Sea of Marmara: Where Ancient Myth and Modern Science Mix
MODIS image of the Sea of Marmara, acquired on
June 25, 2003, showing a bloom of coccolithophorids covering the
entire sea basin.
1 km resolution JPEG image of entire region
500 meter resolution JPEG image (entire region)
250 meter resolution JPEG image (entire region)
To the north, accessible through the narrow and vital Bosporus Strait,
are the strange waters of the Black Sea. To the south, through
the critically important Dardanelles (known in ancient times as the
Hellespont), lies the historically reknowned Aegean Sea.
In between, and perhaps somewhat ignored, is the Sea of Marmara,
which gets its name from the Greek word for marble. The Sea of
Marmara is an important link for shipping between the Mediterranean
and the Black Sea (including tankers of oil from Russia, which figured in
the plot of a recent James Bond movie) but it might seem less significant
than other, more familiar bodies of water.
Tranquil scene of the Bosporus as a tanker
approaches the entrance to the Black Sea.
Yet as the stunning MODIS image of the Sea of Marmara above
demonstrates, there is plenty of interest for biological and
physical oceanographers to learn about the Sea of Marmara.
This single scene portrays some of the intriguing interplay
of geography, geology, biology, and physics that occurs in this
unique location.
Wondering why the Sea of Marmara is such a bright turquoise color in this
image?. The answer to that is simple;
the color is due to a coast-to-coast bloom of the ubiquitous
coccolithophorid species Emiliania huxleyi. According to Dr. Temel
Oguz - professor in the Institute of Marine Sciences of Middle
East Technical University in Icel, Turkey - the Sea of Marmara
normally has a three-phase phytoplankton bloom sequence: diatoms
in March, dinoflagellates in April, and E. huxleyi in May-June,
which is similar to the pattern observed in the Black Sea.
The MODIS image above captured the E. huxleyi bloom near its
peak. Below is a time-sequence of SeaWiFS images showing the
development of the E. huxleyi bloom in the Sea of Marmara in
spring 2003.
Compilation of SeaWiFS
images showing the development of the coccolithophore bloom in the
Sea of Marmara in spring 2003.
High-resolution
JPEG image of the Sea of Marmara bloom time-series, approx. 2 MB
High-resolution
PNG image of Sea of Marmara bloom time-series, approx. 10 MB
The MODIS image demonstrates how the Sea of Marmara is affected by
the physical dynamics of the Black Sea, and how it affects the Aegean
Sea. A dark tendril of water is visible emerging from the Bosporus
Strait into the Sea of Marmara, indicating the strength of the Black
Sea surface outflow. Even more striking is the extension of the Sea
of Marmara coccolithophore bloom into the Aegean Sea, demonstrating the
influence of the surface current flowing out of the Dardanelles.
These bodies of water are in balance, or else the surface of
these seas would be rising or falling if the flow of water into one was not
counterbalanced by an approximately equal flow of water out of another.
A previous Science Focus! article,
Creeping Dead Zones, includes a schematic diagram of the circulation
in the Black Sea. The surface flow out of the Black Sea and the Sea of
Marmara into the Aegean Sea (and eventually the Mediterranean Sea),
is approximately 600 cubic kilometers per year. This flow is
balanced by an annual input of 300 cubic kilometers of water from rivers
entering the Black Sea, notably the Danube River, and a roughly equivalent subsurface return flow of more saline Mediterranean Sea water. As the denser
water from the Mediterranean flows back into the Black Sea, it sinks, maintaining the "stratification"
(density layering) of the water column and the oxygen-free state of the
Black Sea depths. The surface layer of the Black Sea is considerably less
saline than the salinity of the Mediterranean due to the freshwater
input from rivers.
The low-salinity inflow of water from the Black Sea and the Sea of
Marmara, illustrated by the plume of coccoliths, is very important to
the physical oceanography of the Aegean Sea. The movement of this
water, which remains at the surface due to its lower density, can
be tracked through the Aegean into the Mediterranean Sea.
Finally, regarding the mythical and historical importance of the
Dardanelles and the Sea of Marmara: the ancient city of Troy
commanded the approach to the Dardanelles, which made it a vital
and wealthy trading port and a sea link to Byzantium
(Constantinople/Istanbul). Even though mythology attributes the
main cause of the Trojan War [if it occurred; ancient historians
are not in agreement abou that] to a dispute over a lovely woman named
Helen, the more likely economic cause was the desire of the Greek
kingdoms to remove the dominance of Troy over the sea trade lanes to
the Black Sea, through the Sea of Marmara.
Acknowledgements
This Science Focus! article benefited substantially from an
expert review by Dr. Temel Oguz, Middle East Technical University.
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