Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, California, USA.
Region 3 Bay-Delta Stockton IEP Office, California Department of Fish and Wildlife, Stockton, California, USA.
Glob Chang Biol. 2022 Sep;28(17):5104-5120. doi: 10.1111/gcb.16266. Epub 2022 Jun 16.
Investigating the effects of climatic variability on biological diversity, productivity, and stability is key to understanding possible futures for ecosystems under accelerating climate change. A critical question for estuarine ecosystems is, how does climatic variability influence juvenile recruitment of different fish species and life histories that use estuaries as nurseries? Here we examined spatiotemporal abundance trends and environmental responses of 18 fish species that frequently spend the juvenile stage rearing in the San Francisco Estuary, CA, USA. First, we constructed multivariate autoregressive state-space models using age-0 fish abundance, freshwater flow (flow), and sea surface temperature data (SST) collected over four decades. Next, we calculated coefficients of variation (CV) to assess portfolio effects (1) within and among species, life histories (anadromous, marine opportunist, or estuarine dependent), and the whole community; and (2) within and among regions of the estuary. We found that species abundances varied over space and time (increasing, decreasing, or dynamically stable); and in 83% of cases, in response to environmental conditions (wet/dry, cool/warm periods). Anadromous species responded strongly to flow in the upper estuary, marine opportunist species responded to flow and/or SST in the lower estuary, and estuarine dependent species had diverse responses across the estuary. Overall, the whole community when considered across the entire estuary had the lowest CV, and life histories and species provided strong biological insurance to the portfolio (2.4- to 3.5-fold increases in stability, respectively). Spatial insurance also increased stability, although to a lesser extent (up to 1.6-fold increases). Our study advances the notion that fish recruitment stability in estuaries is controlled by biocomplexity-life history diversity and spatiotemporal variation in the environment. However, intensified drought and marine heatwaves may increase the risk of multiple consecutive recruitment failures by synchronizing species dynamics and trajectories via Moran effects, potentially diminishing estuarine nursery function.
研究气候变异性对生物多样性、生产力和稳定性的影响，是了解加速气候变化下生态系统未来可能情况的关键。河口生态系统的一个关键问题是，气候变异性如何影响不同鱼类物种和将河口作为育幼场的生命史的幼鱼补充？在这里，我们检查了 18 种经常在加利福尼亚州旧金山河口的幼体阶段进行育幼的鱼类的时空丰度趋势和环境响应。首先，我们使用在过去四十年中收集的 0 龄鱼丰度、淡水流量（流量）和海面温度（SST）数据构建了多元自回归状态空间模型。接下来，我们计算了变异系数（CV），以评估（1）种内和种间、生命史（溯河洄游、海洋机会主义者或河口依赖）和整个群落内和间的投资组合效应；（2）在河口内和间的区域。我们发现，物种丰度随时间和空间而变化（增加、减少或动态稳定）；并且在 83%的情况下，对环境条件（干湿、冷暖期）有响应。溯河洄游鱼类对河口上游的流量反应强烈，海洋机会主义鱼类对河口下游的流量和/或 SST 反应强烈，而河口依赖鱼类在整个河口的反应多种多样。总的来说，当整个河口的整个社区一起考虑时，CV 值最低，生命史和物种为投资组合提供了强有力的生物保险（稳定性分别增加 2.4 到 3.5 倍）。空间保险也增加了稳定性，尽管幅度较小（增加幅度高达 1.6 倍）。我们的研究推进了这样一种观点，即鱼类在河口的补充稳定性是由生物复杂性-生命史多样性和环境的时空变化控制的。然而，加剧的干旱和海洋热浪可能会通过 Moran 效应同步物种动态和轨迹，增加多次连续补充失败的风险，从而可能削弱河口育幼场的功能。
