Ecosystem overviews

Bay of Biscay and Iberian Coast ecoregion

Climate change effects


Climate change has already influenced the Bay of Biscay and Iberian Coast ecoregion. Studies have shown that sea surface temperatures have increased.

The southern part of the ecoregion is strongly influenced by upwelling events, which are in turn influenced by wind intensity and direction. Off northern Iberia, upwelling intensifies during northerly winds. The winters of recent years have had more northerlies, coupled with strong upwelling events. Furthermore, it has been demonstrated that winter northerly wind regime shifts have occurred since 2005 in western Iberia.

Upwelling intensity and river outflow off Galicia have been seen to affect the degree of synchrony (and stability) of the zooplankton community, which in turn is likely to impact upper trophic levels.

The timing of the mackerel fishery has changed, showing an earlier peak of landings in the Cantabrian Sea. This could reflect a change in the timing of migration in response to climate change effects on upwelling patterns.

An increase in the richness of the demersal fish community, together with a western shift in the distribution of many species has been reported in the Cantabrian Sea and Galicia over the last three decades, along with a northwards distributional change of species previously distributed further south. New occurrences and distributional changes of fish in the Bay of Biscay are attributed to increasing temperatures. Examples include changes in the nursery areas of some flatfish and the increased occurrence of deep-water species previously found further south.

In the Gulf of Cadiz, the African coral Dendrophyllia laboreli has undergone an expansion in recent years; this has been attributed to increasing temperatures. From the single, isolated, individuals described in 2010, communities now exist in several rocky-bottom sites.

Fish recruitment was reduced by the occurrence of winter northerly winds over the western coast of Portugal at the time of fish spawning. Sea surface temperature, wind regimes, and river discharges have been identified as factors influencing anchovy early life stages at sea. However, no evidence of the effects of warming have been detected during investigations at one of the essential habitats (nursery) of anchovy in the Gulf of Cadiz.

A marked decrease in the physical condition of several small pelagic fish, including anchovy and sardine, has been noted in the Bay of Biscay since the mid‑2000s. Studies are being conducted to assess the respective roles of density‑dependence, fishing, and climate change in this weakening of condition.

Sea warming, acidification, and eutrophication have been seen to positively affect the palatability of seagrass in the Gulf of Cadiz, triggering an increase in grazing by sea urchins, which may, in turn, have implications for habitat and trophic regulation changes in coastal areas, with potential consequences for artisanal and recreational fisheries.

Climate change-induced changes in temperature and salinity have affected the biological communities of the Gironde estuary and modified its nursery function for marine juvenile fish and potentially migration routes for diadromous species.

​At the global level, current greenhouse gas emissions are most closely following the IPCC Regional Concentration Pathway (RCP) 8.5 scenario. Within the Bay of Biscay and Iberian Coast ecoregion, this scenario projects a 1.5°C to 3.0°C warming above mean conditions for the years 2050–2099. Positive anomalies are forecasted everywhere in the region, and are most pronounced in the shelf areas (Figure 8).

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​Figure 8: Ensemble mean sea surface temperature (SST) from the 5th Coupled Model Intercomparison Project (CMIP5), interpolated on a 1×1 grid for the entire year in the Bay of Biscay and Iberian Coast ecoregion. (Left) Historical SST for the period 1956–2005. (Right) Difference in the mean climate in the future time period (RCP8.5: 2050–2099) compared to the historical reference period​.
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Bay of Biscay and Iberian Coast ecoregion

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