Spatial Variability in the Resistance and Resilience of Giant Kelp in Southern and Baja California to a Multiyear Heatwave
Spatial Variability in the Resistance and Resilience of Giant Kelp in Southern and Baja California to a Multiyear Heatwave
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DOI：
10.3389/fmars.2019.00413
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发表时间：
2019-07-23
影响因子：
3.7
通讯作者：
Beas-Luna, Rodrigo
中科院分区：
文献类型：
--
作者：
Cavanaugh, Kyle C.;Reed, Daniel C.;Beas-Luna, Rodrigo
2014-2016年，北美西海岸经历了一场海洋热浪，其持续时间和强度在历史上都是前所未有的。这一事件预计将对巨藻种群产生毁灭性影响，巨藻是一种重要的海岸基础物种，发现于凉爽、营养丰富的水域。为了评估这一预期，我们使用了卫星图像的时间序列来检查在南加利福尼亚和下加利福尼亚州超过7度纬度的热浪之前，期间和之后的巨型海带冠层生物量。我们研究了海带的抵抗性（即初始反应）和恢复力（即热浪结束2年后海带的丰度）的空间格局。热浪对巴哈南部极限附近的巨型海带产生了巨大而直接的负面影响。相比之下，热浪的影响在我们研究区域的大部分中部地区被延迟，而我们研究区域的北部地区尽管存在较大的正温度异常，但对变暖表现出了高水平的抵抗和恢复能力。整个区域的巨藻抗性与热浪最温暖月份的平均温度相关性最强，表明冠层损失对超过绝对温度阈值的敏感性大于对相对温度变化幅度的敏感性。海带的恢复力存在空间差异，与海温指标或抗性无关，表明局地尺度的环境和生物过程在决定海带从极端变暖事件中恢复的过程中发挥了更大的作用。我们的研究结果强调了巨型海带的弹性，但也指出了与海带森林迅速消失有关的绝对温度阈值。
In 2014-2016 the west coast of North America experienced a marine heatwave that was unprecedented in the historical record in terms of its duration and intensity. This event was expected to have a devastating impact on populations of giant kelp, an important coastal foundation species found in cool, nutrient rich waters. To evaluate this expectation, we used a time series of satellite imagery to examine giant kelp canopy biomass before, during, and after this heatwave across more than 7 degrees of latitude in southern and Baja California. We examined spatial patterns in resistance, i.e., the initial response of kelp, and resilience, i.e., the abundance of kelp 2 years after the heatwave ended. The heatwave had a large and immediate negative impact on giant kelp near its southern range limit in Baja. In contrast, the impacts of the heatwave were delayed throughout much of the central portion of our study area, while the northern portions of our study area exhibited high levels of resistance and resilience to the warming, despite large positive temperature anomalies. Giant kelp resistance throughout the entire region was most strongly correlated with the mean temperature of the warmest month of the heatwave, indicating that the loss of canopy was more sensitive to exceeding an absolute temperature threshold than to the magnitude of relative changes in temperature. Resilience was spatially variable and not significantly related to SST metrics or to resistance, indicating that local scale environmental and biotic processes played a larger role in determining the recovery of kelp from this extreme warming event. Our results highlight the resilient nature of giant kelp, but also point to absolute temperature thresholds that are associated with rapid loss of kelp forests.