Human activity is causing different hazards to natural ecosystems which could compromise their continued functioning. To be sustainable, an ecosystem must be robust, which means it should have the ability to maintain its metabolic activity and also internal structure or organization. A robust system is categorized by there being balance among activity, organization, and resilience. Thus, “a ‘healthy’ system is one that can develop an efficient diversity of components and exchange pathways (high organization) while maintaining some overhead (redundancy) or resilience as insurance against stress, and substantial vigor to quickly recover or utilize stress in a positive manner"  From the different views of robustness and the importance of robustness in ecological systems, the present study corroborates the views of .
Ecological network analysis (ENA), is used to explore whole system interactions. Ecosystem networks of one South African estuary, the Mdloti on the KwaZulu-
Among all the network indices (TST, AMI, H, A/C, R, FCI), all indices are good indicators of some scenarios but not consistent in all scenarios in both networks. Robustness measure and redundancy are quite consistent in all the three scenarios in both networks and show some good information about the system health. These are able to reflect the information about the system even when the system faces small scale perturbations. Increase or decrease in the values and the pattern of change of these two indices with robustness are quite consistent with different perturbations. Therefore, these are sensitive enough to be considered as indicators. They reveal the change in robustness of the system in different scenarios and can portray the pattern of changes in the flow structure or magnitude which brings about the actual change in the condition of the system. The change in behavior of the indices might help us to understand the type of food chain (grazing or detritus) which is more important for the system.
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Ursula Scharler, School of Life Sciences, University of KwaZulu Natal, South Africa
Brian Fath, Advanced Systems Analysis Program (ASA), IIASA
Joyita Mukherjee of the Department of Zoology, Visva- Bharati, Santiniketan, India, is an Indian citizen. She was funded by IIASA's Indian National Member Organization during the YSSP.
Please note these Proceedings have received limited or no review from supervisors and IIASA program directors, and the views and results expressed therein do not necessarily represent IIASA, its National Member Organizations, or other organizations supporting the work.
Last edited: 23 March 2015
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