Impact of human activities on global marine environment


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The oceans are enormous in their size, volume and depth.
Animal life in the sea is very varied and more diversified in terms shape, size, form and weight-right from microscopic plankton to the giant whale.
Marine pollution is the introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries), resulting in such deleterious effects as; harm to living resources: hazards to human health

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Impact of human activities on global marine environment

  1. 1. Impact of human activities on global marine environment Presented by Dr. B. Victor., Ph.D., email : blog :
  2. 2. Presentation out line Oceans and seas are largest ecological system. The oceans of the world - Importance and functions Global marine environmental changes Marine Biodiversity-components Global and Indian coastal lines Global marine pollution – Definition and negative impacts Direct and indirect effects of human activities Natural and cultural Eutrophication Marine pollutants and effects Conservation of global marine habitats Critical marine habitats
  3. 3. Oceans and seas arelargest ecological system
  4. 4. The oceans of the world The oceans are enormous in their size, volume and depth. The oceans are complex and extensive ecosystems, controlled by a variety of physical, chemical and biological processes. The marine environment dominates that of land ( 70% of the earth’s surface.)
  5. 5. Importance of oceans and seas -1 Oceans and seas are  Rich reservoir of carbon extensive and stable dioxide (130 trillion tons : habitats 50 times more than air ). All oceans and seas are  Richest source of oxygen – continuous. They form a largest ecological system. replenish the atmospheric The giant reservoir of oxygen. water – water wealth 97.3  Large reservoir of % in oceans and 2.7 % on momentum and energy. the land.  Mineral wealth – 50 Complex chemical system million billion tons. – 96.6% of seawater is pure water and only 3.4% contain dissolved solids.
  6. 6. Importance of oceanic habitat -2Oil and Natural gas – Off-shore waters have nearly 20% of world’s oil resources. Biological wealth – 180 thousand species from small bacteria to huge mammals – 25000 varieties of fish. At present 75-80 % of the total global transports by world oceans and seas.
  7. 7.  The life on earth first originated in the seas and oceans. Oceans contain roughly 97% of the earth’s water supply. Ocean moderate earth’s surface temperature. Oceans currents distribute heat energy around the globe. Significance of oceans
  8. 8. Life support functions of oceans
  9. 9. Ocean as the great carbon sink The ocean is a natural sink of co2. The net annual uptake of co2 by oceans is estimated to be approx. 2 thousand million tonnes. The Co2 dissolves in sea water and forms carbonic acid. It hydrolyses into carbonates and bicarbonates. About 90 % of co2 exists as carbonates and bicarbonates. Co2 is taken up by phytoplankton in photosynthesis and converted into plant material.
  10. 10. Global marine environmental changes About 390 million tonnes of run-off water enters our marine environment each year. Approx. 7 billion tons of litter enters the worlds oceans each year. Approx. 35% of mangrove area has been lost or converted. Approx. 20% of coral reefs have been destroyed globally in the last few decades. Coastal wetland loss in some places has reached 20% annually. Indiscriminate fishing practices kill and waste between 18 - 40 million metric tons of "unwanted" fish, seabirds, sea turtles, marine mammals, and other ocean life annually ( FAO - U.N).
  11. 11. Oil spills in the oceanOil spills may occur when an ocean oil rig springs a leak or when an oil tanker wrecks.E.g., The Santa Barbara spill in 1969, and the Exxon Valdez spill in Alaska in 1989.In 1991, millions of gallons of oil was released into the Persian Gulf during the Gulf War .
  12. 12. The Indian coastal lines Indian coastal line measures about 7500 km and 2000 km wide Exclusive Economic Zone. The Indian coastline supports almost 30% of its human population. India is the 7th largest marine fishing nation in the world. The Bay of Bengal and the Arabian Sea are rich fishing grounds.
  13. 13. Global coastal lines  Two-thirds of the world population lives in coastal lines.  Over 90% of the world’s living biomass is contained in oceans.  Coastal areas produce 80% of the marine resources.
  14. 14. Marine Biodiversity
  15. 15. Marinebiodiversity Animal life in the sea is very varied and more diversified in terms shape, size, form and weight-right from microscopic plankton to the giant whale.  The total number of marine species is ranging from 178,000 species to more than 10 million species.
  16. 16. Biggest biodiversity repositories of marine species
  17. 17. Regions of the sea
  18. 18. Oceanic provinces and zones
  19. 19. Ecosystem services of Continental shelf Continental shelves account for at least 25% of global primary productivity. 90–95% of the world’s marine fish catch. 80% of global carbonate production. 50% of global de-nitrification. 90% of global sedimentary mineralization (UNEP 1992).
  20. 20. Composition of Marine Biodiversity  321 species of marine fungi  40000 species of foraminifera  Of the 28000 fish species , ¾ colonizes marine habitats  More than 2500 macro fauna species  More than 600 species of Benthic algae
  21. 21. Marine species diversity gradients
  22. 22. Marine Biodiversity
  23. 23. PlanktonFeatures ofplanktonMostly of minute ormicroscopic sizeHave no means oflocomotion or self-propulsionSurface large inrelation to bulkOften with elongatebody parts
  24. 24. Nekton
  25. 25. Benthos  Bottom dewelling organisms  Epifauna - those living on the sea floor  Infauna - those living in the sea floor  Sessile – sea weeds, sponges, anemones, corals, barnacles, oysters  Creeping – crabs, lobsters, snails, echinoderms  Burrowing – clams and worms
  26. 26. Diversity of coastal habitats Mangrove swamp ecosystem – water logged saline soil Sea grass ecosystem – highly productive macro algae Coastal lagoon ecosystem – Most fertile littoral ecosystems Coral ecosystem – richest in species Estuarine ecosystem - meeting place of river and sea Delta ecosystem – Sandy beach ecosystem – intertidal zone Rocky shore ecosystem – intertidal zone Coastal upwelling ecosystem
  27. 27. Hydrologic parameters of sea water
  28. 28. Overview –Global marine pollutionHuman negativeimpactsHarvesting sea foodsThe impacts of humanactivities on landThe introduction of marinepests.Global changesa.Climate change,b.Rising atmosphericcarbon dioxide,c.Excess nutrient inputs,d.Pollution
  29. 29. Human impacts onmarine environment
  30. 30. Direct human impacts
  31. 31. Direct human impacts
  32. 32. Direct human impacts Coastal aquaculture can contribute to degradation of coastal habitat. Land based discharge (sewage, industrial effluent and urban/river run off etc.) and atmospheric inputs from industry sources account for some 77% of marine pollution. Maritime transport is responsible for some 12% of the total.
  33. 33. Marine Environmental ProblemsCoastal erosion – sand erosion by strong winds, high waves, heavy rains, flooding, and storm waves.Pollution with toxic substancesEutrophication – over-enrichment with nutrientsSedimentation- Land based discharge and deposition of sedimentsOver exploitation of living resources- selective commercial exploitationOver exploitation of non-living resources
  34. 34. Definition of marine pollutionMarine pollution is the introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries), resulting in such deleterious effects as; harm to living resources: hazards to human health; hindrance to marine activities including fishing; impairing the quality for use of sea water and reduction of amenities (The Inter-Governmental Oceanographic Commission, -UNESCO).
  35. 35. Causes of coastal marine pollution
  36. 36. Pollutants in the marine environment
  37. 37. Marine eutrophication
  38. 38. Natural eutrophicationupwelling nutrient inputs, river-borne nutrients (not polluted)slow process (time scale 10³-10years)induce ecosystem adaptations
  39. 39. Coastal marine cultural eutrophication cultural or man-•(made)•sewage,•solid wastes,•industrial•effluents,•agriculturalfertilizers, Anthropogenic nutrients
  40. 40. Features of Eutrophication high nutrient concentrations high phytoplankton densities high densities of herbivores and predators depletion oxygen level in bottom waters by decomposition of organic matter. presence of red tides Near -bottom anoxia-loss of benthos mass mortalities-ecosystem crisis
  41. 41. Eutrophying substances
  42. 42. Sources of Eutrophying substances
  43. 43. Eutrophication – induced changes Increased input of nutrients – deterioration of water quality Increased plankton blooms or coastal macro algal vegetation Decreased water transparency due to mineral turbidity , cloudy detritus – reduced euphotic layers -occlusion of gills Acute/sub-lethal toxicity by industrial or domestic effluents- toxic metals, detergents, pesticides,phenols,ammonia,H2S etc. Reduced species and tropic diversity Loss of fisheries resources
  44. 44. Eutrophication – induced changes Hindrance of aquaculture and/or impairing quality of its products Reduction of tourist – recreational value – loss water clarity, dead animals on shore, foul smells, toxic shell fish etc. Hazards to human health.
  45. 45. Negative impact of sewage disposalEcosystem effects  Turbidity – depresses phytoplankton production  Sedimentation – changes benthic environment – anoxic benthos  Reduces species diversity leads to species – poor communitiesHabitat unsuitable for benthic organisms of commercial importanceHuman health effects  Offensive odor  Cause bacterial and viral enteric infections  Contaminated shell fish – affect human consumers
  46. 46. Negative impact of pesticide contaminationEcosystem effects  mortality  reduction of growth  impairment of reproduction fish and invertebrates  egg-shell thinning in marine birds Human health effects  Potential toxic effects  Neurological disorders
  47. 47. Negative impact of petroleum hydrocarbonsEcosystem effects  mortality  smothering and clogging of organs  Interfere with feeding , reproduction, growth and behaviour  Tainting leads to unmarketability Human health effects  Cancer risks
  48. 48. Negative impact of heavy metalsEcosystem Effects  mortality of juvenile stages of marine organisms  affect morphology, physically and behaviour of marine organisms.  Toxic to phytoplankton, invertebrates, fish. Human health effects  potential mammalian toxicity.  Skeletal, muscular and neurological problems
  49. 49. Negative impact of radionuclidesSomatic effects – acute lethality. skin allergies Genetic effects – cause mutations, cancers
  50. 50. Conservation of global oceanic environmentThe ocean is international property-global commons. No nation has any right , moral or legal to pollute any part of it, including territorial waters.Habitat protection is the most serious need for coastal and marine biodiversityThe presence of toxic wastes in offshore waters must be curtailed by stricter laws.There should be an optimum exploitation of living and non-living resources.
  51. 51. Conservation of global oceanic environment Co-ordinated , centralized and highly sophisticated research programmes are needed i) to identify various pathways by which pollutants enter the ocean. ii)to analyse the behavior of individual pollutants Restoration of habitat by re-vegetation of mash grasses, mangroves and sea-grasses. International and national bodies should be initiated to monitor the growth of marine pollution.
  52. 52. Impact of Global Climate Change on coastal and marine environment Climate change will affect plant and animal physiology, abundances, and distributions. Climate change will alter bio-productivity and species interactions. Climate change may decrease or increase precipitation, thereby altering coastal and estuarine ecosystems. Species that are unable to migrate or compete with other species for resources may face extinction.
  53. 53. Impact of Global Climate Change on coastal and marine environment Changes in precipitation and sea-level rise affect the water balance of coastal ecosystems. The increases in precipitation and runoff may cause the risk of coastal flooding . Climate change affect the structure (e.g., plant and animal composition) and function (e.g., plant and animal production, nutrient cycling) of estuarine and marine systems .
  54. 54. Critical coastal ecosystems Wetlands, estuaries, and coral reefs are particularly vulnerable to climate change. Such ecosystems are among the most biologically productive environments in the world. Climate change may degrade these valuable ecosystems, threatening their ecological sustainability and the flow of goods and services they provide to human populations.
  55. 55.  Dr.B.Victor is a highly experienced professor, recently retired from the reputed educational institution- St. Xavier’ s College, Palayamkottai, India-627001. He was the dean of sciences, IQAC coordinator and assistant controller of examinations. He has more than 32 years of teaching and research experience He has taught a diversity of college courses and guided 12 Ph.D scholars. He has published 5 articles in international and 35 articles in national research journals. send your comments to :