Spatial and seasonal variability of the macrobenthic fauna in Mediterranean solar saltworks ecosystems

1. Solar saltworks are man-made systems for the production of salt and are characterized by high habitat heterogeneity owing to the existence of a strong salinity/confinement gradient. Although solar saltworks are considered to be artificial systems, they are also coastal aquatic ecosystems sharing common characteristics with natural transitional waters ecosystems, which are of special interest to the Water Framework Directive (2000/60/EC). 2. Spatial and seasonal distribution of macrobenthic invertebrates in relation to the abiotic environment of two Mediterranean solar saltworks ecosystems were assessed in this study. The spatial distribution investigated in this study ranged from the regional scale (Kalloni Saltworks, NE Aegean and Margherita di Savoia Saltworks, S. Adriatic) down to a local scale of 100s of metres in each ecosystem. 3. The macrobenthic community was variable at most spatial and seasonal scales examined in this study: spatial variability at the regional level was greater than seasonal variability within ecosystems and spatial variability among the salinity/confinement gradient levels was greater than within-level variability. 4. The abiotic environment, in both its spatial and seasonal aspects, was found to be crucial in determining the macrobenthic community structure. Biotic factors such as the life cycle of key species, the inter-specific competition as well as dispersion/colonization/extinction processes were also found to play an important role in structuring the macrobenthic fauna both in space and time. 5. A strong similarity of the macroinvertebrate faunal composition and community structure of the lower salinity ponds of solar saltworks with that of natural transitional waters ecosystems was observed. Therefore, solar saltworks ecosystems can be considered as important sites of study for the purposes of the Water Framework Directive.