A rapid temperature increase in the 1980-90s has been accompanied by dramatic and unprecedented changes in the biota and communities of the Ligurian Sea.

This review uses existing historical series to assess the extent and consequences of such changes.

The results show that a number of warm-water species, previously absent or occasionally in the comparatively cold Ligurian Sea, has recently established thanks to warmer winters. The authors state that occurrence among them of invasive alien species is causing concern because of their capacity of outcompeting autochthonous species.

On the other hand, it is shown that summer heatwaves caused mass mortalities in marine organisms, some of which found refuge at depth. While new marine diseases appeared, as well as other dysfunctions such as the formation of mucilage aggregates.

The authors highlight that human pressures have combined with climate change to cause phase shifts in different habitats. It is stated that these phase shifts implied biotic homogenization, reduction of biodiversity, and dominance by invasive aliens, and may be detrimental to the resilience of the Ligurian Sea ecosystems.

The authors underline that only well addressed long-term studies will help understanding the future dynamics of Ligurian Sea ecosystems and their possibilities of recovery.

https://www.tandfonline.com/doi/full/10.1080/24750263.2019.1687765

Bianchi et al. (2019) Consequences of the marine climate and ecosystem shift of the 1980-90s on the Ligurian Sea biodiversity (NW Mediterranean). The European Zoological Journal 86:458-487.