ABSTRACT: Ecological indicators performance during a re-colonisation experiment and its compliance with ecosystem theories
PATRÍCIO J.1, SALAS F.1, PARDAL M.A.1, JØRGENSEN S.E.2 and MARQUES J.C.1 2006.
Ecological indicators performance during a re-colonisation field experiment and its compliance with ecosystems theories.
Ecological Indicators 6: 43-57.
Through a re-colonisation field experiment 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?
The study was carried out in an intertidal rocky community dominated by the algae Corallina elongata . Experimental plots were cleared and macroalgae nad fauna were removed. Multivariate analysis was performed to examinate the convergence of the disturbed plots with the surrounding community during recovery. Shannon-Wiener Index, Margalef Index, Pielou eveness, Eco-Exergy and Specific Eco-Exergy were applied to characterise the state of the community during the process. Results show that the replacement of species over time happens both with the macroalgae and associated macrofauna community. Species richness increased rather rapidly and species composition was similar in disturbed and undisturbed areas. After 7 months, 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.
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1 IMAR - Institute of Marine Research, c/o Department of Zoology, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra Portugal
2 Environmental Chemistry Section, Danish, 3004-517 Coimbra Portugal