Data from: Forty years of seagrass population stability and resilience in an urbanizing estuary

Coasts and estuaries contain among the most productive and ecologically important habitats in the world and face intense pressure from current and projected human activities, including coastal development. Seagrasses are a key habitat feature in many estuaries perceived to be in widespread decline owing to human actions.
We use spatio-temporal models and a 41-year time-series from 100s of km of shoreline which includes over 160,000 observations from Puget Sound, Washington, USA to examine multi-scale trends and drivers of eelgrass (Zostera spp.) change in an urbanizing estuary.
At whole estuary scale (100s of km) we find a stable and resilient eelgrass population despite a more than doubling of human population density and multiple major climactic stressors (e.g. ENSO events) over the period. However, the aggregate trend is not reflected at the site scale (10s of km), where some sites persistently increase while others decline.
Site trends were spatially asynchronous; adjacent sites sometimes exhibited opposite trends over the same period. Substantial change in eelgrass occurred at the sub-site (0.1 km) scale, including both complete local loss and dramatic increase of eelgrass.
Metrics of local human development including shoreline armoring, upland development (imperviousness), and human density provide no explanatory power for eelgrass population change at any spatial scale.
Our results suggest that the appropriate scale for understanding eelgrass change is smaller than typically assumed (approximately 1 to 3 km scale) and contrasts strongly with previous work.
Synthesis. Despite ongoing conservation concern over seagrasses worldwide, eelgrass in Puget Sound has been highly resilient to both anthropogenic and environmental change over four decades. Our work provides general methods that can be applied to understand spatial and temporal scales of change and can be used to assess hypothesized drivers of change.

海岸与河口是全球生产力最高、生态价值最为重要的栖息地之一，同时正面临当前及未来人类活动（包括海岸开发）带来的强烈胁迫。海草（seagrass）是众多河口的关键栖息地特征，而这类栖息地因人类活动正经历广泛衰退。
本研究采用时空模型（spatio-temporal model），结合来自美国华盛顿州普吉特海湾（Puget Sound）数百公里岸线的41年时间序列数据（包含超过16万条观测记录），对城市化河口内鳗草（eelgrass，Zostera spp.）变化的多尺度趋势与驱动因子展开分析。
在全河口尺度（数百公里级）下，尽管研究期内人类人口密度增长了一倍以上，且遭遇了厄尔尼诺-南方涛动（ENSO）事件等多起重大气候胁迫因子，普吉特海湾的鳗草种群仍保持稳定且具有较强恢复力。然而，这一整体趋势并未在位点尺度（数十公里级）得到体现：部分位点的鳗草覆盖持续增加，而另一些位点则出现衰退。
位点变化趋势在空间上呈现异步性：相邻位点在同期有时会表现出截然相反的变化趋势。在亚位点尺度（0.1公里级），鳗草种群发生了显著变化，包括局部完全消失与覆盖量的大幅增加。
当地人类开发相关指标，包括岸线加固、高地开发（不透水面占比）及人口密度，在任何空间尺度上均无法解释鳗草种群的变化。
研究结果表明，解析鳗草变化的适宜空间尺度远小于通常假设的水平（约1至3公里级），这与既往研究结论存在显著差异。
综合与结论：尽管全球范围内海草保护始终受到关注，但普吉特海湾的鳗草种群在过去四十年间，对人为活动与环境变化均表现出极强的恢复力。本研究提出的通用方法可用于解析变化的时空尺度，也可用于验证已提出的变化驱动因子假说。