Authors:  Victoria Sánchez & Hannah Hermann 

Our research started when we were introduced to the world of invasive algaes and how they threatened Posidonia oceanica forests. We learnt how they originated and spread and about their negative impacts in the sea. In Spain, the expansion of Rugulopteryx okamurae is one of the major concerns. Solutions are needed… We began our adventure. 

P. oceanica is a native species in the Mediterranean Sea. Thanks to its existence, our coasts are more biodiverse. It provides food and habitat for many species. It is one of the oldest living beings on the planet (over 100,000 years) according to the scientist Sophie Arnaud-Haond, and it produces more oxygen per hectare than the Amazon jungle. It traps the carbon dioxide in its rhizomes, being a natural sink of CO2, helping to stop Climate Change. 

 

Rugulopteryx okamurae is an Asian algae which spread to the Strait of Gibraltar, Spain in 2015. It sticks to anything and spreads easily, which causes harm in P. oceanica. The situation in the Strait is irreversible, but prevention can be thought for other areas, like Mallorca, before it arrives. 

“Invasive” species are harmful only when taken out of their own environment, they are beneficial in their native habitat. We thought it would be interesting to focus on the positive uses of rugulopteryx, since it is painted all over the media already as a “negative” species that can’t be stopped from spreading. 

Kitchen Experiment

Invasive algae have been used for many different things like textiles, composts, biofuels… Our hypothesis questions gastronomic use. Have you ever wondered what spicy pasta or oil tastes like? We think this would be a great use of R.okumurae, as it does the seabed a favour by encouraging its extraction. What could be better than making a pasta dish or an algae oil to help? 

Chef Maria Salinas offered her kitchen at LJs Ratxó for an experiment. As we do not have R.okamurae in Mallorca, we tried with another species. MedGardens’ scientists, with whom we collaborated for this project, got us Asparagopsis taxiformis (native to Australia) from their marine expeditions.

In the kitchen, we started by “touching, smelling, and tasting”, the three most important steps, Maria said. We took the precautions needed so that the small pieces of algae didn’t end up in the sea, by pouring the water that was in contact with the algae onto the ground outside.

The crude algae was “sweet, and it had a very strong taste of chlorine.” The cooked algae was salty, like “explosions of flavour bursting in your mouth”. We proceeded to make oil by chopping the cooked algae, adding sunflower oil and infusing the water that the algae came in with the oil.

Once you put it in your mouth it was soft and sweet, but after it suddenly became salty, and with an intense flavour. We put it into a salad, and it was the perfect combination. 

Maria said that this could be sold as a delicatessen oil and you could charge 25€ for a bottle of 1 litre.  

Would this be profitable?

 Now that the culinary experiment had been successful, we needed to evaluate the extraction and commercialisation process. 

Safety needs to be taken into account as the algae reproduces so fast with asexual reproduction that any loose piece could create another individual. It must be ensured that no trace of the algae is left. Ways of achieving this, according to oceanographer Laura Royo would be:

  • Manually, branch by branch.
  • Mechanically, with 10cm bombs or hoovers, that destroy the algae and everything around it.

The manual extraction method would be preferred as the two other methods harm everything around it, and would only be recomendable where rugulopterix has taken over and has left no other species. 

Iñaki Miniño, co-owner of Marexi, a marine advance technology business, recommended that we look at the economic side of the idea: Laura Royo informed us that the cost of a professional diver is 400€ per day, with a maximum of 4hrs in the water, and 2hrs to process the material. In one day, one diver could get an average of 50 kg of humid algae. Since half a gram of algae can make 20 ml of oil, 50 kg would make 2,000 litres of oil (2000 b0ttles), which charged at 25€ would give a revenue of 50,000€.  Of course there are other costs to consider, like transport, bottles, labelling, marketing.. but these numbers show a profitable margin.

 Conclusion 

When considering the extraction of R.okamurae for culinary uses as an environmental solution, we need to look at two possible situations:

For areas that have already been invaded, like the Strait of Gibraltar, where there are more tons of algae produced every month, we could use the mechanical methods of extraction: larger quantities can be extracted, and there are no other species that can be harmed around it. This would involve a large investment, and the investors might be discouraged by the fact that the algae will disappear someday. The authorities might also be nervous about giving permits for these uses, because they might encourage the continuation of the algae. 

If the algae were to reach Mallorca, and it was spotted early enough,  a manual extraction  would be better to not destroy the posidonia and its ecosystem. If one diver only can extract around 50 kg  per day in small areas, this could make a difference. We have also seen that selling the final product as a delicatessen would be profitable. We believe this can also help in the long run to prevent the expansion of  R. okamurae. We will continue our research in culinary uses of invasive species. We hope that this will inspire others to take action in a creative way towards important problems. 

 

Top left: Hannah and Victoria with Chef María Salinas and her team at the kitchen of LJs Ratxó.

Top right: Rugulopteryx okamurae. Photo credit:  María Altamirano / Observadores del Mar

Right: Salad with delicious invasive algae oil made in the kitchen lab.

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