Podcast: Sargassum, Balancing Nature and Tourism

For over a century, Galveston has been a destination for beachgoers to enjoy a day playing and relaxing in the Gulf. During the summer, First-time visitors might be surprised to see the shoreline covered in green or brown tangled blobs of seaweed washed up on the sand or clumped up in the shallow waves. The seaweed that most commonly washes up on our shore is known as sargassum. Don't let this essential and naturally occurring process of the marine ecosystem ruin your day trip or vacation. Instead, understand and appreciate why sargassum is important for beaches along the Texas coast and elsewhere.

Sargassum is a leafy type of seaweed that appears on Galveston's beaches every year, starting in the late spring and lasting through the summer. This seaweed species doesn't attach to the seafloor, so clumps of sargassum float freely on the ocean's surface. If you look closely, you'll see air-filled pods which look like berries, which allow the sargassum to stay on the surface of the ocean. The seaweed relies on these pods of air, called pneumatocysts, to float in the open ocean. Sargassum relies on the sun and photosynthesis to grow, just like plants on land. Sargassum is widespread in the Gulf, the Caribbean Sea, and the tropical Atlantic Ocean, and the amount of sargassum in the ocean is increasing every year.

Scientists use satellite imagery to monitor the Great Atlantic Sargassum Belt. This massive bloom stretches and shifts from the coast of West Africa to the Gulf. Sargassum does not blanket the entire ocean surface in these regions but rather floats in patches ranging from a few centimeters to hundreds of meters wide. These sargassum patches have been significantly larger in recent years.

When sargassum is offshore and floating in the open ocean, it's an important part of the marine ecosystem. It forms what are essentially floating islands that provide habitat for sea turtles, crabs, shrimp, fish, and seabirds. It is even considered a critical habitat for loggerhead sea turtles. Some animals, like the sargassum fish, live their whole lives in this habitat. The sargassum fish is camouflaged perfectly to ambush its prey and can change its colors to match the surrounding sargassum in order to hide from predators. When a sargassum fish feels threatened by an underwater predator, it can jump out of the water onto the top of the seaweed. This is called a seaweed mat. The sargassum fish can stay on top of the seaweed mat until the danger has passed.

Most of this sargassum does not float on the open ocean forever but washes on shore. Once the current and winds push the sargassum onto the shoreline, it can be a bit aggravating for those visiting the beach expecting no naturally occurring marine life or vegetation. Sargassum on the beach serves as a home for crabs and a nesting area for sea turtles, and sargassum on the sand helps prevent beach erosion. These piles of seaweed eventually form the base of new sand dunes, which help protect the island during storms with high tidal surges that would otherwise wash across the island without the sand dunes. Over the years, these large sargassum blooms have had various effects on Galveston Island. Sometimes, Galveston will only have small amounts of sargassum wash on its beaches. In other years, so much sargassum can wash on shore that it creates miles-long piles of seaweed a few feet high. After sargassum is out of the water for a few days, this decomposition process gets a little smelly. Decomposing sargassum releases a gas called hydrogen sulfide, which smells like rotten eggs, which, of course, can be an unpleasant aroma.

When large amounts of sargassum wash up on Galveston's shore, it can have consequences for the island's tourism industry. But all of this sargassum has an immense effect on keeping the beaches intact. The Galveston Park Board works hard to maintain the beach and its delicate ecosystem for visitors. On some of Galveston's beaches, during the seaweed season, the Galveston Park Board works night shifts, pushing the sargassum away from the shoreline so that beachgoers can enjoy their visit the next day. But the seaweed that's removed from the shoreline is done so strategically. If the sargassum was completely removed from the beach, miles and miles and tons and tons of sand would go along with it. So, instead, the sargassum is pushed a few hundred feet away from the shoreline and piled up to help build up the sand dunes, which allows it to decompose naturally while building up an organic protective barrier for Galveston Island.

Scientists are working to understand all of the effects of sargassum in the open ocean and on beaches like Galveston and elsewhere. Marine scientists at Texas A&M at Galveston use satellite imagery provided by NASA to monitor sargassum mats in the Gulf. These scientists are also working on other ways to use and deal with sargassum. For instance, researchers at Texas A&M have developed a machine that can bale seaweed like hay, which they can then use to place on the beach and create sand dunes. This innovative approach to managing sargassum not only helps with beach preservation but also provides a potential solution to the issue of excess seaweed, which can affect tourism. Scientists around the world are exploring ways to use seaweed as a biofuel or even an agricultural feed supplement, and in 2015, a group of former Texas A&M Galveston students even used it to brew a beer. These ongoing research and technological advancements are crucial in our efforts to understand and manage sargassum effectively.

As you explore Galveston's beaches, be mindful of the sargassum. It might initially seem like an inconvenience, but it's an essential part of our marine ecosystem that deserves our appreciation. As you enjoy your time at the beach, take a moment to marvel at the sargassum and the hidden world it supports. If you place some in a bucket and shake it, you might find seahorses, mole crabs, shrimp, small fish, or various other sea creatures. Explore the fascinating creatures that call it home and appreciate the natural processes that keep our coastline vibrant and resilient.