The Story of Sargassum

The first day of our Belizean journey began at Jaguar Reef Lodge, located in the small fishing village of Hopkins, Belize.  The morning breeze was gentle and refreshing as we walked along the beach.  But, something seemed out of place -large amounts of Sargassum algae had washed up on the shore. Upon further investigation, we learned that this was the time of year that the ocean currents shift slightly and bring additional Sargassum to the shores of the Caribbean.

The Biology of Sargassum

While at first glance, Sargassum may seem like an annoyance.  But, it is an important part of the marine ecosystem.  Sargassum belongs to the Phylum Phaeophyta (brown algae).  It contains the pigment fucoxanthanin, which gives it its characteristic brown color.  One should also notice the small round “balls” attached to the algae.  These balls are hollow, gas-filled floats that enable Sargassum to float on the surface of the water.  Brown is not the best pigment for photosynthesis and if Sargassum was several meters below the surface of the water, it would not be able to photosynthesize very efficiently.  Floating on the surface gives Sargassum more sunlight and thus the opportunity for photosynthesis.  Interestingly, Sargassum can reproduce vegetavitely while floating.  Most other seaweeds reproduce and begin life on the ocean floor.

Located hundreds of miles off the Atlantic coast of the U.S., where the ocean currents form an enormous circle, Sargassum collects into large masses forming algae “islands”.  These islands like the Sargasso Sea are destinations for many juvenile marine organisms like shrimp, crab and fish.  Various species of sea turtles will use the Sargassum islands as nurseries and endangered eels use the sites for spawning.  Commercial fish like tuna, humpback whales and many migrating birds also use the Sargasso Sea as a vital food source.

At first glance it may have seemed like the Sargassum ruined our chances of playing on the beach but that was far from the case.  Once we made it past the line of Sargassum we were in relatively clear water.  While snorkeling 50 feet from the shore we had the opportunity to swim with manatees.  They were drawn to the shores as a result in the shift in the ocean currents and the drifting of the Sargassum.  A small pod of dolphins was also spotted playing in the waves next to the dock.  While nature does what it wants, unexpected changes can often bring about new opportunities.

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Article and photos by Dave Cox.


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