Fish-based indices for assessing ecological quality and biotic integrity in transitional waters: A systematic review

In the last decades, the need to develop biotic metrics that best represent the ecological quality and biotic integrity of a given environment has been discussed. Functional, ecological group and multimetric indices based on organisms such as fishes have been developed and analyzed, mostly in temperate regions. In this context, this study performed the first systematic review concerning the use of fish-based indices in assessing ecological quality and biotic integrity of transitional waters (i.e. estuaries, bays, coastal lagoons). The main driving questions approached the using status of fish-based indices in aquatic ecosystems, as well as their application in estuaries and the existent knowledge gaps (especially in tropical environments). A systematic review was performed on the Web of Science, Scopus, and SciELO research platforms (1945-2018). After screening all listed publications applying the inclusion/exclusion criteria, a total of 324 publications were included in the analysis. Most studies assessed rivers and streams from temperate zones, by studying fishes using the Index of Biotic Integrity (IBI) and its many regional adaptations. Few studies (13%) were performed in transitional aquatic ecosystems. For estuaries, the index Estuarine Fish Assessment Index (EFAI) was the most validated index based on its efficacy (10 publications). Only five studies were performed outside the temperate region, revealing an evident knowledge gap for tropical estuaries in this issue. Seven priority knowledge gaps concerning the further development of fish-based indices are listed as concluding remarks.