By William H Harriss. 9 April 2026
For decades, scientists believed sargassum was largely restricted to the nutrient-poor waters of the Sargasso Sea. It is now clear that this seaweed has become a widespread and fast-growing presence across the World, with its expansion tied to both natural variability and human-driven nutrient inputs.
After seeing what was happening in the Caribbean and Americas, last year I wrote about sargassum running out of control and polluting the whole of the worlds seas. I also said when it got bad enough there would no longer be a way of controlling it. Well fortunately it has not quite reached the stage of no return yet. But that is looming on the horizon and unless the world acts fairly quickly it will all end in tragedy. Apparently sargassum is able to double in size and volume every eleven days.
My original prediction has started to come true. Sargassum has reached Australia. A catastrophic bloom of the toxic algae sargassum horneri has occurred in South Australia, impacting marine life and affecting fishing and tourism sectors. The bloom has covered an estimated 4,400 square kilometers and is part of a broader environmental crisis affecting various coastal regions.
The spread of Sargassum has reached the Pacific, posing a significant environmental challenge. The seaweed is being observed in various locations across the Pacific Ocean, leading to concerns about its impact on marine ecosystems, coastal economies, and public health. Efforts are being made to monitor and manage the spread of Sargassum, with a focus on detection through satellite monitoring, forecasting using ocean models, and response strategies such as sustainable harvesting and valorization into useful products like fertilizers, biofuels, and bioplastics. But that is the same old nonsense that the Caribbean and American countries started with. Sargassum is much more powerful than any schemes to deal with it and make use of it can ever be. It multiplies and grows so rapidly that all the schemes man can invent or think of just will not be able to control or use it all. Supply exceeds demand.
The further bad news is that it has now reached the Indian Ocean. the Indian Ocean like the Pacific Ocean is also warming at the same rate as the Atlantic, so generating faster currents and winds; spillage around the horns has become a reality. The Bay of Bengal is experiencing a micro sargassum gyre. It will most certainly suffer a similar fate to the Caribbean Sea, where the islands/shores therein suffer beaches strewn with mounds of sargassum, to ruin fishing, tourism and marine ecology.
India: A significant contributor to ocean pollution, with major coastal areas affected by sargassum blooms.
The following countries are experiencing challenges due to the rapid growth and spread of sargassum, which poses ecological and economic problems.
China: Known for high levels of pollution, including sargassum, in the Indian Ocean. China is located along the western shore of the Pacific Ocean. It is bordered by several bodies of water, including the East China Sea, South China Sea, and Yellow Sea. Additionally, China has access to the Indian Ocean and the Arctic Ocean, but its primary ocean is the Pacific.
Indonesia: Also contributes to the pollution in the region, impacting coastal areas. Indonesia, the world’s largest archipelagic country, spans over 17,000 islands and lies strategically between the Indian and Pacific Oceans, making it a crucial maritime crossroads in Southeast Asia and Oceania. The Indian Ocean lies to the west and south of Indonesia, influencing its climate, monsoon patterns, and ocean currents, while the Pacific Ocean borders the north and east, contributing to Indonesia’s rich marine biodiversity.
Malaysia: Another country with notable sargassum issues in the Indian Ocean. Malaysia is located in Southeast Asia and is bordered by the South China Sea, the Straits of Malacca, the Celebes Sea, and the Sulu Sea, all part of the Pacific Ocean system.
Philippines: Floating Sargassum in the Philippines is a growing concern due to its impact on marine ecosystems and coastal communities.
Sargassum seaweed has been spreading dangerously since 2011, primarily due to human pollution, and has reached 43 countries, including the Philippines.
In the Philippines, the Philippine Fisheries Code regulates the collection and harvesting of Sargassum, with specific provisions for washed ashore Sargassum. While the Philippines is surrounded by several marginal seas, all of these are ultimately part of the Pacific Ocean, making it the primary ocean in which the country is located. This positioning is crucial for understanding the Philippines’ maritime trade, climate, and geological activity.
The Sargassum Monitoring Network is actively tracking and reporting on Sargassum landings, providing real-time data and forecasts to help manage the situation.
The Mediterranean has several species of Sargassum itself but is recently being invaded by the sargassum from the Sargasso Sea. Reports indicate that massive sargassum blooms have become a recurring challenge across the Mediterranean region, disrupting marine ecosystems and coastal economies. Monitoring efforts are ongoing to track the distribution and impact of these floating mats in the Mediterranean. Egypt, Floating sargassum is a problem in several countries in the Mediterranean Sea, particularly affecting areas like Egypt, Turkey, and Italy.
So what now, how can we control it? Do we still have a chance? Unless the worlds scientists get together under a group umbrella and pool information and resources, within the next ten to 20 years the whole worlds seas and oceans will completely overgrown and stifled with sargassum. There will be no beaches and no seaside holiday resorts anywhere. Seaside hotels and resorts will be something only left in peoples memories. Yes it is that serious.
The problem is dozens of Universities and governments are all encouraging students and private industry to try and deal with sargassum as a windfall product that can be converted into dozens of different uses and products. They are all ignoring the fact that sargassum is loaded with heavy metals, the highest rate of those being arsenic. Those metals have to be removed from the sargassum before it can be, or should be used for converting into any other useful product. Removing the metals from sargassum quite simply is not cost effective and suddenly makes the products expensive and labour intensive.
WARNING< Under no circumstances should sargassum be used on the land as a soil additive or fertilizer until the heavy metals are removed. It contains arsenic 20,000 to 40,000 times more than occurs naturally in sea water. Anything grown in soil treated with heavy metal laden sargassum will take up the heavy metals and will then be ingested by humans. Sargassum metals are carcinogenic and therefore cancerous.
It really is important to deal with sargassum at sea long before it enters coastal waters or lands on beaches. Ideally it should be dealt with in the Atlantic, not in the Caribbean.
The problem is massive and cannot be left to individual governments, and universities who just want to use the problem as a learning and training feature for their students. The whole world has to work in unison. And it has to start right now.
It started as a West African problem, then a Caribbean and Americas problem, now it is spreading world-wide and is starting to gallop out of control.
I have the answers, perhaps not all the answers, but basically there really is a way. But the time is short.
If anyone reads this and knows anyone in the appropriate section of the UN, please forward them a copy of this letter. I am fed up with sending them emails and being ignored.
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