Seaweed in the Algarve. “We will hardly be able to control it and it could spread to the rest of the coast”

Often those who are used to going to the beach have already become accustomed to the presence of seaweed which, from time to time, gives an air of grace. But not everyone who has been to the beach in the Algarve in recent weeks may have found it so funny. Seaweed from Asia is invading the western Algarve coast, with beaches where accumulation has created a 1.20 meter high barrier.

At I, Francisco Ferreira, president of the environmental association Zero, assumes: “This question is a drama”. And he explains why: “Dealing with invasive species is already complicated on land – as is the case with ferrets, for example – but at sea it is even more problematic”, explaining that this situation “clearly has to do with the climate itself. changes we are going through.

The manager recalls that in the Mediterranean and also in the Atlantic area there is an invasive species every four or five weeks. “There are clearly favorable conditions for these species in which they could even be present but they were not viable before and now they find conditions in which they develop abruptly”.

The problem is that, says Francisco Ferreira, “there is no method of control because there are no predators, which means that it will always require human intervention to try to clean or eliminate these algae which, in addition, destroys the ecosystem, which is to say that a very productive area, coastal, close to the beaches, with these algae, is purely and simply completely threatened in terms of biodiversity and the point of view of the fish as well.

And it also threatens fishing because you can’t fish. “With the height of seaweed that I have, I cannot use fishing equipment and, in addition, I make unfeasible what I have on the platform. Basically, I no longer have a seabed available for the different species that occupy it,” he laments.

Asked if this problem is here to stay, the president of Zero considers so. “I think it will be difficult for us to control it and it could spread to the rest of the coast if the conditions are right in terms of temperature and depth, it is perfectly doable. There are nuances in which we can find it more with south-east winds, in the Algarve it comes, on our west coast it is perhaps more unlikely but on our Algarve coast, which is the one facing south and which faces the Mediterranean, that’s more complicated,” he concludes.

O I he also spoke with Dina Simes, professor at the University of the Algarve (UAlg) and researcher at the Centro de Ciências do Mar (CCMAR) who explained that this “plague” of algae “comes from the cultivation of oysters in Japan, and was first observed in Lake Thau (France), from where it spread to southern Spain and Portugal”, explaining that “the favorable conditions allow this seaweed to grow rapidly, causing large accumulations”.

Asked about the consequences of this invasion, Dina Simes has no doubt: “The consequences are both socio-economic, with major impacts on tourism and fishing, and environmental, leading to a reduction in the diversity of other species. native”.

And, although he guarantees that it poses no risk to human health, the professor and researcher affirms that “this species seems to have strategies with which it manages to inhibit most herbivores. In addition, its wide cover on rocky bottoms reduces the diversity of native species on the Portuguese coasts”.

And, like the president of Zero, he also defends that it can be extended to the whole of the national territory. “Due to its highly invasive behavior and the presence of favorable conditions for its development along the Portuguese coast, it is possible that it will spread along the entire coast. In fact, there are already records of accumulations in northern Algarve,” explains Dina Simes, who is collaborating on a project that aims not only to study the spread and monitoring of the proliferation associated with these phenomena of large accumulations, but also to enhance the biomass of these macro algae not indigenous and invasive species for research and industry, either by obtaining high value-added products for industries such as cosmetics, pharmaceuticals, agri-food, or for other types of industries such as fertilizers, the production of bioplastics, etc. The project, Algae on the Beach, is an initiative that is part of the NutriSafe project of the University of Algarve (project financed with CRESC ALGARVE 2020 funds).

What are the municipalities saying?

O I he also spoke with some of the most affected municipalities to try to understand what is happening and how they are getting around the situation.

One of them is Lagos, who tells our newspaper that, given “the magnitude of the situation and the unavailability of its own resources to respond to this volume of waste to be collected, the municipality resorted to the contracting of external services (machines and labour) to carry out the removal and transport of algae”. This work began last Thursday “and will continue in the coming days, until all the volume of algae accumulated on the sands is removed”.

If it is possible to remove all the algae, the municipality argues that “being a phenomenon that arises from the speed of spread and growth of this invasive species, the cleaning works are intended to have no end in view, that is to say that we will be able to achieve this in the next few days to clean all the algae that has already accumulated on the sand, but this will not prevent the situation from happening again during the bathing season, ”adds he.

In this municipality, the entire seafront between the city and Ponta da Piedade has been invaded by algae, “with three sands classified as bathing areas affected: Praia da Batata; Praia D. Ana and Praia do Camilo”. And he adds that “this situation had already occurred in 2022, all indications that it is becoming more and more frequent and more serious, due to the large volume of algae that is deposited by the sea on the sands”.

Just for this bathing season, the municipality has already been forced to contract services worth 100,000 euros, but “the final cost will depend on the frequency and extent of this invasion”. The chamber specifies that it is “a complex, long and costly operation”, explaining that “firstly because it can only be carried out at certain times of the day, more precisely at low tide. In addition, the characteristics of the coast, with several beaches nestled in an area with high cliffs and accessible by stairs (as is the case in D. Ana and Praia do Camilo), impose the bagging of seaweed and its removal by sea, with the use of boats”.

However, the phenomenon did not keep bathers away. “Fortunately, we have other beaches and three large sandy areas which at the moment are not affected by this problem, providing an excellent alternative for those who cannot currently use the aforementioned rocky beaches. We are talking about Meia Praia, a beach and a bay several kilometers long, Porto de Mós and Praia da Luz, which have all the conditions to receive vacationers and bathers and an equally unique beauty, ”explains the municipality.

As to whether there are predictions for the end of this “scourge”, the municipality of Lagos says that researchers, including from the Center for Marine Sciences (CCMAR) and the University of the Algarve, are “studying the phenomenon, so only the scientific community will be able to help the authorities to take the best decisions and measures to stop, or at least minimize, this proliferation of invasive species and the disturbances that result from it, as well as to discover the possibilities of recovering the residues of this organic matter”. However, as this is a problem “that affects various parts of the Algarve coast and involves more than one municipality, we also understand that the matter deserves to be discussed at AMAL headquarters, in order to agree positions and adopt a uniform performance policy.”

For its part, the Municipality of Portimão indicates that, at the moment, “this situation is already quite different, being only part of a very residual part of a beach (Prainha) that has not yet been removed due to “difficult access. All the other beaches – eight kilometers of beaches -, guarantees the municipality, “are free of algae”.

So far, the Portimão Council has already eliminated around 20,000 cubic meters of this algae and “it is estimated that to date around 70,000 euros of the municipality’s money have been spent”.

Assuming this is “an unprecedented situation in Portugal and monitored by the competent authorities”, the board says that, in what it is responsible for, it guarantees a “team ready to support whenever necessary, in order to quickly remove the algae if they are back on the shore.

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