Lessepsian migration in the Mediterranean Sea in an era of climate change: Plague or boon?

The eastern Mediterranean Sea has suffered severe impacts from climate change, causing the decline of native biodiversity. Based on a global systematic review, we found that climate change has been the main driver of local extinctions globally since the 1990s; the eastern Mediterranean is flagged as an extinction hotspot. This region is also a bioinvasions hotspot with ca 1000 reported alien species, most thermophilic, introduced through the Suez Canal (Lessepsian migrants). Although Lessepsian species have been considered a plague for native biodiversity, their positive impacts are increasingly acknowledged. In a land-locked basin like the Mediterranean Sea, where species range shifts from lower latitudes are impossible, the Suez Canal acts as an artificial climatic corridor. Without Lessepsian species, the climate-driven loss of native biodiversity in the eastern Mediterranean would have led to the loss of ecological functions and services with devastating consequences for coastal communities. In that sense, Lessepsian species are considered a boon for fisheries and other ecosystem services. Hence, the ‘alien-bad, native-good’ notion in an era of global change is misleading. In the eastern Mediterranean Sea, a realistic conservation strategy is to focus on the protection of ecosystem functioning instead of the protection of native biodiversity, which will decline anyway.