Have you seen this on the beaches of Hilton Head?
It is sargassum, and it is a brown macroalgae or seaweed. It washes up on our beaches and tends to be a bit sticky and stinky. Sargassum grows in temperate and tropical oceans around the world. It is a free-floating species and floats in mats. These mats provide homes and food for numerous sea life. This makes this seaweed very important to the ecosystem of our waters.
The sargassum patches act as a refuge for many species in different parts of their development. But it also is a permanent residence for others. These species are dependent on it for survival. These creatures’ patterns and colorations mimic the sargassum. The seaweed provides a vital camouflage. Some of these endemic creatures are:
Sargassum may grow to a length of several yards.
They are generally brown or dark green in color and consist of a holdfast, a stipe, and a frond. Some species have berry-like gas-filled bladders that help the fronds float to promote photosynthesis. Many have a rough, sticky texture that, along with a robust but flexible body, helps them withstand strong water currents.
Sargassum is commonly found in the beach drift near their beds. It undergoes seasonal cycles of growth and decay in concert with changes in sea temperature. In limited amounts, it plays an important role in maintaining coastal ecosystems. Once ashore, sargassum provides vital nutrients such as carbon, nitrogen, and phosphorus to coastal ecosystems. Additionally, it decreases coastal erosion.
Recently, though, unprecedented quantities began inundating some beaches in the US.
The decomposition of large quantities of this seaweed along coastlines consume oxygen, creating large oxygen-depleted zones resulting in fish kills. Decomposing sargassum additionally creates noxious hydrogen sulfide gas, causing health impacts in humans.
On the water, massive amounts of floating sargassum make a barrier from the surface of the water. This prevents corals and seagrasses from receiving sufficient light. It also fouls boat propellers, and entangles marine turtles and mammals. Winds and ocean surface currents cause this inundation.
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What to do about it?
Turning sargassum into bioenergy and fertilizer is an idea. Another option is currently happening. Cosmetics and the food industries are importing sargassum. They are implementing a bioprocess, converting it into raw materials that are useful for their products.
Certainly, there is still much to be learned. Sargassum is a home for so many sea creatures. Therefore, further research is crucial to understand and best conserve this natural resource.