Distribution of aquatic invertebrates and of their predator the Greater Flamingo (Phoenicopterus roseus), evaluation of the impacts of a change of activity on a salt works in the Camargue (France)

Abstract

Salt works are important areas for waterbirds around the world, providing food supply and shelter. Due to economic constraints, a large abandonment of salts works occurred in the last decades, threatening the biodiversity contained in these particular habitats. Nowadays, more and more reconversion projects are developed to implement economically viable activities. The salt works of Salin-de-Giraud is an important breeding place for the Greater flamingo and contain a characteristic invertebrates’ assemblage which is its main food supply. Since 2007, 6575 hectares on 12 000 hectares of the salt works were sold to the Conservatoire du littoral and now have a natural functioning which not aims to produce salt anymore. The future of the remaining part of the salt works remains uncertain. Through this study, we determined the main variables influencing both the aquatic invertebrates’ distribution and the flamingos’ distribution in order to make hypotheses about what would be the impact of a changing of the land use in salt works. Using redundancy analyses and generalised linear mixed models, we found, that salinity is an important environmental factor, structuring the invertebrate communities and influencing Artemia spp. densities distribution. We also demonstrated the relationship existing between flamingos’ distribution and their main prey, Artemia spp.. In addition, we highlighted that ponds’ area affects the flamingos’ distribution in the salt works of Salin-de-Giraud. According to our results, change in land use in salt works to another use could result in the loss of Artemia spp. biomass, thus in a loss in large amount of resource for flamingos.