Impact of Humans on the Marine Environment

1. Impact of Humans on the Marine Environment

2. Impact of Humans on the Marine Environment • Anthropogenic impacts – effects of human activities on the marine environment. • Modification/Destruction of Habitats and Pollution can lead to: • Loss of estuaries, mangrove forests and coral reefs • Decrease in biodiversity • Loss of habitat

3. Modification and Destruction of Habitats • Modification & Destruction includes activities such as dredging, dumping silt or mud, land filling, or the use of explosives. • The effects of such disturbances are direct and immediate. • Most destruction takes place along the coast.

6. Dredging results in the short term degradation of animals, vegetation and microbial communities that live in the dredged sediment. This reduces the estuary's capacity for nutrient cycling, primary production and habitat provision and can have effects up the food web. Though these effects tend to be short lived, in some cases they may trigger long-term changes. (Larkum and West, 1990; Lewis et al, 2001; Thrush and Dayton, 2002; Lohrer and Wertz, 2003; da Silva et al, 2004; Waycott et al, 2004; Ohimain et al; 2005) • Changes in channel profile caused by dredging can increase tidal area, wave height and water velocity, resulting in bank erosion. Eroding banks threaten mangroves and other mudbankcommunitites and can lead to increased turbidity. Suspended sediment in the water column blocks light, reducing benthic primary productivity and inhibits the ability of benthic plants to recover from impacts of dredging. (Pringle, 1989; Larkum and West, 1990; Lewis et al, 2001; Rasheed and Balchand; 2001; Lohrer and Wertz, 2003; Sampson et al, 2005)

7. Dredging exposes anaerobic layers of sediment, potentially disturbing and remobilizing toxic sediments, releasing contaminants. This has implications for water quality. (Linkov et al, 2001; Thibodeaux and Duckworth, 2001; Van Den Berg, 2001; Nayar et al, 2004) • Dredge spoil needs to be deposited somewhere, though this could be deemed habitat creation, it can smother existing habitats and frequently contains contaminants which often move and bioaccumulate through the food web. The impacts of dredge spoil disposal can range from short term to long term (Linkov et al, 2001; Smith and Rule, 2001; National Ocean Disposal Guidelines for Dredged Material, 2002; Fredette and French, 2004)

8. Modification and Destruction of Habitats • Estuariesand Salt Marshes • One of the most productive and biodiverse ecosystems on earth • Many species that reproduce in these ecosystems are economically important • Serve as breeding and resting grounds for many migratory species • Provide natural water purification systems • Provide protection from the damaging wind and rain of hurricanes

9. Modification and Destruction of Habitats • Estuariesand Salt Marshes • Increasing pressures from human-induced activities are causing habitat loss and degradation, fisheries declines, and overall reductions in estuarine health and productivity. Associated physical alterations, such as dredging, damming, and bulkheading, change the natural flow of fresh water to estuaries, dramatically affecting water quality. Toxic substances and excess nutrients contribute to fish diseases, algal blooms, and low dissolved oxygen and can pose a threat to the health of humans and estuarine wildlife

10. Modification and Destruction of Habitats

11. Modification and Destruction of Habitats

12. Modification and Destruction of Habitats • Mangrove Forests • Also an ecosystem that is very productive • Provide food and shelter to many species • Help reduce coastal erosion • Shrimp mariculture is very destructive • Forests are destroyed to build shrimp ponds • Water from ponds, which contains large amounts of waste and excess nutrients is flushed into mangrove forest

13. Modification and Destruction of Habitats • Mangrove Forests • Have been cleared away for crops and urban development • Used as fuel and timber • Approximately half have been destroyed

14. Modification and Destruction of Habitats Shrimp Mariculture

15. Modification and Destruction of Habitats Mangrove forest destruction for aquaculture in Indonesia

16. Modification and Destruction of Habitats • Coral Reefs • High productivity and biodiversity • Provides potentially life saving drugs • Threatened by • Agricultural runoff • Overgrowth of seaweeds • Over fishing • Mining of coral for construction material • Clearing of rainforests causes increase sediment buildup on coral reefs. Higher sediment levels cause a decrease in photosynthesis which is detrimental to reefs

17. Modification and Destruction of Habitats • Coral Reefs • Bleaching of corals occurs when zooxnthellae (symbioses) are expelled and white patches form. • Bleaching is a result of “stress” to corals which may be caused by in increase in water temperatures

18. Modification and Destruction of Habitats

19. Modification and Destruction of Habitats

20. Modification and Destruction of Habitats • Trawling – nets are dragged across the bottom for shrimp and fish

21. Pollution • Pollution - The presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects.  • Naturally occurring pollutants include: • Natural oil seeps • http://video.nytimes.com/video/2011/03/21/science/100000000737132/22conversation.html (natural oil seep) • Volcanic eruptions • Synthetic pollutants include: • DDT • PCB (polychlorinated biphenols) • Metals released from mining operations • Oil from human operations

22. Pollution

23. Pollution

24. Pollution • Eutrophication – excessive algal growth as a result of excessive amounts of nutrients present in water • Usually occurs along coasts • Increases phytoplankton abundance sometimes causing “blooms” which decreases dissolved O2 • Reduces penetration of sunlight • Some sources of nutrients include • Agricultural runoff • Fossil fuel combustion • Sewage runoff

27. Pollution

28. Pollution • Sewage - human domestic and industrial waste matter from buildings that is carried away through sewers • Most sewage is dumped in oceans and rivers • Poses serious health hazards • Diseases such as hepatitis and brain infections • Beaches and rivers may be closed because of risks to health • Sewage may be treated in different ways to reduce health risks • Sludge – waste that remains after sewage is treated is much more concentrated than the original sewage and can be more toxic to environment

29. Pollution • Oil (crude oil or petroleum) – a mixture of hydrocarbons and certain chemicals; used as fuel and raw material for plastics, synthetic fibers, rubber, fertilizers • Sources • About 210,056 gallons enter world oceans from pollution • About 179,872 gallons enter world oceans from natural seepage (not a pollutant) • 85% of polluting oil in North America comes from river runoff, coastal cities, fuel from small boats/jet skis, and fuel jettisoned by planes. • 15% comes from tanker and pipeline spills

30. 1979 oil spill in the Gulf of Mexico (Blowout of an exploration well)

31. Pollution • Oil is insoluble in water and therefore floats • Some oil evaporates • Some is broken down by bacteria • http://video.nationalgeographic.com/video/player/environment/habitats-environment/habitats-oceans-env/declining-fish.html (oil eating bacteria) • Some sinks to the bottom and accumulates in sediments, some remains at the surface • Oil that is not biodegraded may persist in the environment for decades

33. http://www.youtube.com/watch?v=YkzB1ZYcTwM (Exxon Valdez oil spill 1989) • http://www.youtube.com/watch?v=bXtsB4Go0hg&feature=related (Exxon Valdez oil spill 1 of 10) • http://www.youtube.com/watch?v=MG6O92XIvFw&feature=related (Exxon Valdez oil spill 2 of 10) • http://www.youtube.com/watch?v=rgEi7kxGXeo&feature=related (Exxon Valdez oil spill 3 of 10) • http://www.youtube.com/watch?v=78bw1RdAh30&feature=related (Exxon Valdez oil spill 4 of 10) • http://www.youtube.com/watch?v=CmczMUB07kw&feature=related (Exxon Valdez oil spill 5 of 10)

34. http://www.youtube.com/watch?v=vB6m-CUqg2w&feature=related (Exxon Valdez oil spill 6 of 10) • http://www.youtube.com/watch?v=eDTnfypbl0g&feature=related (Exxon Valdez oil spill 7 of 10) • http://www.youtube.com/watch?v=s3L-WTmlXB8&feature=related (Exxon Valdez oil spill 8 of 10) • http://www.youtube.com/watch?v=5LVv5EMwQ4M&feature=related (Exxon Valdez oil spill 9 of 10) • http://www.youtube.com/watch?v=xj4mre_9boo&feature=related (Exxon Valdez oil spill 10 of 10)

36. Pollution • Effects of oil pollution on marine life include • Interference with reproduction, development, growth and behavior of organisms • Increases susceptibility to diseases in fishes • Inhibits growth of phytoplankton • Many seabirds and marine mammals die of exposure when feathers of hair become coated with oil • Many organisms starve to death

39. Pollution • Containing an oil spill and clean up efforts can be as harmful to organisms as the oil itself • Chemical dispersants used to break down oil are toxic • Powerful streams of hot water used to clean oil off of rocks can damage marine life • Local economies suffer from oil spills

40. Pollution http://news.discovery.com/videos/earth-gulf-coast-expert-oil-spill-threatens-seafood.html (gulf oil spill) http://www.youtube.com/watch?v=mCWW5xt3Hc8 (satellite view growing gulf oil spill) http://video.nationalgeographic.com/video/player/environment/habitats-environment/habitats-oceans-env/declining-fish.html (stop oil from sticking to bird feathers) http://www.nasa.gov/topics/earth/features/oilspill/ http://www.education.noaa.gov/Ocean_and_Coasts/Oil_Spill.html (use this site for educational materials) http://oceanexplorer.noaa.gov/edu/guide/gomdse_edguide.pdf (another site for oil education – make copy using color printer)

41. Persistent Substances • Many pollutants never biodegrade and remain in the environment for decades • Major group of synthetic chemical pollutants is the chlorinated hydrocarbons, these include • Pesticides such as DDT • PCBs (polychlorinated biphenyls) • Chlorinated dioxins and furans • Heavy Metals

42. Persistent Substances • Chlorinated hydrocarbons dissolve in fats and are not excreted because the body can not metabolize them • At each level of the food chain the chlorinated hydrocarbons are more concentrated. • This is known as biological magnification

43. Biological Magnification

44. Persistent Substances • DDT levels were so high in fish that they had to be destroyed (too high for human consumtion) • DDT caused a decrease in the deposition of calcium in bird eggs. The shells became so thin that they broke during incubation. • DDT was banned in 1972 in the US • PCBs were widely used in electrical transformers and in the manufacturing of plastics and paints • PCBs caused cancer and birth defects • PCBs banned in the US in 1979

45. Ibis Eggs that failed to hatch as a result of DDT

46. Incinerating PCBs (See fig. 18-10)

47. Persistent Substances • Dioxins and Furans enter the environment from pulp mills and waste incinerators • They are carcinogenic and cause birth defects and damage to the immune system in many vertebrates • Have been implicated in abnormal sexual behavior and reproductive ability in seabirds, marine mammals, and fishes. (PCBs form chemicals that are similar in structure to sex hormones and seem to disrupt reproduction)

48. Persistent Substances • Heavy Metals • Relationship to living organisms • Living organisms require varying amounts of "heavy metals." Iron, cobalt, copper, manganese, molybdenum, and zinc are required by humans. • Excessive levels can be damaging to the organism. Other heavy metals such as mercury, plutonium, and lead are toxic metals that have no known vital or beneficial effect on organisms, and their accumulation over time in the bodies of animals can cause serious illness.

49. Persistent Substances • Heavy metal pollution • Heavy metal pollution can arise from many sources but most commonly arises from the purification of metals, e.g., the smelting of copper and the preparation of nuclear fuels. • Through precipitation of their compounds or by ion exchange into soils and muds, heavy metal pollutants can localize and lay dormant. • Unlike organic pollutants, heavy metals do not decay and thus pose a different kind of challenge for remediation.

50. Persistent Substances • Heavy Metals • One of the largest problems associated with the persistence of heavy metals is the potential for bioaccumulation and biomagnification causing heavier exposure for some organisms than is present in the environment alone.