The impact of human activity in the Mar Menor He has been a protagonist several times in all the media in recent years. One of the most recent episodes happened last summer, when the Murcian Government had to remove 4.5 tons of fish that had died due to lack of oxygen in the water. Or what is the same, the excess of nutrients derived from the fertilizers used in agriculture and that end up in the lagoon, favoring the proliferation of algae and phytoplankton. This pollution process is called eutrophication and it is what the Spanish Institute of Oceanography (IEO-CSIC) intends to stop with the help of the flat oyster (ostrea edulis).
The flat oyster has filtering capacity because it feeds on microalgae that cause eutrophication. However, its population in the Mar Menor has been reduced due to the arrival of invasive species. For this reason, the IEO directs the RemediOS project to promote the restoration of this species in the lagoon. The person in charge of the program, Marina Albentosawarns however that it is not a “magic solution” to end the problems of the lagoon. “The Mar Menor requires integrated solutions on land and at sea,” says the researcher from the Oceanographic Center of Murcia of the IEO.
The first step, explains Albentosa, will be to capture flat oysters from the Mar Menor to try to reproduce them in a laboratory. Once achieved, the larvae will be allowed to grow for a few weeks and then they will be sent to the Marchamalo salt flats. In this protected area of La Manga del Mar Menor they will grow, in what is intended to be an intermediate step of semi-freedom. Once they are strong enough to be transferred to the lagoon, their ability to help reduce eutrophication will be evaluated.
The program, made up of scientists from different institutions, also consists of a part of dissemination for different sectors of society on the concept of bioremediation, which consists of seeking solutions based on nature to recover an ecosystem. Albentosa argues that when the hand of the human being causes the decrease or disappearance of a population, the service that these individuals provided to the natural environment is also being eliminated. In the case of flat oysters, this service is the filtering of the water and “the removal of phytoplankton blooms or developments”. With this type of action, an attempt is made to restore stability to the ecosystem. “The solution is being given to us by the nature that we have destroyed,” summarizes the researcher.
flat oyster population
The flat oyster reached 135 million specimens in the Mar Menor during the eighties and nineties, quantifies Albentosa. This organism, as detailed, comes from the Mediterranean and entered the lagoon in the seventies when there was a drop in salinity. However, the arrival of caulerpa has decimated its population. This invasive macroalgae has become strong at the bottom of the Mar Menor, which has left the oyster larvae with no space to settle. This weakening has in turn favored certain opportunists, such as the sponge that invades oyster shells. “Not always a green soup is the only sign that the system is going wrong. Many times the dynamism and the relationship between the species that inhabit the ecosystem are telling you that something is not working”, he points out.
Regarding the deterioration of the Mar Menor, the researcher recalls that there was already talk of it a couple of decades ago, although “the system is destabilized between 2015 and 2016”. The causes are related to human action: “All studies are concluding that it is mainly agriculture and in second place, but with a great impact, tourism development. They are the two classic factors of the eutrophication process”, she synthesizes.
RemediOS is part of the European network NORA (Native Oyster Restoration Alliance), which was created in 2017 to support and promote the conservation and ecological restoration of the flat oyster throughout Europe. This initiative has the collaboration of the Biodiversity Foundation, from the Ministry for the Ecological Transition and the Demographic Challenge, which has partially financed the project with an aid of 172,022.25 euros. This work is part of IEO’s work to promote bioremediation actions in degraded ecosystems through aquaculture techniques.
You can follow MATTER in Facebook, Twitter and Instagramor sign up here to receive our weekly newsletter.
#oyster #recover #Mar #Menor