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    What is Oceanography?
    The scientific study of the ocean and its inhabitants
Major Subdisciplines
  • Marine geology & geophysics
  • Chemical oceanography
  • Physical oceanography
  • Biological oceanography and marine biology
  • Ocean Engineering
  • Marine policy and laws
Marine Biology, Marine Ecology and Biological Oceanography – only synonyms?
  • Marine Biology – biological discipline; focused on the biology and physiology of marine organisms
  • Marine Ecology – ecological discipline; focused on the interaction of organisms with their environment and mass or energy cycles within ecosystem
  • 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”?
  • ~71% of the earth’s surface are oceans
  • Maximum depth: ca. 11,022 m (Trieste) (Land: Mt Everest 8,848 m)
  • Average depth: ca. 3800 m
  • Total volume: 1370 x 106 km3
  • Presents 300 times space for life than land and freshwater combined. 
  • All known phyla originated in the sea, and life on earth is believed to have begun in the ancient oceans
  • 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
  • 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
  • Plenty of water for life 
  • Temperature variation low
  • Light limited: reflection of light at sea surface and rapid light absorption with water depth
  • Nutrient limited: nitrate, phosphate, silicate, iron
  • Major part of nutrient regener- ation in the dark deep-sea
  • Physically unstable habitats
  • Organisms – much higher density than air
    … than to walk or fly.
    High gravity impact (fall down)
  • Need strong skeletal material (animals: bones; trees: trunks)
  • May become water limited
  • Temperature varies strongly
  • Light energy substantially higher than in aquatic systems, low absorption by air
  • High nutrient concentrations in natural soils
  • Nutrient regeneration in soil close to plant uptake
  • Physically stable environment

Comparison of Oceans

Ocean Area
(106 km2)
(106 km3)
Depth (m)
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

Distribution of Land and Water

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