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Unit 6
Human Impact
What we do to the oceans.
Human Impact
• Pollution – anything introduced into the
environment by humans that is harmful
oChemicals, trash, noise, heat,
sewage, etc.
o Biodegradable – can be broken down by bacteria.
(paper)
o Nonbiodegradable – can not be broken down by
bacteria (plastic)
Where does the pollution
come from?
• Most of the pollution (75%) come from human
activities
• How do marine species handle
pollutants?
o Depends on
• Its sensitivity
• Toxicity of pollutants
oPersistence – how long it remains in
the remains in the environment
Pollutants
Oil
• Natural leaks only
account for 10% of the
6 million metric tons
that enter into the
ocean
Effects of Oil on Marine
Life
• Can be ingested through food
o Interferes with reproduction,
development, and growth
o Young are most affected
• Birds and Mammals
o Can get trapped in fur or feathers
o Inhibits ability to stay warm or to fly
Oil spill clean up
• worst oil spills
• Fencing Off
o Use fire-retardant booms to contain oil
• Skimmers
o Scrape oil off of surface of water
• Dispersants
o Chemicals that break oil into small
droplets
o Dispersants can be toxic
• Hot or Cold Water Washing
o To remove oil from shorelines
o Can be harmful to microorganisms
• Bioremediation
o Use of engineered bacteria to detect
and break down oil
Heavy Metals
• High molecular weight elements that can
cause damage to organisms in small
concentrations
o Interfers with a cells normal metabolism
o Found in industrial waste, land fills, gasoline
o Human activities release 5X more than natural soruces
• Examples:
oMercury, Cadmium, Nickel,
Lead, Zinc, Copper, Chromium
Mercury
• Sources: incineration of mercury containing
waste (hospital waste, mercury lamps,
metal recycling smelters, coal power plants
(#1)), dental wastewater (fillings),
Caribbean folk medicine, gold mining
http://www.chicagotribune.com/news/chi-mercury-htmlpage,0,6027124.htmlpage
• Most harmful when in form of methyl
mercury (converted by bacteria) [CH3Hg]+
• Can accumulate in seafood
• Causes brain, kidney, and liver damage
and birth defects in people
Pesticides
• Enter oceans: wind, runoff
o Farmers spray crops
o It can blow in
o It can be washed in by rain
• Created to kill life
• Can affect reproduction and growth
of marine organisms
• Biological amplification occurs with
pesticides too
DDT:
dichloro-diphenyl-trichloroethane
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Pesticide to kill mosquitoes
Killed many birds and fish
Is currently banned in the US
Used in third world countries where
diseases like malaria are prevalent
• Solid Waste
o we generate over 1100 million metric tons of solid waste a
year per person!
• Plastic – 10%
o Basically doesn’t degrade for 1000s of years or
never!
What is the solution to all this solid waste?
• Sediment
o Runoff from mining, farming, forestry
o Destroys coastal ecosystems (marshes)
o Kill reefs
• Sewage
o Treated sewage water
o Contributes to eutrophication
Biological Amplification
• Persistent chemicals do not break
down
• Organisms absorb or digest pollutants
• Pollutants accumulate in top
predators
• Phytoplankton
absorb mercury
• Shrimp eat
thousands of
phytoplankton
• Small fish eats
hundreds of these
shrimp
• Large tuna eats
thousands of
these fish
• This is why
pregnant women
shouldn’t eat too
much fish
Alien Species
• Any species that is not native to the environment
• Harmful for several reasons:
o May carry parasites
o No natural predator
o Compete with natives for resources
• Enter other oceans through ballast water
o (Water holds in cargo ships)
Endangered Species
• Extinction of marine animals can
be caused by
oOverfishing/overhunting
oHabitat destruction
oPollution
oCompetition with alien species
Whaling: Hunting of
Whales
• Led to all whales being endangered
• 1994 many countries banned whaling in Antarctica
o Except: Norway and Japan
• Started hunting dolphins instead
The costs of pollution
Habitat Destruction
• Estuaries
o Dredged for ships
o Filled in for building on
o 1/3 of estuaries have disappeared in
the US
• Mangroves
o Similar to estuaries
o Also cut for timber and fuel
• Coral Reefs
o Clearing of
rainforests:
causes soil to
wash into the
water
o Explosives for
hunting fish
o Bleaching
Global Changes
• Ozone depletion
o UV damages DNA
• Climate change
o Increase in ocean temperatures
• Harms sea life
• Increases sea levels
• Changes in weather patterns
• Changes in ocean currents
What can be done?
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Slow population growth
Cut down on consumption
Be careful what you buy
Conservation
Reduce your waste
recycle