Ecological status: ECOSTRIMED index

The main objective of the ECOSTRIMED index (ECOlogical STatus Rivers MEDiterranean) is to provide an integrated quality value for fluvial ecosystems, including as main parameters the riparian habitat and the biological quality of the water. it has been designed as an RBP (Rapid Bioassessment Protocol) in order to be performed directly in the field with a short sampling time schedule.

The Ecostrimed value is calculated by combining the values of two other quality indices:

1. A biotic index based on macroinvertebrates (FBILL or BMWP)

2. The riparian habitat quality index (QBR)

The Ecostrimed value is simple to calculate using the following table, which gives the ecological status of the studied reach:

QBR

FBILL BMWP > 75 45-75 <45

8-10 > 100 High Good Fair

6-7 61-100 Good Fair Poor

4-5 36-60 Fair Poor Poor

0-3 < 36 Poor Bad Bad

The main value in determining the ecological status is the biotic index, because we consider that, even when the riparian habitat has an excellent conservation status, very polluted waters make the functioning of the freshwater ecosystem impossible. However, the riparian habitat is also a key factor and in the case of very good biological conditions in the river but low riparian quality, the highest value of the ecological status will be only fair. The five classes of the ecological status are those put forward in the European Union Water Framework Directive.

In this RBP version, the ECOSTRIMED index does not consider the status of the fish community, the bird community, amphibians, reptiles or the physicochemical characteristics of the water (which we consider to be already included in the value of the biological index). Most of these parameters are reflected totally or partially in the values of either the biotic indices (e.g. physicochemical characteristic of the water or the fish community) or the QBR (birds). Non-native fishes and other introduced species (such as the American freshwater crayfish, Procambarus clarki,) should be considered in the future, and if they are present and abundant, the ECOSTRIMED value should be corrected. In many of our rivers the status of fishes and the importance of non-native species is not known at present, and methods of studying these animals are complicated and time consuming. For this reason they are not considered in the first version of the protocol for the calculation of ECOSTRIMED but should be included in future studies when information about them becomes available.

Source: Diputació de Barcelona 2000 (Copyright)

Developed by the Department of Ecology, University of Barcelona, with the collaboration of the Department of Environment of the Barcelona Council