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  • 1
    Language: English
    In: Ecological Modelling, June 24, 2015, Vol.306, p.160(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ecolmodel.2014.10.027 Byline: Joyita Mukherjee, Ursula M. Scharler, Brian D. Fath, Santanu Ray Abstract: * Robustness in estuarine ecosystem is investigated through ENA. * Mdloti, a temporarily open or close estuary in South Africa is considered as study site. * Different ENA indices are calculated and analyzed for original and perturbed networks. * Change in robustness is not significant for change in the autotrophic biomass scenario but is significant for the other two scenarios. * Robustness is proved to be a good measurement for ecosystem health in this study. Author Affiliation: (a) Ecological Modelling Laboratory, Department of Zoology, Visva-Bharati University, Santiniketan, India (b) School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa (c) Department of Biological Sciences, Towson University, Towson, MD, USA (d) Advanced Systems Analysis Program, International Institute for Applied Systems Analysis, Laxenburg, Austria
    Keywords: Estuaries – Measurement ; Ecosystems – Measurement
    ISSN: 0304-3800
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Ecological Modelling, 24 June 2015, Vol.306, pp.160-173
    Description: Robustness is a universal feature of ecological systems which promotes sustainability over time. Robustness of an aquatic ecosystem, specifically an estuarine system, is investigated here using indicators derived from ecological network analysis. Estuaries provide us with many ecosystem services and these are consequently prone to face anthropogenic stresses. In South Africa, temporarily open/closed estuaries occupy a significant percentage of coastal boundaries. One of the South African estuaries, namely Mdloti, is studied here using network-based, Ecopath software. The estuarine energy flow networks are perturbed following different scenarios, which are assumed to be a result of selected anthropogenic stresses (eutrophication, overfishing) to the system. Several network indices such as total system throughput (TST), redundancy ( ), Finn’s Cycling Index (FCI) and ascendency over development capacity ratio ( / ) are calculated and analyzed for the original field-based network and three perturbed networks under different scenarios (change of autotrophic biomass, fish yield, and detritus import). The change of ecosystem robustness from the unperturbed network is more pronounced in the perturbed networks of fish biomass change and detritus import than change in autotrophic biomass scenario. These indicators reliably reflected the relative change of flow pattern if any changes occur and magnitude in the networks in different scenarios. From the present study, we show that certain common network indices as mentioned above provide a measure of robustness and can be used for the assessment of ecosystem organization and function. ENA properties and also robustness change depending on the type and magnitude of stress imposed on the system.
    Keywords: Network Analysis ; Ascendency ; Development Capacity ; Redundancy ; Perturbation ; Mdloti Estuary ; Environmental Sciences ; Ecology
    ISSN: 0304-3800
    E-ISSN: 1872-7026
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  • 3
    Language: English
    In: Ecological Modelling, 10 November 2017, Vol.363, pp.207-220
    Description: Anthropogenic intervention along with natural variability can both influence and compromise continued ecosystem functioning. Ecological network analysis (ENA) was used to explore ecosystem functioning following disturbances to food web networks of a South African estuary, Mdloti, under different seasons. Keystone species, in particular, play an important structural role in spite of having low levels of presence in terms of biomass. From networks of carbon exchanges, the keystone species are identified which include high trophic level carnivorous fish species like Argyrosomus japonicus, Caranx sexfasciatus and Monodactylus falciformis. It is observed that keystone species differed between seasons, according to changing conditions of the estuary. The positive and negative direct and indirect effects that the keystone species have on the different components of the system are evaluated by a Mixed Trophic Impacts (MTI) analysis and results of the direct-indirect impacts analysis are not consistent across seasons.Results reinforce the fact that the keystone species are context dependent as they show variation over the different networks following species composition change following alteration of the estuaries physical status and season. To simulate disturbance, the keystone species biomass in the initial five networks was changed by 10% in stepwise intervals up to ± 99% and it was observed that the system is somewhat resistant to the perturbation effects of the keystone species.
    Keywords: Food Web ; Ecological Network Analysis ; Mixed Trophic Impacts ; Keystoneness Index ; Mdloti Estuary ; Environmental Sciences ; Ecology
    ISSN: 0304-3800
    E-ISSN: 1872-7026
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  • 4
    Language: English
    In: Ecological Indicators, August, 2012, Vol.19, p.130(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ecolind.2011.06.014 Byline: Helena Verissimo (a), Joao M. Neto (a), Heliana Teixeira (a), J.N. Franco (a), Brian D. Fath (b)(c), Joao Carlos Marques (a), Joana Patricio (a) Keywords: Ecological indicators; Subtidal benthic macroinvertebrates; Management; Ecological quality; Estuaries; Portugal Abstract: Robust approaches to evaluate ecological quality in aquatic ecosystems become demanding concomitantly with the degradation resulting from increasing human-induced pressures. Aiming at a successful management, numerous evaluation tools are currently available and have been widely used for quality status assessment in estuaries mainly through the analysis of macrobenthic communities. The Mondego estuary (Portugal) has been under severe environmental pressure since the early 1990s due to different anthropogenic stresses. To improve the ecological condition and mainly to ameliorate the risk of eutrophication symptoms in an estuarine section (south arm), in 2006, the upstream connection between the north and south estuarine arms was re-established. Data on subtidal macrobenthic communities and environmental variables over a 5-year interval, covering the pre-management (from 2004 to 2006) and post-management (2007 and 2008) periods were used to assess restoration effectiveness. Firstly, temporal differences in the structure and composition of the macrobenthic assemblages between periods were assessed. Secondly, the relative performance of different ecological indicators (Shannon-Wiener, Margalef, Pielou, Simpson, AMBI, taxonomic diversity measures and Eco-exergy based indicators) to capture potential ecological changes between periods was analyzed. Lastly, indicators' performance was compared with the information given by the analysis of macrofauna composition and structure to distinguish their usefulness for addressing specific management objectives. In the post-management, water quality did not reflect considerable changes while macrobenthic assemblages responded to restoration variably along the estuarine gradient. Overall, ecological indicators effectively detected the prevailing ecological conditions and behaved consistently with the subtidal community ecological context. Most indicators were able to capture temporal changes in macrobenthic assemblages structure and performed differently for the distinct estuarine zones assessed, not always indicating a quality improvement. Further monitoring and assessment on subtidal macrobenthic communities' structure and functioning is needed to understand better the restoration effects. Recognize the success of such actions in aquatic systems is crucial for their adequate management. Author Affiliation: (a) IMAR - Institute of Marine Research, Department of Life Sciences, FCT, University of Coimbra, 3004-517 Coimbra, Portugal (b) Biology Department, Towson University, Towson, MD 21252, USA (c) Advanced Systems Analysis Program, International Institute for Applied Systems Analysis, Laxenburg, Austria Article History: Received 7 April 2011; Revised 9 June 2011; Accepted 12 June 2011
    Keywords: Aquatic Ecosystems ; Biological Indicators ; Estuaries ; Eutrophication ; Ecosystems ; Universities And Colleges
    ISSN: 1470-160X
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Ecological Indicators, August 2012, Vol.19, pp.130-143
    Description: Robust approaches to evaluate ecological quality in aquatic ecosystems become demanding concomitantly with the degradation resulting from increasing human-induced pressures. Aiming at a successful management, numerous evaluation tools are currently available and have been widely used for quality status assessment in estuaries mainly through the analysis of macrobenthic communities. The Mondego estuary (Portugal) has been under severe environmental pressure since the early 1990s due to different anthropogenic stresses. To improve the ecological condition and mainly to ameliorate the risk of eutrophication symptoms in an estuarine section (south arm), in 2006, the upstream connection between the north and south estuarine arms was re-established. Data on subtidal macrobenthic communities and environmental variables over a 5-year interval, covering the pre-management (from 2004 to 2006) and post-management (2007 and 2008) periods were used to assess restoration effectiveness. Firstly, temporal differences in the structure and composition of the macrobenthic assemblages between periods were assessed. Secondly, the relative performance of different ecological indicators (Shannon–Wiener, Margalef, Pielou, Simpson, AMBI, taxonomic diversity measures and Eco-exergy based indicators) to capture potential ecological changes between periods was analyzed. Lastly, indicators’ performance was compared with the information given by the analysis of macrofauna composition and structure to distinguish their usefulness for addressing specific management objectives. In the post-management, water quality did not reflect considerable changes while macrobenthic assemblages responded to restoration variably along the estuarine gradient. Overall, ecological indicators effectively detected the prevailing ecological conditions and behaved consistently with the subtidal community ecological context. Most indicators were able to capture temporal changes in macrobenthic assemblages structure and performed differently for the distinct estuarine zones assessed, not always indicating a quality improvement. Further monitoring and assessment on subtidal macrobenthic communities’ structure and functioning is needed to understand better the restoration effects. Recognize the success of such actions in aquatic systems is crucial for their adequate management.
    Keywords: Ecological Indicators ; Subtidal Benthic Macroinvertebrates ; Management ; Ecological Quality ; Estuaries ; Portugal ; Environmental Sciences
    ISSN: 1470-160X
    E-ISSN: 1872-7034
    Source: ScienceDirect Journals (Elsevier)
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  • 6
    Language: English
    In: Ecological indicators, 2012, Vol.19, pp.130-143
    Description: Robust approaches to evaluate ecological quality in aquatic ecosystems become demanding concomitantly with the degradation resulting from increasing human-induced pressures. Aiming at a successful management, numerous evaluation tools are currently available and have been widely used for quality status assessment in estuaries mainly through the analysis of macrobenthic communities. The Mondego estuary (Portugal) has been under severe environmental pressure since the early 1990s due to different anthropogenic stresses. To improve the ecological condition and mainly to ameliorate the risk of eutrophication symptoms in an estuarine section (south arm), in 2006, the upstream connection between the north and south estuarine arms was re-established. Data on subtidal macrobenthic communities and environmental variables over a 5-year interval, covering the pre-management (from 2004 to 2006) and post-management (2007 and 2008) periods were used to assess restoration effectiveness. Firstly, temporal differences in the structure and composition of the macrobenthic assemblages between periods were assessed. Secondly, the relative performance of different ecological indicators (Shannon–Wiener, Margalef, Pielou, Simpson, AMBI, taxonomic diversity measures and Eco-exergy based indicators) to capture potential ecological changes between periods was analyzed. Lastly, indicators’ performance was compared with the information given by the analysis of macrofauna composition and structure to distinguish their usefulness for addressing specific management objectives. In the post-management, water quality did not reflect considerable changes while macrobenthic assemblages responded to restoration variably along the estuarine gradient. Overall, ecological indicators effectively detected the prevailing ecological conditions and behaved consistently with the subtidal community ecological context. Most indicators were able to capture temporal changes in macrobenthic assemblages structure and performed differently for the distinct estuarine zones assessed, not always indicating a quality improvement. Further monitoring and assessment on subtidal macrobenthic communities’ structure and functioning is needed to understand better the restoration effects. Recognize the success of such actions in aquatic systems is crucial for their adequate management. ; p. 130-143.
    Keywords: Risk ; Water Quality ; Estuaries ; Environmental Factors ; Monitoring ; Fauna ; Eutrophication ; Aquatic Ecosystems ; Species Diversity ; Temporal Variation
    ISSN: 1470-160X
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 7
    Language: English
    In: Ecological Indicators, 2009, Vol.9(1), pp.1-25
    Description: Recently there has been a growing interest and need for sound and robust ecological indices to evaluate ecosystem status and condition, mainly under the scope of the Water Framework Directive implementation. Although the conceptual basis for each index may rely on different assumptions and parameters, they share a common goal: to provide a useful tool that can be used in assessing the system's health and that could be applied in decision making. This paper focuses mainly on benthic community-based, biotic indices. We supply a general overview of several indices premises and assumptions as well as their main advantages and disadvantages. Furthermore, an illustrative example is provided of a straightforward application of benthic index of biotic integrity and benthic condition index. As a reference, their performance is compared to the Portuguese-benthic assessment tool. Limitations of the tested indices are discussed in context of the Mondego estuary (Portugal) case study.
    Keywords: Ecosystem Integrity ; Estuaries ; Biotic Indices ; Benthic Communities ; Mondego Estuary ; Ecological Indicators ; Environmental Sciences
    ISSN: 1470-160X
    E-ISSN: 1872-7034
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  • 8
    Language: English
    Description: Recently there has been a growing interest and need for sound and robust ecological indices to evaluate ecosystem status and condition, mainly under the scope of the Water Framework Directive implementation. Although the conceptual basis for each index may rely on different assumptions and parameters, they share a common goal: to provide a useful tool that can be used in assessing the system's health and that could be applied in decision making. This paper focuses mainly on benthic community-based, biotic indices. We supply a general overview of several indices premises and assumptions as well as their main advantages and disadvantages. Furthermore, an illustrative example is provided of a straightforward application of benthic index of biotic integrity and benthic condition index. As a reference, their performance is compared to the Portuguese-benthic assessment tool. Limitations of the tested indices are discussed in context of the Mondego estuary (Portugal) case study.
    Description: http://www.sciencedirect.com/science/article/B6W87-4S38C07-1/1/8a495b1458d35c6ecf614eab10816ca3
    Keywords: Ecosystem Integrity ; Estuaries ; Biotic Indices ; Benthic Communities ; Mondego Estuary ; Ecological Indicators
    Source: Repositório Cientfico de Acesso Aberto de Portugal
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