生态学代谢理论(metabolic theory of ecology, MTE)指的是生物的代谢速度随着温度的升高而增加,随生物个体大小(即生物量)的增加而异速增长.根据MTE理论可预测异养过程与自养过程对温度的反应不同,低温对异养代谢的抑制要明显;而随着温度升高,异养代谢升高的速度比自养代谢升高的速度要快.MTE理论可以对海洋浮游微食物网生物的代谢研究进行理论指导,用于解释一些低温造成的海洋浮游生态学现象,以及预测全球变暖的影响.多年来人们一直根据MTE理论开展理论分析和实验检验,发现低温会抑制细菌和微型浮游动物的生长,并可以降低微型浮游动物的摄食率.春季高纬度海区的海水温度会抑制细菌的生长,而浮游植物则几乎不受影响,从而造成春季水华发生.温度和底物浓度是冷海(水温≤4℃)细菌生长率低的原因,但在永冷海(周年温度≤4℃的海区,包括极地海区和深海的大部分)中究竞是低温还是底物浓度限制了细菌的生长率仍被争论.全球变暖的预测认为本世纪海洋表层温度会升高2~6℃.根据MTE理论,温度升高对自养和异养过程的影响不同,围隔实验证明全球变暖将导致水华与细菌、水华与微型浮游动物的时滞变小,促进微型浮游动物对细菌和浮游植物的摄食,改变有机物质自养生产和异养消耗之间的平衡,使更多的物质和能量进入呼吸作用,使得生态系统变得更加异养.但在温度升高对海洋细菌生长效率和细菌生物量变化的研究方面,MTE理论还有一定的局限性,需要进一步的理论分析和实验检验.
英文摘要:
The metabolic theory of ecology (MTE) refers to the increase in the metabolic rate of a living being with increases in temperature and individual size (i.e., biomass). According to MTE, the responses of the heterotrophic and autotrophic processes to temperature are different. There could be obvious inhibition of heterotrophic metabolism due to low temperature. With increasing temperature, the increase in heterotrophic metabolism is faster than autotrophic processes. MTE can provide theoretical guidance for studying the metabolism of the marine microbial food web to explain the phenomenon of marine planktonic ecology caused due to low temperature, and to predict the impact of global warming. Scientists have been conducting theoretical analysis and experimental tests based on MTE, and found that low temperature could inhibit the growth of bacteria and microzooplankton, as well as reduce the feeding rate of microzooplankton. In spring, the temperature in the high latitude sea area inhibits the growth of bacteria, whereas the phytoplankton remains almost unaffected, resulting in spring blooms. Temperature and substrate concentration are the reasons for the low bacterial growth rate in the cold sea (water temperature ≤4℃). However, the question of whether the low temperature or the low substrate concentration limits the growth rate of bacteria in the permanently cold sea (annual temperature ≤4℃ including the polar sea and most of the deep sea) has still been debated. Global warming predictions suggests that the ocean surface temperature will increase by 2~6℃ by the end of this century. Enclosure experiments have confirmed that global warming will lead to shorter time lag between phytoplankton bloom and bacteria and microzooplankton maximum, stimulating the feeding of microzooplankton on bacteria and phytoplankton. Global warming will change the balance between autotrophic production and heterotrophic consumption of organic matter, which allows the entry of more substances and energy into cellular respiration, resulting in a more heterotrophic ecosystem. MTE has some limitations in the investigation of the growth of marine bacteria and the changes in bacterial biomass with increasing temperature, which will require further theoretical analysis and experimental testing.