Geoscience Reference
In-Depth Information
I. Open ocean (6 trophic levels)
nanoplankton
(flagellates)
microzooplankt
on
(protozoa)
macrozooplankt
on
(copepods)
megazooplankton
(chaetognaths)
zooplanktivorous fish
(myctophids)
piscivorous fish
(tuna, squid)
II. Continental shelf (4 trophic levels)
macrozooplankton
(copepods)
zooplankivorous fish
(herring)
piscivorous fish
(salmon, shark)
microphytoplankton
(diatoms, dinoflagellates)
benthic herbivores
(clams, mussels)
benthic carnivores
(cod)
III. Upwelling regions (3 trophic levels)
planktivorous fish
(anchovy)
macrophytoplankton
(chain-forming diatoms)
or
megazooplankton
(krill)
planktivorous whales
(baleen whales)
Figure 11.19
A comparison of food chains in three different marine habitats with organisms representing each trophic level as
selected examples. (Organisms not to scale.)
Source: Lalli and Parsons (1997)
wave also catches up on decelerating waves ahead,
compressing the wave train and so shortening wavelength.
This is demonstrated dramatically by
seismic sea waves
or tsunamis, triggered by earthquakes. They can travel at
over 500 km h
-1
but at almost imperceptible heights of less
than 0ยท5 m - until they decelerate on approaching land,
where wave heights build progressively and catastrophi-
cally to 30 m or more. Geomorphic impacts of wave-
related processes are examined in
Chapter 17.
Ma old, owing to the repetitive growth and consumption
of dense oceanic crust through the supercontinental cycle.
In that time a former super-ocean has shrunk considerably
(surviving mainly in the Pacific), the Atlantic and
southern oceans have formed and the Arctic Ocean has
become encircled by continents. Oceans play an important
but hidden role in most stages of the rock cycle, since
their products are concealed until uplift or sea-level fall
exposes them. Modern oceanic research reveals the extent
to which environmental history is both influenced by,
and recorded in, the oceans. Observed changes in ocean-
atmosphere coupled systems and more sophisticated
AOGCMs justify much greater interest in our oceans and
ocean basins.
CONCLUSION
Earth's ocean basins are its largest individual surface
feature and also collectively its youngest, at less than 200
