Sargassum

By James Heller

Memorial Day weekend has come and gone and the beach season is in full gear. Beach visitors come to Brazoria County beaches to play in the sand and surf, fish and relax on the beach. Clean beaches are attractive to visitors and local communities strive to accommodate the tourists. However at this summer season, maintaining clean beaches is a challenge.

It’s not litter causing the current concern on the beaches. It is seaweed, and lots of it. This seaweed is commonly known as Gulfweed, the brown alga, Sargassum, for which the Sargasso Sea is named. The various species of sargassum are ‘holopelagic’ — this means that the algae not only freely floats around the ocean, but it reproduces vegetatively on the high seas. The Gulfweed washes ashore on our beaches in large mats, sometimes two to three feet thick. That is what most beach goers find unsightly, smelly and unattractive. But wait; here is some food for thought.

Beach with Sargassum resized

Beach with Sargassum- photo by Sue Heath

After beachgoers find a spot of groomed beach or create one, the seemingly nuisance of Gulfweed can become a great source of entertainment. Many children bring buckets to play with in the sand, and these same buckets can be used to find many fascinating creatures living in the Gulfweed before it washes ashore. After strapping on the children’s life jackets, wade into the water (knee deep is deep enough) and look for large, intact clumps of Gulfweed. Gently allow the clump of Gulfweed to flow into the bucket. Be sure to scoop clumps as the broken bits will not hide the treasure of critters. Slowly lift the Gulfweed up and gently shake directly above the bucket and watch for your own touch tank to form. One of the most frequently found critters is the sargassum shrimp. While very small at about one inch long, it has bright blue spots and colors of yellow and red. The sargassum pipefish, whose shape mimics a blade of Gulfweed, hides in the mass where it forages for shrimp and other tiny life forms. The pipefishes are related to seahorses, and like them, females deposit eggs in male brood pouches, where fertilization and development occur.

One of the best finds in a clump of Gulfweed is a sargassum fish, the largest creature of the seaweed, but not the most obvious. Not only is its body misshapen in the pattern of branching Gulfweed, but it is colored in mottled pattern of browns and creams that mimic the light and dark patches of floating Sargassum.  The pectoral fins are hand-like and are used to crawl though the seaweed mat, slowly stalking its prey and ingesting them with a forceful slurp. Check the weed in hand as the sargassum fish may still be clinging to the strands. Also watch for sargassum crabs, nudibranchs, snails, and sea spiders. Many of these critters are very cryptic and blend in very well with their home, making them difficult to find.

Many shorebirds make great use of the sargassum. There is no shortage of food for these birds as they walk and peck their way over the mounds. It is part of the habitat necessary for these birds to survive.

Playing in the surf is great fun but be sure to make safety first. While not known to specifically harbor stinging creatures like jellyfish (sea nettles) or Portuguese Man-o-war, always be on the lookout for these organisms any time you are in the water.

 

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