Bioluminescent 'Sea of Fire' phenomenon returns to Galicia's coasts

The "mar de ardora" (sea of fire), a bioluminescent phenomenon that turns coastal waters into a neon-blue spectacle, is drawing crowds to the Rías Baixas in Galicia this summer. The display is caused by microscopic organisms, primarily the dinoflagellate Noctiluca scintillans, which emit light as a defense mechanism when agitated Source: lavanguardia.

The science

The bioluminescence occurs when the organisms are physically disturbed – by breaking waves, boat wakes, or even splashing. Francisco Rodríguez, researcher at the Centro Oceanográfico de Vigo (IEO-CSIC), explains: "It is a defense mechanism against predators. By lighting up, they put the predators at risk, making them more visible to larger predators" Source: infobae. Different species dominate different areas: Noctiluca scintillans is common in the Rías Baixas, while Alexandrium tamarense appears in Costa da Morte, and Lingulaulax polyedra near Betanzos and A Coruña.

Cultural and tourist impact

Historically, fishermen used the glow to locate fish schools, and those who fished the "sardina de ardora" were called "ardoristas" Source: lavanguardia. Today, the phenomenon has become a social media sensation, with Telegram groups of nearly 900 members sharing sightings. Tourism companies like Fishterra in Fisterra offer nocturnal boat trips, and touroperator Viajes InterRías has promoted it on Instagram to boost bookings Source: infobae. Despite its popularity, the exact appearance remains unpredictable – "It is unpredictable", says Rodríguez, though it often persists for days in the same area.