Introduction: Changes and Crises in the Mediterranean Sea: Current problems

As a contribution to the World Environment Day 2017, the Accademia Nazionale dei Lincei promoted the meeting "Changes and Crises in the Mediterranean Sea" devoted to the effects of climate change and human impact on the Mediterranean ecosystems and biodiversity. Here is presented a selection of papers given at the meeting held in Rome, on October 17, 2017. Studies deal with structural changes in the marine communities, the impact of thermal stress, acidification, pollution and fishing activities on benthic communities, and on deep-sea biodiversity and ecosystems. Understanding human impact on the Mediterranean Sea is the first step to manage and protect marine environments in a sustainable way.