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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

We Are Here

Posted on: February 17, 2017
By: Michaela J. Kenward , A Watch, University of New England
Colonization to Conservation in the Caribbean

I could hardly believe it when Jeff reminded me that today – Friday – was my turn to write this blog. It’s hard to believe we’ve already been sailing for that many days. In my mind, all of the hours of the past few days have blurred together into one very, very long day, broken up by very satisfying naps. However, the passage of time is very evident not only by our movement through the clear blue Caribbean waters, but by the weathering skin and tired eyes of all of those aboard Mama Cramer.

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SEA alumni present Sargassum findings at Gulf & Caribbean Fisheries Institute conference

Posted on: November 28, 2016
By: Doug Karlson, communications@sea.edu
SEA Semester

Recent SEA graduates Maddie Taylor (C-264) and Corey Wrinn (C-257), and former SEA Associate Professor (and SEA alumna, C-142) Dr. Amy Siuda (now at Eckerd College) attended a meeting of the Gulf and Caribbean Fisheries Institute (GCFI) in Grand Cayman earlier this month to present the results of their research related to drifting Sargassum.

The GCFI is a forum that brings together scientific, government, and commercial stakeholders to share scientific findings to better understand and manage the marine ecosystem of the Caribbean and Gulf region.

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SEA Semester Faculty Report on Sargassum Beaching Phenomenon

Posted on: September 07, 2016
SEA Semester

SEA Semester in the News
Sargassum Watch Warns of Incoming Seaweed
Eos

SEA Semester professors Deborah Goodwin, Jeffrey Schell and Amy Siuda contributed to this Eos article on efforts to track Sargassum - including by satellite and from the deck of the SSV Corwith Cramer - to better understand and mitigate the recent phenomenon of Sargassum beaching events.

Read the article


Big Science Push!!!!!!!

Posted on: April 28, 2016
By: Alesia Hunter, A Watch, Beloit College
Marine Biodiversity and Conservation

Hey Everyone!!! We have made it to the North Sargasso Sea. It has been science all day today for me. A-Watch (my watch team) started our day of with a presentation on the coral reefs that are present in Bermuda from our visiting professor, Dr. Robbie Smith. I also got to work in the lab this morning during my watch, we completed a 100 count of the midnight Neuston net tow, and I got to do my first morning deployment of our CTD and Neuston net.

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The Great SSV Corwith Cramer Line Chase!

Posted on: April 26, 2016
By: Shalagh Canning, B Watch, Boston College
Marine Biodiversity and Conservation

Hello to all on land and greetings from the Southern Sargasso Sea! As we head into our second week here on the Cramer, we are all getting into our routines and keeping very busy with our work. We are working around the clock on our watches to take care of the Cramer as she carries us north while deploying our science gear and collecting samples for our research.

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Resources

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