OCEANOGRAPHYOCEANOGRAPHYOCEANOGRAPHYOCEANOGRAPHY

KASHMEERA N.A

III SEM MSc ZOOLOGY

ROLL NO : 37

CHRIST COLLEGE

KASHMEERA N.A

III SEM MSc ZOOLOGY

ROLL NO : 37

CHRIST COLLEGE

Super science Super science which study the which study the biology,chemistry,biology,chemistry,geology and geology and physics of the physics of the oceanocean

The Beginnings of the Science of The Beginnings of the Science of OceanographyOceanography

• The beginning of oceanography is The beginning of oceanography is typically dated to the “Challenger typically dated to the “Challenger Expedition” of 1872-1876.Expedition” of 1872-1876.

• The Challenger went all the way The Challenger went all the way around the world, surveying the life, around the world, surveying the life, sediments, water chemistry, winds, sediments, water chemistry, winds, currents, etc. of all the of the currents, etc. of all the of the world’s oceans (except the Arctic). world’s oceans (except the Arctic).

• Its work was funded by the British Navy.Its work was funded by the British Navy.they needed to dominate the seas to maintain and they needed to dominate the seas to maintain and protect their empire.protect their empire.

Matthew Fontaine MauryMatthew Fontaine Maury

• "Father of Oceanography”"Father of Oceanography”

• “ “Pathfinder of the Seas" Pathfinder of the Seas"

• "Scientist of the Seas," "Scientist of the Seas,"

• Physical Geography of the SeaPhysical Geography of the Sea (1855), the first extensive and (1855), the first extensive and comprehensive book on comprehensive book on oceanography to be published oceanography to be published

• Maury made many important Maury made many important new contributions to charting new contributions to charting winds and ocean currentswinds and ocean currents

Matthew Fontaine Maury

Oceanography: A “Young” ScienceOceanography: A “Young” Science

• Oceanography is still a quite young science and many fundamental ocean processes and systems await exploration.

Oceanography: An Interdisciplinary ScienceOceanography: An Interdisciplinary Science

Difference b/n sea & oceanDifference b/n sea & ocean• There is a difference between the two terms when There is a difference between the two terms when

speaking of geography speaking of geography

• Seas are smaller than oceans Seas are smaller than oceans

•   Seas are found on the margins of the ocean and are Seas are found on the margins of the ocean and are partially enclosed by land. partially enclosed by land.

• Eg : Bering Sea is part of the Pacific Ocean Eg : Bering Sea is part of the Pacific Ocean

Ecological subdivisions of seaEcological subdivisions of sea

Major topographic features of continental Major topographic features of continental shelf,continental slope and ocean floorshelf,continental slope and ocean floor

Physico – chemical properties of sea waterPhysico – chemical properties of sea water

ECOLOGICAL ECOLOGICAL SUBDIVISIONS OF THE SUBDIVISIONS OF THE

SEASEA

Ecological subdivisions of seaEcological subdivisions of sea

PELAGIC BENTHIC

NERITIC PROVINCE

OCEANIC PROVINCE

-Epipelagic zone

Mesopelagic zone

Bathypelagic zone

Abyssopelagic zone

Hadopelagic zone

LITTORAL ZONE

SUBLITTORAL ZONE

BATHYAL ZONE

ABYSSAL ZONE

HADAL ZONE

EUPHOTIC ZONE

DISPHOTIC ZONE

APHOTIC ZONE

ECOLOGICAL SUBDIVISIONS ECOLOGICAL SUBDIVISIONS OF SEAOF SEA

• 2 main divisions :

Pelagic / whole body of water

Benthic / bottom region.

PELAGIC PELAGIC

ENVIRONMENT

ENVIRONMENT

PELAGIC ENVIRONMENTPELAGIC ENVIRONMENT

• Include entire ocean except sea floor.Include entire ocean except sea floor.

• Pelagic organisms – live in open sea – not Pelagic organisms – live in open sea – not closely associated with shore or sea floor.closely associated with shore or sea floor.

• Further subdivided into zones on the basis of Further subdivided into zones on the basis of water depth , light distribution etc.water depth , light distribution etc.

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

of plantsof plants

Pelagic region – 2 provinces: Pelagic region – 2 provinces: neriticneritic

oceanic oceanic

• Neritic pelagic regionNeritic pelagic region

• Water over continental shelf

• Depth – 200m

• Most productive parts of oceans

• Depth of light penetration ↓

Oceanic pelagic regionOceanic pelagic region

• Water beyond continental shelf.

• Surface – trenches.

• Poorer in nutrients – production ↓.

• Tremendous pressure – still animals exist.

Epipelagic zoneEpipelagic zone –

euphotic upper layereuphotic upper layer

animals – daily vertical migrationanimals – daily vertical migration.

Mesopelagic zoneMesopelagic zone –

200 – 1000 m200 – 1000 m

reduced light – twilight zone reduced light – twilight zone

(disphotic)(disphotic)

Bathypelagic zoneBathypelagic zone –

1000 – 3000 m1000 – 3000 m

isolated from surface water & benthic envt isolated from surface water & benthic envt

(except at con. Slope)(except at con. Slope)

food – migrating animals & descending food – migrating animals & descending detritus.detritus.

Abyssopelagic zone & Hadopelagic zoneAbyssopelagic zone & Hadopelagic zone

• Abyssopelagic zone –Abyssopelagic zone – 3000 - 6000 m3000 - 6000 m• Hadopelagic zone –Hadopelagic zone – deeper than 6000 mdeeper than 6000 m

• Animals associated with animals of deep sea floor.

• Animals + detritus – food of deepsea animals.• Constant cold & darkness.

BENTHIC ENVIRONMENT

BENTHIC ENVIRONMENT

BENTHIC ENVIRONMENTBENTHIC ENVIRONMENT

• Sea floorSea floor

• Plants & animals – benthic organismsPlants & animals – benthic organisms

• Require proper substrata – great variety Require proper substrata – great variety of niches.of niches.

• Rocky coast has more niches than sandy coast Rocky coast has more niches than sandy coast – so diversity more in rocky coast– so diversity more in rocky coast

• Different species tolerate different ranges of - Different species tolerate different ranges of - temperature,salinity,[Otemperature,salinity,[O2 2 ]]

BENTHIC ENVIRONMENT – BENTHIC ENVIRONMENT – SUBDIVISIONSSUBDIVISIONS

• LITTORAL ZONE LITTORAL ZONE

• SUBLITTORAL ZONESUBLITTORAL ZONE

• DEEPER BENTHIC ZONESDEEPER BENTHIC ZONES

- bathyal- bathyal

- abyssal- abyssal

- hadal- hadal

LITTORAL ZONELITTORAL ZONE

• Intertidal zone - area between tide marksIntertidal zone - area between tide marks

• the area that is above water at low tide and under water at high the area that is above water at low tide and under water at high tidetide

• Organisms – periodic wetting by waves & tides.Organisms – periodic wetting by waves & tides.

• 3 general ways of adaptation –3 general ways of adaptation –

1. Some adapt to alternate periods of submersion & exposure to 1. Some adapt to alternate periods of submersion & exposure to air.air.

2. Some migrate with tide – fairly stable envt.2. Some migrate with tide – fairly stable envt. 3. Some buried constantly in moist sand / tide pools3. Some buried constantly in moist sand / tide pools

SUBLITTORAL ZONESUBLITTORAL ZONE

• Extends from low tide mark to the edge of Extends from low tide mark to the edge of continental shelf.continental shelf.

• Well nourished Well nourished → diverse flora & fauna.→ diverse flora & fauna.

• Organisms never exposed to drying Organisms never exposed to drying influence of atm. – so no adaptationsinfluence of atm. – so no adaptations.

DEEPER BENTHIC ZONESDEEPER BENTHIC ZONES

• Entire ocean floor deeper than Entire ocean floor deeper than continental shelves.continental shelves.

• Lack sunlight & plant growth.Lack sunlight & plant growth.

• Principal source of food - detritus & Principal source of food - detritus & migrating animals.migrating animals.

Bathyal zoneBathyal zone• Benthic envt. of con.slope.Benthic envt. of con.slope.

• 200 – 2000 m in depth.200 – 2000 m in depth.

• Temperature Temperature < 10< 10ooC & nearly unchanging.C & nearly unchanging.

• Wide variety of animal life.Wide variety of animal life.

Abyssal zoneAbyssal zone

• Comprises abyssal plains & hills.Comprises abyssal plains & hills.

• Rep. more than 80% of seafloor.Rep. more than 80% of seafloor.

• ↓ ↓ animal life.animal life.

• Dark; temperature < 4Dark; temperature < 4o o C.C.

Hadal zoneHadal zone• Long narrow oceanic trenches.Long narrow oceanic trenches.

• Most extreme of oceanic habitat.Most extreme of oceanic habitat.

• Temperature : 1.2 – 3.6Temperature : 1.2 – 3.6ooC.C.

• Pressure Pressure >600 atm.>600 atm.

• Large predators absent.Large predators absent.

• Dominant animals – slow moving Dominant animals – slow moving

Mud-eaters - seacucumbers.Mud-eaters - seacucumbers.

CONTINENTAL SHELFCONTINENTAL SHELF

• Shallow & flat portion of sea floor.

• Extend from shoreline to shelf break.

• Part of continents.

• Produced by – glaciation

sediment accumulation.

CONTINENTAL SLOPECONTINENTAL 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.

CONTINENTAL SLOPECONTINENTAL SLOPE

• Currents & submarine land slides

– sediments transported across c.shelves & slopes

– deposited into deep ocean

↓

continental rises

CONTINENTAL SLOPECONTINENTAL SLOPE• ½ of c.slopes descend to deepsea

trenches or shallower depressions.

• Remainder terminate in fans of marine sediment or continental rises

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

OCEAN FLOOROCEAN FLOOR

OCEAN FLOOROCEAN FLOOR

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

OCEAN FLOOROCEAN FLOOR

• . . Sedimenting comes from various sources:Sedimenting comes from various sources:

• Land erosion sediments, brought mainly by Land erosion sediments, brought mainly by rivers,rivers,

• New "young rock" – New magma from the New "young rock" – New magma from the mid-ocean ridge.mid-ocean ridge.

• Underwater volcanic ash spreading. Underwater volcanic ash spreading. • Microorganism activity.Microorganism activity.• Sea currents eroding the seabed itself.Sea currents eroding the seabed itself.

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

PHYSICO – CHEMICAL PHYSICO – CHEMICAL PROPERTIES OF SEA WATERPROPERTIES OF SEA WATER

PHYSICO – CHEMICAL PHYSICO – CHEMICAL PROPERTIES OF SEA WATERPROPERTIES OF SEA WATER

LIGHTLIGHT

TEMPERATURETEMPERATURE

SALINITYSALINITY

PRESSUREPRESSURE

SOUNDSOUND

DENSITYDENSITY

VISCOSITYVISCOSITY

SURFACE TENSIONSURFACE TENSION

LIGHTLIGHT

LIGHTLIGHT• Velocity of light – air Velocity of light – air > water.> water.

• Therefore when light enters sea it is refracted.Therefore when light enters sea it is refracted.

• As light travels it becomes progressively dimmer As light travels it becomes progressively dimmer – absorption & scattering.– absorption & scattering.

• Light absorbed in sea → heat.Light absorbed in sea → heat.

• ,, by living plant → chemical ,, by living plant → chemical energy for growth.energy for growth.

LIGHTLIGHT

• Most light absorbed near surface, so Most light absorbed near surface, so greatest warming occurs here.greatest warming occurs here.

• Warm water less dense than cold water Warm water less dense than cold water → → stratification.stratification.

• Warm surface water over cold deeper Warm surface water over cold deeper water.water.

Thermocline Thermocline

• Between these Between these 2 layers.2 layers.

• Transition zoneTransition zone

• Rapid temperature change with depth.Rapid temperature change with depth.

Usually blue.Usually blue.

Blue light scattered most.Blue light scattered most.

Estuaries – brownish.Estuaries – brownish.

Organisms detritus.Organisms detritus.

Coast lines – green.Coast lines – green.

Photosynthetic planktons & suspended Photosynthetic planktons & suspended particles.particles.

TEMPERATURETEMPERATURE

TEMPERATURETEMPERATURE

• Distribution of temperature in oceans Distribution of temperature in oceans controls distribution of marine organisms.controls distribution of marine organisms.

• ↓ ↓ variation in surface temperature of sea variation in surface temperature of sea compared to land – ↑ specific heat capacity.compared to land – ↑ specific heat capacity.

• Stable envt. for marine life.Stable envt. for marine life.

Low temperature

Low temperature

High temperature

SEA SURFACE TEMPERATURE.

Temperature ranges from -2oC to 30oC.

Distribution of temperature depend on current patterns.

Temperature variation less in deep water than in surface water.

ThermoclineThermocline

• Thermocline (sharp temp.decline with Thermocline (sharp temp.decline with depth) may be present near surface during depth) may be present near surface during summer & fall,summer & fall,

• Owing to seasonal variation in amount of Owing to seasonal variation in amount of solar heat reaching the area.solar heat reaching the area.

• In addition a deep permanent thermocline In addition a deep permanent thermocline may be present in many regions.may be present in many regions.

SALINITYSALINITY

SALINITYSALINITY• Weight of dissolved salts in a mass of sea water expressed in Weight of dissolved salts in a mass of sea water expressed in

parts per thousand.parts per thousand.

• Depends on evaporation,precipitation,fresh water input from Depends on evaporation,precipitation,fresh water input from rivers & mixing by currents.rivers & mixing by currents.

• Nearly all naturally occuring elements present in dissolved salt Nearly all naturally occuring elements present in dissolved salt compounds in sea water.compounds in sea water.

• Average salinity for all oceans – 35 parts per thousand.Average salinity for all oceans – 35 parts per thousand.

• Variations in salinity fatal to marine life.Variations in salinity fatal to marine life.

HaloclineHalocline• Salinity of sea water varies with depth Salinity of sea water varies with depth

• Salinity Salinity ↑ - ↑ - density density ↑↑

High salinity water sinks.High salinity water sinks.Especially well developed haloclines occur Especially well developed haloclines occur in the Atlantic Ocean, in which salinities in the Atlantic Ocean, in which salinities may decrease by several parts per thousand may decrease by several parts per thousand from the base of the surface layer to depths from the base of the surface layer to depths of about one kilometre. of about one kilometre.

In higher latitudinal areas of the North In higher latitudinal areas of the North Pacific in which solar heating of the surface Pacific in which solar heating of the surface waters is low and rainfall is abundant, waters is low and rainfall is abundant, salinities increase markedly with depth salinities increase markedly with depth through the halocline layer.through the halocline layer.

PRESSPRESSUREURE

PRESSUREPRESSURE

• Pressure increase by1 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.

SOUNDSOUND

SOUNDSOUND

• Speed of sound waves increase with Speed of sound waves increase with increase in salinity,temperature or increase in salinity,temperature or pressure.pressure.

• Speed range in water – 1400 to 1550 m/s.Speed range in water – 1400 to 1550 m/s.

SOUNDSOUND• As temperature increases, speed of sound As temperature increases, speed of sound

increases at a rate of 3 m/s per degree celsius increases at a rate of 3 m/s per degree celsius increase.increase.

• An increase in pressure causes a concurrent An increase in pressure causes a concurrent rise in speed at a rate of 2 m/s for every 100 rise in speed at a rate of 2 m/s for every 100 metres of depth.metres of depth.

• An increase in salinity causes an increase in An increase in salinity causes an increase in speed of 1.3 m/s for every increase in salinity speed of 1.3 m/s for every increase in salinity of one part per thousand.of one part per thousand.

SOUNDSOUND

http://en.wikipedia.org/wiki/http://en.wikipedia.org/wiki/Reginald_FessendenReginald_Fessenden

Reginald Fessenden Reginald Fessenden (1866-1932)(1866-1932)• Canadian inventorCanadian inventor

• in 1914, developed a in 1914, developed a type of sonar system for type of sonar system for locating icebergslocating icebergs

““Iceberg Detector”Iceberg Detector”

““Echo Depth Sounder”Echo Depth Sounder”

Echo sounders sense the contour of the seafloor by Echo sounders sense the contour of the seafloor by

beaming sound waves to the bottom and measuring the beaming sound waves to the bottom and measuring the

time required for the sound waves to bounce back to the time required for the sound waves to bounce back to the

ship.ship.

DENSITYDENSITY

DENSITYDENSITY• Function of temperature,salinity and Function of temperature,salinity and

pressure.pressure.

• Density increase with decreasing Density increase with decreasing temperature and increasing salinity and temperature and increasing salinity and pressure.pressure.

• Uniform increase in density with depth Uniform increase in density with depth has little effect on organisms.has little effect on organisms.

• In pycnocline areas striking phenomenas In pycnocline areas striking phenomenas occur.occur.

VISCOSITYVISCOSITY

VISCOSITYVISCOSITY

• Resistance of a liquid to flow.Resistance of a liquid to flow.

• Decrease with increasing temperature.Decrease with increasing temperature.

• Tropical water less viscous than polar waterTropical water less viscous than polar water

– – less resistance to sinking of tropical plankton less resistance to sinking of tropical plankton

– – tropical sps. of minute organisms have longer tropical sps. of minute organisms have longer spines & hairs.spines & hairs.

• Salinity slightly increases viscosity.Salinity slightly increases viscosity.

SURFACE TENSIONSURFACE TENSION

• Tendency of the liquid surface to resist Tendency of the liquid surface to resist penetration.penetration.

• Decrease with increasing temperature.Decrease with increasing temperature.

• Increase with increasing salinity.Increase with increasing salinity.

• Important in supporting weight of organisms Important in supporting weight of organisms resting on water surface – Halobates.resting on water surface – Halobates.

• Changes has no great effect on organisms.Changes has no great effect on organisms.