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![• Rocky coast has more niches than sandy coast
– so diversity more in rocky coast
• Different species tolerate different ranges of -
temperature,salinity,[O2 ]](https://image.slidesharecdn.com/edtd-oceanography-kashmeeran-a-130111080331-phpapp01/85/Oceanography-I-Kashmeera-N-A-24-320.jpg)
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Oceanography I - Kashmeera N.A.
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.
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Oceanography I - Kashmeera N.A.
- 1. OCEANOGRAPHY KASHMEERA N.A III SEM MSc ZOOLOGY ROLL NO : 37 CHRIST COLLEGE
- 2. Super science which studythe biology,chemistry, geology and physics of the ocean
- 3. The Beginnings ofthe 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.
- 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 ofsea Major topographic features of continental shelf,continental slope and ocean floor Physico – chemical properties of sea water
- 11.
- 12. Ecological subdivisions ofsea 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 • Includeentire 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 lightdistribution • 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 • Seafloor • Plants & animals – benthic organisms • Require proper substrata – great variety of niches.
- 24. • Rocky coasthas 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 • Intertidalzone - 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 • Extendsfrom 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 narrowoceanic 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 • Narrowband (~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 • ½of c.slopes descend to deepsea trenches or shallower depressions. • Remainder terminate in fans of marine sediment or continental rises
- 41. Deep sea fansexist where sediment is accumulated and falls off of the continental slope.
- 42.
- 43. OCEAN FLOOR Each areaof 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 PROPERTIESOF SEA WATER LIGHT TEMPERATURE SALINITY PRESSURE SOUND DENSITY VISCOSITY SURFACE TENSION
- 47.
- 48. LIGHT • Velocity oflight – 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 lightabsorbed 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.
- 53. TEMPERATURE • Distribution oftemperature 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 (sharptemp.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.
- 57. SALINITY • Weight ofdissolved 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.
- 60. PRESSURE • Pressure increaseby 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.
- 62. SOUND • Speed ofsound waves increase with increase in salinity,temperature or pressure. • Speed range in water – 1400 to 1550 m/s.
- 63. SOUND • As temperatureincreases, 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.
- 65. Reginald Fessenden (1866-1932) • Canadianinventor • in 1914, developed a type of sonar system for locating icebergs http://en.wikipedia.org/wiki/Reginald_Fessenden “Iceberg Detector”
- 66. Echo sounders sensethe 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.
- 68. DENSITY • Function oftemperature,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.
- 70. VISCOSITY • Resistance ofa 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 • Tendencyof 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.