What Every Student Ought to Know About
of Key Concepts
Bob Stewart (editor), and Gary
The national education standards for teaching science provide
little guidance for teaching about the ocean and atmosphere. As a result,
information about the oceans, atmospheres, and hydrology are usually taught
in separate, unconnected modules. Worse, many texts include much trivia,
neglecting the most important issues.
To provide teachers with better guidance, we have outline
what, in our opinion, every high-school student ought to know about the oceans
The following is our preliminary document listing key concepts
in oceanography. The document is open for comments and revisions by all who
are interested in teaching oceanography. What is appropriate, what is not?
Is the list complete? At what level should the different concepts be taught?
Regarding Earth System Science
- “We are not merely inhabitants of a planet, adapting ourselves
to it. Life has verily constructed the planet. It would not behave as it
does, even in its deep interior, were it not for life.” [Most of that
life was in the ocean.] —Oldroyd (1996: 297)
- Earth processes are the
result of many different, interacting biological, chemical, and physical
systems, many of which are strongly influenced by the ocean.
- The ocean stabilizes
climate and makes the Earth habitable, sending moist winds to bring
rain to the vegetation on land.
- Because we are now geologic agents capable of
interfering with the processes that make Earth a habitable planet,
we have become custodians of planet Earth.
Regarding Physical Geography
- The ocean covers 70 percent of Earth’s
surface and is on average 4 km deep.
- The continents are surrounded by
shallow shelf seas, from 0 to 100 m deep.
- There is only one ocean, and all
its parts are interconnected. The largest part is the Pacific, which is
half of the ocean. The rest are the Atlantic, Indian, Antarctic, and Arctic
- The location of important seas: Japan Sea, the Sea of Okhotsk, the
Bering Sea, the Gulf of California, the Caribbean Sea, the Gulf of
Mexico, the Hudson Bay, the Norwegian Sea, the North Sea, the Mediterranean,
the Black Sea, the Caspian Sea, the Arabian Sea, the Red Sea, the Persian
Gulf, and the Bay of Bengal.
- The locations of some of the most important
currents: Where the Gulf Stream flows and that it moves heat into the northern
North Atlantic. Where the California Current flows, and that it brings
cold water all the way down to the shores of Baja California. The location
of the subtropical gyre, north and south equatorial currents, and Alaskan
- Sea level is lower by 70 m than it would be if there were no ice
- Chemical studies of the distribution of isotopes and
trace chemical in water and sediments is leading to a new understanding
of climate change over the past hundreds to hundreds of million years.
- Ocean water contains about 36 grams of salt (dissolved
material) per kilogram of sea water (3.6% by weight). The ratio is called
- The main ingredients
of sea salt are sodium and chlorine.
- Elements required for life that are
in limiting supply in the ocean are phosphorus, nitrogen, silicon and iron.
varies little, but is slightly higher in regions of evaporation and slightly
lower in rainy regions, and near the mouth of rivers.
- The salt in sea water
increases the water density by 3.6%, it lowers the freezing point to -2
degrees C, so the the most dense water is at the freezing point, it greatly
increases the conductivity, so sea water is a good conductor, and it alters
- In contrast with the land, the ecology of the ocean is microbe based.
A large fraction of the biomass and biological activity in the ocean
is microscopic, and it is an important part of earth's carbon cycle. There
are more bacteria in the ocean than stars in the known universe, and
there are a thousand times more viruses than bacteria. Yet we know little
about the microbial ecology of the ocean because only one tenth of one percent
of the bacteria have ever been cultured.
- There are a million bacteria
of a thousand different types in a milliliter of sea water.
- There are more
viruses in sea water than all organisms combined, and they are a normal,
essential, and integral part of the food web.
- The entire ocean food web
relies on photosynthesis by phytoplankton, single-celled, microscopic bacteria
and protists living in the in the upper 200 meters of the ocean, that turn
carbon dioxide, nutrients, and sunlight into organic matter.
- About half
of the photosynthesis (net primary productivity) on earth occurs in the
- The burial of organic carbon, mostly in the oxygen-poor areas of
the ocean and in marshes and swamps along the sea, maintains the oxygen
in the atmosphere over millions of years.
- The oceanic food web is micro-centric.
The traditional “diatom-copepod-fish” food
chain has been expanded to include a vast microbial food web
whose ecology is only poorly known.
- Bacteria are a critical part of the
marine food web, processing more than half of all the flow of organic carbon.
in the ocean is for the most part limited by the availability of light,
N, P, Si, and Fe.
- Nutrients in surface waters tend to have the highest concentrations
along coasts, in shallow seas, and along the equator, and they are much
less abundant elsewhere.
- The deep ocean is filled with life, of great diversity,
most of which depends on the rain of carbon from above.
- There are deep ocean
ecosystems that rely on chemosynthesis... that is using chemical energy
from hydrothermal vents to synthesize organic carbon.
- High levels of nutrients
due to coastal pollution cause increased productivity, which in turn can
cause oxygen depletion in the water and “dead
- Coral reefs are among the most diverse
and productive communities on earth (Turner),
they are the richest of the tropical marine habitats,
they are an important part of the tropical ocean ecosystem,
they protect the shore inland of the reefs from storm
waves, tsunamis, and erosion, and they are a beautiful
example of how life creates planetary structures.
- Almost all coral reefs on earth have been altered by human
activity. Many have been severely degraded, some have been destroyed.
(Pandolfi et al, 2003)
- Overfishing and pollution are the primary causes
of coral reef decline. In addition, the recent rise in sea-surface temperatures
in many areas has caused coral bleaching, and the increased CO2
in the atmosphere, and hence in surface waters, is causing dissolution
and decline of the reefs.
- Each transfer to a higher level in the food chain
is only efficient 10% by mass.
- There are typically between 2 and 5 transfer
steps from the phytoplankton to large fish. The shortest chain is in upwelling
regions, the longest in the open ocean.
- The abundance of fishes depends on
these food chain properties.
- Students should know some common examples of
sea life. They should know the three domains of life: the archea, the eubacteria
(bacteria) such as prochlorococcus, and the eucaryotes. For single-celled
eucaryotes, they need to know coccolithophorids , diatoms, and
dinoflagellates. For protozoans: copepods, euphausids, tintinnids, and the
fact that larvae of all major types are present. They need to know that the
major large-animal phyla are arthropods, chordates and mollusks.
They should know that major multi-cellular organisms are grouped into
sponges, cnidarians (corals, jellyfish), echinoderms (starfish, sea urchins),
a number of worms (e.g., polychaetes), arthropods (pill bugs, crabs,
shrimps), mollusks (squids and octopuses, clams and mussels, snails and slugs)
and chordates (sea squirts -- with a tadpole-like larva -- jawless fishes,
sharks and rays, bony fishes, snakes and turtles, sea birds, sea mammals).
Among the mammals, they need to know that there are whales, sea cows
and seals. For whales, they need to distinguish baleen whales from toothed
- Steady winds produce
currents. Variations from region to region in the force of the steady
winds create geostrophic currents (The currents shown on maps and in textbooks).
- The top 100 meters of most of the ocean is warmed by the sun, and below
that is a vast pool of very cold water that fills the ocean basins.
- The cold
water is formed at high latitudes where seawater is cold and salty, and
it sinks to fill the ocean basins. The sinking of cold water at high latitudes
in the North Atlantic is an important part of the world-wide “conveyor
belt” that transports
water and heat around the world.
can reach only about 130 meters
into the clearest water, (the
depth where the light intensity
is 1% of its value at the surface)
and only a few meters into
turbid water close to shore,
limiting the depths where warming
and photosynthesis can occur
136). The sunlit surface layer
is called the daylight (euphotic)
zone. Below this there is no
sunlight, the very cold midnight
- Winds and currents mix the upper ocean.
- The moon and the sun are responsible
for making tides, causing sea level to rise and fall every 12 to 24
hours depending on location along the shore.
- Winds make waves, and storm
winds make big waves that can travel great distances.
- Tsunamis are generated
by earthquakes. Big earthquakes can generate waves that cause major damage
far away from the earthquake region.
- Most of the economic resources worth considering, mainly
a wealth of oil and gas and some fish, are on the shelf and
in the continental slope.
- Much of the trade of the world goes over the
- Economic activity along the coast causes pollution and
this conflicts with recreational values.
- The total value of fish landed
in the US is only about 4% of the total value of livestock
and poultry raised on the land in the US.
Regarding the Law
- The solutions to serious environmental problems will
elude us unless we are all aware of, and respect the profound
differences between the world of science and human affairs (See also Hardin,
1968 and 1998, in which he notes that most environmental problems
have no technical solution).
- All countries control access to resources within
200 nautical miles of their shores. This area is called the Exclusive
Economic Zone. All ships have the right to free passage through
- The largest expansion of territory under US sovereignty
occurred when President Reagan issued Proclamation 2030 on March 10, 1983
declaring a 200 mile economic zone for the United States. The proclamation
doubled the size of the country. It opened up 3.4 million square miles of
new territory, six times the size of the Louisiana Purchase, and 30% larger
than the land in the continental US. (Helvarg, 2003: 2; and Wilder, 1998:
- All countries control all activity
within three nautical miles of their shores, their territorial waters.
- The United Nations Convention on the Law of the Sea, which came into force
on 16 November 1994, sets forth navigational rights, territorial sea limits,
economic jurisdiction, legal status of resources on the seabed beyond the
limits of national jurisdiction, passage of ships through narrow straits,
conservation and management of living marine resources, protection of the
marine environment, a marine research regime, and a binding procedure for
settlement of disputes between States. The US Senate has not ratified the
Regarding Marine Geology and Geophysics
- The sea floor is poorly mapped, although recent global maps
based on satellite altimeter observations are much better
than older maps. Still, we have better maps of Moon, Venus, and
Mars than we have of the sea floor.
- "Marine life changed the planet’s appearance through its
cumulatively astonishing biomineralization, which has amassed enormous
volumes of carbonate sediments, and subsequent tectonic processes turned
many of these sediment into Earth’s most formidable mountain ranges.” —Smil (2003: 230)
- The sea
floor is relatively
with the continents.
The oldest sea floor
is only about 180 million
years old, while the
oldest continental rocks
are more than 3 billion
- The sea floor is young because plate tectonics continuously regenerates the sea floor. New sea floor
is created at mid-ocean ridges and consumed in oceanic trenches.
- Newly created sea floor is magnetized by earth’s magnetic field,
recording the many changes in earth’s magnetic field
over the past 150 million years, and providing key
support for the theory of plate tectonics.
- Crustal rocks below the
sea floor cool and become denser as they move away from the mid-ocean ridges.
When this cold, dense crust plunges into the mantle under trenches, it
pulls oceanic crust with it, helping to drive plate motion.
in the mantle brings hot liquid rock to the surface in hot spots such as
Hawaii and Iceland.
- Sediments in the deep ocean
come primarily from the shells of
microscopic marine organisms such
as coccolithophores, diatoms and
foraminifera, from cosmic dust (tiny
meteorites), and directly precipitated
from the water (manganese nodules).
- Sediments on continental shelves come primarily
from the land.
- A volume of water equal to the volume of the ocean circulates
through the sea floor and upper
lithosphere in a few million years. It enters into sediments on either side
of mid-ocean ridges and exits through hydrothermal vents along the crest
of the mid-ocean ridge system.
- Water circulating through the sea floor
extracts minerals from the crust in a manner similar to weathering, and
the minerals reach the ocean through hydrothermal vents,
- The sea floor
is not a flat plain. It has a worldwide chain of mountains, the mid ocean
ridge, many old and new volcanos, many of which are below sea level, fracture
zones, plateaus, and deep trenches.
- There is more water in the ocean than
fits within the ocean basins. The overflow creates the continental shelves.
The volume changes over geologic time as does the extent of
continental shelves and the biological productivity at the
edges of the sea.
Regarding the Role of the Ocean in Weather and Climate
- We cannot understand
climate and climate change without understanding the ocean. The ocean dominates
the global energy, carbon, and hydrological systems.
- Most of the solar energy
reaching earth is absorbed by the ocean.
- The ocean lose heat primarily
by evaporation, a process called latent heat release.
- Heat lost by the
ocean drives the atmospheric circulation, mostly when water vapor condenses
as rain, mostly in the tropics, especially in the atmosphere above the
tropical Pacific and Indian oceans. Evaporation of water from warm seas
provides the energy to drive hurricanes.
- El Niño, the most important
cause of changes in global weather
patterns, is the result of changes in the way heat is released to the
atmosphere in the Pacific.
- The scientific challenge of predicting
El Niño is very different
from the challenge of mitigating the impact of an imminent El Niño.
A failure to
due to increases
in carbon dioxide in
the atmosphere will
alter El Nino.
- The hydrological cycle is dominated by the tropical oceans.
Most of the rain
that falls on land comes from the tropical oceans.
- The ocean helps keep
earth’s temperature constant from
day to night and summer
to winter by storing and releasing heat and water.
- Currents help carry
heat from the tropics to mid latitudes.
- Earth’s climate has been
very different in the past. By collecting
information about past climates and climate change we are much better
able to understand our present climate and how it might change as we add
CO2 to the atmosphere. (See 1. in Regarding Chemistry).
- Forty times more carbon dioxide is
stored in the ocean than in the atmosphere.
The carbon cycle in the ocean and the calcite
compensation depth greatly influence earth’s climate.
- Large quantities
of methane (a potent greenhouse gas) is frozen in the
sediments of the continental margins, posing a threat to climate if warming
- Changes in the ocean’s deep circulation have
produced large, rapid changes in the climate during
the last 50,000 years.
Regarding Coastal Processes
- The number of people living
close to the ocean grows by about
30 million a year worldwide, putting
great stress on coastal ecosystems,
- Storm waves and currents erode the coasts,
and most coasts move slowly inland
at a rate of a few feet per century along rocky coats, and several meters
per year along low, sandy coasts.
- Most beach sand is carried
to the coast by rivers and redistributed by currents. Damming rivers, and
building structures along coasts interrupt the flow leading to increased
- The biodiversity of coastal marine areas is threatened
by over exploitation and overfishing, as well as by
pollution. Example include the effects of deforestation on reefs, along shores
where the hinterland has forests. Alien species carried into new areas by
people can upset local communities. Coastal pollutants come mostly
from the land. They include nutrients, heavy metals, trash, and
pesticides carried from cities and farms by runoff and sewers.
and salt marshes are important parts of the marine ecosystem. They are
home to many plants and animals, and they they are the nursery for many types
of coastal and open ocean invertebrates, fish, and wildlife.
- Oceanographers are relying more and more on satellites,
drifters, subsea observatories and unmanned submersibles to study
the ocean. Fewer and fewer are going to sea. Most do not scuba
- Ocean-observing satellites have revolutionized our understanding
of the ocean by producing global,
daily to weekly maps of winds, surface currents, surface temperature,
solar heating, and ocean color due to phytoplankton concentration.
are relying more and more on satellites, drifters, subsea observatories
and unmanned submersibles to study the ocean. Fewer and fewer are going
to sea. Most do not scuba dive.
- Ocean-observing satellites
have revolutionized our understanding of the ocean by producing global,
daily to weekly maps of winds, surface currents, surface temperature, solar
heating, and ocean color due to phytoplankton concentration.
of drifting buoys are now measuring ocean currents, temperature, and salinity
in the upper kilometer of the ocean. Thousands of large tagged fish are
providing information on their location and environmental conditions.
ocean is so complex oceanographers must use computer models to help understand
the ocean. The models process observations; they calculate currents, temperature,
and density; and they describe the interactions among systems. “Modeling
has become a mainstream activity. Today’s biological oceanography
student is more likely to have a model than a microscope.” (Barber
and Hilting, 2000: page 19)
- Models that combine winds, currents, and temperature
are being used to produce forecasts of ocean currents many
weeks in advance.
- The number of large vertebrates in the ocean, including whales, seals,
sharks, fish, and turtles, are only a few percent of their original,
pre-industrial values (Jackson et al, 2001, Myers
and Worm, 2003).
large vertebrates are gone and are not recovering because they or their
prey have been caught or continue to be caught by humans. There are almost
40,000 industrialized fishing vessels fishing the ocean.
- Population growth
is driving up the worldwide demand for fish, which has caused the world’s
fish catch to declined since the 1980’s.
- Marine fishes off developing
countries are being overfished because the countries lack the ability
to enforce fisheries laws.
- There is an unequal competition for the ocean's
fish resources, with the nations having factory ships winning, and small
coastal nations using traditional fishing methods losing out.
- A major culprit
in overfishing is the industrialized, pelagic longlining, gill netting,
and trawling which indiscriminately fish the ocean.
- Regardless of gear type,
unenforced fishing is unregulated fishing.
- We get out of this mess through
change in policy and science.
- The primary goal of new policy is to control
fishing effort at a sustainable level.
- The best way to protect fish stocks
is to set aside no-fishing zones and perhaps limit the gear to be used.
The precautionary principle (in the absence of certain knowledge) must be
used to better advantage.
Richard T. and Hilting, Anna
K. (2000). Achievements
in biological oceanography In:
of Ocean Discovery: National Science Foundation 1950–2000.
National Academy Press.
Hardin, G. (1968). "The
tragedy of the commons." Science
162 (3859): 1243-1248.
Hardin, G. (1998). "ESSAYS
ON SCIENCE AND SOCIETY: Extensions of The Tragedy
of the Commons?" Science 280
Helvarg, David (2001). Blue Frontier:
Living Seas. Henry Holt and Company.
Jackson, J. B. C., M. X. Kirby, W.
H. Berger, K. A. Bjorndal, L. W. Botsford, B. J. Bourque, R. H. Bradbury,
R. Cooke, J. Erlandson, J. A. Estes, T. P. Hughes, S. Kidwell, C. B. Lange,
H. S. Lenihan, J. M. Pandolfi, C. H. Peterson, R. S. Steneck, M. J. Tegner
and R. R. Warner (2001). "Historical
Overfishing and the Recent Collapse of Coastal Ecosystems." Science 293 (5530):
Jumars, P. A. (1993). Concepts in Biological
Oxford University Press.
Myers, R. A. and B. Worm (2003). "Rapid worldwide
depletion of predatory fish communities." Nature 423 (6937): 280-283.
D. R. (1996). Thinking About the Earth: A History
of Ideas in Geology.
Cambridge Massachusetts, Harvard University Press.
Pandolfi, J. M., R. H.
Bradbury, E. Sala, T. P. Hughes, K. A. Bjorndal, R. G. Cooke, D. McArdle,
L. McClenachan, M. J. H. Newman, G. Paredes, R. R. Warner and J. B. C.
Jackson (2003). "Global
Trajectories of the Long-Term Decline of Coral Reef Ecosystems." Science 301 (5635): 955-958.
V. (2002). The Earth's Biosphere. Cambridge Massachusetts, MIT Press.
Robert J. (1998). Listening to the Sea: The Politics
of Improving Environmental Protection. University of Pittsburgh Press.
Please send comments to Dr.
Bob (Bob Stewart).
16 July, 2008
6 January, 2009