Integrated Human Practicies
Our project lasted 2 years. We, therefore, invite you to consult the integrated HP page from last year. We interviewed other stakeholders in 2020 to build our current project.
Human Practicies updates for 2021
I - Understanding the problem
Green tides have been a scandal for decades. They first appeared in France in 1971 on the Brittany beaches. At that time, France decided to make Brittany a productive region to get out of poverty.
Intensive agriculture was born.
50 years later, the green tides are still there, even more frequent. Since the beginning of the year 2000, Brittany has listed 141 places affected by green algae blooms.
To better understand this issue, we have reviewed many documents and interviewed several people involved. We have noticed that many local newspapers and TV stations mention the problem of green tides, without talking about solutions. They regularly mention disturbing facts:
In 2009, the sudden death of a horse intoxicated by hydrogen sulfide (H2S) produced by the decomposition of green algae caused a " wave of panic " and the responsibility of the State was questioned.
In 2011, 36 wild boars died because of this gas
In 2011, 36 wild boars died because of this gas
In 2019, an 18-year-old oyster farmer died suddenly on the beach
Green tides are more dangerous than they seem. Not only for people but also for the fauna and flora and the local economy.
Few studies have been carried out and no general effect can be put forward. However, CEVA (Center for the study and valorization of algae) notes locally obvious effects on fauna and flora in areas where green algae are present.
For example, the algae cover feeding areas for birds, making it difficult to access food resources.
The ecosystem on the beaches is also disturbed and weakened by the mechanical collection of seaweed, the machines emitting fine particles.
Once deposited, green algae tend to release a particularly unpleasant smell, constituting a particular discomfort for residents. Moreover, the waters infested with green algae are a brake on the economic development of the affected coastlines.
Nautical activities and swimming are totally compromised by the presence of algae on the beaches or in the water curtain. Christian Colliou, mayor of the village of Kerlouan in Brittany, told us about the consequences of green tides. A few years ago, the coastline in Fanal, an ideal beach with fine sand, was very popular with families and tourists.
There was even a nightclub! Today, because of the green tides and their nauseating smell, there are fewer activities and therefore fewer tourists.
Moreover, Ifremer (French Research Institute for the Exploitation of the Sea) showed in 1993 that the quality of bathing waters in which green algae were present dropped drastically. Green algae promote the proliferation of coliform bacteria, providing nutrition and heating of the aquatic environment.
According to the conclusions of this study, there is a risk of bacterial contamination of bathing water and shellfish when a floating mass of green algae pollutes the water.
The ARS (Regional Health Agency) analyzed the beaches in the village of Kerlouan and announced that the rates of contamination of colibacilli were limited. The mayor of Kerlouan, like many other mayors in Brittany, will have to close their beach to the public if the situation continues.
Since 2002, the Ceva has been conducting a surveillance flight every month between April and October to measure the surface area of green tides. The first observations have shown a proliferation much higher than in other years: +40% or +50% compared to the multiannual average.
Freshly stranded green algae are not dangerous to health and are odorless.
48 hours after their stranding, they decompose and become dangerous. The municipalities are therefore forced to act quickly to collect them. Some years, 600 tons of seaweed per day are collected all summer. It is an eternal restarting.
More generally, the quantity of green algae collected on the beaches is 300 000 to 700 000 tons per year
Several million euros are used each year to pay the removal by companies. The collected green algae are often burned or buried.
Couldn't we make the cost of removal more profitable by using these algae ?
II - Perception of solutions and social, legal, and safety considerations
In 2020, our first idea was to eliminate green tides directly on the beaches. But our discussions with researchers like Justine Dumay and Paul Déléris (teacher-researchers) made us realize that we cannot spray the algae from our bacteria directly on the beaches.
This year, we interviewed Anne Pajot , a Ph.D. student at Ifremer . During her second year of master's, she completed a 6 months project on the valorization of green algae.
She wanted to remove the sulfate-reducing bacteria by treating the biomass with chlorine and thus prevent the danger of green tides. But from a legal and environmental point of view, it is just as difficult to introduce chlorine on the beaches.
It is also complicated to solve the problem at the root with synthetic biology, i.e. limiting the number of nitrates in soils and waters.
84% of the people who completed our survey (70 participants in all) find the research application to stranded green algae useful.
This confirmed our decision to valorize or rather to use the algae.
The legal framework is favorable to an industrial valorization whatever the quality of the harvested algae. A collection process for industrial valorization is allowed whatever the quality of the harvested seaweed.
The legal framework allows it, the technical processes must be adapted if possible. It is the technique and its cost of implementation that remains the major obstacle to the industrial recovery of stranded algae.
The emergence of a recovery policy raises the fear among some that we will forget to treat the problem at the source, namely the excess of nitrogen in the water. Taking into account the numerous exchanges with the public and the comments of last year's jury, we have oriented our project as well as possible.
In 2020, we aimed to produce sulfuric acid from the degradation of our algae using modified bacteria. This year, we went further by proposing different uses for the remaining biomass to limit waste. Fertilizers and methanization from green algae would replace the spreading of animal waste.
Eric Feuillet, (Head of Research and Development at GRDF), gave us some insight into these possibilities.
We would limit the impact on soils thanks to methanization, to the change of agricultural practices (less breeding) and we would decrease the use of synthetic fertilizers and nitrogen leaks in the soil. During our research, we visited SAS Méthatreil, in Machecoul, which is an innovative methanization factory near Nantes.
The visit was very interesting and allowed us to develop our project. We took into account, for example, that we have to sterilize the remaining biomass if we want to use it as fertilizer or compost.
We have contacted farmers to get their vision on our project and our solutions but we have not had any feedback from them.
The green tides are a national disaster which is a controversy. It is difficult to ask someone about this sensitive subject which is in fact a French political issue. It is like a family secret, everyone knows about it but nobody talks about it.
The administrative court of Rennes (city of Brittany) condemned last June the State to revise its plan of fight against the green algae. These are associations that regularly bring complaints against the State or the region. It is a first victory for them.
85% of the adults who completed our survey have already heard about green tides. 68% have already seen them in Brittany, Normandy or Pays de La Loire. It is a phenomenon that tends to spread on the French coasts.
Although only 55% of the participants feel affected by the phenomenon of green tides, it is not absurd to say that in several years this number will increase. Because even if the State and the farmers try to decrease the quantity of nitrate released in the soils, we will not see the results of the efforts made before 10 years.
In our survey, we asked the question, "Why do you feel affected by green tides? ". The answers are very interesting and show that this local issue should be considered as national.
Here are some answers from our survey:
"I feel concerned because it is the consequence of our French industrial and agronomic system engaging the ecological balance of our Earth"
"it is because of human activity that they appear so it means that I may have participated in it"
"This affects the ecosystem, and I am in a process of protecting the environment"
"Destruction of biodiversity so I feel concerned (indirectly)"
"It's due to pollution, it affects everyone in some way"
Beyond the scientific issues, the sociological approach of the problem of green tides and our project requires the greatest pedagogy.
You will find below our survey and the answers
To go further in the implementation of our project : HP Implementation Page