Franks, J.S.

Johnson, D.

Ko, D.S.

Moreno, P.

Sanchez-Rubio, G.

English

Aquatic Commons

 Proceedings of the 65th Gulf and Caribbean Fisheries Institute                  November 5 – 9, 2012   Santa Marta, Colombia 
The Sargassum Invasion of the Eastern Caribbean and Dynamics of the  
Equatorial North Atlantic 
 
Invasión de Sargazo en el Caribe Oriental y la Dinámica en la  
Zona Ecuatorial del Atlántico Norte 
 
L'Invasion de Sargasse dans les Caraïbes Orientales et leur Dynamique dans la  
Partie Nord de l'Atlantique Ėquatorial 
 
DONALD R. JOHNSON1*, DONG S. KO2, JAMES S. FRANKS1,  
PAULA MORENO1, and GUILLERMO SANCHEZ-RUBIO1 
1Center for Fisheries Research and Development, Gulf Coast Research Laboratory, University of  Southern Mississippi, 
Ocean Springs, Mississippi 39564 USA. *donald.r.johnson@usm.edu. jim.franks@usm.edu. paula.moreno@usm.edu. 
guillermo.sanxhez@usm.edu.  2Ocean Dynamics and Prediction Branch, Naval Research Laboratory,  
Stennis Space Center, Mississippi 39529 USA. dong.ko@nrlssc.navy.mil. 
 
EXTENDED ABSTRACT 
In the spring and summer of 2011, unprecedented quantities of pelagic sargassum came ashore on many islands of the 
eastern Caribbean (Figure 1), seriously affecting fishery and tourism industries. Concurrently, pelagic sargassum also 
washed ashore in massive amounts along the coasts of western Africa (Sierra Leone and Benin) and was spotted in large 
mats by aircraft off northern Brazil (Széchy et al. 2012). Two species were identified in the invasion: Sargassum natans and 
Sargassum fluitans, both of which coexist throughout the North Atlantic with large mats and long lines commonly found in 
the Sargasso Sea (Winge 1923) and in the northern Gulf of Mexico (Comyns et al. 2002). Using satellite tracked mixed-
layer drifters during 2010 and 2011 we were unable to connect the Caribbean invasion to the central North Atlantic and the 
Sargasso Sea. However, from archived results of a numerical circulation model (HYCOM), back-tracking from where 
landfalls were reported suggested that the sargassum may have bloomed in the north equatorial recirculation region (NERR) 
where conditions in the spring/summer of 2010 were conducive to growth and consolidation. Further backtracking from the 
NERR indicated that the equatorial water carrying the sargassum came from the south Atlantic where the presence of these 
species has not been verified. This suggests that the sargassum bloomed in the NERR where it flourished under high ocean 
temperatures and high nutrient inputs and was entrained in south Atlantic water. It may have recirculated for an extended 
time in the NERR before being released into the North Brazil Current (Fonseca et al. 2004) flowing into the eastern 
Caribbean or drifting to the coast of western Africa. 
 
Figure 1.  Locations of Sargassum landfall or where large mats/lines 
were spotted by aircraft – black squares.  Ellipse roughly outlines the 
North Equatorial Recirculation Region – formed seasonally by the 
equator, the North Equatorial Counter Current and the North Brazil 
Retroflection. 
    Johnson, D.  et al.    GCFI:65   (2013) Page 103 
 
The NERR region extends from the equator to the 
seasonally forming North Equatorial Counter Current at 
about 5 – 10oN, and from Brazil to Africa (Philander 
2001). Satellite chlorophyll images show that this region is 
influenced by nutrients from the Amazon and Congo 
Rivers, and by equatorial upwelling. Ocean dynamics in 
the NERR are strongly affected by the location and 
intensity of the atmospheric Inter-Tropical Convergence 
Zone, modulated by global scale climate oscillations. The 
unusual nature of this event suggests that it may be coupled 
to larger swings in regional ecosystem dynamics due to 
global temperature increases. 
 
LITERATURE CITED 
Comyns, B.H., N.M. Crochet, J.S. Franks, J.R. Hendon, and R.S. Waller. 
2002. Preliminary assessment of the association of larval fishes with 
pelagic Sargassum habitat and convergence zones in the northcentral 
Gulf of Mexico.  Proceedings of the Gulf and Caribbean Fisheries 
Institute 53:636-645. 
Lenes, J.M., J.M. Prospero, W.M. Landing, J.I. Virmani, and J.J. Walsh.  
2012. A model of Saharan dust deposition to the eastern Gulf of 
Mexico.   Marine Chemistry 134-135:1-9. 
Philander, S.G. 2001. Atlantic Ocean equatorial currents. Pages 188 – 191 
in: Encyclopedia of Ocean Sciences. Elsevier Press, Amsterdam, 
The Netherlands. 
 Széchy, M.T.M. de, P. M. Guedes, M.H. Baeta-Neves, and E. N. 
Oliveira. 2012. Verification of Sargassum natans (Linnaeus) Gaillon 
(Heterokontophyta: Phaeophyceae) from the Sargasso Sea off the 
coast of Brazil, western Atlantic Ocean.  Check List 8(4):638-641. 
Winge, O. 1923. The Sargasso Sea, its Boundaries and Vegetation.  
Report on the Danish Oceanographic Expeditions 1908 – 1910 to the 
Mediterranean and Adjacent Seas.   III. Miscellaneous Papers. 
 
 


The Sargassum Invasion of the Eastern Caribbean and Dynamics of the Equatorial North Atlantic

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The Sargassum Invasion of the Eastern Caribbean and Dynamics of the Equatorial North Atlantic

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