A comparative analysis of habitat quality between artificial and natural creeks in the Mediterranean killifish Aphanius fasciatus: Implications for conservation

1. In transitional water ecosystems, habitat loss is one of the major threats to fish biodiversity. This is particularly true in the case of temperate salt marshes. Good quality artificial novel habitats may compensate for the loss of natural habitats, acting as a refuge for fish populations. 2. The aim of this study was to use coloured ornamental traits exhibited by the males of a small lagoon-resident fish, the Mediterranean killifish Aphanius fasciatus (Valenciennes, 1821), to assess habitat quality in both the natural and artificial creeks of the Venice lagoon. 3. The conspicuousness of two secondary sexual traits, the yellow/orange caudal fin pigmentation and the contrast between white and dark vertical bars on body sides, proved to be greater in artificial habitats compared to natural salt marshes, highlighting the refuge function of artificial creeks. 4. The use of secondary sexual traits could be extended to other fish species and to other aquatic habitats as a non-invasive approach. This would allow the identification of good quality habitats in the context of fish population management and conservation.