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Asian Seaweed Invades Strait of Gibraltar, Threatening the Ecosystem

Martin Serrano // Photos: Fran Montes & Sourced

A Foreign Asian seaweed ‘Rugulopteryx Okamurae’ is invading the Straits of Gibraltar, damaging local marinelife and threatening the ecosystem.

In December 2008 a large commercial delegation from the Port of Algeciras visited South Korea, the third highest economic world power at the time, with the aim of increasing trade.

A few years later in 2015, the South Korean shipping company Hanjin Shipping – which belonged to ‘CKYH Alliance’ – the world’s second largest ‘megacarrier’ – made its first investment into Spain and the western Mediterranean at the Port of Algeciras.

In 2016, large quantities of stranded seaweed of the ‘Rugulopteryx Okamurae’ species – an invasive seaweed – appeared along the coasts of Ceuta and Tarifa.

Asian Seaweed Strait Gibraltar

The scientific community couldn’t rule out the possibility that this seaweed may have been transported into the Strait by leakage of ‘ballast water’ from ships coming in from Pacific Northwest countries – i.e. China, Korea and Japan – since it originates in that part of the world.

Ballast water is the seawater carried on board ships that provide greater stability and manoeuvrability when sailing without cargo. In addition to seawater, particles, sediments and organisms are able to pass through the pumping systems of these tanks.

These particles are released along with the ballast water when discharged at the port. It should be considered that the Port of Algeciras has fourteen weekly routes to South Korea where this invasive seaweed originates. The increase in maritime traffic is causing serious problems in the bay due to the uncontrolled discharge of ballast water.

Ballast water Rugulopteryx Okamurae
A ship releasing ballast water

The responsibility of these discharges – which has most likely caused the environmental disaster in the Strait and the Bay – lies both with the ship’s captain and the shipowner, who must comply with the 2004 IMO International Convention.

The Algeciras Bay Port Authority is also responsible since they have a legal requirement to monitor and control ballast water discharge.

Of the 26,000 ships operating in the Port of Algeciras yearly, only 220 are inspected. This demonstrates the lack of protection against invasive species in the waters of the Strait and the Bay. In this case, it is causing an environmental catastrophe of unimaginable proportions on the seabed.

Rugulopteryx Okamurae is a species that grows on hard surfaces. Once the seaweed establishes itself, it grows rapidly and ends up displacing or even eliminating other species in the area.

Rugulopteryx Okamurae Seaweed Tarifa

As has been observed, it also grows over other algae and coral, suffocating the marine life underneath by robbing them of light. Ultimately, the seaweed that has been found stranded on our beaches will soon change the ecological landscape of this sea-land border.

Not only does this have an ecological impact, but it will also have an economic one. The seaweed regularly becomes entangled in fishing nets and impacts the quality of the Strait’s water – and, therefore, the fishing trade – will be affected.

Consequently, displacement of local species, especially the sea urchin, have been observed in areas where this seaweed is most prevalent.

Likewise, there is great concern that this will affect tourism in the area due to the beaches being filled with tons of washed up seaweed. Affected municipalities like Tarifa and Algeciras have to bear the cleaning costs.

Rugulopteryx Okamurae
Asian Seaweed Rugulopteryx Okamurae

John Cortes, ecologist and Minister for Health, Environment, Energy and Climate Change of the Government of Gibraltar, told Reach that this has also affected Gibraltar, mainly on the Western side.

Since 2017, the presence of seaweed has forced local governments to undertake extraordinary clean-up measures along the coast.

Cortes also confirmed that there is already evidence of Rugulopteryx Okamurae affecting the biodiversity of the seabed – which is becoming increasingly covered by this seaweed. This is having a serious impact on unique species from the island of Las Palomas, Tarifa, which is a biosphere reserve.

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“This seaweed is so widespread that there is little we can do other than to prevent it from spreading further to other areas. This is a tragedy; it’s taking over the entire seabed…” Click ‘Next’ to continue reading

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