While extreme climatic events (ECEs) are predicted to become more frequent, reliably predicting their impacts on consumers remains challenging, particularly for large consumers in marine environments. Many studies that do evaluate ECE effects focus primarily on direct effects, though indirect effects can be equally or more important. Here, we investigate the indirect impacts of the 2011 “Ningaloo Niño” marine heatwave ECE on a diverse megafaunal community in Shark Bay, Western Australia. We use an 18‐year community‐level data set before (1998–2010) and after (2012–2015) the heatwave to assess the effects of seagrass loss on the abundance of seven consumer groups: sharks, sea snakes (multiple species), Indo‐pacific bottlenose dolphins (Tursiops aduncus), dugongs (Dugong dugon), green turtles (Chelonia mydas), loggerhead turtles (Caretta caretta), and Pied Cormorants (Phalacrocorax spp.). We then assess whether seagrass loss influences patterns of habitat use by the latter five groups, which are under risk of shark predation. Sharks catch rates were dominated by the generalist tiger shark (Galeocerdo cuvier) and changed little, resulting in constant apex predator density despite heavy seagrass degradation. Abundances of most other consumers declined markedly as food and refuge resources vanished, with the exception of generalist loggerhead turtles. Several consumer groups significantly modified their habitat use patterns in response to the die‐off, but only bottlenose dolphins did so in a manner suggestive of a change in risk‐taking behavior. We show that ECEs can have strong indirect effects on megafauna populations and habitat use patterns in the marine environment, even when direct effects are minimal. Our results also show that indirect impacts are not uniform across taxa or trophic levels and suggest that generalist marine consumers are less susceptible to indirect effects of ECEs than specialists. Such non‐uniform changes in populations and habitat use patterns have implications for community dynamics, such as the relative strength of direct predation and predation risk. Attempts to predict ecological impacts of ECEs should recognize that direct and indirect effects often operate through different pathways and that taxa can be strongly impacted by one even if resilient to the other.

中文翻译：

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极端气候事件对海洋巨型动物群落的间接遗留影响

尽管预计极端气候事件（ECE）会更加频繁，但可靠地预测其对消费者的影响仍然具有挑战性，特别是对于海洋环境中的大型消费者而言。尽管间接影响可能同等或更重要，但许多评估ECE效果的研究主要集中在直接效果上。在这里，我们调查了2011年“ NingalooNiño”海洋热浪ECE对西澳大利亚鲨鱼湾不同的大型动物群落的间接影响。我们使用热浪之前（1998–2010）和之后（2012–2015）的18年社区级数据集来评估海草损失对七个消费群体（鲨鱼，海蛇（多种物种），印度洋宽吻海豚（Tursiops aduncus），儒艮（Dugong dugon）），绿海龟（Chelonia mydas），黑头海龟（Caretta caretta）和Pi（Phalacrocorax spp。）。然后，我们评估海草的流失是否会影响后五类鲨鱼捕食风险下的栖息地使用方式。鲨鱼的捕获率主要由通才虎鲨（Galeocerdo cuvier），变化不大，尽管海草大量退化，但导致恒定的食肉动物密度。随着食物和避难所资源的消失，大多数其他消费者的数量显着下降，通才海龟除外。有几个消费者群体根据死亡情况大大改变了栖息地的使用方式，但只有宽吻海豚这样做是暗示冒险行为发生了变化。我们表明，即使在直接影响很小的情况下，欧洲经委会也可以对海洋环境中的大型动物种群和栖息地使用方式产生强烈的间接影响。我们的结果还表明，在分类单元或营养水平上，间接影响并不统一，这表明，与专家相比，通才海洋消费者更容易受到ECE的间接影响。种群和栖息地使用方式的这种不均匀变化对社区动态具有影响，例如直接捕食的相对强度和捕食风险。尝试预测欧洲经委会的生态影响的努力应认识到直接和间接影响通常通过不同的途径发挥作用，而且即使一个单元能够抵御另一个单元，它也可能受到其强烈影响。