# Cantabrian Sea warming and marine species shifts

> Live situation record from CLSTR: https://clstr.news/situations/cantabrian-sea-warming-and-marine-species-shifts
> Updated: 2026-08-22T09:34:22.000Z. Sources: 7. Developments: 2.

The Cantabrian Sea is undergoing a process of ‘mediterraneization’ driven by rising water temperatures. Reports indicate that sea surface temperatures in the Bay of Biscay have increased by approximately 0.25 degrees per decade since the 1980s, with recent anomalies exceeding one degree compared to the 1991-2020 average.

This warming trend has facilitated the arrival of various invasive and tropical species. Documented arrivals include the Portuguese man o' war, toxic microalgae, and the invasive Asian algae, Rugulopterix Okamurae, which has caused issues with decomposing organic matter. 

As temperatures reach historic highs—with surface waters recorded at 25.2 degrees Celsius in late June and 25.4 degrees Celsius in late July—tropical and subtropical species such as barracuda, lampuga, and grouper are appearing in the region. Consequently, native species are migrating toward cooler waters to find refuge.

## Timeline

### 2026-08-22: Cantabrian Sea warming leads to arrival of tropical species

Rising temperatures in the Cantabrian Sea are causing tropical species like barracuda to appear in Spanish waters, a phenomenon experts call the ‘mediterranization’ of the region.

3 sources. https://clstr.news/cluster/cantabrian-sea-warming-leads-to-arrival-of-tropical-species

### 2026-08-18: Cantabrian Sea faces rising temperatures and invasive species

Rising temperatures in the Cantabrian Sea are driving a ‘mediterraneization’ of the ecosystem, leading to the arrival of invasive species like the Portuguese man o' war and toxic algae.

4 sources. https://clstr.news/cluster/cantabrian-sea-faces-rising-temperatures-and-invasive-species

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Cite as: Cantabrian Sea warming and marine species shifts. CLSTR, https://clstr.news/situations/cantabrian-sea-warming-and-marine-species-shifts