Chapter 11 The Coastal Ocean

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Chapter 11 The Coastal Ocean

• Essentials of Oceanography
• 7th Edition

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Coastal waters

• Relatively shallow areas that adjoin continents
• Heavily used for commerce recreation fisheries
  and waste disposal
• Experience dramatic changes in salinity and
  temperature

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Salinity and temperature in the coastal ocean
Figure 11-1
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Estuaries

• Estuaries are partially enclosed coastal bodies
  of water
• Examples of estuaries include
• River mouths
• Bays
• Inlets
• Gulfs
• Sounds
• Formed by a rise in sea level after the last Ice
  Age

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Classifying estuaries by origin

• Coastal plain
• Fjord
• Bar-built
• Tectonic

Figure 11-3
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Examples of estuaries
Tectonic estuary (San Francisco CA)
Fjord estuary (Norway)
Figure 11-4
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Classifying estuaries by water mixing

• Vertically mixed
• Slightly stratified
• Highly stratified
• Salt wedge

Figure 11-5
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Coastal wetlands

• Coastal wetlands are saturated areas that border
  coastal environments
• Brackish water conditions
• Two most important types of coastal wetlands
• Salt marshes (mid-latitudes)
• Mangrove swamps (low latitudes)

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Coastal wetlands Salt marshes and mangrove swamps
Figure 11-8
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The value of coastal wetlands

• Coastal wetlands are highly productive areas that
  serve as fish nurseries for many important
  species
• Effectively filter polluted runoff from land
• Problem are viewed as worthless land so are
  often replaced with developments (roads housing
  shopping etc.)

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Lagoons

• Lagoons are shallow coastal bodies of water
  separated from the ocean by a narrow strip of
  land such as a barrier island

Figure 11-9
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Mediterranean circulation

• The Mediterranean Sea experiences high rates of
  evaporation
• Causes inflow of water at the surface and outflow
  of high salinity water below

Figure 11-11b
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Pollution in coastal waters

• Coastal waters are highly affected by pollution
  because they are
• Heavily used
• Close to sources of pollution
• Shallow-water bodies
• Not as well circulated as the open ocean

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Marine pollution A definition

• The introduction by man directly or indirectly
  of substances or energy into the marine
  environment including estuaries which results
  or is likely to result in such deleterious
  effects as harm to living resources and marine
  life hazards to human health hindrance to
  marine activities including fishing and other
  legitimate uses of the sea impairment of quality
  for use of sea water and reduction of amenities.
  (World Health Organization)

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Main types of marine pollution

• Petroleum (oil)
• Sewage sludge
• DDT and PCBs
• Mercury
• Non-point-source pollution

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Marine pollution Petroleum

• Oil spills can be caused by
• Tanker accidents
• Intentional dumping
• Drilling/pumping operations

Figure 11-12
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Marine pollution Petroleum

• Petroleum is biodegradable
• Many pollution experts consider oil to be among
  the least damaging ocean pollutants
• Data from the 1989 Exxon Valdez oil spill shows
  the recovery of key organisms

Figure 11-13
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Marine pollution Petroleum

• Various processes act to break up and degrade oil
  in the marine environment

Figure 11-18
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Marine pollution Petroleum

• When oil washes up at a beach it can negatively
  affect the marine environment
• Oil can coat marine organisms and render their
  insulating fur or feathers useless

Oil on the beach from the Exxon Valdez oil spill
Alaska
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Marine pollution Sewage sludge

• Sewage sludge is the semisolid material that
  remains after sewage treatment
• Much sewage sludge was dumped offshore until laws
  restricted sewage dumping

Figure 11-21
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Marine pollution DDT

• DDT was a widely used pesticide that became
  concentrated in marine fish
• DDT caused brown pelicans and ospreys to produce
  thin egg shells
• Worldwide DDT has been banned from agricultural
  use but is still used in limited quantities for
  public health purposes

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Marine pollution PCBs

• PCBs are industrial chemicals used as liquid
  coolants and insulation in industrial equipment
  such as power transformers
• PCBs enter the marine environment through leaks
  and from discarded equipment
• PCBs can accumulate in animal tissues and affect
  reproduction

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Marine pollution Mercury and Minamata disease

• Mercury has many industrial uses but is extremely
  toxic
• A chemical plant released large quantities of
  mercury into Minamata Bay Japan
• Residents who ate highly contaminated fish
  suffered neurological disease and birth disorders
  (Minamata disease)

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Marine pollution Non-point- source pollution

• Non-point-source pollution comes from material
  washed down storm drains as poison runoff
• Includes fertilizers pesticides road oil and
  trash

Figure 11-26
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Current law regulating ocean dumping

• The only substance that is illegal to dump
  anywhere in the ocean is plastic

Figure 11-27
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Plastic in the marine environment

• Plastic
• Does not biodegrade
• Floats
• Has high strength
• Is ingested by and entangles marine animals

Figure 11-28
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End of Chapter 11

• Essentials of Oceanography
• 7th Edition