intro and oceanography Flashcards
3 main pillars of marine biology
- functional biology
- ecology
- biodiversity
functional biology
how organism carries out basic functions (eg. reproduction)
ecology
how organisms interact with their env
biodiversity
variety of species
what 4 factors determine the density of seawater?
- TEMP
- SALINITY
- depth
- pressure
hypsographic curve
comparing land and oceans
ring of fire
string of volcanoes
-> seismic activity and earthquakes all caused by PLATE TECTONICS
pacific plate
- huge
- its fringes interact with smaller plates around it -> causing activity
Mariana Trench
in NW pacific - deepest trench in world
CONVERGENT boundary -> pacific plate faster than philippine plate
isostasy
rising / settling of bit of Earth’s lithosphere
-> where gravity & buoyancy act on earth’s outer layers to bring them closer together
bathymetry
mapping ocean floor
-> measurement of ocean depths & charting of shape of ocean floor
3 regions of ocean floor
continental shelf - shallow
mid-atlantic ridge
abyssal region - v v deep
describe how and who created the first bathymetric contour map of the world’s oceans
HMS challenger in 1872 for 4 yrs
-> covered 127,600km
-> 1st voyage to record scale of Mariana Trench
-> 4,700 new species of marine life discovered
-> collected DEPTH MEASUREMENTS and “SOUNDED” THE SEA FLOOR using variety of sounding devices
ocean ridges
occupy 33% of oceanic floor and always spreading
4 principal oceans (plus 1)
- pacific
- atlantic
- indian
- arctic
- (southern)
abyssal plains
- gradients < 0.05°
- flattest ocean feature -> only interrupted by seamounts
- covered in deep layers of sediment
sea mounts
-> most are ocean-floor volcanoes that don’t rise above sea level
-> rise abruptly and usually found rising from seafloor to 1,000–4,000 m in height
eg. Mauno Loa sea mount -> as high as mount Everest
guyots
flat topped seamounts -> planed off by wave erosion
hydrological cycle
cycle of water through atm, water and earth
residency time of water in atm (clouds)?
6.9 days
residency time of water in ocean
3060 yrs
how long does water spend in lakes
6.6 yrs
residency time of water in earth / underground?
600 yrs
how is cod shape useful to function?
v hydrodynamic
so used in ship design
how are aquatic animals adapted to sea water
saltwater (in sea) has HIGHER VISCOSITY than fresh water
-> so has driven morphological evolution in all marine life so they are adapted to it
-> speed in sea water requires morphology that …
↑ laminar flow through a fairly viscous and dense liquid
**THE CORIOLOS EFFECT
- earth’s rotation causes deflection in surface current direction (Coriolis effect)…
- which affects water flow on many geographic scales.
gyres
large system of rotating ocean currents
how are oceans split into zones?
zones defined by depth & proximity to continents
lithosphere
earths crust
oceanic crust vs continental crust
oceanic crust much thinner
divergent plate boundary
- drifting away from each other
- constructive -> oceanic lithosphere created from magma below
- volcanoes
transform plate boundary
- lateral sliding (rubbing in opp directions against each other)
- conservative -> oceanic lithosphere neither created nor destroyed
- NO VOLCANOES
convergent plate boundary
- subduction -> one plate moves under other -> MAKES TRENCH
- destructive -> oceanic lithosphere destroyed
- volcanoes
mid-atlantic ridge
divergent plate boundary
why are zones in ocean useful?
easier to consider distributions of life in those oceans
why do marine biologists study oceanography?
use satellites to generate chlorophyll map to analyze phytoplankton distribution
- e.g. MODIS
zones of ocean temp
- surface zone / mixed layer
- thermocline -> rapid ↓ in temp as surface heat diffuses down and advection of cool water
- deep zone (below 1000m) -> stable temp ~1℃
mixed layer
layer where there is active turbulence and mixing of oceanic waters …
due to …
- winds
- heat fluxes
- evaporation
- salinity fluxes
thermocline
transition layer between warmer mixed water at surface & cooler deep water below
halocline
- vertical zone in the oceanic water column…
- where SALINITY CHANGES RAPIDLY with depth
- located below well-mixed, uniformly saline surface water layer
pycnocline
boundary separating 2 liquid layers of diff densities
stratification
- when 2 distinct layers occupy vertical water column in sea…
- near-surface one = less dense than near-bed one
salinity
measure of dissolved salts in water
how is temp and salinity measured in ocean?
- CTD -> used to detect how conductivity and temp of water changes relative to depth
-> conductivity is measure of how well sol conducts electricity and is directly related to SALINITY
for salinity:
- niskin bottle water samples
- electronic meter (measure conductivity)
ocean currents can be driven by 2 diff things….
- wind driven -> generally surface currents
- density driven
Global Overturning Circulation
- influences climate by transporting heat north in Atlantic by supplying warm water at Antarctic margin…
- … & by controlling **exchange of carbon and nutrients **between deep ocean & euphotic zone where p/s occurs
littoral zone
part of ocean close to shore
why does temp vary with ocean depth?
- water gets colder with depth …
- … cause cold, salty ocean water sinks to bottom of ocean basins below less dense warmer water near surface
constraints on biological production in ocean?
- light
- nutrients
suggest why tropical oceans are highly stratified
surface layers separated from deep & quickly become nutrient depleted
how is conductivity related to salinity?
salinity = dissolved ions present (Na+ and Cl-)
presence of ions = conductivity as ions are mobile
