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Sargassum Ecosystem

Sargassum Ecosystem

Pelagic Sargassum is a macroalgae that drifts at the ocean surface in small clumps or extensive mats, creating a unique and ecologically-significant marine ecosystem. Two species are common in the North Atlantic, S. natans and S. fluitans. Serving as a food source, nursery for juveniles, spawning ground, and/or protective habitat, Sargassum mats support diversities of invertebrates, fish, turtles, and seabirds at various points of their life cycle.

For more than 40 years, SEA has been documenting Sargassum species, abundance, and distribution along repeated cruise tracks through the Sargasso Sea, Caribbean Sea, and Gulf of Mexico. More recent investigations include associated epibiont and mobile fauna communities, genetic diversity, seasonal and interannual variability, and unique Caribbean inundation events. SEA Semester students also contribute to marine spatial planning and policy initiatives working to conserve the Sargasso Sea ecosystem.

Research Themes

Sea Education Association Research

Community of organisms

A uniquely adapted pseudo-benthic community of organisms lives among the dense vegetation of each pelagic Sargassum clump, including common epifauna such as hydroids and mobile fauna such as shrimp, snails, and crabs. At SEA, we are interested in understanding the factors that affect the diversity and composition of the associated Sargassum community, such as host species, geographic location, clump size, and clump aggregation/dispersion pattern. Both visual/microscope-aided identification and genetic population analyses are utilized to characterize Sargassum communities.

Selected Community of organisms papers and publications

Sea Education Association Research

Distribution patterns

SEA’s 40-year plankton net tow data set indicates that distinct seasonal and interannual distribution patterns exist for each Sargassum species. S. natans is most commonly found in the central Sargasso Sea while S. fluitans is more abundant in the Gulf Stream, North Equatorial Current, and Caribbean Sea. Our field observations complement satellite detection methods by providing species identification and finer spatial resolution.

Selected Distribution patterns papers and publications

Sea Education Association Research

Inundation events

During 2011-2012 and 2014-2015, pelagic Sargassum washed ashore in unprecedented quantities throughout the tropical Atlantic, including on many Caribbean islands. Once-pristine tourist beaches were covered by meters of stranded seaweed. Researchers at SEA have discovered that the Sargassum inundating the Caribbean in 2014-2015 is a previously rare form of S. natans, potentially originating in the equatorial region. Inundation events have ecological consequences at multiple scales, such as impacts to Sargassum mobile fauna communities, dependent fisheries and iconic species, and coastal ecosystem function.

Selected Inundation events papers and publications

Sea Education Association Research

Taxonomy

Sargassum natans and S. fluitans each exhibit a diversity of morphological forms that have distinct but overlapping ranges; correct identification in the field is critical for understanding species dynamics and resolving questions of Sargassum connectivity among geographic regions. Presence or absence of thorns on the stem distinguishes between species: S. natans has smooth stems while S. fluitans has thorns. Within a species, leaf and bladder attributes can differ widely among forms. SEA uses both dip nets and surface neuston tows to collect Sargassum, then makes careful visual observations to determine the species and form.

Selected Taxonomy papers and publications

Papers and Publications

Peer-reviewed publications

Stoner*, A. W. and H. S. Greening, 1984. Geographic variation in the macrofaunal associates of pelagic Sargassum. Mar. Ecol. Prog. Ser. 20, 185-192.

doi: 10.3354/meps020185

Butler, J. N. and A. W. Stoner*, 1984. Pelagic Sargassum: has its biomass changed in the last 50 years? Deep-Sea Res. Part A 31, 1259-1264.

doi: 10.1016/0198-0149(84)90061-X

Stoner*, A. W., 1983. Pelagic Sargassum: Evidence for a major decrease in biomass. Deep-Sea Res. Part A 30, 469-474.

doi: 10.1016/0198-0149(83)90079-1

Selected student research

Olson, E. and E. Tonkin, 2015. A Genetic and Morphological Analysis of Atlantic Sargassum. Unpublished student research paper, Class C-259, Sea Education Association, Woods Hole, MA.

Tyrrell, S., 2015. Sargassum Species Distribution in the North Atlantic. Unpublished student research paper, Class C-257, Sea Education Association, Woods Hole, MA.

Wooster, S., 2015. Sargassum Community Comparison Between Isolated Clumps and Windrows. Unpublished student research paper, Class C-257, Sea Education Association, Woods Hole, MA.

Disbrow, M., 2015. Community Composition on Three Sargassum Morphological Forms. Unpublished student research paper, Class C-257, Sea Education Association, Woods Hole, MA.

Matthews, T., B. Stockdale and M. Howard, 2013. Zoogeography of Floating Sargassum in the Caribbean. Unpublished student research paper, Class C-250, Sea Education Association, Woods Hole, MA.

Bishop, E. and A. Mackie-Donnelly, 2013. Investigating Sargassum's Distribution Pattern: A Pelagic Seaweed's Relation to Plastic and Epifauna in the North Atlantic. Unpublished student research paper, Class C-249, Sea Education Association, Woods Hole, MA.

Mygas, S. and M. Opela, 2012. Age and Distribution of Sargassum natans and S. fluitans in the North Atlantic. Unpublished student research paper, Class C-243, Sea Education Association, Woods Hole, MA.

Urban, E., 2012. Sessile Epibiont Variety and Abundance as a Method of Correlating Sargassum Age and Geographic Location in the Sargasso Sea. Unpublished student research paper, Class C-243, Sea Education Association, Woods Hole, MA.

Pinheiro, V., 2012. The Role of Sargassum fluitans and S. natans in the Ontogeny of Anguillid Leptocephali in the Sargasso Sea. Unpublished student research paper, Class C-240, Sea Education Association, Woods Hole, MA.

Wylie, B. and K. Gonzalez, 2010. Long-term Trends and Distributions of Holoplanktonic Sargassum in the Caribbean Sea from 1981 to 2010. Unpublished student research paper, Class C-232, Sea Education Association, Woods Hole, MA.

Sargent, S., 2010. Camouflage in Sargassum Habitat Choice in Sargassum Shrimp and Crabs in the Caribbean Sea. Unpublished student research paper, Class C-232, Sea Education Association, Woods Hole, MA.

Presentations

Wrinn, C.^, J. M. Schell*, D. S. Goodwin and A. N. S. Siuda, 2016. Taxonomic Guide to Pelagic Sargassum in the Caribbean Sea and North Atlantic. In: Proceedings of the 69th Annual Gulf and Caribbean Fisheries Institute Conference, Nov. 7-11, 2016. Gulf and Caribbean Fisheries Institute, Grand Cayman.

Taylor, M.^, A. N. S. Siuda, D. S. Goodwin*, G. Huston^ and J. M. Schell*, 2016. Biogeographic and temporal changes in mobile fauna community on pelagic Sargassum in the Caribbean Sea, 2015-2016. In: Proceedings of the 69th Annual Gulf and Caribbean Fisheries Institute Conference, Nov. 7-11, 2016. Gulf and Caribbean Fisheries Institute, Grand Cayman.

Schell, J. M.*, D. S. Goodwin* and A. N. S. Siuda*, 2015. Shipboard Observation of Pelagic Sargassum spp. Reveals Proliferation of a Rare Form and Differences in Asociated Mobile Fauna Community Structure. In Proceedings of the 68th Annual Gulf and Caribbean Fisheries Institute Conference, Nov. 9-13, 2015. Gulf and Caribbean Fisheries Institute, Panama City, Panama.

Schell, J.*, 2014. Drifting Oases of Life in the Sargasso Sea. Fish, Fishing, and Fisheries. Cataumet Schoolhouse Summer Series, Cataumet, MA.

Goodwin, D. S.*, J. S. Schell* and A. N. S. Suida*, 2014. Sargassum natans and S. fluitans Exhibit Geographically Distinct Distributions in a 20-year Neuston Net Dataset from the Western North Atlantic, 2014. Ocean Sciences meeting, Honolulu, HI.

Siuda, A.* and D. Goodwin*, 2013. Sargassum sp. Distributions in the Western North Atlantic - Implications for Conservation and Management. BioNES meeting, Bristol, RI.

Other

Hu, C., B. Murch, B. B. Barnes, M. Wang, J.-P. Maréchal, J. Franks, D. Johnson, B. Lapointe, D. S. Goodwin*, J. M. Schell* and A. N. S. Siuda*, 2016. Sargassum Watch warns of incoming seaweed. EOS Earth and Space Science News 97, 10-15.


* SEA faculty and staff
^ SEA Semester alumnus

News

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O-fish-ially deep into the Sargasso Sea

Posted on: May 03, 2018
By: Helena McMonagle, Lab Hand

As our second week comes to a close, I already feel like our community aboard Mama Cramer is gelling. You can get used to almost anything: flushing the head (aka toilet) with a hand pump, showering about once every three days, and eating on gimbled tables that continuously tilt to counteract the ship’s rocking.

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Sargy Success!

Posted on: May 02, 2018
By: Jenny Renee, B watch, University of Washington

I’m happy to report Sargy Success from the Sargassum group (Alena, Dani and I)! Sargy, as we have affectionately started calling Sargassum - ok, maybe it’s just me - is a seaweed that spends its entire life floating in the open ocean.  This floating Sargassum supports a diverse community of mobile and sessile fauna, small islands of diversity within a blue desert.

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A week at sea & the Great Pin Rail Chase!

Posted on: April 27, 2018
By: Nate Lammers, C Watch, 3rd Mate

A week ago, at 12:13 EDT, we cast off our last line in Nassau, Bahamas and motored out to sea. It’s hard to believe we have officially been underway for a week! The days are flying by and just seem to blend together. With the revolving 6 on, 12 off watch schedule we are constantly changing our work and sleep schedule which really makes it hard to keep track of the time.

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Caribbean Study Abroad

Setting Sail!

Posted on: April 20, 2018
By: Carly Carter, A Watch, Longwood University, Cormier Honors College

TGIF! Well, not so much on the Cramer, especially with our work just beginning! We spent the morning doing our last bit of orientation and getting the ship ready before shipping out to begin our voyage. We have had so much information thrown at us the past few days that I don’t know what stuck and what didn’t, so being underway will sure test our knowledge. We have a lot of new skills to learn, and a lot of old skills to re-learn.

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Ocean Exploration

Arrival in Carriacou, Grenada

Posted on: November 15, 2017
By: Farley Miller, 2nd Assistant Scientist

In the words of Anna yesterday, “Here we are.” This evening, however, that phrase has a whole new meaning, and we aboard have the firmest sense of where we are yet. Land! Sighted early this morning as distant flickering lights 38 nm away, then rising out of the gloaming as the sun comes up and gives us colors to behold; then we are between two islands and in the lee and the smell of the land is overwhelming. Wet dirt, fresh wood smoke and an entirely new array of ocean smells not encountered in the open ocean.

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Resources

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