College of Wildlife and Protected Area, Northeast Forestry University, Harbin 150040, PR China; Feline Research Center, Chinese State Administration of Forestry and Grassland, Harbin 150040, PR China.
Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, MS 39762, USA.
Sci Total Environ. 2021 May 20;770:144722. doi: 10.1016/j.scitotenv.2020.144722. Epub 2021 Jan 22.
Warming, land-use change, and habitat loss are three major threats to aquatic biodiversity worldwide under the influences of anthropogenic disturbances. Positive feedback between warming and bottom-up regulation may cause irreversible ecological regime shifts. Threshold dynamics of interspecific interactions have been rarely studied in freshwater fish communities using threshold community models. Here we use 66 years (1950-2015) of data to link four ecological regime shifts of 9-species fish communities to climatic and land use changes in Lake Hulun, the largest freshwater lake of Northern China. Overfishing caused the collapse of piscivorous fish populations and an ecological regime shift of Lake Hulun in the late 1950s. The first recorded algal bloom of Lake Hulun took place in 1986, with accelerated warming and rapid increases in livestock grazing. The dominance of planktivorous minnow populations reduced fish biodiversity in a nonlinear, threshold manner when annual mean ambient temperature was >0.12 °C. Multivariate environmental vector regression demonstrated that warming, eutrophication, and water-storage reduction (i.e., habitat loss) were related to three ecological regime shifts of Lake Hulun from 1960 to 2015. Multivariate autoregressive models (MAR) did not detect predation by piscivorous fish in Lake Hulun after 1960. Threshold MAR models indicated that dominant minnow populations and other prey fish populations switched from top-down to bottom-up control during the 1980s. Sustained positive feedback between warming, the dominance of planktivorous fish populations, and bottom-up regulation caused predator-prey role reversal, and probably resulted in three regime shifts of Lake Hulun over 56 years. This study provides a comprehensive analysis of ecological regime shifts in Hulun Lake fish communities, and has potential implications for fish species living in similar environments that are subject to global warming, land-use changes, and overfishing.
变暖、土地利用变化和生境丧失是全球水生生物多样性受到人为干扰影响的三大威胁。变暖与自上而下的调节之间的正反馈可能导致不可逆转的生态系统状态转变。在使用阈值群落模型的淡水鱼类群落中，种间相互作用的阈值动力学很少得到研究。在这里，我们使用了 66 年（1950-2015 年）的数据，将 9 种鱼类群落的 4 次生态系统状态转变与中国北方最大的淡水湖呼伦湖中气候和土地利用变化联系起来。过度捕捞导致了肉食性鱼类种群的崩溃，并导致呼伦湖在 20 世纪 50 年代末发生了生态系统状态转变。呼伦湖的第一次藻类爆发发生在 1986 年，当时变暖加速，畜牧业迅速发展。当年平均环境温度>0.12°C 时，浮游食性小鱼种群的优势以非线性、阈值的方式降低了鱼类生物多样性。多元环境向量回归表明，从 1960 年到 2015 年，变暖、富营养化和蓄水减少（即生境丧失）与呼伦湖的三次生态系统状态转变有关。多元自回归模型（MAR）没有检测到 1960 年后呼伦湖中肉食性鱼类的捕食作用。阈值 MAR 模型表明，20 世纪 80 年代，优势小鱼种群和其他猎物鱼类种群的作用从自上而下的控制转变为自下而上的控制。变暖、浮游食性鱼类种群的优势以及自上而下的调节之间的持续正反馈导致了捕食者-猎物角色的反转，这可能导致呼伦湖在 56 年多的时间里发生了三次状态转变。本研究全面分析了呼伦湖鱼类群落的生态系统状态转变，对生活在类似受全球变暖、土地利用变化和过度捕捞影响的环境中的鱼类物种具有潜在意义。
