 Home
 About AIMS
Research
Facilities
News
Search
Site
map
Site
index
Topics
index
|
Coral
sea region billfish atlas
Plateaus,
Troughs and Trenches
This region is one
of extremely complex underwater bathymetry.
Currents, upwellings of nutrient-rich waters and
concentrations of fish, even in the waters
closest to the surface, can be profoundly
influenced by underwater mountains and valleys a
kilometre or more below them. For example, major
seasonal concentrations of black marlin occur in
oceanic troughs, such as the Queensland Trough
and the Okinawa Trough in the East China Sea.
Pre-spawning aggregations of striped marlin off
eastern Australia are closely associated with
surface waters far above deep underwater ridges
and seamounts. Broadbill, too, tend to
concentrate over and around seamounts.
Geologists
have classified bathymetric features by specific
names.
| Trench |
a narrow, elongate depression of
the deep-sea floor, with steep sides,
oriented parallel to the trend of the
continent and between the continental
margin and the abyssal hills. Such a
trench is about two kilometres deeper
than the surrounding ocean floor and may
be many kilometres deep. |
| Trough |
an elongate depression of the
sea floor that is wider and shallower
than a trench, with less steeply dipping
sides; a trough may develop from a trench
by becoming filled with sediment. |
| Basin |
a depression in the sea floor
more or less as long as it is wide. |
| Ridge |
an elongate, steep-sided
elevation of the ocean floor, having
rough topography. |
| Seamount |
an elevation of the sea floor,
1000m or higher, either flat-topped
(called a guyot) or peaked (called a
sea-peak). |
| Plateau |
a broad, more or less
flat-topped and ill-defined elevation of
the sea floor, generally over 200m in
elevation. |
 |
This
map shows the major bathymetric
features of the Billfish Atlas. Click
on the map to view a high resolution
image. (1400Kb 1600x1100) Not
recommended if you have a slow
Internet connection.
To
return to this page use your
browser's back button.
|
AIMS
home page
web@aims.gov.au
Last updated - 22 August 98
Copyright ©1996-1998 Australian Institute of
Marine Science
URL
http://www.aims.gov.au
|
