Department of Watershed Sciences and the Ecology Center, Utah State University, Logan, Utah, USA.
Native Fish Ecology and Conservation Program, Division of Science and Resource Management, Grand Canyon National Park, National Park Service, Flagstaff, Arizona, USA.
Conserv Biol. 2023 Feb;37(1):e13993. doi: 10.1111/cobi.13993. Epub 2022 Dec 30.
Invasive species can dramatically alter ecosystems, but eradication is difficult, and suppression is expensive once they are established. Uncertainties in the potential for expansion and impacts by an invader can lead to delayed and inadequate suppression, allowing for establishment. Metapopulation viability models can aid in planning strategies to improve responses to invaders and lessen invasive species' impacts, which may be particularly important under climate change. We used a spatially explicit metapopulation viability model to explore suppression strategies for ecologically damaging invasive brown trout (Salmo trutta), established in the Colorado River and a tributary in Grand Canyon National Park. Our goals were to estimate the effectiveness of strategies targeting different life stages and subpopulations within a metapopulation; quantify the effectiveness of a rapid response to a new invasion relative to delaying action until establishment; and estimate whether future hydrology and temperature regimes related to climate change and reservoir management affect metapopulation viability and alter the optimal management response. Our models included scenarios targeting different life stages with spatially varying intensities of electrofishing, redd destruction, incentivized angler harvest, piscicides, and a weir. Quasi-extinction (QE) was obtainable only with metapopulation-wide suppression targeting multiple life stages. Brown trout population growth rates were most sensitive to changes in age 0 and large adult mortality. The duration of suppression needed to reach QE for a large established subpopulation was 12 years compared with 4 with a rapid response to a new invasion. Isolated subpopulations were vulnerable to suppression; however, connected tributary subpopulations enhanced metapopulation persistence by serving as climate refuges. Water shortages driving changes in reservoir storage and subsequent warming would cause brown trout declines, but metapopulation QE was achieved only through refocusing and increasing suppression. Our modeling approach improves understanding of invasive brown trout metapopulation dynamics, which could lead to more focused and effective invasive species suppression strategies and, ultimately, maintenance of populations of endemic fishes.
入侵物种会显著改变生态系统，但由于难以彻底根除，且一旦入侵物种建立了种群，抑制其扩散的成本就会很高。由于对入侵物种潜在扩张和影响的不确定性，可能会导致抑制措施延迟和不足，从而为其建立种群提供机会。复合种群生存力模型有助于制定策略，以改善对入侵物种的应对措施，减轻其影响，而在气候变化的背景下，这些策略可能尤为重要。我们使用了一个具有空间显式特征的复合种群生存力模型，来探讨针对科罗拉多河及其位于大峡谷国家公园支流中建立的具有生态破坏性的入侵褐鳟（Salmo trutta）的抑制策略。我们的目标是：估计针对复合种群不同生命阶段和亚种群的策略的有效性；量化对新入侵物种迅速做出反应相对于延迟行动直至其建立种群的效果；并估计与气候变化和水库管理有关的未来水文学和温度模式如何影响复合种群的生存力，并改变最佳管理对策。我们的模型包括针对不同生命阶段的情景，涉及空间变化强度的电鱼、破坏产卵床、奖励性垂钓、使用杀鱼类药物和设置鱼栅。只有通过针对多个生命阶段的复合种群范围的抑制才能实现准灭绝（Quasi-extinction，QE）。褐鳟种群增长率对 0 龄鱼和大个体成鱼死亡率的变化最为敏感。与对新入侵物种迅速做出反应相比，达到大种群规模的 QE 所需的抑制时间是 12 年，而不是 4 年。孤立的亚种群容易受到抑制的影响；但是，连通的支流亚种群通过作为气候避难所增强了复合种群的生存能力。由于水库蓄水减少导致的水资源短缺和随后的变暖会导致褐鳟数量下降，但只有通过重新聚焦和增加抑制才能实现复合种群的 QE。我们的建模方法提高了对入侵褐鳟复合种群动态的理解，这可能会导致更有针对性和有效的入侵物种抑制策略，并最终维持特有鱼类的种群。
