#11. Weeds in the Wind
In which the E@L considers the inundation of coastal ecosystems by Sargassum
The beach was perfect. A curving, crescent-shaped strand of fine white sand. At one end, a picturesque lighthouse sat atop a high bluff that shielded the little bay from oceanic swells. Behind the beach, palm trees wafted gently in the breeze and cast just enough shade to provide a respite from the hot sun. It was the perfect place to while away a few hours in the sultry afternoon. And its location, known mostly to locals, along with the long dirt road that led to it, was just enough of a barrier to keep the crowds of tourists away. Known as Bahia Sucia, or “dirty beach” it was a little hidden tropical paradise at the southwestern tip of Puerto Rico. But that was 2016.
When I returned in 2018, the beach was covered with a foot-deep mass of rotting seaweed called Sargassum. The rotten-egg odor, a product of hydrogen sulfide produced by the rotting algae, was detectable from 100 meters away. You couldn’t wade through it to the water, and even if you did, the water near the beach was covered with more sargassum. And not a bather in sight, because, on one hand, it was kind of disgusting, and on the other, it was just sad.
Attack of the Blob
Sargassum accumulations on a beach in Palm Beach County, Florida (Photo credit: B. Lapointe, Florida Atlantic University.)
This scenario is playing out all over the Caribbean where, on many beaches, dead sargassum is piling up more than a meter deep. What many news sources have called the “Atlantic Blob” is actually just the fringes of an oceanic mass of drifting Sargassum – a type of algae (seaweed) that floats. The preponderance of Sargassum occupies a vast area in the North Atlantic Ocean known as the Sargasso Sea. At the southern border of this, a region known as the “Great Atlantic Sargassum Belt” stretches from Western Africa to Brazil.
Sargassum grows in large patches that drift around in the ocean, forming an independent ecosystem, and providing shelter for many types of fish, crabs, turtles, birds, marine mammals and other creatures. It’s the spawning ground for most American eels, as well as a nursery for juvenile mahi-mahi and tuna.
Sargassum patches typically die back in winter, then expand in spring, stretching across the ocean, and into the Caribbean and the Gulf of Mexico. Throughout the Caribbean, Sargassum was an occasional visitor, a curiosity for beachcombers. That all changed in 2011, when, for unknown reasons, the Sargassum patch expanded beyond its normal boundaries, and started piling up on beaches in unprecedented amounts. And it just kept getting worse, increasing in size steadily, until it now occupies an area almost 5000 miles across. By all accounts, 2018 was a record year, with blooms 33% greater than the previous decade.
Sargassum density in the central Atlantic Ocean (including the Caribbean Sea and Gulf of Mexico) in March 2023 (Image Credit: NASA)
According to Brian Lapointe, a scientist at Florida Atlantic University, the expansion of Sargassum is primarily the result of increased oceanic nitrogen levels, due to runoff of nutrients from land, especially the Amazon River, as well as increased oceanic deposition of atmospheric nitrogen as a result of energy production and biomass burning.
The unprecedented accumulation of Sargassum on Caribbean and west African beaches is not only unsightly and a significant damper on coastal tourism but has created a host of other environmental problems. The dying algae gives off toxic hydrogen sulfide fumes which, in combination with reduced oxygen levels, have killed fish in adjacent waters. It also damages coastal mangrove systems, and buries the nests of sea turtles, entombing their hapless offspring.
An Awful Mess
Many island and coastal nations have begun clean-up campaigns, and a manual of best practices for prevention and clean-up has been developed. Small amounts of sargassum don’t create much of a problem, and left alone, natural degradation of the algae stabilizes beaches and adds nutrients. Although it can be removed from the water before hits the beach, that risks damaging the fish and other creatures that depend on it. Once it comes ashore, it can only be removed by raking, harvesting, using fish nets, and in extreme cases, using bulldozers. Pumps or conveyor belts risk damaging fish, and containment booms can work but can break loose or deflect algae to other sites.
Workers removing Sargassum from a beach in San Pedro, Belize (Photo: San Pedro Sun)
In many areas of the coast, it is out of sight and out of mind, and can probably be left alone. But in higher value ecosystems such as seagrass, mangroves, turtle nesting beaches, and Coral reefs, it can create havoc and needs to be removed. It may also be necessary to remove it from economically valuable areas such as harbors or high-use beaches. Hydrogen sulfide gas is also a danger to clean-up workers at concentrations as low as 5 ppm.
But cleaning it up is expensive – to the tune about US$3 Million per mile of beach cleaned. For this reason scientists at North Carolina State University are trying to develop methods to convert it into aviation fuel and graphite for batteries, as a sustainable alternative to normal production methods that generate large amounts of greenhouse gases.
The invasion of Sargassum is not just a problem for the Caribbean. It has now become a common sight around Florida beaches as well. Scientists at the University of South Florida are monitoring the spread of sargassum using NOAA satellites, and it appears that levels are beginning to decrease as of mid-June of 2023. But satellite data are not detailed enough for small bays and islands, where local watch teams are necessary. Scientific organizations including the Gulf and Caribbean Fisheries Institute (GCFI) and SPAW-RAC (The Regional Activity Centre for the Protocol Concerning Specially Protected Areas and Wildlife for the Wider Caribbean Region; I know, it’s a mouthful) are also coordinating research and activities related to Sargassum across many island and coastal nations.
A Wake-up Call?
But the big question is: How soon will we be seeing Sargassum on beaches north of Florida? It has yet to find its way north to the Carolinas, but that could happen next year. And what about the Mid-Atlantic beaches of Virginia, Maryland, and Delaware? When will we wake up to find a soggy green swamp has replaced the white sand beaches of Assateague Island, or Ocean City?
The explosive growth of Sargassum can be directly linked to a deteriorating climate and is another symptom of an imbalance in world ecosystems. Warming of the oceans and increasing nutrient saturation are both the results of human induced climate change, the use of fossil fuels, deforestation, and the increase in atmospheric greenhouse gases.
Maybe this phenomenon will finally serve as a wake-up call, and bring what many consider to be a third-world problem to the attention of more affluent nations like ours. And perhaps this disaster can lead to progress.
The only way to prevent this type of ecological disaster and to solve climate change is by reducing our dependence on fossil fuels. And the best way to do that is with renewable energy – wind and solar. So which would you rather see – the faint image of a wind turbine twenty miles out to sea, or a giant, stinking, oozing mass of dead seaweed all over the beach? To me, it’s a clear choice.
I've diverted off climate change for a few weeks while I look at water quality issues, but overgrowths of algae in the marine environment are a tragic intersection of both issues.