Garth Rattray | The Sargassum seaweed can be useful

Recently, I saw a short documentary on the Sargassum seaweed ‘invasion’ of the Caribbean Sea. Then I recalled that my wife and several of her relatives encountered mounds of the seaweed on the beach and a very large quantity floating near the shore on their recent visit to a popular St Catherine beach

The workers forewarned visitors of the seaweed, created an access pathway to the water, and gave them the opportunity to have a look and to decide whether they would stay. Despite the seaweed and the unpleasant odour that it emitted, they decided to stay anyway because they badly wanted to swim and figured that the seaweed was at the other beaches.

I still remember the first time that I smelled Sargassum seaweed. I was driving easterly towards Port Maria one evening, and the stink entered the vehicle through the vent system. It clung to us for many miles, and I deduced that it was the infamous Sargassum seaweed. As we journeyed along, the moonlight hit the nearby water, and an expansive and ugly flotilla of the seaweed could be seen heaving clumsily towards the shore.

Our coastline is invaded by this unwelcome immigrant every year. More than 24 million tonnes of the Sargassum seaweed struck coastlines in June 2022. This seaweed is thought to originate from the Sargasso Sea in the North Atlantic Ocean. However, perhaps it comes from the nutrient-rich equatorial region of the Atlantic.

The influx of Sargassum seaweed is a fairly recent phenomenon believed to be caused by climate change (warmer waters) and changing ocean currents. It is also postulated that the runoff from rivers might be nourishing the growth of the seaweed.

If the Sargassum seaweed is prolific, it can be very offensive smelling, toxic to sea creatures, affect fishing, negatively impact water quality, and become hazardous to humans. Obviously, its presence can seriously damage our tourism product and even lead to beach closures.

As the Sargassum seaweed breaks down, it releases hydrogen sulphide gas. This is the same colourless, toxic, and flammable gas that is released by rotten eggs. It can cause, appetite loss, eye irritation, headaches, respiratory problems (like bronchial constriction), dizziness, memory problems, and irritability. The gas can affect communities near to where the weed approaches the shoreline. Citizens should avoid direct contact with this seaweed and wear protective gear if they are handling it or working in areas where it is decomposing.

Since we can’t stop the immigration of the Sargassum seaweed, perhaps we should consider ways to remove (harvest) it and put it to good use. It can be used as a fertiliser. This seaweed is nutrient rich and can improve soil health and fertility through composting. It can also be used as a feed supplement for livestock, including in aquaculture.

BIOFUELS

Sargassum seaweed may be converted into biofuels (biogas and bioethanol). It can be a source of renewable energy through anaerobic digestion. The seaweed has even been researched for its potential use in pharmaceuticals and cosmetics. It can have wound care / healing potential and perhaps other medical applications. It can also be utilised to clean pollutants from contaminated environments.

Some countries are already finding use for this appalling seaweed in a variety of ways. In the United Kingdom, they have developed a cost-effective process of converting Sargassum into fertiliser, biofuel, and other products. Indonesia has an entire industry around this seaweed. They use it for food (including as chips or used as a flavouring for other foods), animal feed, and fertiliser. Sargassum is rich in proteins, carbohydrates, minerals (such as calcium and iron), and essential amino acids. Indonesia is also exploring its use in cosmetology, the pharmaceutical industry, and renewable energy. The Germans (at the Fraunhofer Institute for Chemical Technology … the Fraunhofer-Gesellschaft is touted as the world’s leading applied research organisation) have converted another seaweed waste into superior building insulation.

Spain (at the Universidad de Alicante) is exploring Sargassum for use as biomass for power plants. In the Dominican Republic (DR), at the Pontificia Universidad Católica Madre y Maestra – PUCMM, Sargassum is used to create concrete blocks for sustainable and low-cost construction. The seaweed is collected, washed, dehydrated, and powdered for use in concrete mixtures. The DR exports dried Sargassum to Mexico, the United Kingdom, Finland, Australia, the United States of America, and China. Some countries use the product for cosmetics, some use it to increase the level of iodine in livestock feed, and others use it to make flour for human consumption.

Because there is a growing international trade in Sargassum, the DR company SOS Carbón, has developed an innovative and cost-effective way of harvesting the seaweed. The process not only cleans the coastlines of the pesky and potentially hazardous seaweed, but it also renders the Sargassum usable and profitable.

In Canada, researchers are keeping a close eye on the developing and growing utilisation of Sargassum. Companies like New Atlas in Edmonton are reporting innovative uses of Sargassum.

Sargassum needs to be harvested and processed. The process must be cost-effective (economically viable), sustainable, and environmentally friendly. Pilot projects are being conducted into the feasibility and scalability of the product. The seaweed must be rinsed with fresh water, dried (which helps with desalination), washed and soaked in fresh water, then pressed or centrifuged. The degree of desalting Sargassum is dependent on its intended use. The most cost-effective source of fresh water is our rivers.

We can ‘turn the tide’ on Sargassum and seriously investigate putting the menace to good use.

Garth Rattray is a medical doctor with a family practice and author of ‘The Long and Short of Thick and Thin’. Send feedback to columns@gleanerjm.com and garthrattray@gmail.com.