ORIGINAL PAPER Evaluation of the FORAM index in a case of conservation Benthic foraminifera as indicators of ecosystem resilience in protected and non-protected coral reefs of the Southern Caribbean Johanna Vela ´squez • Juliana Lo ´pez-Angarita • Juan A. Sa ´nchez Received: 16 March 2011 / Accepted: 3 September 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Localized and global impacts are responsible for driving the current decline in coral reef ecosystems. The worldwide debate over the efficacy of Marine Protected Areas (MPAs) as a conservation measure for coral reefs highlights the importance of acquiring accurate indicators of reef resilience and recovery under stressful conditions. Marine benthic foraminifera, considered outstanding indicators for environmental changes, are unicellular eukaryotes that inhabit sandy sediments in coral reefs. There are three kinds of benthic foraminifera: symbiotic, opportunistic, and other small heterotrophic. Symbiosis with microalgae is not favorable under high nutrient conditions. This study compared the FORAM Index (FI) in different sites inside and outside MPAs. The index was also compared with coral and algae cover. High FI values are characteristic of healthy oligo- trophic reefs whereas low values represent eutrophicated ecosystems. A community structure analysis was done in order to determine the compositional change of functional groups, and thus, to test spatially the index efficiency and performance. In general, MPA sites presented lower indexes compared to Non-MPA sites, probably due to the higher impact of tourism and agriculture in these areas. On the other hand, the index was not correlated with coral nor algae cover, even though positive and negative trends were found. Assemblage analyzes corroborated that the symbiotic foraminifers’ high susceptibility is the main source for the index variation, which was independent of the substrate type from which it was sampled. Our results show both the efficiency of this index and the impor- tance of its application for evaluating conservation strategies. Keywords Anthropogenic impact  Coral reefs  Eutrophication  FORAM Index  Marine Protected Area  MPA  Phase shift  Symbiont-bearing foraminifera J. Vela ´squez  J. Lo ´pez-Angarita  J. A. Sa ´nchez (&) Departamento de Ciencias Biolo ´gicas-Facultad de Ciencias, Laboratorio de Biologı ´a Molecular Marina (BIOMMAR), Universidad de los Andes, Carrera 1E No 18A–10, DC, Bogota ´, Colombia e-mail: juansanc@uniandes.edu 123 Biodivers Conserv DOI 10.1007/s10531-011-0152-7