The EEI index

According to Orfanidis et al. (2001, 2003) the Ecological Evaluation Index (EEI) was designed to estimate the Ecological Quality Status (EQS) of transitional and coastal waters, as defined in the Water Framework Directive (WFD, 2000/60/EC). Marine benthic macrophytes (seaweeds, seagrasses) were used as bioindicators of ecosystem shifts due to anthropogenic stress, from the pristine state with late-successional species to the degraded state with opportunistic species. The relation of EEI to the function and the resilience of the marine ecosystem, and its possibility for comparing and ranking at local, national and international levels, are some of its main management implications. An Ecological Evaluation Index continuous formula (EEI-c) has been also developed (Orfanidis et al. (2011).

According to reports of the Mediterranean Geographic Intercalibration Group (MedGIG, 2011, 2013) the EEI is considered as an ecological index suitable for the EQS evaluation.

For the calculation of EEI values an open software is available in the link


MedGIG (2011). Intercalibration Phase 2. Coastal waters macroalgae group of MEDGIG. Milestone 6 Report.

MedGIG (2013). WFD intercalibration technical report. Part 3 – Coastal and Transitional Waters. Mediterranean Sea GIG: Coastal Waters – Macroalgae.

Orfanidis S., Panayotidis P. & Stamatis N. (2001). Ecological evaluation of transitional and coastal waters: a marine benthic macrophytes model. Marine Mediterranean Sciences,2: 46-65.

Οrfanidis S., Panayotidis P. & Stamatis N., (2003). An insight to the ecological evaluation index (EEI). Ecol. Indicators 3: 27-33.

Orfanidis S., Panayotidis P. & Ugland K. (2011). Ecological Evaluation Index continuous formula (EEI-c) application: a step forward for functional groups, the formula and reference condition values. Mediterranean Marine Science, 12: 199-231.