0
Excellent answer by Lila Koumandou here:
http://www.bluesci.org/index.php?option=com_content&task=view&id=127&Itemid=504
To summarize, it's because there is very little phosphate in the water to support plankton.
The nearly land locked waters are heated by the sun. This drives evaporation. The water grows more saline, and denser, until it sinks. This sinking occurs at the east end of the Mediterranean. Surface waters flow east to replace the sinking water. The dense salty water flows west on the bottom, and out the straight of Gibralter, carrying most of the nutrients with it. Cold surface water from the Atlantic flows in to replace it.
Interesting related points:
A similar process drives the Atlantic current, which is responsible for northwest Europe's relatively mild climate. The major difference is that the Atlantic current is mainly north-south. Heating takes place at tropical latitudes. The surface water flows north, getting saltier due to evaporation but also getting colder as it goes. It is losing heat to the winds that blow towards England and France. Massive sinking of cold, salty water in the extreme north Atlantic is what drives the rapid flow of the "gulf stream," which is just the most famous part of this system.
Flows of this sort occur in all the oceans and redistribute heat from the tropics toward to poles. Interruptions in these patterns may be what trigger ice ages. We are in an ice age now (no really, look it up) probably because the current positions of the continents tend to isolate the poles from ocean currents.
What else can I help you with?
What is important about the Mediterranean?
Mediterranean Sea is also important because its colour is so blue as compare to other sea.
Why is the Mediterranean sea so close to Malta?
Malta IS in the Mediterranean Sea!!
What color is the Mediterranean Sea?
a greenish blue color
Where are the Mediterranean Sea and the Black Sea located?
they love in a big blue planet
Seas that are near the Nile River?
The Nile flows into the Mediterranean Sea, so that is the closest sea to it.
Is Athens on the Aegean Sea or the Mediterranean Sea?
The Aegean sea is part of the Mediterranean Sea, so it is accurate to say both are true.
What is the capital of the Mediterranean?
The Mediterranean is not a country, so it does not have a capital. It is a Sea.
What body of water did the roman and Carthaginian's share?
The Mediterranean Sea.
What color is aegean?
Vivid blue. Aegean blue refers to the blue waters of the Mediterranean Sea between Greece and Anatolian peninsulas.
Where does the river nile rise?
The Nile empties into the Mediterranean Sea.
What sea is by Algeria?
Mediterranean Sea
What body of water would the Romans call the roman lake?
The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".The Mediterranean Sea. They referred to it as either "our lake" or "our sea".
