Here's a brainteaser for you: Name the only sea that does not border land.It is the Sargasso Sea.In your mind–you will not find it named on any maps–draw a line from Miami southeast to Puerto Rico, then north to Bermuda, and back southwest to Miami. That's the Bermuda Triangle, an area of myth and folklore. Open yourself to fanciful stories, and you will learn about spinning compasses, UFO's, lost ships and planes that vanished in midair. This area has long inspired dread and mystery.
Where did this recollection come from? It is a collective memory, passed down through generations of seafaring cultures.The Sargasso Sea, which extends across about 3,500,000 square km of the North Atlantic, covers much of the Bermuda Triangle. It is probably the cause of this culturally and historically imprinted tradition of an area where the unexpected will happen.
It may be the strangest sea on the planet. The thick mats of sargassum seaweed that cover it characterise it. Sargassum is a yellow-brownish plant with rolled leaves and air bladders that keep it afloat.
The Sargasso Sea is surrounded by some of the ocean's most powerful currents that compose the North Atlantic Gyre: the Florida, Gulf Stream, Canary, North Equatorial, Antilles and Caribbean currents. Inside the Sargasso Sea the currents are weak. The result is a kind of water trap: many things drift in–including nowadays a lot of plastic rubbish–but very little drifts out again.
It is famous for periods of wind stillness and it is one of the areas that are called "the doldrums," which have entered colloquial language, signifying inactivity and sluggishness. Christopher Columbus sailed through it in 1492. It took him and his crew 23 days to struggle through the still mats of sargassum.
Columbus took the seaweed as a sign that he was close to shore and was confused when depth soundings proved his small fleet was still in deep waters. His crew was not quite as convinced that land was near. They mostly feared getting stuck in the seaweed.
The memories are older than Columbus. He was the first to be recorded sailing across it, but Portuguese sailors found the Sargasso Sea earlier. They may have been latecomers. A poem by the fourth-century Latin author Avienus describes a seaweed covered part of the Atlantic, based on a now-lost, two-and-a-half-millennia-old account of the 5th century BC Carthaginian explorer Himilco the Navigator.
The sargassum itself forms an important ecosystem. It has been called the rainforest of the Atlantic. To name some charismatic species, it is a hatching area for European and American eels, and a place where loggerhead sea turtles spend their juvenile years, feeding and hiding in the seaweed jungle.
Starting in 2011, massive amounts of sargassum started washing up on the Eastern Caribbean, Gulf of Mexico and West Africa coastlines. We are not talking about a few strands of sargassum here: some beaches get covered by sargassum three feet high.
The sargassum becomes an inconvenience for beachgoers and coastal residents. It can make it difficult to find a clean spot to spread out a towel to lie on, but then that is if you would want to sunbathe on a beach that smells of decomposing seaweed, and all the dead little organisms that once found a home in it.
The real impact of this sargassum invasion started to dawn on me earlier this year, during leatherback turtle nesting season, when I came upon a member of the Fishing Pond Turtle Conservation Group raking sargassum from the beach. It turns out that leatherback turtles do not like to nest on sargassum-filled beaches.
They come on land, feel the unfamiliar surface, and head straight back to sea. If there was a successful nesting, then turtle hatchlings become entangled in the sargassum carpets, resulting in dead leatherback hatchlings.
I asked older folks, fishermen and people who have lived on the coast all their lives, if they remember events like this from before. They all agreed that it was something new. From time to time they recall strands of sargassum, but never the quantities that we see today. Some younger folk, on the other hand, have already accepted it as the new normal. How quickly new memories are formed!
The sargassum invasion is just a symptom of something larger. We do not yet know what it is.Whatever brings the sargassum to the Caribbean, and to the Gulf of Mexico and West Africa in such big quantities has to do with changing wind and current patterns, or maybe it is blooming in new, unexpected places. Obviously something has changed, at least within the timespan of recorded history.