Marine Protected Areas (MPAs): Sargasso Sea


 Map of Sargasso Sea

Photo 72: Map of Sargasso Sea.
(NOAA Photo Library.)

The Sargasso Sea is located entirely within the Atlantic Ocean and characterized by the presence of holopelagic Sargassum. Holopelagic Sargassum is free-floating algae that remains in the open ocean for its entire life cycle. No other marine region, anywhere in the world, is known to support a community of holopelagic algae.

The Sargasso Sea lies within the Northern Atlantic Subtropical Gyre where ocean currents define the Sargasso’s boundaries. The Gulf Stream establishes the Sargasso Sea’s western boundary, while the Sea is further defined to the north by the North Atlantic Current, to the east by the Canary Current, and to the south by the North Atlantic Equatorial Current.

The self-sustaining Sargassum serves a variety of functions for a diverse range of marine species throughout the Sargasso Sea. Turtles use Sargassum mats as nurseries where hatchlings have food and shelter. Sargassum also provides essential habitat for marine species, such as shrimp, crab, and fish, that have adapted specifically to this floating algae. The Sargasso Sea is a spawning site for threatened and endangered eels, as well as white marlin and dolphinfish. Humpback whales annually migrate through the Sargasso Sea. Commercial fish, such as tuna, and birds also migrate through the Sargasso Sea and depend on it for food.

Smaller fishes, such as filefishes and triggerfishes, reside in and among the brown Sargassum

Photo 71: Smaller fishes, such as filefishes and triggerfishes, reside in and among the brown Sargassum
(NOAA Ocean Explorer Gallery.)

The Sargasso Sea faces potential harm from a variety of sources. These sources include pollution from ship– and land-based sources and the harvesting of Sargassum for use as fertilizer and biofuels. The Sargasso Sea ecosystem also may be vulnerable to global threats such as climate change and ocean acidification.

The open-ocean ecosystem of the Sargasso Sea generally lies beyond the jurisdiction of any country. One exception is the portion of the Sargasso Sea surrounding Bermuda. Although Bermuda is undertaking various steps to protect the sea within its jurisdiction, improved protection of the Sargasso Sea requires international coordination. Such coordination is being pursued under international instruments such as the International Commission for the Conservation of Atlantic Tunas (ICCAT) and through organizations such as the Sargasso Sea Alliance.

The Sargasso Sea Alliance is an initiative to secure international recognition of and protection for the Sargasso Sea through the use of existing legal mechanisms and the support of governments and international organizations. This effort is led by the Government of Bermuda in coordination with scientists, international marine conservation groups and private donors. Four objectives guide the Alliance. These are:

Additional reference information: Some of these links are to external sites.

U.S. Resources

International resources


 Last updated September 8, 2020