SARGASSUM: FROM SEA TO SHORE

What is Sargassum, where does it come from, and what happens when it washes ashore?

Sargassum is a type of floating brown
algae. Historically, the majority of
Sargassum aggregated in the Sargasso
Sea in the western North Atlantic. In
2011, the geographic range expanded
and a new source region emerged.
Shifting wind patterns has led to a newly
established population, the “Great
Atlantic Sargassum Belt.” Massive
amounts of Sargassum from this area are
transported west into the Caribbean Sea,
Gulf of Mexico, and tropical South
Atlantic via ocean current systems.

Pelagic Sargassum

2

Pelagic Sargassum provides habitat, food
resources, protection, and breeding
grounds for hundreds of diverse marine
species. This includes commercially
important fisheries species such as gray
triggerfish, amberjack, and mahi mahi
that feed on the smaller marine life
present in Sargassum mats. In the South
Atlantic, Gulf of Mexico, and the
Caribbean, areas of Sargassum are
designated as Essential Fish Habitat.
Juvenile sea turtles and sea birds also
use Sargassum for feeding and shelter.
In the South Atlantic and portions of the
Gulf of Mexico, Sargassum is designated
as Critical Habitat for threatened
loggerhead sea turtles under the
Endangered Species Act.

rafts/lines

Sargassum
inundation
event

©

Sargassum inundation events (SIEs)
occur when rafts are carried to shore by
winds and currents. These events are a
type of harmful algal bloom that can
adversely impact coastal ecosystems,
tourism, and public health. SIEs can form
brown tides nearshore, smothering fauna
and flora including coral reefs. Fresh
Sargassum mats can clog water intake
pipes at critical infrastructure like
desalination plants for drinking water.
Sargassum contains high levels of
arsenic and other heavy metals, organic
contaminants, and marine debris.
Sargassum decomposing on the beach
also produces hydrogen sulfide, which
can cause respiratory irritation. Cleanup
options are limited and costly.

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$ Great Atlantic “ES

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* Sargassum belt my %S =
oo 8 6,8 .

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NOTE: This diagram is not drawn
to scale and is meant for
illustrative purposes only


SARGASSUM: FROM SEA TO SHORE

What is Sargassum, where does it come from, and what happens when it washes ashore?

HABITAT MANAGEMENT

A # Sargassum is designated as Essential Fish
me” Habitat (EFH) for several species

“Ne managed by fisheries management
councils in the South Atlantic, Gulf of

' Mexico, and the Caribbean, including: gray
triggerfish, amberjacks, and mahi mahi.
EFH status does not restrict harvest, but
NOAA Fisheries consultation is required for
activities in EFH areas. In a separate manage-
7 ment plan, NOAA Fisheries further prohibits
harvest of Sargassum in all U.S. federal waters
south of the NC/SC state boundary.

NOAAs Atlantic Oceanographic and
Meteorological Lab (AOML) and National
Environmental Satellite, Data, and ie
Information Service (NESDIS), and the U.S. SQ&
Integrated Ocean Observing System
(IOOS) and regional Caribbean CariCOOS
monitor and track Sargassum, producing
weekly Sargassum |Inundation Risk Maps.
Ongoing research leverages citizen science
reports to improve this product.

RESEARCH ON IMPACTS RESPONSE AND MITIGATION

NOAAs National Centers for Coastal
Ocean Science (NCCOS) is investigating
the presence of heavy metals and
contaminants in Sargassum mats. NCCOS
funded partners are improving technologies
to detect and forecast Sargassum and
associated impacts during inundation
events, engaging with stakeholders to design
more accurate and timely warnings, and
studying the socioeconomic impacts of
Sargassum beaching.

ADDITIONAL LINKS AND RESOURCES

NOAA Fisheries Southeast Regional Office, Frequently Asked Questions Regarding Annual Inundations of Sargassum in the Southeastern United States
NOAA AOML, Sargassum Frequently Asked Questions

NOAA CoastWatch, Sargassum General Information and FAQs

NOAA AOML and University of South Florida, Experimental Weekly Sargassum |Inundation Report

NOAA OR&R, On Sea Turtles, Seaweed, and Oil Spills

NOAA OR&R, Oil Spills and Pelagic Sargassum Planning and Response Considerations

Puerto Rico Sea Grant, Sargassum Impacts at Palmas del Mar

PHOTO CREDITS

Track and Forecast: Marine Macroalgae Research Lab - Florida International University (MMRL - FIU)

Research on Impacts: Life on the Edge 2004, https://photolib.noaa.gov/Collections/Voyage/Other/emodule/1340/eitem/77225
Habitat Management: Florida Fish and Wildlife, https://creativecommons.org/licenses/by-nd/2.0/

Response and Mitigation: NOAA OR&R

NOAA‘s Office of Response and Restoration
(OR&R) engages in declared disasters for
inundation events. The Office of Coastal
Management (OCM) provides on-the-ground
expertise to affected communities. NCCOS
coordinates cross-agency actions through
the Interagency Working Group for the
Harmful Algal Bloom and Hypoxia Research
and Control Act (HABHRCA) and funds
research to understand and manage harmful
algal blooms.