Episode 107 – Sargassum Report — Part 1: What Is Sargassum and Where Does It Come From

If you've visited any Caribbean beach in the last decade, you've probably encountered sargassum — brown seaweed piling up on shore, sometimes with a distinctive smell. It's become one of the most discussed topics in Caribbean tourism. This is Part 1 of our 4-part Sargassum Report series.What Is Sargassum?Sargassum is a type of brown algae — a free-floating seaweed that lives its entire life cycle in the open ocean. Unlike most seaweed that attaches to rocks or the sea floor, sargassum floats on the surface, forming large mats that can stretch for miles.Is It Harmful?In the ocean, absolutely not. It's actually incredibly beneficial:NOAA designates sargassum as essential fish habitatFloating mats provide food, protection, and breeding grounds for hundreds of marine speciesCommercially important fish like mahi-mahi, amberjack, and gray triggerfish feed on smaller marine life in sargassum matsJuvenile sea turtles use it for shelterDesignated as critical habitat for threatened loggerhead sea turtles under the Endangered Species ActThe problem is when massive amounts wash ashore — what scientists call a "sargassum inundation event."Where Does It Come From?Historically, most sargassum was located in the Sargasso Sea — a region in the Western North Atlantic between Bermuda and the Azores. It's the only sea in the world defined by ocean currents rather than land boundaries.In 2011, everything changed. Scientists observed a massive new population forming in a completely different location — the tropical Atlantic, stretching from West Africa to the Gulf of Mexico. They call it the Great Atlantic Sargassum Belt.What Caused This New Belt?Several factors combined:Shifting wind patterns and ocean currents pushed sargassum out of the traditional Sargasso SeaIncreased nutrients in the water — Woods Hole Oceanographic Institution research identified enhanced nitrogen and phosphorusAmazon River discharge — massive amounts of nutrient-rich water into the AtlanticAgricultural runoff from South America and Africa adding fertilizersSaharan dust carrying iron and nutrients across the AtlanticWarmer sea temperatures from climate change accelerating growth and reproductionMore nutrients + warmer water + shifting currents = explosive sargassum growth. Ocean currents then push it west, directly into the Caribbean Sea, the Gulf of Mexico, and onto the beaches of Belize.Is This New?Sargassum has always washed ashore occasionally, but the scale changed dramatically starting in 2011. Before that, beach accumulations were manageable. Since then, we've seen unprecedented volumes. 2025 was described as Belize's worst year yet, with the government declaring a national emergency.The National Meteorological Service now issues sargassum forecasts similar to weather forecasts. The government has created a national response plan.Will It Get Better?The honest answer: we don't know for certain. The Great Atlantic Sargassum Belt appears to be a new normal, not a temporary phenomenon. Scientists are still researching whether it will stabilize, grow, or eventually diminish. For now, coastal communities need to adapt.Series OverviewPart 1: What Is Sargassum and Where Does It Come From (this episode)Part 2: The Impacts on Beaches, Tourism, and PropertyPart 3: What Belize Is Doing About ItPart 4: Practical Advice for Buyers and VisitorsQuestions? Email David at [email protected]]]>