The Professor of Ecology points out that this problem “would have been easily solved three years ago by acting on the aquifer”
“From now on, this episode can be repeated more days and with greater severity, as the temperature rises,” warned Ángel Pérez Ruzafa, professor of Ecology at the UMU and member of the Scientific Advisory Committee, yesterday, following the appearance of dead fish on the beach of Castillicos in Santiago de la Ribera. Although a small amount was collected, indicators of lack of oxygen and low salinity do not bode well. He regretted that the forecast of a few weeks ago was fulfilled, when they warned of the advancement of these episodes.
Based on the first data collected, Pérez Ruzafa explained that fresh water must have entered with a delay in the last rains, since very low salinities have been detected on that beach. It is probably a pluvial flow that arrives through the urban drains that flow into the area, to which the outcrops of the Quaternary aquifer are added.
“Traditionally, the water bubbles in the beach area that goes from Los Narejos to Santiago de la Ribera, so water with many nutrients, nitrates and phosphates is entering”, something that will determine the analyzes that Imida is carrying out, explains Pérez Ruzafa. He considers that both factors have contributed to the decrease in oxygen and salinity, and points out that the combination of an osmotic shock with the decrease in oxygen levels has caused this situation. The decrease in oxygen has been detected in the coastline closest to the shore, although the levels have recovered throughout the day. He specifies, in this sense, that hypoxia can be more intense at night than during the day.
TRIGGER
«There must have been an entry of fresh water; the salinity and the level of oxygen on the shore have been reduced»
Ruzafa points out that the temperature has not been the main trigger in this case, since it is between 22 and 25 degrees, although it is still high for this time of year. However, since the heat will increase, more serious situations are feared. The dead specimens are fish of benthic origin that live at the bottom of aquatic ecosystems and that, in this case, are more vulnerable, points out the professor.
The key to the aquifer
As immediate actions, Pérez Ruzafa points out that works must be undertaken to separate the urban water networks; as well as acting urgently on the Quaternary aquifer, a measure that has been demanding for years and that is gaining supporters.
MEASURES
“It is urgent to create separate networks for urban and rainwater; and also act on the aquifer to lower the water table»
“This is slow agony if we deny the major. And she will totally get out of hand », she assures. “This will continue if the water table is not lowered. Denying at this point that this is one of the origins of the problem only serves to delay the solution. When it comes to acting at source, the aquifer is too. The problem would have been solved three years ago in a very easy way », she points out. And he explains that the water table was previously below sea level, but in 2019 it began to recharge after the ban on drawing water and with the rainy episodes.
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