Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey.
Department of Biology, East Carolina University, Greenville, North Carolina.
Glob Chang Biol. 2019 Aug;25(8):2544-2559. doi: 10.1111/gcb.14650. Epub 2019 May 31.
Substantial interannual variability in marine fish recruitment (i.e., the number of young fish entering a fishery each year) has been hypothesized to be related to whether the timing of fish spawning matches that of seasonal plankton blooms. Environmental processes that control the phenology of blooms, such as stratification, may differ from those that influence fish spawning, such as temperature-linked reproductive maturation. These different controlling mechanisms could cause the timing of these events to diverge under climate change with negative consequences for fisheries. We use an earth system model to examine the impact of a high-emissions, climate-warming scenario (RCP8.5) on the future spawning time of two classes of temperate, epipelagic fishes: "geographic spawners" whose spawning grounds are defined by fixed geographic features (e.g., rivers, estuaries, reefs) and "environmental spawners" whose spawning grounds move responding to variations in environmental properties, such as temperature. By the century's end, our results indicate that projections of increased stratification cause spring and summer phytoplankton blooms to start 16 days earlier on average (±0.05 days SE) at latitudes >40°N. The temperature-linked phenology of geographic spawners changes at a rate twice as fast as phytoplankton, causing these fishes to spawn before the bloom starts across >85% of this region. "Extreme events," defined here as seasonal mismatches >30 days that could lead to fish recruitment failure, increase 10-fold for geographic spawners in many areas under the RCP8.5 scenario. Mismatches between environmental spawners and phytoplankton were smaller and less widespread, although sizable mismatches still emerged in some regions. This indicates that range shifts undertaken by environmental spawners may increase the resiliency of fishes to climate change impacts associated with phenological mismatches, potentially buffering against declines in larval fish survival, recruitment, and fisheries. Our model results are supported by empirical evidence from ecosystems with multidecadal observations of both fish and phytoplankton phenology.
海洋鱼类补充量（即每年进入渔业的幼鱼数量）的年际变化很大，据推测与鱼类产卵的时间是否与季节性浮游植物繁殖相吻合有关。控制浮游植物繁殖时间的环境过程（例如分层）可能与影响鱼类产卵的过程（例如与温度相关的生殖成熟）不同。这些不同的控制机制可能导致这些事件在气候变化下的时间不同，从而对渔业产生负面影响。我们使用地球系统模型来研究高排放、气候变暖情景（RCP8.5）对两种温带、上层鱼类产卵时间的未来影响：“地理产卵者”，其产卵场由固定的地理特征定义（例如河流、河口、珊瑚礁）和“环境产卵者”，其产卵场会根据环境特性（如温度）的变化而移动。到本世纪末，我们的研究结果表明，分层增加的预测导致北纬 >40°地区的春、夏浮游植物繁殖平均提前 16 天（±0.05 天 SE）开始。与浮游植物相比，地理产卵者的与温度相关的繁殖时间变化速度快两倍，导致这些鱼类在该地区 >85%的地区的繁殖时间早于浮游植物开始繁殖的时间。“极端事件”，在这里定义为季节性不匹配>30 天，可能导致鱼类补充失败，在 RCP8.5 情景下，地理产卵者在许多地区的极端事件增加了 10 倍。环境产卵者与浮游植物之间的不匹配较小且范围较小，但在某些地区仍出现了相当大的不匹配。这表明，环境产卵者的范围转移可能会增加鱼类对与物候不匹配相关的气候变化影响的恢复能力，可能缓冲幼鱼存活率、补充量和渔业的下降。我们的模型结果得到了具有鱼类和浮游植物物候多十年观测的生态系统的实证证据的支持。
