Decadal increase in the ecological status of a North-Atlantic intertidal seagrass meadow observed with multi-mission satellite time-series

Ecological Indicators

Pierre Gernez¹  Steef Peters²  Laurent Godet³  Maria Laura Zoffoli³  Laurent Barillé³  Simon Oiry⁴ 

[1] Corresponding author.;CNRS, Université de Nantes, UMR LETG, B.P. 81223, 44312 Nantes, France;Université de Nantes, Laboratoire Mer Molécules Santé, Faculté des Sciences, 2 rue de la Houssinière, 44322 Nantes, France;Water Insight, 6709 PG 22 Wageningen, the Netherlands;

关键词: Water Framework Directive;    Interannual variability;    Ecosystem monitoring;    Earth Observation;    Recovery;    Zostera noltei;   

DOI  :  

来源: DOAJ

【 摘 要 】

Seagrass meadows are monitored in the frame of several environmental programs worldwide, including the Water Framework Directive (WFD), to evaluate the ecological status of European coastal and transitional water bodies. The large size, spatial complexity, and interannual variability of seagrass ecosystems significantly challenge field monitoring. In this study, a multi-mission satellite time-series was used to estimate long-term changes in seagrass status in a macrotidal system dominated by Zostera noltei, at Bourgneuf Bay (French Atlantic coast). Metrics of seagrass extent and density were obtained from Earth Observation (EO) using validated and inter-calibrated Landsat, SPOT and Sentinel2 data from 1985 to 2020. The information provided by satellite data made it possible to compute and compare several seagrass indicators currently in use in several European countries (France, Portugal and UK) within the WFD. Both the seagrass extent and meadow-averaged density displayed increasing trends since 1985. A time-series of merged observations from various satellites revealed a high degree of interannual variability in seagrass extent, with abrupt losses (up to 50% within one year) alternating with periods of slow recovery (typically 4–6 years). The seagrass meadow which was in a moderate status (sensu the WFD) in the 1980s, achieved an overall recurrent good or high status since the mid-1990s. Altogether, the methods and results presented here demonstrated that EO is a reliable source of information for mapping and assessing the status of intertidal seagrass, complementing in situ measurements by providing long-term, spatial view and standardized observation framework. We recommend the systematic use of EO time-series in complement to traditional field measurements in seagrass monitoring programs such as the WFD.

【 授权许可】

Unknown