division in the ocean?
Warm surface layer: 400m
Gradual decrease: 400-1800 m
Constant cold: >1800m
What is the salinity at the sea base?
35 practical salinity units
Why is salinity greater in hotter areas?
The higher temperatures cause increased evaporation, and increased concentration of saline ions
What are the psi values for tropical and arctic waters?
Surface tropical: 35psu
Arctic Ocean: 29psu
Subtropical waters have greater a greater psu value than arctic waters, why don’t they sink?
Unequal distribution iPod incoming solar radiation makes these waters warmer, and more buoyant
Why does oxygen solubility increase in cold waters?
The h2o molecules have less kinetic energy, and the forces holding oxygen in water molecules are less likely to break
Which had more oxygen, top or bottom oceans?
Bottom layer, due it’s cooler temperatures allowing it to hold more oxygen
Why do oceans have a clearer light climate than rivers?
The bulk of oceans (as coastlines are just a small part) have no catchments so there’s no influx of unwanted humid material. There is also little sediment in surface waters, as the ocean depth is so deep
What is the average section depth in oceans?
300 m
Which light wavelengths penetrate the deep ocean and which are absorbed by surface layers?
Blue light (short wavelength)penetrates deep layers, red light is absorbed at the surface
What are the two uses of blue light in oceans?
Photosynthesis and bioluminescence
Which algae produce white light when disturbed? What’s produced when undistrubed?
Dinoflagellates. Blue light
What is the trophic status of all oceans?why?
Oligotrophic as no nutrient inflow from catchments
What are the limiting nutrients in oceans?
Iron and nitrogen
What are the four main ocean depths? In order from surface to bottom
Epipelagic
Mesopelagic
Bathypelagic
Abyssopelagic
In which ocean zone is phytoplankton based?
The epipelagic
Which are the main algae in oceans? Hint:frustruals
Diatoms, requiring silica for frustruals
Cocoliphophores
Which of the two dominant species blooms closer to land? Why?
Cocoliphophores, as they require higher levels of nutrients than diatoms
What is the general distribution of algae in oceans?
Random, with hotspots and coastlines containing higher primary production as more nutrients are preset (eg from a river catchment). The rest of oceans are fairly nutrient poor, so contain lesser algae biomass
What is the difference between the freshwater and ocean microbial loop?
The only difference is the lesser variety of algae than freshwater, and the fact that all the nutrients within the loops and in house
Where do bacteria in the microbial loop get carbon?
As there’s no river catchments, they rely solely on algae for carbon
What is the metazooplanton distribution in oceans?
Copepods dominate with very few cladocerans or Rotifers. There is no seasonal variability like in the peg model
What is a holoplankton?
Plankton that spend their entire life in the water column. Eg . Krill
What is meroplankton?
Meroplsnkton are organisms that are planktonic in their larvae stage and benthic when they become adult invertebrates
