Productivity in natural and artificial habitats in brackish water systems: an example from Aphanius fasciatus populations

1 - Venice Lagoon is characterized by many different shallow-water habitats, where salt marshes represent important habitats for many nektonic species. On the other side, small lagoon islands show a typical landscape dominated by agricultural gardens and orchards, that still host small ditches once used in traditional fishery activities but now abandoned.
2 - Aims of this study is to determine the productivity of these habitats for the nektonic community, referring to the small teleost Aphanius fasciatus (Valenciennes, 1821), listed in Annex II of �Habitat� Directive 92/43/CEE.
3 - One year monthly samplings were performed in four sites: two natural salt marshes and two systems of artificial ditches. All collected fish were photographed and then released. Only a sub-sample was preserved for laboratory analysis.
4 - Data show that artificial habitats host higher biomass of A. fasciatus, yielding higher secondary production respect to natural salt marshes, while P:B ratios vary in accordance to different environmental features and the related life history strategies adopted by the four populations. 5 - Results of this study highlight the relevance of these artificial habitats in the conservation of an important resident fish species.