ARCHIVED - Scientists unanimously reject Vox proposal to widen channels between the Mar Menor and the Mediterranean

To widen the golas could spell the end of the Mar Menor as we know it

Last week the political party Vox, which polled more votes than any other in the Region of Murcia in the general election on 10^th November, re-opened a debate which frequently crops up in relation to the marine environment in the Mar Menor by proposing that water quality should be “improved” by widening the “golas”, the channels through which water flows between the lagoon and the Mediterranean.

The theory behind this proposal is a simple one: if what is needed is a regeneration of the Mar Menor, what better way to achieve it than allowing “healthy” water to enter the lagoon from the Mediterranean? But the almost unanimous reaction of biologists and ecologists is that the logic in this case is too simple, and that rather than saving the unique ecosystem of the Mar Menor this would effectively sound its death knell.

One of the reasons most often cited is that the high salinity of the water in the Mar Menor is one of the characteristics which make it so special, and that to allow an easier exchange of water between the two seas would effectively dilute it. To a certain extent this is what happened in the “gota fría” storm of September, when the arrival of a quantity of fresh water, much of it carrying fertilizers and nutrients picked up from the farm land of the Campo de Cartagena, lowered the salinity of the lagoon by approximately 15 per cent (from 45 Practical Salinity Units to 39 PSU) in just a couple of days.

At the same time, scientists are quick to point out that widening or deepening the golas would not actually solve the underlying problems of the Mar Menor at all, since the substances which have done the damage to the marine environment would continue to make their way into the lagoon from the crop fields of the Campo de Cartagena and the aquifer which lies beneath it.

According to Julio Mas, a Doctor of Biology, before the Gola de El Estacio was dredged in 1975 to make it navigable the salinity of the water in the Mar Menor was 53 PSU, but the prioritization of tourism and the construction of marinas in La Manga and along the inland shore led to that figure falling to between 42 and 47 PSU, much closer to that of the Mediterranean (37 to 39 PSU). This led to the spread of a seaweed called Caulerpa prolifera and a reduction in the numbers off fish species including the flathead grey mullet, while the crisis in September represented a severe threat to the survival of the giant fan mussel (Pinna nobilis) which has found in the Mar Menor one of its last refuges after being all but wiped out by a parasite in the Mediterranean.

Scientifically, then the proposal aired by Vox is hard to justify, but even more difficult to understand is the specification that they should be returned to the dimensions they enjoyed in 1950. This is because in 1950 they were actually narrower than they are now, as the Gola de El Estacio had not been dredged.

The only kind of dredging being contemplated by the government of Murcia at the moment in the golas is the recovery of “a few centimetres” of depth and width in order to maintain the depth of the Marchamalo and to stimulate a recovery of traditional “encañadizas” fishing technique in El Ventorrillo at the northern end of La Manga.

It was in order to create more encañizadas that a licence was granted to create the artificial Gola de Marchamalo in 1762, and even almost 250 years ago it proved difficult to alter the course of nature without negative consequences. Originally the plan was for the canal to be built some 1.5 kilometres further north, but seaweed made fishing difficult or impossible, and when it was moved south the construction was hampered by a series of heavy storms.

The other three golas, those of El Ventorrillo, La Torre and El Charco, all have a tendency to become clogged with sediment, and the company operating the only remaining functional encañizada is obliged to clear it by limited dredging periodically in order to allow fish to continue swimming into the maze of reeds of which the technique consists.

In short, if the golas were to be widened and deepened, the result would be that the Mar Menor would no longer be the Mar Menor. Instead, according to scientists of various disciplines, it would be no more than a semi-enclosed bay on the Mediterranean coast, similar to that of Venice, where the water in the lagoon is entirely regenerated in a week or so. At present the same process takes around 8 months in the Mar Menor, and to accelerate that rate would be to rid it of precisely the unique characteristics which it is necessary to find a way of preserving.

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