Recently, at IRTA Sant Carles de la Ràpita, a salinity-tolerant plant, Salicornia or sea asparagus, has been grown for the first time in aquaponics in combination with mullet (Mugil cephalus), an omnivorous fish mainly exploited for fishing and local consumption in the Ebro Delta. The experiment is part of the European project NewTechAqua of the H2020 program, which aims to innovate in sustainable aquaculture production systems.
In the first phase, the system has been tested by growing lettuce. "In January 2021, in less than three months, we harvested 90 kg of lettuce. After ensuring the system's smooth operation, in the second phase, we have already grown Salicornia, of which we harvested 250 kg on 18 m². This proves that mullet is a good choice of fish to have an efficient aquaponics model," says Enric Gisbert, head of the Aquaculture program at IRTA.
Salicornia is a halophilic, succulent plant species that grows in coastal systems with high salt concentration, such as beaches and mangroves. However, in some regions, such as the Ebro Delta, it cannot be harvested because it is protected. Currently, it is considered of high gastronomic value because of its intense salty flavor. However, in the first half of the 20th century, it was a very valuable source of food for coastal populations and contributed to reducing hunger.
"Aquaponics could be an alternative to continue using this plant in the culinary world, with controlled management and food safety conditions and, at the same time, protecting the environment," says Gisbert. This plant also has the particularity of being able to thrive in infertile soils with little freshwater. Initial trials found that using sea bass feces, Salicornia increased its total content of fatty acids and did not need such high water salinity, which is an advantage over other plants.