Exergy作为生态学指标用于底栖动物群落恢复监测

Application of Exergy as an indicator in the restoration of benthic fauna communities

Exergy作为热力学指标是指系统从给定状态到与其周围介质达到热力学平衡所需做的最大功,Exergy概念被生态学家借鉴应用于生态系统的研究,使它有了生物学的含义。应用Exergy作为生态指标,用于指示崇西潮滩湿地生态工程中受到干扰的大型底栖动物群落结构的复杂的恢复过程。用BACI(before versus after,control versus impact)方法进行底栖动物采样,根据(a)不同食性类群的代码基因数;(b)储存在有机体基因内的信息;(c)种水平上的基因组尺度(C值)作为参数估算局域Exergy。结果显示工程区的Exergy值在工程干扰后9d时降到最低,接着工程区大型底栖动物群落的Exergy值逐渐与周围对照区趋向平衡。270d后,工程区的大型底栖动物群落得到恢复。3种不同方法估算的区域Exergy值表现出极为相似的动态趋势,进一步证实了用基因组尺度数据估算Exergy的可行性和优越性。研究表明Exergy指标不但适用于干扰后底栖动物群落恢复过程的监测,而且适合更广泛的生物系统研究。用周边对照区作为计算受干扰群落的局域Exergy值的动态参考比用历史资料更合适。

Thermodynamic function Exergy, which represents the distance of an open system from equilibrium, is proposed as an ecological indicator for summarizing the complex dynamics occurring in a disturbed community during the recovery processes. This quantity has been difficult to capture using classical indices. Exergy storage is estimated for benthic communities in response to experimental disturbance, as induced by ecological engineering, at the Chongxi tidal wetland of Chongming Island. Exergy storage was sampled using the BACI scheme （before versus after, control versus impact）. The control area is proposed as a dynamic reference for estimating the local Exergy storage of the benthic community. Three different methods were used for estimating Exergy on the basis of coefficients： （a） taken from trophic groups, （b） estimated from coding genes for broad taxonomical groups and （c） estimated from genome size and taken as close as possible to the taxonomical level of the species, providing a basis for inferring upon their similarities. The results show a decrease of local exergy content in the disturbed area, with a minimum in the area exposed to the engineering 1 month after the experimental disturbance. Subsequently, the Exergy of the benthic community increased to the reference level, i. e. , the surrounding control area, in accordance with the proposed hypothesis on the dynamics of Exergy storage during a system＇ s development. Moreover, the adjacent control samples represented an appropriate dynamic reference for estimating the local Exergy of the experimentally disturbed community. The three methods for estimating the local Exergy values provided comparable results. Therefore, we discuss the feasibility of using the more available genome size data set for estimating Exergy and the broader implications of using this indicator in other biological systems. Exergy was demonstrated to be a useful indicator that integrates the processes underlying the recovery of the benthic community after disturbance.