Rugulopterix Okamurae, or how ecosystems collaps

by Jörn Selling

Since 2015, the cliffs between Tarifa and Algeciras have been suffering from accumulations of alluvial algae, which have suffocated all life on the rocky cliff under them and cause an unbearable stench of rot in the harbour on days with wind from the east (Levante).

This happens in summer, when more intense sunlight and higher temperatures lead to an increase in algae growth. Meanwhile, the alga has already spread to Portugal in the north and Marbella in the east and affects tourism on many beaches. The fishermen also complain about losses because fishing has collapsed to a depth of 40 metres in the Strait of Gibraltar, the trawl nets are full of algae and the Almadraba, especially the part closer to the coast, is overgrown by said alga.


It has always been the case that algae grow better in summer and this explains, for example, why large baleen whales visit the polar regions during the warm season. The microscopic phytoplankton (unicellular alga floating in the water) is multiplying rapidly and serves as food for small crustaceans (krill), which in turn are the most important source of energy for the baleen whales.

That algae bloom, until the affected water bodies tip over has also happened again and again. In the worst case this is called a "red flood". These are dinoflagellates, the second most common phytoplankton species after the diatoms, which colour the water red with the toxins they produce and therefore killing everything. Less dramatic algae blooms were those of the gulf seaweed (brown algae of the genus Sargassum), which had already been identified by Columbus in the form of surface-drifting carpets of algae in the Sargasso Sea.

Algae bloom when there are enough nutrients and also sunlight. Over fertilization can be caused by natural causes, e.g. when nutrients are carried from the mainland into the sea by massive rainfall; but it also has more and more to do with us humans. We use artificial fertilizers in agriculture and discharge effluents into the oceans, both sources of excessive fertilization called "eutrophication". The deforestation of the Amazon causes erosion, the washed-out soil fertilizes the Atlantic Ocean at the Amazon estuary, which makes the gulf seaweed bloom to such an extent that ever larger carpets have been measured since 2011. Last year, the affected region stretched over a length of 8850 kilometres from West Africa to the Gulf of Mexico, as an analysis of satellite images has shown. The Caribbean island state of Barbados declared a state of emergency. At several beaches in Mexico, Barbados and in the south of Florida the beaches were covered with smelly carpets. Sargassum muticum is a new player and particularly "successful". Originally from Japan, the imported algae spread in the North Atlantic.

Imported species can sometimes become extremely "virulent", as in our case in Andalusia, which could become a problem for the whole of Europe. It is the Japanese brown alga Rugulopteryx okamurae, which probably has travelled in the ballast tank of a cargo ship - and thus reached the Bay of Gibraltar. The problem of species carried in ballast water has been known already for a while. Worldwide 12.000.000.000 tons of ballast water are released into the environment every year. This leads to an unwanted transfer of species every 9 days. On the 7th of October 2017 an agreement came into force which obliges ships to disinfect the ballast water. This is best done with a combination of UV radiation and ozone, but other methods are also used. However, 68.000 ships will have to invest around € 1.000.000 before the whole world fleet will be upgraded. The agreement is therefore not expected to be fully functional until 2024. But only if the ports invest in the needed infrastructure and hire enough inspectors.

The agreement is too late for the Bay of Gibraltar. Rugulopterix has arrived to stay. Not only that, the alga has come to capture the ecosystem. It has become a dominant organism and is now tipping over parts of the ecosystem. It has no natural enemies and grows everywhere, even on the bodies of sea cucumbers. When sea urchins die (they can live up to 8 years), their place is also colonized by algae. The result is a completely changed seabed on the coasts, which is the nursery for most marine organisms. It is hard to imagine what will happen to the local flora and fauna if the alga stays so virulent. Between Algeciras and Tarifa it has covered the whole seafloor. There is nothing more we can do except hope that the ecosystem itself will find a way to set the algae limits. Divers report that they rarely see the fish they know. The limpet Patella ferruginea and the sea snail Dendropoma petraeum, both protected species because they are endemic to the southern coast of Spain (that means they are not found anywhere else in the world) may become extinct. Useful algae such as the "kelp" Laminaria achroleuca and Gelidium spinosum, both producing alginate, are disappearing from the Strait of Gibraltar.

Is there a solution?

The society in Andalusia has realized the seriousness of the situation and because of that they organized a conference of G.A.L.P. (Local Fishing Action Group, Cádiz-Strait of Gibraltar coastline), the guild of fishermen of Cádiz and OPP72 (Fishermen of Conil) in Tarifa on July 1st, 2019.

Dr. José Carlos García Gómez of the University of Sevilla, first scientist on the microphone, has been researching Rugulopterix for several years. It reproduces asexually via sporulation - as well as sexually via the formation of gametes. It appears in four different forms (probably all clones that have formed asexually) and Dr. José Carlos García Gómez fears that a hybridization with the brown alga Dictyota dichotoma (Divided Net Weed), which is related and globally spread, might already have happened. That would increase its already extraordinary fitness (led to the algae becoming so virulent in the first place). But he still has to substantiate all of this with genetic studies.

The next speaker is the fisherman Gregorio Linde González. He confirms that in a depth of 40 meters there are more algae than fish and even nets from a depth of 400 meters are full of Rugulopterix. Responsible for the vertical transport of water masses (and algae) to such depths in the Strait of Gibraltar is a soliton wave that is created at the Camarinal sill when the tide changes from high to low. The wave forms in the interface (in red) between the Atlantic water, which flows at the surface towards the Mediterranean Sea, and the heavy, cold and salty deep water from the Mediterranean Sea, which flows from the Strait into the Atlantic Ocean. For submarines which want to cross the Strait of Gibraltar undetected with their technology switched off, these waves can become dangerous because they can transport diving objects hundreds of meters vertically.

At the mentioned sill of Camarinal, an upwelling occurs at the same tidal change, especially when the tidal range is high at full moon and new moon. These are masses of water which rise from the depth. The reasons for this are different in various marine areas; in the Strait of Gibraltar it is a combination of seabed topography, directions of currents and tides. Upwellings supply nutrients to phytoplankton which is living on the surface (where there is light). This is why the region has always been very productive. In the case of Rugulopterix, the natural fertilization, together with our nutrient inputs, seems to turn into overfertilization.

Dr. Enrique Nebot Sanz from the University of Cádiz is investigating how ballast water can be best biologically neutralised. Electro-chlorination, in which with the aid of electricity in the ballast water the chlorine gas is produced by splitting the sea salt appears to be very promising for continuous use during the ship's voyage.

Dr. Féliz López Figueroa from the University of Málaga informs that Rugulopterix was first seen in Europe in 2002, at an oyster farm in France, where it did not cause any problems. He points out that the alga must be included in the list of invasive species in Spain in order to apply to the administrations for resources. It should also be mentioned that algae contain valuable substances: Antioxidants, environmentally friendly dyes, cancer inhibitors and immune-enhancing substances (as feed supplement in aquaculture).

The captain of the port of Algeciras, Julio Berzosa Navazo, then explains the successes and failures encountered during the inspection of the ballast water of the 26,000 ships that are docking in Algeciras every year. With more than 100,000 vessels in the Strait every year, inspection is a mammoth task.

The last speaker is Antonio Vegara Jiménez from SEPER-Tarifa (Sección de Educación Permanente de Tarifa). He and his students produced the first skin creams based on Rugulopterix.

The alga contains Fucoxanthin and Diterpenes, both medical active ingredients.

In Betijuelo (near Tarifa) an architect is testing the alga as building material. The living algae, which float in the water and are caught by nets, are suitable for human use. The dead algae could still be processed into agricultural fertilizer. During the following round table it became clear that there is no single solution to this environmental crisis. There are plenty of examples of species introductions that got out of hand: the zebra mussel (Dreissena polymorpha) which is now growing on half the globe's water pipes and the Shanghai hairy crab (Eriocheir sinensis) are two famous cases.

Everyone agrees that this is a crisis that must be fought by all parts of society

  • Biodiversity hotspots should be defined where it is worth picking algae from the seabed.
  • The alluvial algae must be removed from the coasts, at least where they can be accessed by machinery.
  • Research should be conducted in a targeted and coordinated manner; it would be conceivable to develop repellent substances that would prevent algae from settling on the Almadraba nets.
  • Pilot projects on use and removal should be encouraged.
  • Fishermen could be employed in a newly developed exploitation chain or their loss of earnings would have to be compensated with money or a larger fishing quota in other areas.

Now we have another example on our doorstep of the consequences that our intervention in natural cycles can have. The more we change and then have to take corrective action, the more we have to actively manage ecosystems and our responsibilities will continue to grow. As a child I still learned at school how immense the resources of the oceans are, and now they are in danger to tip over, with introduced species being just one of the many problems. Will we be able to live up to our responsibilities? The task of science is to identify the problems and find possible solutions, and to ensure that society is aware of the consequences of wrong decisions. The window of time for the conservation of our species continues to close and there are still too many who accept from science only what suits them!

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