New sargassum invasion underway

POSTED: 05/3/12 4:35 PM

GREAT BAY – The St. Maarten Nature Foundation is once again warning about the possibility of large amounts of sargassum seaweed washing ashore on local beaches. Based on surveys at sea and in the air there are several large patches of the seaweed are heading into the general direction of St. Maarten.

Sargassum is a genus of brown (class Phaeophyceae) seaweed which is distributed throughout the temperate and tropical oceans of the world. Most of it lies concentrated in the Sargasso Sea, a region in the middle of the North Atlantic Ocean surrounded by ocean currents. It is bound on the west by the Gulf Stream; on the north, by the North Atlantic Current; on the east, by the Canary Current; and on the south, by the North Atlantic Equatorial Current.


Sargassum seaweed had been plaguing the Caribbean and St. Maarten last year. The Foundation warned swimmers to avoid swimming in Guana Bay in August and September due to the large amount of sargassum seaweed. Many beach front residences and hotels are forced to continuously clean up the seaweed.

After a few months’ respite large mats of sargassum have once again started to appear in the area. The resulting large influx has been due to a suspected southward shift in the Gulf Stream, which has pushed the Sargasso Sea towards our area.


“We started to notice patches of sargassum appearing in the area around the beginning of March and we have seen a steady increase since then. We did an aerial survey recently and patrols in that direction and we have indeed seen some large mats of the seaweed headed in our direction. We will monitor the situation closely not only for the interest of the population but also as it relates to the sea turtles that come to nest on our beaches,” Nature Foundation manager Tadzio Bervoets said.


The Nature Foundation will continuously monitor the status of the sargassum seaweed and notify the authorities if there is an imminent risk of a large influx of it in the St. Maarten area.


Last year August the French-side Vice President Pierre Aliotti called a press conference to warn citizens against the health risks sargassum poses. “In the water, the seaweed is harmless, but once they land on our beaches they start to decompose. During this process they emit hydrogen sulfide. Because of the local temperatures, the seaweeds decompose and dry quickly, usually within 48 hours,” Aliotti said. Hydrogen sulfide is a colorless, very poisonous and highly flammable gas. It spreads an unpleasant odor much like the smell of rotten eggs.

Aliotti said that inhaling the gas in small doses could trigger irritation of the eyes and the respiratory system, especially among people who are sensitive to it. The groups at risk are people with respiratory problems, asthma patients, elderly people, babies and pregnant women. Aliotti added that certain animals, especially dogs, are also sensitive to the inhalation of hydrogen sulfide.


“We know what we have to do to solve the problem,” Aliotti said last year. “We have to spread it out in thin layers to let it dry.”

Fishermen are happy with the arrival of the sargassum and that is not surprising. Sargassum is an important habitat for a variety of marine animals in the open ocean. The sea underneath free floating mats of sargassum is rich in mahi mahi, tuna, dolphins, wahoo and billfish. Sea turtles and marine birds also make sargassum their home.

In 2003, a fishery management plan was put in place for pelagic sargassum in the South Atlantic region. The plan implements restrictions on commercial harvesting, as was done by a North Carolina company who used the seaweed for the feed supplement industry. The plan limits harvest to a maximum of 5,000 pounds wet weight per year. Harvesting is only allowed between November and June to protect turtles. Harvesting within 100 miles of shore is also prohibited.

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