Climate change is causing an increase in the frequency and intensity of marine heatwaves (MHWs) and mass mortality events (MMEs) of marine organisms are one of their main ecological impacts. Here, we show that during the 2015–2019 period, the Mediterranean Sea has experienced exceptional thermal conditions resulting in the onset of five consecutive years of widespread MMEs across the basin. These MMEs affected thousands of kilometers of coastline from the surface to 45 m, across a range of marine habitats and taxa (50 taxa across 8 phyla). Significant relationships were found between the incidence of MMEs and the heat exposure associated with MHWs observed both at the surface and across depths. Our findings reveal that the Mediterranean Sea is experiencing an acceleration of the ecological impacts of MHWs which poses an unprecedented threat to its ecosystems' health and functioning. Overall, we show that increasing the resolution of empirical observation is critical to enhancing our ability to more effectively understand and manage the consequences of climate change.

The Atlantic crab Callinectes sapidus was recently recorded in Tunisia and presents an invasive behavior. This study aims to evaluate its socio-economic impacts on small-scale fisheries and to analyze variations in chemical composition, fatty acids profile, and nutritive value according to sex and edible tissues. Socio-economic surveys via face-to-face revealed a decline in fishermen’s income from 15% to even 70% (damages on fishing nets and catches). Muscles yield of Callinectes sapidus ranged between 36.07±2.84% and 42.83±6.53% respectively for females and males. All the analyzed tissues contained high protein contents (> 23%) and particularly cephalothorax muscles reaching 27.05±0.16%. This new exotic food can be recommended in low fat diets since it contained less than 5% of total fats. The fatty acid profile was dominated by the polyunsaturated fatty acids (PUFA) for both sexes and all the analyzed tissues. Eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid were the most abundant PUFA in all tissues ranging respectively from 9.31% to 15.64%, from 8.74% to 13.78% and between 6.81% and 9.21%. All the nutritional indexes of lipids indicated that this crab could be beneficial for human health. In addition, it constitutes a new marine resource with high economic opportunity.