Transcript Ixtoc 1

Chapter 20
Oceans in Jeopardy
© 2006 Thomson-Brooks Cole
Key Concepts
• Dumping wastes into coastal seas
decreases their economic and
recreational value and creates health
hazards.
• Pollutants enter coastal seas by way of
agricultural and urban runoff as well as
by direct dumping.
• Some pollutants accumulate and
magnify in food chains, posing serious
problems for higher-order consumers.
© 2006 Thomson-Brooks Cole
Key Concepts
• Plastic trash is deadly to large marine
animals.
• Oil spills damage significant amounts
of habitat and injure and kill marine
life.
• Development of coastal areas leads to
loss of habitat and diminished numbers
of marine life.
© 2006 Thomson-Brooks Cole
Key Concepts
• Destruction of wetlands results in
decreased ocean productivity.
• It is not too late to become involved
with conserving the oceans and their
resources.
© 2006 Thomson-Brooks Cole
Pollution
• Ocean dumping
– trash – 17th annual Coastal Cleanup in
September 2002
• 2.8 million lb. of trash and debris in 3 hours
• 1.3 million cigarette butts and filters
• 226,251 glass bottles
• 238,826 metal cans
• 2,529 syringes
• 61% of trash collected was plastic
• 82 animals found trapped in the debris
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Ocean dumping (continued)
– plastic
• strength and durability of plastic make it one
of the most hazardous materials in the sea
• marine animals and plastic
• controlling plastic – Marine Plastic Pollutino
Research and Control Act of 1987
– commercial dumping
• garbage, sewage and toxic chemicals have
been dumped into the New York Bight since
1890
© 2006 Thomson-Brooks Cole
Pollution
• Ocean dumping (continued)
– military refuse
• discarded military hardware and munitions
• toxic gases and chemicals
– radioactive wastes
• disposal of radioactive materials in trench
subduction zones has been proposed
• currently, this is prohibited by the Ocean
Dumping Act of 1972, which requires an
environmental impact statement and approval
of the Congressional House and Senate
© 2006 Thomson-Brooks Cole
Pollution
• Pollution via land and air
– urban pollution
• 50% of the U.S. population lives within 50
miles of coastline (including the Great Lakes)
• this population needs energy, industry and
waste treatment
• coastal seas and habitats are polluted by
associated runoff from land
– pesticides, fertilizers, gasoline, oil, sewage,
chemicals used to treat sewage
• organic lead entering the sea has been
decreased by use of unleaded fuels since 1980
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Pollution via land and air (continued)
– pesticides and toxic materials from
industry
• pesticides (e.g. DDT), toxic organic compounds
(e.g. PCBs), heavy metals (e.g. mercury, lead,
zinc, and chromium)
• biological magnification—concentration of
toxins in the tissues of animals as they are
passed up the food chain without being broken
down or excreted
• effects of toxic compounds on plankton
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Pollution via land and air (continued)
– air pollution
• sulfur dioxide from burning of fossil fuels can
precipitate in water and lower pH
• greenhouse gases (e.g. CO2, methane)
contribute to global warming
• global warning is thought to cause coral
bleaching, and might raise sea levels, killing
corals that must remain close to the surface to
obtain sufficient sunlight for zooxanthellae
© 2006 Thomson-Brooks Cole
Pollution
• Nutrient pollution
– human wastes
• disease agents
– coliform bacteria, found in the intestines of many
animals, are counted to monitor water quality
• eutrophication – leads to blooms of
phytoplankton and other marine microbes
• increased productivity
– sometimes, the addition of sewage and animal
wastes can boost the productivity of a marine
community
© 2006 Thomson-Brooks Cole
Pollution
• Nutrient pollution (continued)
– agricultural wastes
• fertilizers and animal wastes have effects
similar to those of human wastes
• pesticides are also found in runoff from farms
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Controlling pollution
– legislation was passed to prohibit dumping
of sewage sludge or industrial wastes in
the ocean after Jan. 1, 1992
– largest threat is increasing coastal
populations and improperly controlled
commercial and residential development
© 2006 Thomson-Brooks Cole
Pollution
• Petroleum pollution
– petroleum products
• crude oil contains aromatic hydrocarbons and
aliphatic hydrocarbons
• aromatic hydrocarbons—molecules made up of
carbon atoms in ring structures (e.g. benzene,
naphthalen, cyclohexane)
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Petroleum pollution
– petroleum products
• aliphatic hydrocarbons—straight-chain
molecules (e.g. heptane, octane, nonane)
• petroleum products are persistent, difficult for
microbes to degrade, and toxic to organisms
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Petroleum pollution (continued)
– oil spills
• largest oil spill in the U.S. was in March 1989,
when the tanker Exxon Valdez ran onto a
rocky reef 25 miles from Valdez, Alaska
• largest and longest-lasting oil spill ever was in
June 1979, when an offshore oil well in the
Gulf of Mexico, the Ixtoc 1, blew out and
caught fire
• oil spills are deadly for marine organisms
© 2006 Thomson-Brooks Cole
Pollution
• Petroleum pollution (continued)
– ecological effects of oil spills
• effects on birds and mammals
• effects on invertebrates and algae
• community effects
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Pollution
• Petroleum pollution (continued)
– oil spill cleanup
• oil booms and oil skimmers help to confine the
spill to a smaller area and recover some of the
oil
• straw is used to soak up the oil, then burned
• a bacterium genetically engineered to degrade
crude oil is being tested
© 2006 Thomson-Brooks Cole
Habitat Destruction
• Wetlands
– provide nutrients, shelter and spawning
grounds for a variety of marine organisms
– have been drained, filled or dredged to
provide more ground for industry,
channels into ports/harbors, and beachfront real estate
– legislation now protects wetlands, but the
government continually changes the
definition of “wetlands”
© 2006 Thomson-Brooks Cole
Habitat Destruction
• Beaches
– direct effects of beach use and
development on marine life
• disturbs nesting sites of birds, sea turtles and
horseshoe crabs
– destruction of habitat
– interfering with natural processes
• longshore currents—generated by waves that
break at an angle to the beach, moving
parallel to the beach
• longshore transport process—transport of
sediments by longshore currents
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Epilogue
• Natural changes are small and occur
over long periods of time
• Changes caused by humans can be
instantaneous and involve entire
marine communities
• Understanding the underlying patterns
and processes of the sea allows people
to use the sea’s resources without
jeopardizing its environmental or
economic value for the future
© 2006 Thomson-Brooks Cole