CubeSats show persistence of bull kelp refugia amidst a regional collapse in California
CubeSats show persistence of bull kelp refugia amidst a regional collapse in California
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DOI：
10.1016/j.rse.2023.113521
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发表时间：
2023-05
影响因子：
13.5
通讯作者：
K. Cavanaugh;K. Cavanaugh;Camille Pawlak;T. Bell;V. Saccomanno
中科院分区：
文献类型：
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作者：
K. Cavanaugh;K. Cavanaugh;Camille Pawlak;T. Bell;V. Saccomanno
公牛海带种群在北方加州急剧下降，以应对2014-2016年的海洋热浪，海星星消耗病，以及随后的大量增加，在草食性紫海胆种群。尽管该地区的海藻森林崩溃，但仍有少量的残余种群能够生存下来。中等分辨率卫星（即，Landsat）对于创建公牛海带森林的长期，大规模时间序列非常重要，但是，由于其密度低且靠近海岸线，这些都被证明低估或完全排除了避难所。虽然无人驾驶飞行器（UAV）的测量数据在空间上很详细，但它们在时间上有限，难以在区域尺度上收集。CubeSat星座的发展为这些权衡提供了一个解决方案，几乎每天都可以获得米级的全球图像。我们开发了一种方法，用于在PlanetScope星座的不同传感器队列中绘制公牛海带冠层。这需要校正表面反射率测量值，以考虑传感器之间光谱响应函数的差异，并利用PlanetScope数据的时间频率，以提高图像中噪声增加的海带冠层分类的自动化程度。使用PlanetScope派生的海带树冠范围，我们确定了公牛海带避难所坚持在北方加州的位置。我们发现，公牛海带避难所占该地区总可用栖息地的2%左右，约占2014年之前观察到的平均冠层面积的9.4%。这些地区可能是至关重要的海藻森林重建成功的北方加州，这增加了他们的重要性，正在进行的监测，保护和恢复工作。
Bull kelp populations in northern California declined drastically in response to the 2014–2016 marine heatwave, sea star wasting disease, and subsequently large increases in herbivorous purple urchin populations. Despite the regional kelp forest collapse, there were small, remnant populations where bull kelp was able to survive. Moderate resolution satellites (i.e., Landsat) have been important for creating long-term, large-scale time series of bull kelp forests, however, these have been shown to underestimate or entirely exclude refugia due to their low densities and proximity to the coastline. While measurements from Unoccupied Aerial Vehicles (UAV) are spatially detailed, they are temporally limited and difficult to collect over regional scales. The development of CubeSat constellations has enabled a workaround for these tradeoffs, with global imagery available near-daily at meter-scale.We developed a method for mapping bull kelp canopy across the different sensor cohorts in the PlanetScope constellation. This required correcting surface reflectance measurements to account for differences in the spectral response functions among the sensors and leveraging the temporal frequency of PlanetScope data to increase the automation of classifying kelp canopy in imagery with increased noise. Using the PlanetScope derived kelp canopy extents, we identified locations where bull kelp refugia have persisted in northern California. We found that bull kelp refugia occupied about 2% of the total available habitat in the region and about 9.4% of the average canopy area observed prior to 2014. These areas may be critical to the success of kelp forest re-establishment in northern California, which increases their importance for ongoing monitoring, conservation, and restoration efforts.