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Chapter 1

BIOL3450 Chapter 1: CH.1 Notes.docx

Course Code
BIOL 3450
Beren Robinson

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BIOL*3450 CH.1 notes
Hydrological cycle
1.4x10^9 km^3 of water
Water is very dynamic, with all of its aquatic features connected in an active hydro state-
generated by processes which lead to the evaporation of surface water, transport by atmospheric
circulation and subsequent precip
Water moves between its various components as evaporation and precip and within its
Habitats are unevenly distributed, can be seen in the ocean where it is really single body of
Habitat diversity inland is higher due to the fragmented nature of the habitat
Most non-marine aquatic lives live in rivers, lakes and wetlands, few specialists live in ice on
the surface and groundwater where there is very little diversity and biomass
Largest body of water
The pelagic zone is the largest part (water column)- diff parts of the pelagic zone interact
through ocean circulation
Surface ocean circulation
Generated by wind friction resulting in global patters of currents resembling atmospheric
Coriolis force effects movement, with the layer moving at 45 degrees to the wind direction
Net motion of the wind influenced layer is 90 degree to the wind direction ( Ekman Layer)
Land masses interfere with H20 movement, which tend to pile up against downward coasts,
creating a slope in the sea surface ie North Atl. Slopes up from America to Eur and North Africa,
so a true horizontal surface across it will have more water above it and therefore creates more
water pressure on the Euro side than the Atlantic
H20 tries to equalize pressure by going from high to low pressures, generating a horizontal
pressure gradient force and which are deflected by the Coriolis force (90 degree to the right in N.
hemi and left in the S. hemi)
Geostrophic currents- currents driven by pressure gradients
Deep ocean circulation
Initiated by water cooling at high latitudes, which then sinks(downwelling)
In most of the world ocean water mass in contact with the abyssal sea floor in the antartic
bottom water (AABW) which downwells in the ross and weddell seas of Antartica
Northern North Atlantic this is replaced by the North Atlantic Deep Water composed of the
Norwegian sea deep water and arctic intermediate water
Continual sinking drives a slow circulation throughout the deep ocean
510,250,275 years spent below 1500m in the Pacific, Indian and Atlantic oceans
Water resurfaces from deep water
Happens where surface area water circulation diverges, leaving a gap filled from beneath
and where s.w is forced from edge of continents, in the absence of an extensive continental shelf
Produced by cyclonic and anticyclonic winds, creating local upwellings and downwellings
Coriolis strength increases at high latitudes
Winds at low pressure systems are known as cyclonic and rotate anticlockwise in the N.
hemi, clockwise in the S. hemi

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High pressure systems are known as anticyclonic, winds rotating clockwise in the N hemi
and counter-clockwise in the S hemi
An anticyclonic wind forces water into the centre of the gyre, creating a certain area of
downwelling , where a cyclonic wind pushes surface water out the gyre generating an upwelling
The ocean bed
Benthic zone, small component of the marine environment but highly diverse
The coastal zone
Where the sea meeting the land, diversity is determined by typography of land
Highest diversity of marine habitats including intertidal, corals, estuaries and coastal
The continental shelf and slope
the edge of continents , shallow seas associated with the continental plates
when the continent and adjacent ocean are of the same plate, the shelf may be very wide
extending km out to sea
some places it is very narrow like the Pacific ocean and deep water is a few km off shore
zone of deposition for terrigenous sediments produced by weathering continental crust and
therefore originating from coastal erosion or input from rivers
boulders, pebbles,sand or muds create slopes can form 10k thick or more deposits
what accumulates on the upper continental slope is unstable and will likely move down the
slope, debris that moves down contribute to the formation of the continental rise ( the region of
increased angle of slope at the base of the continental slope
slides can on slopes as little as 2 degrees due to eathquakes or rapid accumulation of
sediment, there is little deformation of the original mass
debris flows occur in the same way but are sluggish due to sediment mixture down slopes of
0.1 degrees-obliterates the original layer of the deposit
turbidity currents are triggered by the same mechanism as slides and flows but travel up 90
km/h-1 and transpot 3 kgm-3 of sediment in suspension, move material up to a 1000 km- likely
create canyons and the deposition of sand layers in the abyssal plain
Ocean ridges
33% of ocean floor, site of new sea floor production
Magma is released from, the ridge as the plates separate, so sea floor spread is symmetrical
and perpendicular to ridge
Mid Atlantic is slow spreading ridge, east pacific is quick
Deep sea floor
Btwn mid ocean ridges and the continental margins lies the abyssal plain
Less than 0.05 degree slope and 42% of earths surface
Covered by pelagic sediments which are biological in origin
Formerly called oozes, aggregate slowly dominate only when terrigenous inputs are low
There are rapid rising abyssal hills ( <1km) and sea mounts (>1 km)
Hills most common near ridge systems where there has been little time for pelagic sediment
to build up
Sea mounts come from subsea volcanoes eventually forming islands
Guyots are sea mounts which flat top created by wave erosion
Deep trenches form when oceanic plate is being subsumed beneath a continental plate and
occur close to land
Inland waters
Ice at high latitudes
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