Coralligenous reefs state along anthropized coasts: Application and validation of the COARSE index, based on a rapid visual assessment (RVA) approach

Abstract

A rapid visual assessment (RVA) approach for the characterization and assessment of the integrity of coralligenous reefs was applied in 21 stations subjected to different levels of anthropogenic pressure, along the French Mediterranean coasts. The reefs were characterized from both the geomorphologic and bionomic (biotic cover, conspicuous species richness, canopy-forming species, etc.) points of view, and their health status was estimated through the COARSE (COralligenous Assessment by ReefScape Estimate) index. The sensitivity of the COARSE index and the robustness of the RVA approach to observer biases were analyzed. Results showed that most coralligenous reefs were characterized by (sub) vertical cliffs or platforms with variable slope, usually dominated by biotic facies with Paramuricea clavata and/or Eunicella cavolini in healthy stations, or by algal associations or facies of impoverishment in the most impacted situations. The overall quality scores of the COARSE index generally reflected the putative level of stress of the sampling stations; differences due to observer biases resulted negligible. Coupling the RVA approach with the COARSE index proved an effective protocol for both the characterization and the evaluation of coralligenous reefs: the former is achieved by the analysis of the whole complexity of this habitat, the latter provides for the first time an indication of sea-floor integrity, differently from previous indices that aim at estimating water quality.

Integración de el índice ESCA por medio de los macro-invertebrados sésiles

“…These patterns confirm the sensitivity of coralligenous assemblages to human pressure (Balata et al 2007b, Piazzi et al 2012, Gatti et al 2015b, highlighting the suitability of these assemblages to be used as ecological indicators in monitoring survey and impact evaluation studies (Deter et al 2012, Sartoretto et al 2014, Gatti et al 2015a. Also, local protection might be not enough to prevent impacts on the structure and the ecological quality of coralligenous assemblages, as many organisms are more sensitive to large-scale alterations of water quality than to local disturbances (Parravicini et al 2013).…”

“…Thus, combining macroalgae and macro-invertebrates into the ESCA-TA index may increase the efficiency of the index in determining the ecological quality of marine coastal areas, as the response spectrum of the index to human pressures can be extended by the use of a higher number of descriptors. Moreover, the use of the ESCA-TA index may allow a finer intercalibration with other monitoring methods that consider the whole coralligenous assemblages (Kipson et al 2011, Deter et al 2012, Gatti et al 2015a, and therefore meet the requirements of the European directives.…”

“…The sensitivity of erect bryozoans to different kinds of pressure linked with water quality alteration or mechanical disturbance has already been reported (Sala et al 1996, Garrabou et al 1998, de la Nuez-Hernán-dez et al 2014, although the level of tolerance varies among species (Harmelin and Capo 2001). Thus, these organisms may be considered as valuable indicators of isolated or chronic impacts (Deter et al 2012, Gatti et al 2015a. Gorgonians, because of their long life and slow dynamics, are particularly vulnerable to largescale alterations such as climatic anomalies (Linares et al 2008, Garrabou et al 2009, Teixidó et al 2013, which are independent of the level of local protection (Cerrano et al 2000, Coma et al 2006, Huete-Stauffer et al 2011.…”

“…The development of monitoring programmes to manage and conserve special marine habitats requires effective descriptors to evaluate their ecological status and to detect changes in their ecological quality (Birk et al 2012). Several indices have been proposed for assessing the ecological quality of coralligenous assemblages: the Coralligenous Assemblage Index (CAI) (Deter et al 2012), the Coralligenous Assessment by ReefScape Estimate (COARSE) (Gatti et al 2015a), the INDEX-COR (Sartoretto et al 2014) and the Ecological Status of Coralligenous Assemblages (ESCA) , Piazzi et al 2015.…”

A Catalogue of Marine Biodiversity Indicators

“…Indeed, during the last couple of decades we have witnessed a boom of ecological indicators worldwide (see reviews by e.g., Marques et al, 2009;Cardoso et al, 2010;Birk et al, 2012;Borja et al, 2016a), driven either by environmental policies or research, attempting to cover, for example, the most sensitive habitats and endangered organisms (e.g. Gobert et al, 2009;Waycott et al, 2009;Deter et al, 2012;Gatti et al, 2015), or to detect imminent threats to ecosystems (Halpern et al, 2012;Katsanevakis et al, 2016) and their services (Liquete et al, 2013).…”