Data from: The thin(ning) green line? Investigating changes in Kenya’s seagrass coverage

Knowledge of seagrass distribution is limited to a few well-studied sites and poor where resources are scant (e.g. Africa), hence global estimates of seagrass carbon storage are inaccurate. Here, we analysed freely available Sentinel-2 and Landsat imagery to quantify contemporary coverage and change in seagrass between 1986 and 2016 on Kenya’s coast. Using field surveys and independent estimates of historical seagrass, we estimate total cover of Kenya’s seagrass to be 317.1 ± 27.2 km2, following losses of 0.85% yr-1 since 1986. Losses increased from 0.29% yr-1 in 2000 to 1.59% yr-1 in 2016, releasing up to 2.17 Tg carbon since 1986. Anecdotal evidence suggests fishing pressure is an important cause of loss and is likely to intensify in the near future. If these results are representative for Africa, global estimates of seagrass extent and loss need reconsidering.

目前人们对海草（seagrass）分布的认知仅局限于少数经过充分研究的区域，在资源匮乏的地区（如非洲）相关数据极为匮乏，因此全球海草碳储量的估算存在较大误差。本研究针对肯尼亚海岸区域，分析了公开可获取的哨兵-2号（Sentinel-2）与陆地卫星（Landsat）影像，以量化1986年至2016年间海草的当代覆盖范围及其动态变化。结合野外调查与历史海草覆盖的独立估算数据，本研究估算得出肯尼亚海草总覆盖面积为317.1±27.2平方千米，自1986年以来年均损失率达0.85%。海草的年损失率已从2000年的0.29%升至2016年的1.59%，自1986年以来累计释放的碳量最高可达2.17太克（Tg）。轶事证据表明，捕捞压力是海草损失的重要驱动因素，且未来该压力或进一步加剧。若该研究结果可代表非洲整体海草变化情况，则全球海草分布范围与损失量的现有估算亟需重新审视。