The combined effects of conspecific density and climate warming on the vital rates of invasive fish species have not been well studied, but may be important in predicting how successful they will be in the future. We evaluated the effects of temperature and population density on monthly time series of sizes of age‐0 Blue Catfish Ictalurus furcatus in the James, York, and Rappahannock River subestuaries (defined here as tidally influenced bodies of water that feed into the Chesapeake Bay) from 1996 to 2017, using growing degree‐days (GDDs, °C day) as a measure of thermal time. Our predictive linear mixed‐effects model explained 86% of the variation in the length of age‐0 Blue Catfish. In addition, it indicated a strong positive effect of temperature on the growth rate of age‐0 Blue Catfish, with individual fish biomass during warm years up to 63% higher than during cool years. Growth rate was influenced negatively by the abundance of age‐0 and older fish, resulting in at least fourfold differences in the predicted biomass of Blue Catfish by the end of the first year of life depending on conspecific density. We also observed regional differences in the growth rates of Blue Catfish in the three subestuaries we examined; although growth occurred in all subestuaries, growth was highest for the Rappahannock River population even though this river accumulated the fewest GDDs. Rising water temperatures due to global climate change will likely increase the growth rate of age‐0 Blue Catfish in the Chesapeake Bay region, potentially intensifying the negative impacts of this invasive species on the ecology of Chesapeake Bay. However, individual populations respond differently to warming temperatures, and thus, potential increases in the growth rate of age‐0 Blue Catfish may be partially offset by local conditions that may serve to limit growth.

中文翻译：

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密度依赖性介导温度对非本地生境中少年蓝Cat鱼生长的影响

共生密度和气候变暖对入侵鱼种生命率的综合影响尚未得到很好的研究，但在预测它们将来的成功率方面可能很重要。我们评估了温度和人口密度对0岁年龄蓝色Blu​​e鱼Ictalurus furcatus大小的每月时间序列的影响在1996年至2017年期间，詹姆斯，约克和拉帕汉诺克河河口（这里定义为受潮汐影响的水流入切萨皮克湾）的定义为生长日（GDDs，°C day）作为热时间的度量。我们的线性预测混合效应模型解释了0岁蓝色Blu​​e鱼长度的86％变化。此外，它表明温度对0岁蓝色Blu​​e鱼的生长速度具有强烈的积极影响，在温暖的年份，单个鱼类的生物量比凉爽的时期高63％。生长速度受到0岁及以上年龄鱼类的丰富度的负面影响，根据特定的密度，到生命第一年结束时，蓝Cat鱼的预测生物量至少有四倍的差异。我们还观察了我们研究的三个子河口中蓝Cat鱼的生长速度的区域差异。尽管所有河口都有增长，但拉帕汉诺克河的人口增长最高，尽管该河的GDD最少。由于全球气候变化而导致的水温升高，很可能会增加切萨皮克湾地区的0岁以下蓝Cat鱼的增长率，从而有可能加剧这种入侵物种对切萨皮克湾生态的负面影响。但是，个别种群对变暖的反应不同，因此，0岁蓝色Blu​​e鱼生长速度的潜在增加可能会被可能限制生长的当地条件部分抵消。拉帕汉诺克河的人口增长最高，尽管该河的GDD最少。由于全球气候变化而导致的水温升高，很可能会增加切萨皮克湾地区的0岁以下蓝Cat鱼的增长率，从而有可能加剧这种入侵物种对切萨皮克湾生态的负面影响。但是，个别种群对变暖的反应不同，因此，0岁蓝色Blu​​e鱼生长速度的潜在增加可能会被可能限制生长的当地条件部分抵消。拉帕汉诺克河的人口增长最高，尽管该河的GDD最少。由于全球气候变化而导致的水温升高，很可能会增加切萨皮克湾地区的0岁以下蓝Cat鱼的增长率，从而有可能加剧这种入侵物种对切萨皮克湾生态的负面影响。但是，个别种群对变暖的反应不同，因此，0岁蓝色Blu​​e鱼生长速度的潜在增加可能会被可能限制生长的当地条件部分抵消。潜在地加剧了这种入侵物种对切萨皮克湾生态的负面影响。但是，个别种群对变暖的反应不同，因此，0岁蓝色Blu​​e鱼生长速度的潜在增加可能会被可能限制生长的当地条件部分抵消。潜在地加剧了这种入侵物种对切萨皮克湾生态的负面影响。但是，个别种群对变暖的反应不同，因此，0岁蓝色Blu​​e鱼生长速度的潜在增加可能会被可能限制生长的当地条件部分抵消。