© 2006 thomson-brooks cole chapter 20 oceans in jeopardy

© 2006 Thomson-Brooks Cole

Chapter 20

Oceans in Jeopardy


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.


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.


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.


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


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


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


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


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


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


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


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


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


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)


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


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


Pollution

• Petroleum pollution (continued)– ecological effects of oil spills

• effects on birds and mammals• effects on invertebrates and algae• community effects


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


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 beach-front real estate

– legislation now protects wetlands, but the government continually changes the definition of “wetlands”


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


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 chapter 20 oceans in jeopardy

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