About This Project

The ongoing international effort to protect the Sargasso Sea ecosystem in the NW Atlantic is hampered by limited scientific research on Sargassum - the floating algae common to the North Atlantic gyre. This project aims to provide the first simultaneous examination of Sargassum macrofauna diversity across multiple regions, in order to better understand the impacts of oceanographic variables on Sargassum distribution and to contribute to the international effort to protect the Sargasso Sea.

Ask the Scientists

What is the context of this research?

There are many species of the genus Sargassum distributed in tropical and subtropical waters but only two, S. natans and S. fluitans, have an entirely pelagic life cycle, meaning free-floating in the open ocean, and offer an ecologically-supportive structure in otherwise nutrient-poor environments. Drifting Sargassum is moved through the oceans by surface currents and winds on an annual cycle that begins in the Gulf of Mexico during spring and ends in the southern Sargasso Sea during the following winter. Individual clumps host several cryptically colored, endemic and non-endemic mobile fauna. While scientists have been studying this unique drifting habitat within these three regions for decades, very few comparisons have been made between Sargassum species or regions.

What is the significance of this project?

Sargassum represents a keystone species supporting relatively high levels of biodiversity. For many endangered species of sea turtles, Sargassum represents a vital habitat during their juvenile life stage termed the "lost years." The preservation of high biodiversity is required for the maintenance of the health and resilience of this unique ecosystem currently facing many of anthropogenic pressures. For as yet unknown reasons, a massive bloom representing a nearly two hundred-fold increase from an eight year total biomass average was observed in 2011 ranging from Trinidad across the Atlantic as far as Ghana. Movement of Sargassum between the Gulf, Sargasso Sea, and Caribbean ensures that any event will negatively impact all three regions and beyond.

What are the goals of the project?

Samples will be collected during the spring/summer of 2015 from the Sargasso Sea, Caribbean, and Gulf. Individual clumps and macrofauna will be dip-netted. Video surveys will be conducted to look for the presence/absence of predators. Mobile fauna will be stored for preservation and later analysis, and macrofauna will be identified to the lowest taxon. Sargassum clumps will be weighed and photographed to determine approximate area. The analysis will examine differences in species richness, evenness, and diversity between stations and between regions. The impact of Sargassum species and sub-species differences as well as clump age, size, and condition on community diversity will also be assessed.