L1 Abiotic factors Flashcards
What is a measure of biomass and productivity in the ocean?
Chlorophyll a
Where are areas of more and less chlorophyll?
Hotspots - coastal areas
Coldspots - Mid ocean
What are the vertical ocean regions called?
Littoral - tidal zone
Neritic - above continental shelf
Oceanic - above continental slope and abyss
what are the horizontal regions of the ocean called?
Epipelagic - surface waters
Pelagic - open ocean
Benthic - sea floor
What is the best solvent?
Water
What causes salinity?
River run off, volcanic activity
weathering of rocks - + ions
precipitation and hydrothermal vents - ions
what is the ocean average salinity?
35%, varies btw 31-39%
What instrument measures salinity?
Refractometer
which area of oceans have the highest salinity and why?
when SW freezes, ions are excluded, so icebergs are almost pure and liquid water is saltier. In summer evens out slightly.
Also partially enclosed seas have high salinity, eg Red Sea
which 4 ions are most abundant
Cl- 19.3%
Na+ 10.75%
SO4 2- 2.7%
Mg2+ 1.29%
What unit is salinity measured in?
PSU - Practical salinity unit
what are 3 important nutrients in the ocean?
Nitrate, Silicate and Phosphate
What is a CTD meter?
Measures Conductivity, temp and density
what can be used to trace a body of water?
SO6 -marker
How much do day/night temperatures vary by?
<1 degree C
What percentage of dissolved gas in the ocean is CO2 and O2?
80% CO2 (compared to 0.04% in air)
0-8ml/l of O2 compared to 210 in air.
does cold or hot water have more O2 dissolved?
Cold
2 ways to measure light penetration
Secchi disc
submersible photocells
What is oxygen minima?
regions of the ocean with less available O2 than is needed for life
What causes turbidity?
Phytoplankton and mineral particles
name of zones with enough light for photosynthesis, enough light to see, not enough light to see
Photic/Euphotic
Disphotic/Dysphotic
Aphotic
how is UV light cut out?
Salts absorbing it
Not absorbed in FW lakes or shallow SW
at What depth is there most thermocline?
Intermediate depth, 200-1000m
Temp drops and Density increases
When does salinity vary and when is it constant?
Varies in intermediate layers 200-1000m
Stays constant after 1000, as layers mix.
Why do nutrients run out in summer?
How are they replaced?
Surface layers heat up, creating many small layers which dont mix, so nutrients cant be replenished from below.
In autumn, surface cools and there is downwelling of nutrient low water, displaces deep rich water which rises. Over winter, waters mix and nutrients are replenished.
Where does the Coriolis effect deflect currents to?
currents and winds deflected to the right in N hemisphere
To the L in southern hemisphere.
How does the antarctic conveyor belt work?
Cold water at poles sinks and gets more dense. Movement of this deep cold water across globe.
What is a gyre?
Major circular surface currents in indian, pacific and Atlantic oceans. Very low productivity in the centre.
Descibe Ekman spiral
net movement of water is at 90 degrees to direction of wind. each layer moves in a slightly different direction
What is ENSO?
El nino southern oscillation
Years of abnormal weather patterns
Increased SST with less/no upwelling
reduced primary productivity
What causes SST to rise?
High atmospheric pressure = less offshore winds = thermocline tilts less = no upwellings = higher SST
example of El nino in Peruvian fisheries
Coastal upwelling usually supports lucrative fisheries.
Run of low yieldsof anchoveta 1976 - 1985.
These years had abnormally high SST.
How do el nino years osscillate?
Oscillate between indian and pacific ocean. High pressure on one side = low pressure on other side
Which was a bad el nino year and what were the consequences?
1977-8
Devastation both sides
Fire, drought, tornadoes, famine, cyclones, hurricanes, heavy rainfall, mudslides, ice storms
King penguin pop threatened by southern ocean warming
Example of geo engineering
Iron fertilisation in HNLC areas eg Southern ocean. 2002
Early research shows stimulates growth of algae. change in species composition.
Disregard of whole ecosystem response.
Jellyfish bloom, Algae skeletons sink and cause widespread anoxia.
NOC investigated widespread long term effects. found increased growth of Pseudonitchsia, produce Domoic acid.
