Getting the drift: Sargassum

Sargassum: Who, What, Why, Where, When?

None of those can be fully answered but here are some educated guesses!

Sargassum is a brown seaweed (moss) that is usually attached to the bottom of the ocean but has gas filled berries that help it to float if ripped up by wave action. There are many species, two of which never have contact with the sea floor and live as free floating moss or in the case of recent years, slicks or mats.

Sargassum on the South-East coast of Barbados.

It has been believed that this seaweed originally comes from the Sargasso sea in the North Atlantic gyre and blooms in the Gulf of Mexico being fertilized by the Mississippi River.  However,  ongoing studies including satellite observations suggest potentially new areas of origin & different sources such as the mouth of the Amazon, an area that had not been previously associated with the growth of this seaweed. This may be due to an increase in run-off from land filled with fertilizers that cause the seaweed to grow even more due to the high nutrient content.

It is not uncommon to see two of these species in the Caribbean but what is alarming is the quantity beginning with the 2011 event. A lot is still unknown stemming from the influx of pelagic sargassum onto the coastlines of many Eastern Caribbean countries as well as West Africa such as Ghana & Sierra Leone in 2011.

One set of ocean currents come to the Eastern Caribbean from northern Brazil, French Guiana, Suriname & Guyana and it is believed that the Guyana current is responsible for transporting some of this moss into the Caribbean whereas some is travelling in an equatorial counter-current and reaching the West Coast of Africa (currents are some amazing things!)

Sargassum floating in the sea.

So what does this sargassum mean for Barbados and the rest of the Caribbean and Africa? There are both positive and negative impacts associated with it. Some of these affect the fishing industry through entangled lines & nets, clogging of engines as well as have negative impacts through reducing light levels for fish. However, this seaweed can provide habitat for juvenile fish & sea turtle hatchlings and provides nutrients, supports food webs and acts as both a nursery & spawning area.

In Barbados in 2011, baby dolphinfish arrived earlier but the flying fish season ended earlier and this is being voiced once again this year with the price of flying fish apparently declining from $18 to $15 for 10 flying fish.

Another major negative impact of this moss is the effect on the aesthetics of our advertised pristine beaches for tourism. The moss gives off quite a  smell, which can be a bother for locals and tourists alike and has resulted in expensive & often damaging and fruitless attempts at removal.

Rope entangled with Sargassum seaweed on the East Coast of Barbados.

So many unanswered questions remain: why this increase and what is the best way to utilize it and even profit from it? It may be linked to above normal rainfall and thus run-off filled with nutrients in the outflow of rivers.

Check out this fact sheet from GCFI:

Is there enough to create a sustainable industry in the form of eating, drinking, fertilizers, export? Perhaps if more people follow the lead of Barbadian Mr.Callender and become more innovative, yes there could be a market!

So for now, why not pick up some (not using any heavy machinery), let the rainwater clean it and dry it if using as fertilizer for those kitchen gardens while removing African snails as well?! However, caution must be taken when doing this as the salt and content of other natural chemicals is very high and could also have negative impacts. In Barbados, many fishers voiced that their boats and the rocks on shore are changing colour due to the sargassum.

Remember, this is a natural phenomenon and quite often it is better to let nature run her course!

Hope that you have gotten the drift on Sargassum!

IMG_0242(I must give credit to Hazel, who taught me much of this information).


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