Ecosystem functions and economic wealth: Trajectories of change in seagrass meadows

Increasing anthropogenic pressure on coastal regions, coupled with a conflicting relationship between ecosystem health and economic growth, has resulted in a worldwide deterioration of marine ecosystems and loss of ecosystem services. The seagrass Posidonia oceanica is an emblematic example, constituting extensive and highly valuable meadows whose extent largely declined in the last decades. In this paper, more than one century of history of P. oceanica meadows has been reconstructed in a NW Mediterranean region combining models and historical information. The equivalent economic value of P. oceanica ecosystem functions was evaluated according to a donor-side approach and compared with the main economic sector of the region. A loss of more than 50% of the original surface of P. oceanica meadow extent has been documented between 1850 and around 1980, followed by stabilization in the last decades. Decline of P. oceanica has often been coupled with its replacement by the more tolerant seagrass species Cymodocea nodosa, only partially compensating for the loss of P. oceanica. The loss of the value of ecosystem functions between 1861 and 2009 was computed in 1106.8 billion emergy-euros (em€), a figure greater than the value added in the same period by tourism-related activities. Protection measures undertaken in the last decades slowed down the decline of P. oceanica meadows, while no concomitant decrease of the regional economic growth occurred. This study illustrates the tradeoffs between ecosystem conservation and economy growth, underlining the importance of long-term monitoring for environmental management and preservation of the natural capital.