[Coral-List] Sargassum

[Ulf Erlingsson]

In general terms, the Sargasso Sea is a "hill" in the ocean, created  
by the Coriolis effect as the Meridional Overturning Circulation  
(MOC) circles around it. The MOC is deep, narrow and fast in the west  
(the Gulf Stream), and wide, shallow, and slow in the east (about the  
eastern half of the North Atlantic Ocean. The Coriolis effect pushes  
water to the right, in to the center of circulation, and the hill is  
created. The slope from the hill out balances the Coriolis effect.

If the MOC would weaken, the water would tend to flow from the  
central hill in the Sargasso Sea and out in the gyre. If this happens  
on the eastern or southern side, the sargassum might be expected to  
reach the Lesser Antilles. So far it is simple physics.

What I would look for would thus be indications of a weakening MOC.

Ulf Erlingsson


On 2011-08-12, at 10:59, Arlo Hemphill wrote:

> Dear Jean-Philippe,
>
> Is there any more information you can share on the fishermen  
> reports of unusual oceanographic conditions? Or is there data, a  
> report or overview on these changes available elsewhere?
>
> I am in 100% agreement with your hypothesis that the influx of  
> Sargassum is more related to changes in oceanography (perhaps  
> climate change induced?) than to a sudden proliferation of the algae.
>
> Best,
>
> Arlo Hemphill
>
>> On 8/10/2011 2:08 PM, OMMM Association wrote:
>>> Sargassum species here (Sargassum fluitans probably) are actually
>>> pelagic sargassum that develop at the surface of the water and are
>>> not attached to the substratum. Those algae can bloom in case of
>>> critical amount of nutrient inputs, that might be the cause of the
>>> amount of algae we ahve today. Another reason might be the global
>>> change in the current systems along the Eastern Caribbean that was
>>> not as usual as reported by fishermen in the area. But we would be
>>> interested in looking at the history of this phenomenon as I started
>>> to observe large plates of sargassum by mid May all across the  
>>> Lesser
>>> Antilles. At this time the algae was not accumulating along the  
>>> coast of
> the islands.
>>>
>>> Jean-Philippe
>>>
>>> ****************************************************
>>> Dr Jean-Philippe Mar?chal, DSci
>>> Director
>>> Observatoire du Milieu Marin Martiniquais
>>> 3 avenue Condorcet
>>> 97200 Fort de France
>>> Tel : +33 (5) 96 39 42 16
>>> http://www.ommm.org
>
> Sent from my iPhone
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