Assessing the causes of marine biodiversity loss

Marine (as well as terrestrial) biodiversity is declining at an unprecedented rate due to direct human activities, such as fishing, coastal development, pollution, and climate change. Many exploited marine species have been depleted in recent decades and some groups, such as corals, sharks and marine mammals, are threatened with extinction while others, such as turtles and birds, are heavily affected by plastic pollution. Some marine ecosystems are, as a whole, heavily impacted, particularly coastal ecosystems which are also the most productive and diverse. For example, the extent of seagrass beds has decreased by more than 30%, the coverage of mangroves has decreased by 38%, while the coverage of living corals on the reefs has almost halved.
While this decline in marine biodiversity is now well documented and the subject of consensus in the scientific community, our understanding of the impacts of global change on marine species, communities and ecosystems is still very incomplete and needs to be improved to better preserve and maintain marine biodiversity and ecosystem services.