1. MAN AND OCEANS

2. Man has been associated with the oceans
Oceans are vast resources of biotic and abiotic nature.
Man started using marine resources when he developed the skill to make small boats.
The oceans essential for maintaining ecological balance and ecosystem stability of marine ecosystems.
History tell importance of ocean
oceans are the repository of world history and culture.

3. Man has affected marine ecosystems in a variety of ways.
The natural ecosystem, its stability is disturbed and environmental degradation
increasing economic activities of man in the coastal ecosystems.
Over exploitation of marine biological resources, mainly fishes.
increasing intensity of human presence in the oceans.
coral mining have degraded the marine environment.
The impacts of human activities on marine ecosystems and environment may be studied in two ways as follows:
Manipulation of coastal processes and marine environment
Marine pollution and environmental degradation of marine ecosystems.

4. 1. MANIPULATION OF COASTAL PROCESSES
Sea coastal processes -sea waves and tidal currents.
Erosional landforms - sea cliffs, rocky slopes, indented and crenulated coast lines, coves and caves.
Deposition- beaches and bars.
The direct modifications of coastal processes by man include the following :
Disruption of wave motion and weakening of energy of coast bound waves by injecting air bubble curtains.
Attempts to deflect or resist the effects of sea waves and currents by constructing sea walls, groyne (groins), breakwaters.
trapping or import of sediments to replenish beaches
Plantation of trees to stabilise beaches and coastal dunes.

5. Man's attempts to reduce or stop coastal erosion.
complex nature of mechanisms of coastal processes, both erosional and depositional.
man to manipulate and modify coastal processes for specific purposes
to halt erosion at harbours.
to build beaches
to replenish already depleted beaches
to open inlets
to encourage sea transport
bring in changes in near shore topography.

6. Protective Structures cliff erosion.
seawalls
breakers
Groins
seawalls
breakers
Groins

7. Sea Walls:
Protective structures in the form of concrete sea walls are built
Built due to- hinterlands are either urbanised or industrialised
significant resort centers.
sites of harbours
The construction of sea walls to stop the recession of cliffs at the sites of recreation produces adverse effects on beaches.
In such cases beaches are depleted because
the supply of sands and shingles from the cliff erosion is stopped due to protection provided by extended sea walls parallel to the coast.
waves after striking powerfully against the walls scour the beaches and remove the materials.

8. Types of Sea Walls Concrete Sea wall Wooden Sea wall Boulder Sea wall

9. B. Breakwaters
shelter the harbours and the estuaries of river mouths being used as harbour from strong wave action and drifting of sand and shingle into the harbours through the construction of breakwaters
which are extended from the coast towards the sea.

10. Generally, five types of breakwaters are used as follows:
parallel breakwaters
perpendicular breakwaters
slanting breakwaters
curved breakwaters
enclosing breakwaters.
curved breakwaters
perpendicular breakwaters
parallel breakwaters
enclosing

11. C. Groins
In order to stop beach depletion may be huge rock masses, or of concrete or of wooden logs, are placed at close intervals at right angles to the seawalls or shore lines to reduce the loss of sand and shingle.
Examples Bournemouth (south coast of England), north-eastern shores of Port Phillip Bay (Australia).

12. 2. MARINE POLLUTION

13. 1. Hydrocarbons (mainly oil)
Petroleum is a complex mixture of hydrocarbons, combinations of hydrogen and carbon with various amounts of nitrogen and metals.
Natural sources
seeps of oil from ocean floors.
emission of gas hydrates from fissures of ocean floors
emission of gas hydrates
seeps of oil from ocean floors

14. Natural sources submarine volcano atmosphere Bacteria rivers Bacteria

15. Anthropogenic sources transportation of oil tankers in the oceans
offshore oil drilling and production
oil refineries on coastal lands
aerosol
Oil spill
aerosol
oil refineries

17. 2) Heavy metals Anthropogenic sources industrial effluents
municipal effluents
industrial
municipal

18. Natural sources
submarine volcanic eruptions
river discharge into the oceans
weathering of continental rocks and their transport to the coastal waters by surface runoff
sediments.

19. 3) Nutrients Natural sources River discharge
upwelling of cold seawater
Atmosphere
bacterial decomposition

20. Anthropogenic sources
Municipal effluents
industrial effluents
washout of fertilizers from agricultural fields

21. 4) Synthetic chemicals Anthropogenic sources Industries Transportation
Municipal effluents
fertilizers and pesticides from agricultural fields

22. 3.MAN AND MARINE ECOSYSTEM
The man's presence in the oceans and his economic activities are capable to destabilise marine ecosystems.
Exploitation of marine resources, ocean dredging and mining, global warming.
increasing human activities have great potential for destabilizing, marine ecosystems.

23. 4. OCEAN DREDGING Why Ocean dredging
to clear the harbours from silting
to clear the navigable channels
to replenish the depleting sea beaches
to remove the contaminated deposits in the near shore regions having industrial and urban establishments
to remove the over dumping of materials in the near shore waters.

24. dredged materials are contaminated with urban and industrial sewage, metals such as lead, mercury, nickel, cadmium etc., chemical toxic substances etc.
The dumping of dredge spoils disturbs the marine organisms because they leave the dumping sites and move to other favourable places.
The materials having oils, metals, biocides and other types of wastes, accumulate these toxic substances marine organisms become injurious to large marine animals and humans when they eat them.
The ocean beds contain large deposits of some important minerals such as manganese nodules, phosphates, nitrates, gas hydrates, minerals oil etc.

25. 5. OVERFISHING
The coastal fishermen communities totally depend on fishing for their livelihood.
In Fishing use of modern trawlers has already done great damage to important fisheries.
commercially important fishes like cod, sardine, mackerel, salmon
fish catch exceeds the annual reproductive rate of fishes.

26. OVERFISHING AREA George Bank Alaskan King Crab Japanese mackerel
Californian sardine
Peruvian anchovy

27. The major elements of the 'precautionary principle' fishery management are as follows:
to control access to new fisheries immediately.
to establish conservation cap on both fishing capacity and total fishing catch rate.
to develop conservative catch limit and to set an upper limit of catch that cannot be exceeded.
to implement recovery plans without delay when there is decline in fish stock.
to reduce government subsidies and to develop economically viable fishery.
to establish data collection and reporting system.
to promote selective catching to minimize by catch.
to protect fish refuges.
to develop fishery management policies in cooperation with all the fish catching nations.

28. 6. GLOBAL WARMING AND OCEANS
rise in atmospheric, land surface and sea surfaces temperatures .
Due to ozone depletion and green house effects.
climate changes at local, regional and global levels.
reported by various scientists, agencies, and computer models.
Report of Intergovernmental Panel on Climate Change (IPCC).

29. Following are the evidences of global warming:
Increase in average annual global temperature.
Melting of mountain and continental glaciers.
Melting of Antarctic ice sheets.
Fast rate of melting of Greenland ice sheets.
Melting of Arctic sheet.
Warming of ocean water at global level.
Gradual rise in sea level.
Thawing of permafrost areas.
Upward shifting of snowlines of the tropical and subtropical mountains.
Spreading of tropical diseases towards temperate and polar regions.
Shifting of seasonal weather phenomena and changes in precipitation patterns etc.

30. General Impacts off Global Warming on Marine Ecology
increase in the concentration of atmospheric carbon dioxide.
Significant change in the atmosphere heat balance.
increase in the temperature of the lower atmosphere.
Increase in the activity of hydrological cycle.
Whole marine ecosystems affected.
increase in the acidity of the ocean
decrease in the biological productivity of the marine ecosystems
change in the albedo of the ocean surface.
Melting of continental and mountain glaciers- rise in sea level and flooding of coastal areas of lowland countries, and island nations.

31. Total atmospheric pressure may increase.
Occurrence of tropical cyclones
report of the WMO the northern hemisphere was hottest during 2005 A.D. recorded 27 of tropical cyclones.
May change existing world patterns of precipitation.
Increase in the frequency of extreme weather condition.
Increase in sea temperature has forced many shoreline species of barnacles, snails and limpets around Great Britain further north in search of cooler areas of coastal regions
Likely change of ocean biodiversity due to rise in sea temperature.

32. Thank You