Credit:
© O. Langrand
CEPF is a joint initiative of l’Agence Française de Développement, Conservation International, the European Union, Fondation Hans Wilsdorf, the Global Environment Facility, the Government of Canada, the Government of Japan and the World Bank. A fundamental goal is to ensure civil society is engaged in biodiversity conservation.
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Sargassum seaweed along the shore of Guadeloupe, May 2018.
© O. Langrand
A Surge of Seaweed
In the Caribbean Islands Hotspot, a deluge of Sargassum is causing problems for local people and wildlife
By: Olivier Langrand, CEPF Executive Director
26 June 2018
26 June 2018
During my recent stay in Guadeloupe, a French island that’s part of the Caribbean Islands Biodiversity Hotspot, newspaper headlines and radio and television channels were dominated by concern over Sargassum, a brown seaweed normally found in the northern part of the Atlantic Ocean where eels go to spawn. Massive rafts of Sargassum have recently traveled to the Caribbean, washing up on the beaches of Guadeloupe and several other islands of the Lesser Antilles.
The phenomenon has happened before, in 2011, but this year the quantity of seaweed was much greater. Thousands of tons of Sargassum have accumulated on the island’s shores causing serious negative impacts.
Rotting Sargassum releases ammonia and hydrogen sulfide, resulting in an intense smell similar to rotting eggs. Authorities have been forced to restrict access to beaches, a blow to local tourism, and close several schools near the seashore.
The impact on biodiversity is also measurable: When sea turtles try to access the island’s nesting beaches to lay their eggs, they hit an impenetrable, one-meter long wall of Sargassum.
The sudden proliferation of the seaweed is being intensely studied, but scientists do not yet have a definitive explanation. One theory is that the discharge from the Amazon River, which includes high concentrations of nutrients washed away from Brazilian agricultural areas, has boosted the growth of Sargassum.
Another explanation is that ocean currents altered by climate change may have reduced the ocean gyre that had previously kept the seaweed in the Sargasso Sea. The cause could also be a combination of these two human-caused factors.
Local authorities and communities are struggling to deal with the massive seaweed inundation. The quantities are so significant that removing them to a landfill, for example, is not possible for such a small island. In addition, the emanation of nauseous odors makes the collection, the transport and the management of the seaweed hazardous.
As the likely causes of this environmental crisis are almost certainly related to human activities, the long-term solution can only come from an engagement from the global community.