Brown gunk algae threatens beaches and biodiversity in southern Spain

by Lorraine Williamson
Brown algae in southern Spain

CADIZ – The ‘Rugulopterix okamurae’ is spreading at an unusual pace. It is moving through the Strait of Gibraltar, along the coasts of Huelva, Cádiz and Málaga. As a result, fishermen are catching much less fish and beaches are covered with a brown mass of algae. 

It concerns a type of algae the authorities are now investigating whether and to what extent the algae is invasive. According to El País, Nicolás Fernández, secretary of the Federation of Fishermen’s Guilds, Cádiz said, it is an ‘environmental disaster’. His organisation represents over 170 fishing boats in Conil, Barbate, Tarifa and Algeciras. 

‘Never seen anything like it’ 

Across the Strait of Gibraltar, on the coast of Malaga, Pedro Benzal, the president of the brotherhood of Estepona, gives more details about the extent of the damage. He comments, “I had never seen anything like it.” Fishermen estimate that switch boats have lost nearly 100% of their catch and trawl boats 50%. 

The brown algae was first spotted in Ceuta in 2015. Furthermore, it has only taken four years to extend the entire coastline of Cádiz. It is also visible in some points on the Atlantic coast of Huelva and eastwards towards Marbella. 

On the coast of Tarifa, a year and a half ago, they realised the algae could become a major problem. Mayor and biologist Francisco Ruiz Giráldez says: “It virulently takes over the entire seabed of the Strait.” In fact, the algae occupies up to 50% of the space between 5-25 meters deep. 

Concerned Scientists 

Concerns about the “meteoric and completely unprecedented” growth of the algae are also growing in scientific circles. “We have found no precedent for such an explosive bio-invasion,” said José Carlos García, a researcher at the Marine Biology Laboratory of the University of Seville. “The magnitude of the invasion of sargassum in Mexico and before the ulva (sea lettuce) in China is greater. But they did not expand as quickly as here,” said Félix López, professor of ecology at the University of Malaga. Both are part of dozens of scientists who gathered last week to seek solutions and help the government. 

Cogesa Expats

From Asia 

The Rugulopterix okamurae algae is believed to be native to China, Korea, the Philippines, and Japan. The algae would have come to these parts aboard one of the ships passing through the Strait of Gibraltar. 

Initially, the algae resembled some local species, so the alarm was not raised in time. However,since then, the unstoppable advance has had an adverse affect to fishing. Furthermore, a significant impact on biodiversity because the algae destroys the local algae populations and takes up the space of many animals. 

Brown gunk 

Apart from these consequences, the thick layers of brown gunk that are washed form on the beaches. As a result, this is not attractive to tourists. Therefore, coastal towns fear that the algae could negatively affect tourism – a sector that is already having a hard time after a year and a half of corona. 

The algae can form layers of more than 50 centimetres of decomposing organic material on the coast, especially in summer. On the beaches of Estepona alone, 2,800 tons have been collected in the past six weeks. Of Tarifa’s 22-kilometre coastline, the algae can be found on just 600 metres of beach. However, it still took €10,000 to remove the layer and transfer it to special landfills. 

“It’s like groundhog day. You remove it one day and it’s just as much the next day,” says Ruiz Giráldez, immersed in yet another cleaning. 

Urgent measures needed 

Faced with the rapid spread of the algae, all parties agree that urgent action must be taken. “We are now calling for an eradication program and studies from different perspectives. We must better understand the species and how to act against it,” López emphasises. 


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