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