The use of organisms as bioindicators to evaluate ecosystems has increase considerably along the 20th century. In aquatic ecosystems, a high number of methodologies have been developed to evaluate the ecological status (see Bonada et al. 2006b; Ziglio et al. 2006; Flotemersch et al. 2006), however, since early 80s two approaches have increase in popularity:
- The multimetric approach that uses several metrics or biotic indices, which represent several community characteristics, to summarize the biological quality into a unique value (see Barbour & Yoder 2000)
- The multivariate approach based on similarity indices. These indices provide an indication of how much a biological community from one site is similar to the community from another site, or to the reference community. This approach allows developing predictive models to evaluate the ecological status of aquatic ecosystems (see De Pauw et al. 2006).
The application web MEDPACS allows to evaluate the ecological status by means of both approaches. Nowadays, the use of predictive models for aquatic macroinvertebrates includes the Spanish Mediterranean basins (except the Ebro basin). However, there is a commitment to increase their application area in future updates to the rest of Spain.