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Date Published: 06/07/2022
ARCHIVED - The octopus becomes an unlikely ally in the fight to save the Mar Menor
Scientists believe the octopus could be used to control the Mar Menor’s exploding blue crab population
The deluge of rain in the Murcia region this spring wreaked havoc with the Mar Menor, washing harmful nitrates into the saltwater lagoon and robbing marine life of oxygen. As a result, copious amounts of dead fish and algae washed up onto its shores, and experts feared another deadly episode of anoxia, as occurred last year.
However, the summer looks promising and the tests carried out in recent weeks show normal oxygen levels; the latest area to be analysed, between Los Nietos and the Club Náutico de Los Urrutias, resulted in a measurement of 6.72 milligrams per litre, and nowhere the levels dip below 4 milligrams.
Nevertheless, the experts are still working on a number of proposals to safeguard the Mar Menor in the future and researchers from the Institute of Agrifood Research and Technology (IRTA) and the Polytechnic University of Valencia (UPV) have found that the octopus could be a good ally in controlling the blue crab population.
The American blue crab (Callinectes sapidus) lives in bays, coastal lagoons, estuaries and river mouths, and on shallow beaches and can devastate other marine species with its huge numbers. It’s not a fussy eater and feeds on everything from molluscs and crustaceans to fish and algae, so its uncontrolled expansion can drastically alter ecosystems.
"It has a very high rate of reproduction, and in each clutch it lays between 700,000 and 2 million eggs", explained IRTA researcher Patrícia Prado.
Now, scientists at the IRTA facilities in Tarragona are experimenting with using the octopus as a natural predator against the expanding blue crab population in the Mar Menor.
"We have even seen that the smallest octopuses dare to prey on crabs larger than them, something that we did not expect. A single octopus can eat up to 33% of its weight in crab meat in a single day," Ms Prado added.
In Catalonia, where the crab is also prevalent, fishing has always been the main method of control, but since it has been included in the Spanish Catalogue of Invasive Alien Species, more drastic measures are needed.
The key is not to eradicate the American blue crab from the Mar Menor, but to maintain populations at levels that are acceptable to the ecosystem they occupy.
With the long-term health of the Mar Menor in mind, scientists at the Valencia Oceanographic Centre are also looking at whether eels and loggerhead sea turtles could help fight against the plague of these crabs.
Image: Pixabay
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