**8. Conclusions**

The aim of the present paper was to summarise the information on the fish fauna of Community interest (sensu European Habitat Directive) in coastal lagoons and to highlight how they can provide indications on morphological conservation status of salt marshes and mudflats. The following was achieved:

(1) The complex of species *Aphanius* + *Valencia* could be used as indicator of habitat alterations in coastal lagoons, focusing, in particular, on salt marsh complexity, habitat connectivity within the lagoon or among adjacent lagoon systems and the presence of a system of artificial habitats, such as salt-works and man-made creeks. The presence and abundance of these species indicate, in fact, a mosaic of isolated and closed habitats, with respect to the open lagoons. The complex system of small creeks and pools has a significant role, not only for lagoon residents, but also for many other fish fauna species, also of commercial interest, such as marine migrants, of which juveniles exploit the trophic resource in saltmarsh areas. Together with *A. fasciatus, K. panizzae*, *N. canestrinii,* it is possible to find *A. boyeri*, *Sparus aurata* (L.) and some species of the genus *Chelon* and of the family Sygnathidae [49]. *V. hispanica* was found in the same sampling site as *Anguilla anguilla* (L.), *Mugil cephalus* (L.), *Pomatoschistus microps* (Krøyer) and *A. boyeri* [55]. The lagoon residents are more sensible to local habitat alterations than marine migrants [101], therefore, the species belonging to *Aphanius* + *Valencia* genera can be considered umbrella species, through which protection and broader conservation objectives could be achieved also for other species [113], even of economic interest. Their decrease, as a consequence of habitat degradation due to sea level rise, excavations of canals and infrastructure development, can be recorded earlier than that of other guilds. Mainly *A. fasciatus* responds to the definition of umbrella species, being highly detectable and correlating with species diversity [15].


**Author Contributions:** Conceptualization, C.F. and S.M.; writing—original draft preparation, C.F.; writing—review and editing, F.C., P.F., S.M. All authors have read and agree to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors are thankful to the editors and the anonymous reviewers for their comments and suggestions.

**Conflicts of Interest:** The authors declare no conflict of interest.
