Dramatic loss of seagrass habitat under projected climate change in the Mediterranean Sea.

Glob Chang Biol. 2018 Jul 14. doi: 10.1111/gcb.14401. [Epub ahead of print] Chefaoui RM1, Duarte CM2, Serrão EA1. Author information 1 CCMAR-Centro de Ciências do Mar, CIMAR Laboratório Associado, Universidade do Algarve, Faro, Portugal. 2 Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. Abstract Although climate warming is affecting most marine ecosystems, the Mediterranean is showing earlier impacts. Foundation seagrasses are already experiencing a well-documented regression in the Mediterranean which could be aggravated by climate change. Here, we forecast distributions of two seagrasses and contrast predicted loss with discrete regions identified on the basis of extant genetic diversity. Under the worst-case scenario, Posidonia oceanica might lose 75% of suitable habitat by 2050 and is at risk of functional extinction by 2100, whereas Cymodocea nodosa would lose only 46.5% in that scenario as losses are compensated with gained and stable areas in the Atlantic. Besides, we predict that erosion of present genetic diversity and vicariant processes can happen, as all Mediterranean genetic regions could decrease considerably in extension in future warming scenarios. The functional extinction of Posidonia oceanica would have important ecological impacts and may also lead to the release of the massive carbon stocks these ecosystems stored over millennia. KEYWORDS: Cymodocea nodosa ; Posidonia oceanica ; Mediterranean Sea; climate change; ecological niche modeling; genetic diversity; range shift; seagrass decline