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Sargassum Provides Essential Habitat

To view a video of a dynamic powerpoint presentation by Executive Director of Science & Technology Dr. Brian Lapointe click on the following link:

Secrets of the Sargasso Sea

Although the genus Sargassum are present throughout the temperate and tropical oceans of the world, Sargassum may be best known for its free-floating species (S. natans and S. fluitans). These drift species of Sargassum never attach to the seafloor and are thus considered to be pelagic (living in the open sea.) These species of Sargassum provide one of the most essential habitats on the planet to support productive food webs for many endangered species including sea turtles and fish. Because Sargassum species form the foundation for the food web, their ongoing propagation is vital to dependent species. Fortunately, Sargassum  propagates (reproduces)effectively through vegetative fragmentation-where new organisms grow from a fragment of the parent. The “Sargasso Sea” was named in recognition of the fact that the North Atlantic sub-tropical gyre (where four converging currents form a boundary around a “borderless sea”) is the home of a tremendous amount of this essential floating habitat.

Filefish in Sargassum

COAST’s Executive Director of Science and Technology Dr. Brian Lapointe has been working withSargassum for decades and his research paper, “A Comparison of Nutrient-Limited Productivity inSargassum natans from Neritic vs. Oceanic waters of the Western North Atlantic Ocean” (available here) reveals that Sargassum productivity is enhanced by increased levels of the nutrients phosphorus and nitrogen in neritic (coastal) waters when compared to Sargassum in the oceanic waters of the North Atlantic.  Dr, Lapointe’s research asserts that enhanced productivity in Sargassum along the coast is a result of a variety of nutrient inputs including groundwater discharge, atmospheric pollution, and runoff from agricultural and other human wastewater sources.  The paper also hypothesizes that these productive coastal Sargassum patches flow up through the Gulf Stream and have coupled with the deeper oceanic strains of Sargassum which has facilitated the growth of pelagic Sargassum in the nutrient-poor (oligotrophic) surface waters of the Sargasso Sea.

Sargassum Windrow


To build on Dr. Lapointe’s past research, COAST is now working to assess the ecology (the study of the relationships between organisms and their environments) of the Sargassum and the community of organisms it supports to investigate what factors support high productivity  and how to stop the decline in the amount of quality Sargassum habitat.  This study will illustrate the importance of protecting this unique habitat for numerous species such as bluefin tuna and will be aimed at building momentum to support the enhanced management of the Sargasso Sea.
Dr. Lapointe has also acted as Principal Investigator on research that involved monitoring pelagic Sargassum for oil and tar balls to assess the large-scale impacts of the Deep Water Horizon oil spill. These types of efforts will continue for COAST as we work towards enhancing management of these unique ecosystems.

Fortunately, there are ongoing efforts to promote enhanced management of Sargassum and the famed Sargasso Sea. An NGO has been formed called the Sargasso Sea Alliance. The Alliance is being led by the Bermuda Government and is exploring what international mechanisms are available to improve management of what Sylvia Earle calls the “the golden rainforest of the ocean.” To learn more about the Sargasso Sea Alliance you may visit their official website at:

Also, it should be noted that GOBI- The Global Ocean Biodiversity Initiative- is working towards the designation of the Sargasso Sea as an EBSA (Ecologically and Biologically Significant Area) by the UN, which would protect the Sargasso Sea as a globally unique marine ecosystem. To learn more you can visit:


1 Comment
  1. Who knew that seaweed was so important to ocean ecology?

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