title: Effects of enhanced hydrological connectivity on Mediterranean salt marsh fish assemblages with emphasis on the endangered Spanish toothcarp (Aphanius iberus).
abstract: The hydrological connectivity between the salt marsh and the sea was partially restored in a Mediterranean wetland containing isolated ponds resulting from former salt extraction and aquaculture activities. A preliminary assessment provided evidence that ponds farther from the sea hosted very large numbers of the endangered Spanish toothcarp,Aphanius iberus, suggesting that individuals had been trapped and consequently reach unnaturally high densities. In order to achieve both habitat rehabilitation and toothcarp conservation, efforts were made to create a gradient of hydrologically connected areas, including isolated fish reservoirs, semi-isolated, and connected salt marsh-sea areas that could allow migratory movements of fish and provide some protection forA. iberus. The fish community was monitored prior to, and for three years after rehabilitation. Results showed an increase in the number of fish species within semi-isolated areas (Zone A), whereas areas adjacent to the sea (Zone B) increased the number of marine species and decreased that of estuarine species (ES). Yet overall differences in fish assemblages were much higher between zones than among study years. Generalized linear models (GLMs) evidenced that distance to the sea was the most important variable explaining the local diversity of the fish community after restoration, with occasional influence of other factors such as temperature, and depth. The abundance ofA. iberuswas consistently higher in semi-isolated areas at greater distances from the sea, but a decline occurred in both zones and in isolated reservoir ponds after restoration efforts, which may be attributable to interannual differences in recruitment success and, to a lesser extent, to dispersal into adjacent habitats. A negative effect of restoration works on fish population cannot be excluded, but the final outcome of the intervention likely needs a longer period.
authors.affiliation: Aquatic Ecosystems, Institut de Recerca i Tecnologia Agroalimentàries , Sant Carles de la Ràpita, Tarragona , Spain.
authors.forename: Patricia
authors.identifier: 0000-0002-4986-2010
authors.initials: P
authors.lastname: Prado
authors.affiliation: Aquatic Ecosystems, Institut de Recerca i Tecnologia Agroalimentàries , Sant Carles de la Ràpita, Tarragona , Spain.
authors.forename: Carles
authors.initials: C
authors.lastname: Alcaraz
authors.affiliation: Aquatic Ecosystems, Institut de Recerca i Tecnologia Agroalimentàries , Sant Carles de la Ràpita, Tarragona , Spain.
authors.forename: Lluis
authors.initials: L
authors.lastname: Jornet
authors.affiliation: Aquatic Ecosystems, Institut de Recerca i Tecnologia Agroalimentàries , Sant Carles de la Ràpita, Tarragona , Spain.
authors.forename: Nuno
authors.initials: N
authors.lastname: Caiola
authors.affiliation: Aquatic Ecosystems, Institut de Recerca i Tecnologia Agroalimentàries , Sant Carles de la Ràpita, Tarragona , Spain.
authors.forename: Carles
authors.initials: C
authors.lastname: Ibáñez
keywords: Aphanius iberus; Connectivity; Distance to the sea; Fish dispersal; Fish diversity; Isolation; Salt marsh rehabilitation