Abstract
AbstractThe question of the origin, distribution and fate of the floating seaweed Sargassum has fascinated sailors and scientists from the time of Columbus. Observations from ships are hampered by the large and variable area over which Sargassum is dispersed. Here we use satellite imagery to present the first mapping of the full distribution and movement of the population of Sargassum in the Gulf of Mexico and western Atlantic in the years 2002 to 2008. For the first time, we show a seasonal pattern in which Sargassum originates in the northwest Gulf of Mexico in spring of each year, is advected into the Atlantic in about July, appearing east of Cape Hatteras as a "Sargassum jet", and ending northeast of the Bahamas in February of the following year. This pattern appears consistent with historical surveys. Future satellite observations will show whether this pattern repeats in all or most years.
Highlights
The free-floating pelagic species of Sargassum have been studied since at least the 1830’s and have been acknowledged in marine lore by the naming of the Sargasso Sea, they have only recently been detected in satellite images[1]
Our observations show a large increase in Sargassum in the northwest Gulf of Mexico between March and June each year, and low total Sargassum amounts in the Atlantic before the annual injection from the Gulf of Mexico in July
This suggests that most Sargassum has a life-time of one year or less, with the major “nursery area” being in the northwest Gulf of Mexico
Summary
The question of the origin, distribution and fate of the floating seaweed Sargassum has fascinated sailors and scientists from the time of Columbus. We use satellite imagery to present the first mapping of the full distribution and movement of the population of Sargassum in the Gulf of Mexico and western Atlantic in the years 2002 to 2008. We show a seasonal pattern in which Sargassum originates in the northwest Gulf of Mexico in spring of each year, is advected into the Atlantic in about July, appearing east of Cape Hatteras as a “Sargassum jet,” and ending northeast of the Bahamas in February of the following year. This pattern appears consistent with historical surveys. Future satellite observations will show whether this pattern repeats in all or most years
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