Recent trend reversal for declining European seagrass meadows

Carmen B De Los Santos ,Gérard Pergent ,José Luis Sánchez‐Lizaso ,Jérôme Fournier ,Yolanda Fernández‐Torquemada ,Xavier Seglar Arano ,Juan J Vergara ,Dorte Krause‐Jensen ,Teresa Alcoverro ,Gregori Munoz-Ramos Trayter ,D J De Jong ,Guillem Roca ,Javier Romero ,Monica Montefalcone ,Emilia Jankowska ,Carlos M Duarte ,M.m Van Katwijk ,Kevan J Cook ,Núria Marbà ,Marta Pérez ,José Lucas Pérez‐Lloréns ,Robert Wilkes ,Frithjof E Moy ,Juan Manuel García Ruiz ,Isabelle Auby ,Susana Cabaço ,Rui Santos

doi:10.1038/s41467-019-11340-4

Abstract

Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European seagrass area was lost due to disease, deteriorated water quality, and coastal development, with losses peaking in the 1970s and 1980s. Since then, loss rates slowed down for most of the species and fast-growing species recovered in some locations, making the net rate of change in seagrass area experience a reversal in the 2000s, while density metrics improved or remained stable in most sites. Our results demonstrate that decline is not the generalised state among seagrasses nowadays in Europe, in contrast with global assessments, and that deceleration and reversal of declining trends is possible, expectingly bringing back the services they provide.

Highlights

Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened
Europe is a distinctive geographical region for having adopted in 2000 the seagrasses as sensitive quality elements providing a diagnostic of ecosystem health under the European Union (EU) Water Framework Directive (WFD)[22,23,24,25,26], which aims at maintaining good ecological status in European waters
The highest proportion of declines, integrating extent and density metrics, was reported for Z. marina and C. nodosa, whereas the lowest was for P. oceanica (Fig. 1)

Summary

Introduction

Key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. Seagrasses, marine flowering plants forming underwater meadows, play a key global role in supporting fisheries production[1], climate change mitigation[2], and coastal protection[3] They rank among the most threatened ecosystems on Earth, with global loss rates accelerating from 0.9% yr−1 in the 1940s to 7% yr−1 toward the end of the 20th century[4]. The focus on seagrasses as indicators of ecosystem health of coastal waters has led to increasing monitoring efforts across the European continent in the past two decades[16,24] This monitoring effort, along with older data on seagrass extent in locations with a long history in seagrass monitoring and mapping, provides the basis to examine seagrass trajectories at the continental scale. We conclude that decline is not the generalized state among seagrasses nowadays in Europe

Methods

Results

Conclusion