December 22, 2014 - Phytoplankton bloom off the coast of Tunisia

Phytoplankton bloom off the coast of Tunisia

Milky, yellowish-green swirls stained the waters off the coast of Tunisia in mid-December, 2014. These colors mark the site of a winter phytoplankton bloom. The churning tidal movement in these shallow seas plays a significant role in mixing nutrients into the waters, enhancing conditions required for the small organisms to begin to reproduce in abundance. The frequent sandstorms in this region also likely play a role, as dust and sand can seed the ocean with nutrients and spur rapid growth of phytoplankton.

The swirls are primarily in the Gulf of Gabes, to the west of the square-shaped island of Djerba, although some coloration is also visible in Mediterranean Sea east of Djerba. The Gulf of Gabes is a very shallow body of water which sits over the continental shelf of the African Plate. The depth of the Gulf is less than 200 meters. The bottom is rich is sediment, and is easily disturbed by the very large tides of the region. The difference between low and high tide can be greater than over 2 meters (6.6 feet).

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image on December 13, 2014.

Image Facts
Satellite: Terra
Date Acquired: 12/13/2014
Resolutions: 1km ( B), 500m ( B), 250m ( B)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC