Download Chapter 11: The coastal ocean

CHAPTER 11
The Coastal Ocean
Overview
Coastal waters support about
95% of total biomass in
ocean
 Most commercial fish caught
within 320 km (200 m) from
shore
 Important also for shipping,
oil and gas production, and
recreation
 Many pollutants found here –
that’s a problem!

http://www.safmc.net/Portals/0/shrimp%20trawler2.jpg
Ocean ownership

1609 sea is free to all (mare liberum = free)
 Assumed fish resources are inexhaustible

1702 territorial sea under coastal nation’s
sovereignty (3 nautical miles from shore)
 Distance of cannon shot
Fort Sumter, Charleston
harbor, South Carolina
http://www.kid-friendly-family-vacations.com/image-files/fort_sumter.jpg
United Nations and ocean laws

1958-1982 United Nations Law of
the Sea Conferences
 National sovereignty extends 12
nautical miles
 Exclusive Economic Zone (EEZ) 200
nautical miles (370 km) from land
(mineral and fishing resources)
 Right of free passage for ships
 Open ocean mining regulated by
International Seabed Authority
○ This has changed, still very contentious
 United Nations arbitrates disputes
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Zonmar-en.svg/300px-Zonmar-en.svg.png
EEZ of the U.S.--about 30% more than
land area of entire U.S.
Fig. 11.1
Characteristics of coastal
waters
Adjacent to land (to edge of continental
shelf)
 Influenced by river runoff, wind, tides
 Salinity variable

 Freshwater runoff
 Winds
 Mixing by tides
http://upload.wikimedia.org/wikipedia/commons/5/58/Outer_Continental_Shelf_map.png
Characteristics of coastal
waters

Temperature variable
 Low-latitudes: restricted circulation, very warm
 High-latitudes: sea ice
 Mid-latitudes
○ Seasonal changes
○ Prevailing winds
Types of coastal waters

Estuary
 Partially enclosed coastal area with ocean water
and freshwater (runoff) mixing

Coastal wetland
 Ecosystem with water table close to surface

Lagoon – type of estuary
 Shallow coastal water separated from ocean

Marginal sea
 Relatively large semi-isolated body of water
Estuaries - Origin of estuaries
Rising sea level “drowns” what
was once land
 Coastal plain estuary

 Former river valley now flooded with
seawater

Fjord
 Former glaciated valley now flooded with
seawater

Bar-built estuary
 Lagoon separated from ocean by sand
bar or barrier island

Tectonic estuary
 Faulted or folded down-dropped area now
flooded with ocean
Estuaries - Classification of estuaries
4 types - Based on mixing of freshwater and saltwater

Vertically mixed
 Shallow, low volume
 Salinity uniform

Slightly stratified
 Deeper than previous
 Upper layer less salty; lower layer more salty
 Estuarine circulation

Highly stratified
 Deep, relatively strong halocline

Salt wedge
 Deep, high volume
 Strong halocline
 Typical at mouths of deep, high volume rivers
Figure 11.8
Severely effected by human activity, freshwater wedge can be traceable far out to sea
Indian River Lagoon
Estuary
Well-mixed due to winds and
shallow depths
 Seasonal changes in salinity,
temperature, dissolved
oxygen
 Most biologically diverse
estuary in north
america…over 4,000 species
of plants and animals
 Threats: habitat destruction,
stormwater runoff, and
invasive exotic species

Sebastian Inlet
http://www.indianriverlagoon.org/docs/irlmap.html
Chesapeake Bay Estuary

Anoxic conditions below pycnocline in summer
 Runoff of sewage and fertilizer cause algae bloom
 when these organisms die, increased decomposition causes anoxic
conditions
 Decrease in oxygen levels in water

Major kills of commercially important marine animals
Coastal Wetlands - Types of coastal wetlands
o
o
o
Ecosystems that are saturated with
water
o Swamps, tidal flats, coastal marshes,
bayous
Salt marsh
o Any latitude
Mangroves
o Low latitude
Characteristics of coastal wetlands
Efficiently cleanse polluted water
 Absorb water from coastal flooding during
storms
 Protect shores from wave erosion

http://soundwaves.usgs.gov/2008/03/WetlandLG.jpg
Coastal Wetlands - Loss of coastal
wetlands

Half of U.S. coastal
wetlands lost to
development (housing,
industry, agriculture)

U.S. Office of Wetland
Protection, 1986
 Minimize loss of wetlands
 Protect or restore
wetlands
http://www.on.ec.gc.ca/wildlife/factsheets/images/glfs-coast-stress.jpg
Lagoons
Freshwater zone
 Transition zone of brackish water
 Saltwater zone
 Hypersaline in arid regions

Marginal seas

Mostly from tectonic events
 Ocean crust between continents,
e.g., Mediterranean Sea
 Behind volcanic island arcs, e.g.,
Caribbean Sea
Shallower than ocean
 Connected to ocean

http://www.shinesforall.com/images/Caribbeanmap.gif
Caribbean Sea
On Caribbean plate defined by Greater and
Lesser Antilles – volcanic island arc
 Relatively shallow marginal sea – deepest is
Cancun Trough at 7,686 m (25,220 ft)
 Underlain by oceanic crust

http://woodshole.er.usgs.gov/project-pages/caribbean/images/PBATHY1.GIF
Mediterranean Sea




Remnant of Tethys Sea – when all the continents were
together
Deeper than usual marginal sea
Underlain by oceanic crust
Thick salt deposits – almost dried up about 6 million
years ago
Fig. 11.14a
Mediterranean circulation
Fig. 11.14b
High rates of evaporation
 Mediterranean Intermediate Water very salty

Marine pollution

Any harmful substance or energy put into the
oceans by humans
 Harmful to living organisms
○ Standard laboratory bioassay – concentration of pollutant that
causes 50% mortality among test organisms
 Hindrance to marine activities (e.g., fishing)
 Reduction in quality of sea water
Waste disposal in ocean
Diluting pollutants with huge volume of ocean
water
 Long-term effects not known
 Debate about dumping wastes in ocean

 None at all ??
 Some, as long as properly disposed and
monitored ??
Main types of marine pollution
Petroleum
 Nutrient excess

○ Sewage sludge
○ Fertilizer runoff
DDTs and PCBs
 Mercury
 Non-point-source pollution and trash

○ Drainage from roads, canals, etc.
Petroleum

Biodegradable
hydrocarbons
 Recovery faster than
expected
○ Exxon Valdez oil spill,
1989
 But many organisms
killed outright
 Long-term
consequences
uncertain
○ Research is still being
done in this area,
some animal
populations have not
completely recovered
Fig. 11.16

BP Deepwater Horizon Oil Spill in Gulf
of Mexico
 April 20, 2010
 4.9 MILLION barrels of oil were leaked
 What are future effects?
Cleaning oil spills

Natural processes

Artificial processes
 Volatilization
 Oil dispersants
 Photo oxidation
 Isolate spill with
 Emulsification
 Biodegration by
pelagic organisms
 Biodegration by
benthic organisms
booms
 Skimming or
absorbing surface oil
slick
 Bioremediation by
“hydrocarbon-eating”
bacteria
Preventing oil spills
 Double
hulled oil tankers by 2015
 1990 Oil Pollution Act
 Burn
oil before it spreads
 1999 M/V New Carissa
http://www.ec.gc.ca/EnviroZine/images/aerial.jpg
http://www.modelshipmaster.com/products/ocean_liners/tube.jpg
Sewage sludge
 Semisolid
material after treatment
 No dumping of sludge in ocean after 1981
 Clean Water Act, 1972
 HOWEVER - many exceptions/waivers
New York’s sewage sludge disposal
First, shallow water sites
 Then (1986), deeper
water site
 Adverse effects on fish
 1993 all sewage disposed
on land

Fig. 11.25
DDT and PCBs

Pesticide DDT and industrial chemicals PCBs
(polychlorinated biphenyls)
○ DDT – pesticide that was widely used
○ PCBs – used in transformers and other areas of
industry
Widespread in oceans
 Persistent organic pollutants

 Toxic
 Long life dissolved in seawater
 Accumulated in food chain
 Bioaccumulation – it’s happening in us, also!
Bioaccumulation and biomagnification
Bioaccumulation – organisms concentrate
pollutant from seawater
 Biomagnification – organisms gain more
pollutant by eating other organisms

DDT

Decline in bird
populations and thin
eggshells




Long Island osprey
California brown pelican
DDT banned in U.S. in
1972
Some marine bird
populations rebounded
Mercury and Minamata disease
Methyl mercury toxic to most living organisms
 Chemical plants, Minamata Bay, Japan, released
mercury in 1938
 By 1950 first reported ecological changes
 By 1953 humans poisoned

 Neurological disorder
Bioaccumulation and biomagnification

Safe levels of mercury
determined by
 Rate of fish
consumption by people
 Mercury concentration
in fish consumed
 Minimum ingestion rate
of mercury to cause
damages
Non-point-source pollution and
trash

Not from underwater pipelines
 Hard to regulate
 For example, from storm drains
 Pesticides and fertilizers
 Road oil
 Trash
Trash from dumping

Some trash can be legally
dumped far from shore
 Biodegradable (e.g., food) or
 Sinkable (e.g., glass, metal)

Some trash cannot be dumped
 Plastic
○ Lightweight (floats)
○ Not easily biodegradable
○ Plastic can incorporate
pollutants, such as DDT and
PCBs
http://www.sciencepunk.com/v5/gallery/greenpeace_table.JPG
It is up to us!






Don’t throw trash out your car window
Don’t leave trash on the beach
Don’t throw trash off the side of your
boat
Don’t use fertilizers irresponsibly
Don’t just dump things down the drain
without reading about proper disposal
Get onto people you know that do this!
○ Think of your kids and grandkids!
Problems with Contaminants in
Oceans
Research into immunosuppression and
reproductive problems in many species
 Chemicals that are banned in US and
other countries are still used in others –
it is 1 ocean, doesn’t matter where it is
dumped

○ It will effect us all!
All drains lead to the ocean!
Fig. 11.32a,b
Misconceptions







Science and technology can solve all of our problems.
The Earth can absorb and neutralize any amount of waste
and pollution over time.
Dilution is the solution to the problem.
Microorganisms are not important to human survival.
Local people cannot improve their environments; it is out of
their hands.
If we run out of oil and gas we will just find more.
Earth is both an endless supply of resources and a limitless
sink for the waste products of our society.
Ocean Literacy Principles
1.d - Sea level is the average height of the ocean relative to the
land, taking into account the differences caused by tides. Sea level
changes as plate tectonics cause the volume of ocean basins and
the height of the land to change. It changes as ice caps on land
melt or grow. It also changes as sea water expands and contracts
when ocean water warms and cools.
 1.h - Although the ocean is large, it is finite and resources are
limited.
 5.f - Ocean habitats are defined by environmental factors. Due to
interactions of abiotic factors such as salinity, temperature, oxygen,
pH, light, nutrients, pressure, substrate and circulation, ocean life is
not evenly distributed temporally or spatially, i.e., it is “patchy”.
Some regions of the ocean support more diverse and abundant life
than anywhere on Earth, while much of the ocean is considered a
desert.
 5.i - Estuaries provide important and productive nursery areas for
many marine and aquatic species.

Sunshine State Standards

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



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
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
SC.6.E.6.1 - Describe and give examples of ways in which Earth's surface is built up and torn down by
physical and chemical weathering, erosion, and deposition.
SC.6.E.6.2 - Recognize that there are a variety of different landforms on Earth's surface such as
coastlines, dunes, rivers, mountains, glaciers, deltas, and lakes and relate these landforms as they apply
to Florida.
SC.912.E.6.6 - Analyze past, present, and potential future consequences to the environment resulting
from various energy production technologies.
SC.912.L.17.2 - Explain the general distribution of life in aquatic systems as a function of chemistry,
geography, light, depth, salinity, and temperature.
SC.912.L.17.3 - Discuss how various oceanic and freshwater processes, such as currents, tides, and
waves, affect the abundance of aquatic organisms.
SC.912.L.17.8 - Recognize the consequences of the losses of biodiversity due to catastrophic events,
climate changes, human activity, and the introduction of invasive, nonnative species.
SC.912.L.17.11 - Evaluate the costs and benefits of renewable and nonrenewable resources, such as
water, energy, fossil fuels, wildlife, and forests.
SC.912.L.17.13 - Discuss the need for adequate monitoring of environmental parameters when making
policy decisions.
SC.912.L.17.16 - Discuss the large-scale environmental impacts resulting from human activity, including
waste spills, oil spills, runoff, greenhouse gases, ozone depletion, and surface and groundwater
pollution.
SC.912.L.17.20 - Predict the impact of individuals on environmental systems and examine how human
lifestyles affect sustainability.