Cantabrian Sea faces rising temperatures and invasive species

The Cantabrian Sea is experiencing a process of ‘mediterraneization’ due to rising water temperatures. According to the 2025 State of the Climate Report in Euskadi, sea surface temperatures in the Bay of Biscay have increased by approximately 0.25 degrees per decade since the 1980s.

In 2023, temperature anomalies exceeded one degree compared to the 1991-2020 average. Recent data from 2026 shows this trend continues, particularly during summer months. For instance, a coastal buoy in Bilbao recorded a maximum temperature of 25.4 degrees Celsius in late July.

These warming waters have facilitated the arrival of invasive species, such as the Portuguese man o' war and toxic microalgae. Additionally, the invasive Asian algae, Rugulopterix Okamurae, is expanding through the Cantabrian region, often causing unpleasant odors due to decomposing organic matter.