anthropogenic impacts – effects of human activities on the marine environment. anthropogenic...
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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
Impact of Humans on the Marine Environment
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.
Modification and Destruction of Habitats
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 mudbank communitites 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)
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)
Estuaries and Salt MarshesOne of the most productive and biodiverse
ecosystems on earthMany species that reproduce in these
ecosystems are economically importantServe as breeding and resting grounds for
many migratory speciesProvide natural water purification systemsProvide protection from the damaging wind
and rain of hurricanes
Modification and Destruction of Habitats
Estuaries and Salt MarshesIncreasing 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
Modification and Destruction of Habitats
Modification and Destruction of Habitats
Modification and Destruction of Habitats
Mangrove ForestsAlso an ecosystem that is very productiveProvide food and shelter to many speciesHelp reduce coastal erosionShrimp 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
Modification and Destruction of Habitats
Mangrove ForestsHave been cleared away for crops and urban
developmentUsed as fuel and timberApproximately half have been destroyed
Modification and Destruction of Habitats
Modification and Destruction of Habitats
Shrimp Mariculture
Modification and Destruction of Habitats
Mangrove forest destruction for aquaculture in Indonesia
Coral ReefsHigh productivity and biodiversityProvides potentially life saving drugsThreatened 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
Modification and Destruction of Habitats
Coral ReefsBleaching 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
Modification and Destruction of Habitats
Modification and Destruction of Habitats
Modification and Destruction of Habitats
Trawling – nets are dragged across the bottom for shrimp and fish
Modification and Destruction of Habitats
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 eruptionsSynthetic pollutants include:
DDT PCB (polychlorinated biphenols) Metals released from mining operations Oil from human operations
Pollution
Pollution
Pollution
Eutrophication – excessive algal growth as a result of excessive amounts of nutrients present in waterUsually occurs along coastsIncreases phytoplankton abundance sometimes
causing “blooms” which decreases dissolved O2
Reduces penetration of sunlightSome sources of nutrients include
Agricultural runoff Fossil fuel combustion Sewage runoff
Pollution
Pollution
Sewage - human domestic and industrial waste matter from buildings that is carried away through sewersMost sewage is dumped in oceans and riversPoses serious health hazards
Diseases such as hepatitis and brain infections Beaches and rivers may be closed because of risks
to healthSewage 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
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
SourcesAbout 210,056 gallons enter world oceans from
pollutionAbout 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
Pollution
1979 oil spill in the Gulf of Mexico (Blowout of an exploration well)
Oil is insoluble in water and therefore floatsSome oil evaporatesSome is broken down by bacteriahttp://video.nationalgeographic.com/video/pla
yer/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
Pollution
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)
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)
Effects of oil pollution on marine life includeInterference with reproduction, development,
growth and behavior of organismsIncreases susceptibility to diseases in fishesInhibits growth of phytoplanktonMany seabirds and marine mammals die of
exposure when feathers of hair become coated with oil
Many organisms starve to death
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
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)
Pollution
Many pollutants never biodegrade and remain in the environment for decades
Major group of synthetic chemical pollutants is the chlorinated hydrocarbons, these includePesticides such as DDTPCBs (polychlorinated biphenyls)Chlorinated dioxins and furansHeavy Metals
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
Persistent Substances
Biological Magnification
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 USPCBs were widely used in electrical
transformers and in the manufacturing of plastics and paints
PCBs caused cancer and birth defectsPCBs banned in the US in 1979
Persistent Substances
Ibis Eggs that failed to hatch as a result of DDT
Incinerating PCBs (See fig. 18-10)
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)
Persistent Substances
Heavy MetalsRelationship to living organismsLiving 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.
Persistent Substances
Heavy metal pollutionHeavy 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.
Persistent Substances
Heavy MetalsOne 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.
Persistent Substances
Solid Waste
Solid Waste
Seawater is often used in as a coolant in industries
This heated water is then pumped back into the environment which causes thermal pollution
Higher water temperatures can adversely affect marine life
Thermal Pollution
Species are categorized as rare, threatened, or endangered when they face the possibility of extinction, or extermination.
Causes of extermination (human induced extinction)Overexploitation for food and hidesDiscarded as fisheries by-catchHabitat destructionIntroduction of pest species
Threatened and Endangered Species
By-catch from shrimp trawling
http://www.youtube.com/watch?v=xwOlG8iu7DI&feature=BFa&list=PLDCB132D9DA2AD325&index=2 (whaling – graphic images)
http://videos.howstuffworks.com/animal-planet/28281-caught-in-the-moment-sea-turtle-conservation-video.htm (harvesting turtle eggs)
Threatened and Endangered Species
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