It’s been plaguing the Caribbean islands, Central America and the Southern Coasts of the USA. Since its first attention-grabbing appearance in 2011, sargassum seaweed has returned again with a vengeance, seemingly not willing to let up.
As it washes up on the shores, it brings with it many questions:
What exactly is it? Where is it coming from? Why is there so much of it? And importantly, when will it finally go away?!
What is it?
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.
Where is it coming from?
It is usually believed that this seaweed originally comes from the Sargasso sea in the North Atlantic Gyre and blooms in the Gulf of Mexico, being fertilised 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 fertilisers that cause the seaweed to grow even more due to the high nutrient content.
Why is there so much of it?
It is not uncommon to see two of these species in the Caribbean. But what is alarming is the quantity arriving, 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 African countries 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!)
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 having negative impacts through reducing light levels for fish.
However, this seaweed can provide a habitat for juvenile fish & sea turtle hatchlings. It can also provide nutrients, support food webs and act as both a nursery & spawning area.
The effects of this was seen in Barbados in 2011 – baby dolphinfish arrived earlier, however, the flying fish season ended earlier. This is evident once again this year with the price of flying fish apparently declining from $18 to $15 for ten (10) flying fish.
Let’s face it – It’s ugly, and it smells
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 nauseating smell, which can be a bother for locals and tourists alike and has resulted in expensive & often damaging and fruitless attempts at removal.
So many unanswered questions remain: why this increase and what is the best way to utilise 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.
Is there enough to create a sustainable industry in the form of eating, drinking, fertilisers, export? Innovator, Barbadian Cavendish Atwell has created and successfully marketed Sargassum Seaweed organic mulch.
So for now, why not pick some up (not using any heavy machinery), let the rainwater clean it and dry it, and use as a fertiliser for those kitchen gardens, while removing African snails as well! However, caution must be taken when doing this as the salt content and other natural chemicals are 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!
- GCFI Sargassum Fact Sheet
- I must give credit to Hazel, who taught me much of this information