This document provides an overview of oceanography. It discusses the beginnings of oceanography with the Challenger Expedition in the 1870s. It also covers key figures in the early development of oceanography like Matthew Fontaine Maury. The document then describes various topics in oceanography like the ecological subdivisions of the sea, pelagic and benthic environments, major topographic features, and the physico-chemical properties of seawater like light, temperature, salinity, pressure, sound, density, viscosity, and surface tension.

1. OCEANOGRAPHY
KASHMEERA N.A
III SEM MSc ZOOLOGY
ROLL NO : 37
CHRIST COLLEGE

2. Super science
which study the
biology,chemistry,
geology and
physics of the
ocean

3. The Beginnings of the Science of
Oceanography
• The beginning of oceanography is
typically dated to the “Challenger
Expedition” of 1872-1876.
• The Challenger went all the way
around the world, surveying the life,
sediments, water chemistry, winds,
currents, etc. of all the of the
world’s oceans (except the Arctic).
• Its work was funded by the British Navy.
they needed to dominate the seas to maintain and
protect their empire.

4. Matthew Fontaine Maury
• "Father of Oceanography”
• “Pathfinder of the Seas"
• "Scientist of the Seas,"
• Physical Geography of the Sea
(1855), the first extensive and
comprehensive book on
oceanography to be published
• Maury made many important
Matthew Fontaine Maury
new contributions to charting
winds and ocean currents

5. Oceanography: A “Young” Science
• Oceanography is still a quite young
science and many fundamental ocean
processes and systems await exploration.

7. Oceanography: An Interdisciplinary Science

8. Difference b/n sea & ocean
• There is a difference between the two terms when
speaking of geography
• Seas are smaller than oceans
• Seas are found on the margins of the ocean and are
partially enclosed by land.
• Eg : Bering Sea is part of the Pacific Ocean

10. Ecological subdivisions of sea
Major topographic features of continental
shelf,continental slope and ocean floor
Physico – chemical properties of sea water

11. ECOLOGICAL
SUBDIVISIONS OF THE
SEA

12. Ecological subdivisions of sea
PELAGIC BENTHIC
NERITIC PROVINCE
LITTORAL ZONE
OCEANIC PROVINCE
SUBLITTORAL ZONE
-Epipelagic zone
BATHYAL ZONE
Mesopelagic zone
ABYSSAL ZONE
Bathypelagic zone
HADAL ZONE
Abyssopelagic zone
Hadopelagic zone
EUPHOTIC ZONE
DISPHOTIC ZONE
APHOTIC ZONE

13. ECOLOGICAL SUBDIVISIONS
OF SEA
• 2 main divisions :
Pelagic / whole body of water
Benthic / bottom region.

14. ELA GIC
P
ENT
VIR ONM
EN

15. PELAGIC ENVIRONMENT
• Include entire ocean except sea floor.
• Pelagic organisms – live in open sea – not
closely associated with shore or sea floor.
• Further subdivided into zones on the basis of
water depth , light distribution etc.

16. Based on light distribution
• Euphotic zone –
well lighted water
upper layer of sea
photosynthetic plants seen
• Aphotic zone –
deeper dark water
water – cold
only light → produced by animals
• Disphotic zone –
b/n euphotic & aphotic
light not intense enough for effective production
of plants

17. Pelagic region – 2 provinces:
neritic
oceanic
• Neritic pelagic region
• Water over continental shelf
• Depth – 200m
• Most productive parts of oceans
• Depth of light penetration ↓

18. Oceanic pelagic region
• Water beyond continental shelf.
• Surface – trenches.
• Poorer in nutrients – production ↓.
• Tremendous pressure – still animals exist.

20. Epipelagic zone –
euphotic upper layer
animals – daily vertical migration.
migration
Mesopelagic zone –
200 – 1000 m
reduced light – twilight zone
(disphotic)
Bathypelagic zone –
1000 – 3000 m
isolated from surface water & benthic envt
(except at con. Slope)
food – migrating animals & descending
detritus.

21. Abyssopelagic zone & Hadopelagic zone
• Abyssopelagic zone –
3000 - 6000 m
• Hadopelagic zone –
deeper than 6000 m
• Animals associated with animals of deep sea
floor.
• Animals + detritus – food of deepsea animals.
• Constant cold & darkness.

22. T
EN
O NM
VIR
EN
IC
TH
B EN

23. BENTHIC ENVIRONMENT
• Sea floor
• Plants & animals – benthic organisms
• Require proper substrata – great variety
of niches.

24. • Rocky coast has more niches than sandy coast
– so diversity more in rocky coast
• Different species tolerate different ranges of -
temperature,salinity,[O2 ]

25. BENTHIC ENVIRONMENT –
SUBDIVISIONS
• LITTORAL ZONE
• SUBLITTORAL ZONE
• DEEPER BENTHIC ZONES
- bathyal
- abyssal
- hadal

26. LITTORAL ZONE
• Intertidal zone - area between tide marks
• the area that is above water at low tide and under water at high
tide
• Organisms – periodic wetting by waves & tides.
• 3 general ways of adaptation –
1. Some adapt to alternate periods of submersion & exposure to
air.
2. Some migrate with tide – fairly stable envt.
3. Some buried constantly in moist sand / tide pools

27. SUBLITTORAL ZONE
• Extends from low tide mark to the edge of
continental shelf.
• Well nourished → diverse flora & fauna.
• Organisms never exposed to drying
influence of atm. – so no adaptations.
adaptations

28. DEEPER BENTHIC ZONES
• Entire ocean floor deeper than
continental shelves.
• Lack sunlight & plant growth.
• Principal source of food - detritus &
migrating animals.

30. Bathyal zone
• Benthic envt. of con.slope.
• 200 – 2000 m in depth.
• Temperature < 10oC & nearly unchanging.
• Wide variety of animal life.

31. Abyssal zone
• Comprises abyssal plains & hills.
• Rep. more than 80% of seafloor.
• ↓ animal life.
• Dark; temperature < 4o C.

32. Hadal zone
•Long narrow oceanic trenches.
•Most extreme of oceanic habitat.
•Temperature : 1.2 – 3.6oC.
•Pressure >600 atm.
•Large predators absent.
•Dominant animals – slow moving
Mud-eaters - seacucumbers.

36. CONTINENTAL SHELF
• Shallow & flat portion of sea floor.
• Extend from shoreline to shelf break.
• Part of continents.
• Produced by – glaciation
sediment accumulation.

38. CONTINENTAL SLOPE
• Narrow band (~25km)
• Extend from shelf break to deep ocean
floor.
• Slope – 4o – highly variable.
• 60% mud – rest : sand,gravel,rocks &
organic remains.
• Origin – unknown – plate tectonics.
• Some times c.slope interrupted by c.rises.

39. CONTINENTAL SLOPE
• Currents & submarine land slides
– sediments transported across c.shelves &
slopes
– deposited into deep ocean
↓
continental rises

40. CONTINENTAL SLOPE
• ½ of c.slopes descend to deepsea
trenches or shallower depressions.
• Remainder terminate in fans of marine
sediment or continental rises

41. Deep sea fans exist where sediment is accumulated and
falls off of the continental slope.

42. OCEAN FLOOR

43. OCEAN FLOOR
Each area of the seabed has typical
features such as common soil
composition, typical topography, salinity
of water layers above it, marine life,
magnetic direction of rocks, and
sedimenting.

44. OCEAN FLOOR
• . Sedimenting comes from various sources:
• Land erosion sediments, brought mainly by
rivers,
• New "young rock" – New magma from the
mid-ocean ridge.
• Underwater volcanic ash spreading.
• Microorganism activity.
• Sea currents eroding the seabed itself.

45. Marine life: corals, fish, algae,
crabs, marine plants and other
biological created sediment.

46. PHYSICO – CHEMICAL
PROPERTIES OF SEA WATER
LIGHT
TEMPERATURE
SALINITY
PRESSURE
SOUND
DENSITY
VISCOSITY
SURFACE TENSION

47. LIGHT

48. LIGHT
• Velocity of light – air > water.
• Therefore when light enters sea it is refracted.
• As light travels it becomes progressively dimmer
– absorption & scattering.
• Light absorbed in sea → heat.
• ,, by living plant → chemical
energy for growth.

49. LIGHT
• Most light absorbed near surface, so
greatest warming occurs here.
• Warm water less dense than cold water →
stratification.
• Warm surface water over cold deeper
water.

50. Thermocline
• Between these
2 layers.
• Transition zone
• Rapid temperature change with depth.

51. Usually blue.
Blue light scattered most.
Estuaries – brownish.
Organisms detritus.
Coast lines – green.
Photosynthetic planktons & suspended
particles.

52. RATURE
TEM PE

53. TEMPERATURE
• Distribution of temperature in oceans
controls distribution of marine organisms.
• ↓ variation in surface temperature of sea
compared to land – ↑ specific heat
capacity.
• Stable envt. for marine life.

54. Low temperature
SEA SURFACE TEMPERATURE.
High temperature
Temperature ranges from -2oC to
30oC.
Low temperature
Distribution of temperature depend
on current patterns.
Temperature variation less in deep
water than in surface water.

55. Thermocline
• Thermocline (sharp temp.decline with
depth) may be present near surface during
summer & fall,
• Owing to seasonal variation in amount of
solar heat reaching the area.
• In addition a deep permanent thermocline
may be present in many regions.

56. INI TY
SAL

57. SALINITY
• Weight of dissolved salts in a mass of sea water expressed in
parts per thousand.
• Depends on evaporation,precipitation,fresh water input from
rivers & mixing by currents.
• Nearly all naturally occuring elements present in dissolved salt
compounds in sea water.
• Average salinity for all oceans – 35 parts per thousand.
• Variations in salinity fatal to marine life.

58. Halocline
• Salinity of sea water varies with depth
• Salinity ↑ - density ↑
High salinity water sinks.
Especially well developed haloclines occur
in the Atlantic Ocean, in which salinities
may decrease by several parts per thousand
from the base of the surface layer to depths
of about one kilometre.
In higher latitudinal areas of the North
Pacific in which solar heating of the surface
waters is low and rainfall is abundant,
salinities increase markedly with depth
through the halocline layer.

59. SURE
PRES

60. PRESSURE
• Pressure increase by
1 atm for each 10m depth.
• Life exist at all depth – pressure not a
problem – pressure inside = pressure
outside.
• However chemical reaction rates differ
under various pressures.

61. SOUND

62. SOUND
• Speed of sound waves increase with
increase in salinity,temperature or
pressure.
• Speed range in water – 1400 to 1550 m/s.

63. SOUND
• As temperature increases, speed of sound
increases at a rate of 3 m/s per degree celsius
increase.
• An increase in pressure causes a concurrent
rise in speed at a rate of 2 m/s for every 100
metres of depth.
• An increase in salinity causes an increase in
speed of 1.3 m/s for every increase in salinity
of one part per thousand.

64. SOUND

65. Reginald Fessenden
(1866-1932)
• Canadian inventor
• in 1914, developed a
type of sonar system for
locating icebergs http://en.wikipedia.org/wiki/Reginald_Fessenden
“Iceberg Detector”

66. Echo sounders sense the contour of the seafloor by
beaming sound waves to the bottom and measuring the
time required for the sound waves to bounce back to the
ship.
“Echo Depth Sounder”

67. DENSITY

68. DENSITY
• Function of temperature,salinity and
pressure.
• Density increase with decreasing
temperature and increasing salinity and
pressure.
• Uniform increase in density with depth
has little effect on organisms.
• In pycnocline areas striking phenomenas
occur.

69. VISCOSITY

70. VISCOSITY
• Resistance of a liquid to flow.
• Decrease with increasing temperature.
• Tropical water less viscous than polar water
– less resistance to sinking of tropical plankton
– tropical sps. of minute organisms have longer
spines & hairs.
• Salinity slightly increases viscosity.

72. SURFACE TENSION
• Tendency of the liquid surface to resist
penetration.
• Decrease with increasing temperature.
• Increase with increasing salinity.
• Important in supporting weight of organisms
resting on water surface – Halobates.
• Changes has no great effect on organisms.