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Objective Eume: to recover the shellfish beds
The Eume hydroelectric power station waterfall.
The boat is loaded little by little. It is attached to a small service dock in front of the building of the Fishermen's Association of Pontedeume, a unique town in the province of A Coruña that lives on the edge of the sea. The work team of the University of Santiago (USC), under the coordination of Xosé Lois Otero, is putting all the material to carry out a collection of samples in the six-meter long speedboat. At the stern, with the outboard engine on, waits Valentín Riveiro, biologist of the association and who must guide the researchers through the secrets of one of the best shellfish banks in northern Galicia. The water is calm. With not even a light breeze to stir it. It reflects the grey light of the overcast sky like a mirror.
On the left, general image of the Eume dam; on the right, the upper reaches of the Eume river basin.
The shellfish farmers sounded the alarm. The productivity of the estuary that forms at the mouth of the Eume River has not stopped falling. It used to be a privileged area to find fine clam, slug and japonica and cockle. But now many ordinary shellfish farmers prefer to focus on catching kilos and kilos of an invasive species of oyster that does not stop colonising the area. It doesn't pay too well, but there is so much, and its farming is not so limited that a profit can be made.
Detail of the interior of the Eume hydroelectric power station.
In the left image, the old control room of the Eume hydroelectric power station; in the right, the current operations panel of the Eume hydroelectric power station.
One of the calls made by the president of the association, Santiago Salgado, to try and get help to alleviate this problem was to Endesa. Upstream, after passing the Fragas do Eume, one of the best preserved Atlantic forests in Europe, is the Eume hydroelectric power station. It was built three kilometres from a 101-metre high dam on foundations and 225,000 cubic meters of concrete. It has an installed capacity of 54 MW and, thanks to the abundant rainfall recorded in this basin, a high productivity.
Fraguas del Rio Eume Natural Park.
The call reached the director of Endesa's Northwest Hydraulic Production Unit, José Antonio Galván, who, due to his position, is the head of the plant. After several conversations, Galván explained to the fishermen's association what he thought Endesa could be its role in this matter, assuming the commitment that it has always had with a territory in which it has been operating for a long time.
"We feel," he said, "solidarity with a group to which we are united by the environment and by many years of coexistence."
On the left, the forest of the Fraguas del Rio Eume Natural Park; on the right, the river Eume as it passes through the Fraguas del Rio Eume Natural Park.
And they didn't want it to be just any corporate social responsibility action. They wanted to get to the root of the problem, to have an impact on the future. Therefore, they convinced the association to turn to the USC and put together a pioneering research project in Galicia.
"We wanted to work with rigour and with scientific endorsement."
A collaboration agreement was finally signed to do an in depth analysis of the causes behind the deterioration of the shellfish banks of the Eume. The initiative seeks to address the problem from all angles: quality of water, sediments, changes in the morphology of the estuary, etc. The study includes the collection of more than 60 samples along the entire mouth of the river. These samples that will then be dissected at the Mariña Bioloxía Station in A Graña, Ferrol.
A member of the scientific team of the Estación de Bioloxía Marita de A Graña in Ferrol of the USC, swims towards the dive site at the mouth of the Eume river.
Valentín asks for the rope that moors the boat to land to be released and puts the engine in reverse. Everything is ready. As if in slow motion, the speedboat breaks free from the coastline and gently enters the intense flow that carries the fresh water to the Atlantic. A few metres away, after passing the train bridge, Valentín drops the anchor and turns off the outboard. The GPS indicates that they are right next to one of the checkpoints. Divers adjust the equipment. They put on their fins, bring the regulator to their mouths and fall back off the side. It's not very deep. The bottom is sandy, and through the density of the bubbles they release, it's possible to see how they drive down the PVC tube that will collect the sediment sample.
After repeating the operation in a dozen places, the boat returns to the dock. Guillermo Díaz, one of the people responsible for the project on behalf of the USC, puts the samples in his car to later take them about 20 kilometres away, to the Mariña Bioloxía Station in A Graña, where every day he examines the quality of these ecosystems that have such a fragile balance. There, all the information from the sample will be extracted to begin to compose a puzzle that sheds some light on the notable drop in productivity of shellfish banks.
In the left image, members of the scientific team of the Estación de Bioloxía Marita de A Graña in Ferrol of the USC, check the immersion points for the collection of samples in the mouth of the Eume River; in the right image, Xosé Lois Otero, head of the scientific team of the Estación de Bioloxía Marita de A Graña in Ferrol of the USC, during the extraction of sediments from the seabed of the mouth of the Eume River.
"Such a complete study has never been done before, and it will serve as a reference at the Galician level because the decline in the productivity of banks is something that is happening in a generalised way," explains Xosé Lois Otero, who coordinates the research. "The most logical thing," he continues "is that the problem has multiple causes.' The study will determine the quality of the current system, the variations it experiences throughout the four seasons, and the changes produced in the last 200 years. The analyses that had been carried out to address these alterations in the growth of bivalves focused on the chemical parameters of the water and the possible parasites or microorganisms that affect the shellfish, but when it is something so sustained over time, there has to be more to it. That's why we want to analyse the sediment. What it tells us will be momentous.
On the left, sediment samples from the shellfish beds of the Eume river obtained from the Endesa study in collaboration with the Pontedeume shellfish gatherers' association and the Estación de Bioloxía Mariña de A Graña in Ferrol of the USC; on the right, Xosé Luis and María prepare to cut and analyse a sediment sample from the shellfish banks of the Eume river obtained from the Endesa study in collaboration with the Pontedeume shellfish gatherers' association and the Estación de Bioloxía Mariña de A Graña in Ferrol of the USC.
María analyses in her laboratory a sample of sediment from the shellfish banks of the Eume river obtained from Endesa's study in collaboration with the Pontedeume shellfish gatherers' association and the Estación de Bioloxía Mariña de A Graña in Ferrol of the USC.
Between the microscopes and laboratory tables, another important factor emerges to this problem: climate change. The increase in global temperature may also be behind this phenomenon. In about a year's time, when USC technicians finish their work, we will have the answer.
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