SALINDEX: A macroinvertebrate index for assessing the ecological status of saline “ramblas ” from SE of the Iberian Peninsula

SALINDEX: A macroinvertebrate index for the ecological status assessment of saline “ramblas ” from SE of the Iberian Peninsula A new index (SALINDEX) for assessing the ecological status of saline “ramblas ” from the southeast of the Iberian Peninsula is presented. It was applied in the Protected Area of Ajauque Wetland and Rambla Salada (Murcia). The index is based on four metrics related with macroinvertebrate community: the richness of macroinvertebrate families (FR), the ratio between richness of Coleoptera and Hemiptera species (C/H) and the presence and abundance of species that act as indicators of a healthy (I+) and impaired (I-) status (including exotic species). Metric scores were calculated with regard to reference condition values for each of the 7 ecotypes established according to salinity and water flow velocity gradients. The four metrics that comprise the index have the same weight, although the three first (FR, C/H, I+) score positively and the last one (I-) scores negatively. An ecological status class was assigned to each resulting index value (–1, 0, 1, 2, 3) according with the criteria set out in the Water Framework Directive. SALINDEX is based in ecological patterns typical of inland saline waters ecosystems (e.g., lower taxonomic richness, predominace of Coleoptera and Hemiptera species, presence of halotolerant/halophilic species, etc.), and was able to detect anthropogenic perturbations, such as eutrophication and salinity drop processes, and any subsequent recovery. In contrast, the IBMWP index, commonly used for the ecological evaluation of Iberian streams, was unsuited t