sargasso sea

Sargassum is a free-floating brown seaweed that can drift together in vast mats, sometimes stretching for miles across the ocean’s surface. For centuries, these blooms have been a natural part of the Atlantic, creating food and shelter for many marine creatures. Sargassum was once thought to be confined mainly to the Sargasso Sea in the western Atlantic, but scientists now know it grows rapidly and spreads widely, driven both by natural forces and by nutrients from human activities.

Scientists at Florida Atlantic University have reviewed 40 years of data on sargassum seaweed. Their study, which was recently published in the journal Harmful Algae, points to the rise of what is now called the Great Atlantic Sargassum Belt – a massive seaweed bloom stretching from West Africa to the Gulf of Mexico. First spotted in 2011, it has since appeared every year except in 2013. This past May, the bloom reached a record 37.5 million tons, a number that does not include the 7.3 million tons in the Sargasso Sea.

Sargassum thrives in nutrient-rich waters. Under ideal conditions, controlled studies found sargassum can double its biomass in just eleven days! According to the scientists, nutrient pollution from agriculture and wastewater has fueled these record blooms.

In the ocean, sargassum provides habitat for fish, turtles, and other marine life. But along the coast, it piles up in smelly heaps, clogs waterways, disrupts tourism, and can even threaten power plants.

Understanding why sargassum is spreading so rapidly is key to tackling a problem that now spans an entire ocean.

**********

Web Links

A monster seaweed bloom is taking over the Atlantic

Photo, posted December 24, 2014, courtesy of Roban Kramer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The lifecycle of sea turtles includes a longstanding mystery, often called the “lost years”. Turtles hatching from nests along Florida’s Atlantic coast head into the ocean and are generally not seen again for several years before they return in their adolescence. Very little is known about where they spend this time in the open ocean.

Researchers at the University of Central Florida have learned that green turtles as well as loggerhead turtles – both iconic species in conservation efforts – may be spending their youth in the legendary Sargasso Sea. The Sargasso Sea is located off the east coast of the U.S. in the North Atlantic Ocean. It has frequently been featured in popular culture, such as in the novel Twenty Thousand Leagues Under the Sea, as a place where ships could be trapped in thick mats of floating, brown Sargassum seaweed for which the sea is named.

The researchers tracked the baby turtles by attaching advanced, solar-powered tracking devices, about an inch long, to their shells. They used a special adhesive that held the devices to the turtle shells but would allow the devices to fall off after a few months causing no harm to the turtles or inhibiting shell growth or behavior.

It was previously thought that baby turtles would passively drift in sea currents and simply ride those currents until their later juvenile years. The new research shows that the turtles actively orient to go into the Sargasso Sea.

Studies of where turtles go as they develop are fundamental to sound sea turtle conservation. If we don’t know where turtles are and what parts of the ocean are important to them, we are doing conservation blindfolded.

**********

Web Links

Legendary Sargasso Sea May be Sea Turtles’ Destination during Mysterious ‘Lost Years’

Photo, posted October 23, 2016, courtesy of Kris-Mikael Krister via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Great Atlantic Sargassum Belt

Web Links

Sea Turtles And The Sargasso Sea | Earth Wise

Web Links