Exergy As An Indicator Applied To The Study Of Macrobenthos Ecology In Changjiang Estuary

Application of the energy methods as an indicator in the complexity of the ecosystem is a significant trend. Because energy is the essential term of the ecosystem, further more it is an universal "money". From the enery launching on, it's easy to obtaining breakthrough at the complexity study of the ecosystem. In this paper, Exergy indicator applicated in three aspects of the esturine wetland ecology study. The main conclusions as following: First, State about the health of the macrobenthic ecosystem: North branch was better than south branch, outside was better than inside. The conclusions showed that exergy analyzing was better than analyzing of biomass or abundance. Second, the characteristics of a systems' recovery after disturbance appeared to be dependent on the spatial scale of the disturbance. If a disturbed area was small when compared to a contiguous non-disturbed one, complexity (information and network) would recover prior to biomass. Third, we discussed 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 integrated the processes underlying the recovery of the benthic community after disturbance.(1) Exergy was used to analyze macrobenthic fauna community in the Yangzi estuarySamples of subtidal macrobenthic fauna were collected and environmental factors were measured in the Yangtze Estuary in April, 2005. The community structure of macrobenthic fauna and its correlation with environmental factors were analyzed. Exergy as an indicator used to analyze the state of the macrobenthic ecosystem. Thirty-eight species were identified, belonging to five ecological assemblages. The total number of species was low, but was higher in the outer sampling sites of the estuary. The average abundance was 32.9 ind·m^-2 and the average biomass was 5.035 g·m^-2(fresh weight) at all sampling stations. Compared with historic data from the 1970s and 1980s, the community structure of macrobenthic fauna has changed obviously and the biomass has decreased rapidly. Total abundance and biomass of the species were obviously higher in the outer sampling sites of the estuary. Salinity was the main factor affecting the distribution of the macrobenthic fauna. The Bray-Curtis Cluster analysis showed that the macrobenthic fauna at all sampling station had four assemblages, which accorded with three spatial structural grads of the Yangtze River Estuary.State about the health of the macrobenthic ecosystem: North branch is better than south branch, outside was better than inside.(2) Ecological indicators performance during a re-colonisation field experiment and its compliance with ecosystem theoriesThe study was carried out in an intertidal flat after ecological engineering at the west of the Chongming Island in January, 2006. Succession plots were disturbed by ecological engineering and macrobenthos community were damaged severely. Through a re-colonisation field study three main questions were approached: (1) How do different ecological indicators react during the process of recovery? (2) What does grow first during a community succession, biomass or complexity? (3) Can the chosen ecological indicators help in recognising the three proposed forms of growth: biomass, network and information, throughout re-colonisation? Multivariate analysis was performed to examine the convergence of the disturbed plots with the surrounding community during recovery. Shannon-Wiener Index, Margalef Index, Pielou evenness, Eco-Exergy and Specific Eco-Exergy were applied to characterise the state of the community during the process. Results showed that the replacement of species over time happened associated macrobenthos community. Species richness increased rather rapidly and species composition was similar in disturbed and undisturbed areas. After 1 month, diversity was consistently higher in the community undertaking recovery. Eco-Exergy and Specific Eco-Exergy provided useful information about the structural development of the community but lacked discriminating power with regard to the informational status of the system. The observations appear to illustrate a case explainable by the Intermediate Disturbance Hypothesis (IDH). Overall, the characteristics of a systems' recovery after disturbance appear to be dependent on the spatial scale of the disturbance. If a disturbed area is small when compared to a contiguous non-disturbed one, complexity (information and network) will recover prior to biomass.(3) Application of exergy as an indicator in the restoration of ecosystemThermodynamic 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.