For Immediate Release: Month DD, Year Contact: Vanessa Van Deusen; Madison Lichak; Ridge Pierce; and Sarah Speroff www.sea.edu

Who is Eating Who in the A study of Sargassum predator-prey interactions and genetic analysis of the Slender Sargassum

June 02, 2017, Woods Hole, MA — From eating tiny bug-like creatures, to fish clinging to pieces of far from any coast, there’s a lot happening in the Sargasso Sea. The Sargasso Sea is an economically and socially valuable area located in the heart of the North Atlantic. This area is difficult to access as it is bounded only by currents and lies 600 nautical miles from the coast of Florida; an area only a few people get to see. One month ago, sixteen university students from across the globe embarked on a five-week voyage with the Sea Education Association into the Sargasso Sea to study this unique ecosystem.

Despite being low in nutrients, the region is highly productive due to Sargassum, a genus of free-floating seaweed. Sargassum provides a habitat for floating communities of both fixed organisms such as hydroids and barnacles, and mobile fauna such as crabs, shrimp, and . Understanding this habitat is essential in helping conservation efforts for protecting many beloved migratory species such as sharks, tuna, and whales.

A team of four students focused their research on understanding the predator-prey relationships of Sargassum mobile fauna. They aimed to The team examines a clump of Sargassum for compare the diversity of species across four forms of Sargassum, and mobile fauna. three different regions. The team also conducted molecular analysis with the hopes of understanding the genetic relationship between slender Sargassum shrimp, a prominent member of the mobile fauna community, from different areas in the Sargasso Sea. ` A plethora of different organisms from different forms of Sargassum were collected throughout their voyage. These students collected 108 Sargassum samples from 20 station locations throughout the Sargasso Sea. This included four forms of Sargassum: S. fluitans III, S. natans I, S. natans VIII, and an unknown species of S. fluitans. They found that S. fluitans III, the most abundant form, had the highest total number of mobile fauna species. Out of the 24 species of mobile fauna that they encountered, they identified 23 of these species on S. fluitans III. “It’s interesting to see how many organisms there are on something that looks so unassuming” said Vanessa, a member of the team. The three most common species were Latreutes fucorum, the slender Sargassum shrimp; Bagatus minutus, a small isopod; and Platyneries dummerillii, a segmented marine worm.

Surprising trends in biodiversity were discovered upon closer investigation. Shrimp were most common in the Antilles region, and amphipods were most common in the North Sargasso Sea. The North Sargasso had the highest abundance of organisms across all Sargassum forms. However, the South Sargasso Sea had a higher level of biodiversity. Numbers were assigned to predator-prey relationships (eg. organisms that passively graze on = 1, top predators= 6) and were used to determine who was eating who in the different parts of the Sargasso Sea. Analysis showed that clumps of Sargassum in the Antilles region contained the most predators. “We can expect to find more crabs and in the Antilles region than in other regions, says Ridge Pierce, a member of the team.

These budding scientists expanded their horizons by sailing through the Sargasso Sea and while doing so, acquired vital data about the Sargasso Sea. On their voyage, they were engaged in learning what interesting creatures fight to survive on the region’s floating seaweed and where the larger predators of the mobile fauna community are located. Understanding relationships between predators and prey in Sargassum mobile fauna communities could help future researchers deduce where larger animals like sharks, tuna, and whales are located within the . Sarah Speroff holding the Sargassum Swimming (P. sayi), a top-level predator that lives only within Sargassum.

About Sea Education Association/SEA Semester® Sea Education Association (SEA) is an internationally recognized leader in undergraduate ocean education. For nearly 45 years and more than one million nautical miles sailed, SEA has educated students about the world’s through its Boston University accredited study abroad program, SEA Semester. SEA/SEA Semester is based on Cape Cod in the oceanographic research community of Woods Hole, Massachusetts and has two research vessels: the SSV Corwith Cramer, operating in the Atlantic Ocean, and the SSV Robert C. Seamans, operating in the Pacific.

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