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What
is Oceanography?
The scientific study of the
ocean and its inhabitants
Major
Subdisciplines
-
Marine
geology & geophysics
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Chemical
oceanography
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Physical
oceanography
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Biological
oceanography and marine biology
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Ocean
Engineering
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Marine
policy and laws
Marine
Biology, Marine Ecology and Biological Oceanography – only synonyms?
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Marine
Biology – biological discipline; focused on
the biology and physiology of marine organisms
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Marine
Ecology – ecological discipline; focused on
the interaction of organisms with their environment and mass or energy
cycles within ecosystem
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Biological
Oceanography – interdisciplinary ecological
discipline; focused on the ecology of the ocean, the interaction between
organisms and their environment and takes into account aspects of marine
chemistry, geology and physics
The
Earth – A Planet of Water
 |
Shouldn’t our planet be called “Water” rather
than “Earth”?
|
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~71%
of the earth’s surface are oceans
-
Maximum
depth: ca. 11,022 m (Trieste) (Land: Mt Everest 8,848 m)
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Average
depth: ca. 3800 m
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Total
volume: 1370 x 106 km3
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Presents
300 times space for life than land and freshwater combined.
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All known
phyla originated in the sea, and life on earth is believed to have begun
in the ancient oceans
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Only
2% of human food originates from the oceans but present 20% of high quality
protein nutrition
-
Still
recent NASA scientist said: “We now know more about the backside of the
moon than about the depths of our oceans.”
Marine
vs. Terrestrial Life
Marine
-
Organisms
– similar density as environment (salt water) less energy to float/swim…
small effect of gravity
-
Water
supports bodies, no need to put energy in skeletons
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Plenty
of water for life
-
Temperature
variation low
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Light
limited: reflection of light at sea surface and rapid light absorption
with water depth
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Nutrient
limited: nitrate, phosphate, silicate, iron
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Major
part of nutrient regener- ation in the dark deep-sea
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Physically
unstable habitats
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Terrestrial
-
Organisms
– much higher density than air
… than to walk or fly.
High gravity impact (fall down)
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Need strong
skeletal material (animals: bones; trees: trunks)
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May become
water limited
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Temperature
varies strongly
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Light
energy substantially higher than in aquatic systems, low absorption by
air
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High nutrient
concentrations in natural soils
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Nutrient
regeneration in soil close to plant uptake
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Physically
stable environment
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Comparison
of Oceans
Ocean |
Area
(106 km2) |
Volume
(106 km3) |
Mean
Depth (m) |
Maximum
Depth (m) |
Pacific |
181.3 |
714.4 |
3940 |
11022 |
Atlantic |
94.3 |
337.2 |
3575 |
8605 |
Indian |
74.1 |
284.6 |
3840 |
7450 |
Arctic |
12.3 |
13.7 |
1117 |
4600 |
Total/Mean |
362.0 |
1349.9 |
3800 |
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Distribution
of Land and Water

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The northern
hemisphere comprises substantially more land mass than the southern hemisphere.
-
The Arctic
Sea is land-locked
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The Antarctic
Sea spreads circumpolar around the Antarctic continent
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South
Pole: on land (Antarctica)
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North
Pole: in the ocean (Arctic Sea; ice-covered)
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