Human Impact on The Oceans

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Human Impact on The Oceans
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The Ocean

• One of the most valuable and untapped resources.
• Yet, seriously threatened by what humans have
  done to it.
• The problem of controlling human impacts on the
  ocean boils down to short term costs.
• These short term costs () often prevent
  effective controls.

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Problem 1 Habitat Alteration

• Dredging
• Removing sediment from the bottom of the ocean
  with mechanical force to dislodge and excavate
  material.
• Dredging is used to clear obstructions so larger
  ships can enter ports.
• Used to keep harbors, rivers and other waterways
  from silting up.

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• Dredging is also a method used to collect
  scallops.
• Dredging dramatically
• affects marine ecosystems,
• causing severe seabed
• habitat destruction.
• Sea creatures living on the bottom are crushed,
  buried or exposed to predators, and clouds of
  sediments rise, altering seabed biochemistry.

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Natural healthy undisturbed cobble-shell bottom,
habitat for scallops.
After just one pass of a scallop dredge this is
the result!
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• By leveling the ocean floor, the food chain is
  disturbed, the hiding places have been removed
  and conditions favorable to faster growing
  species take over.
• Seafloor recovery could take centuries.
• Some species of sponges can reach 50 years old.
• Some clams can live for more than 200 years.
• Some individual corals have been estimated to
  live 500 years or more.

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Problem 2 Offshore Drilling (Oil)

• Problems with it
• Noise from Seismic Testing
• Water and air pollution
• Visual impacts
• Coastal Development

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Sonic blasts damage the brain and ears of marine
mammals and other species, disorienting them and
causing them to beach themselves.
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Problem 3 By Catch

• This refers to fish and other marine life caught
  "incidentally" while harvesting another species.
• These are fish that are the wrong type, size,
  sex, or quality as well as marine mammals, sea
  turtles, and seabirds. 

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Facts about Bycatch

• Commercial fishing worldwide wastes approximately
  44 billion pounds of ocean life annually.
• Roughly 25 percent of the entire global catch.
• In the United States, all sea turtles are listed
  as endangered or threatened under the Endangered
  Species Act, as a result of fishing bycatch.

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Whale Entanglement
More whales, dolphins and porpoises die every
year by getting entangled in fishing gear than
from any other cause.
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Problem 4 Toxic Ocean Pollutants

• Our waste, even in small quantities, have huge
  effects on ocean communities and species.
• Toxic pollutants in the ocean ecosystem have
  massive impacts on the plants and animals.

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Some major types of pollutants

• garbage
• sewage
• chemicals
• radioactive waste
• eutrophication
• heavy metals
• oil

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Oil Spills (1)

• The effects of an oil spill of marine life depend
  on a number of physical and biological factors.
• The distribution of the oil spill will be
  affected by currents and wind
• In addition, the amount of oil spilled will
  determine the eventual geographic boundaries of
  the impact area.
• The physical and chemical properties of the oil
  will determine the behaviour of the slick, in
  terms of its thickness and rate of spreading.

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Oil Spills (2)

• Environmental conditions such as salinity, water
  temperature, and type and slope of shoreline will
  determine habitat effects and clean-up procedures
  
• Some example habitats include sandy beach, mud,
  cliffs, estuaries and open water. In terms of
  difficulty of clean-up and relative
  vulnerability, a salt marsh ranks the highest,
  followed by eelgrass, mud, mixed-fine sediment,
  mixed-coarse sediment, rock, sand, algae (kelp)
  and open water.

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Oil Spills (3)

• Biological characteristics of the organisms
  affected will determine the severity of impact.
• These characteristics include the type of
  species, life stage (larval, juvenile or adult)
  and size.

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Cleaning-up oil spills

• 1. Dispersants Oil can be broken down more
  quickly by spraying dispersants (chemicals) on
  the oil slick from boats or planes. This method
  only works on fresh, small oil spills.
• 2. Booms A boom has a floating skirt suspended
  down in the water and a sail holding it above the
  water line. The floating skirt stops the oil from
  passing. These are used to prevent oil from
  entering delicate and protected areas.
• 3. Slick-lickers This method uses a belt of oil
  absorbing material that sucks up the oil from the
  ocean water. The oil is then squeezed out of the
  absorbing material into a collecting bin.

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