Studio sulle diverse forme di adattamento della macrofauna all'ambiente profondo

Deep-sea ecosystems are known to be a large repository of biodiversity and most of them, due to their extreme conditions and remoteness, remain unexplored. In the specific case, deep Mediterranean environments are characterized by strong gradients of pressure, temperature, oxygen and a poor supply of nutrients and sunlight and for this reason they are considered as "fragile ecosystems". Considering the scarcity of news in the literature regarding the bathyalzone of the central-western Mediterranean, the aim of this PhD thesis was focused, primarily, on the ecological status evaluation of the fishery resources present in the south-eastern Sardinia bathyal belt (between 200 and 1890 m) and, subsequently, ecological parameters as abundance, biomass and biodiversity indexes were investigated. Based on the obtained results, two species, considered among the most abundant, were chosen as study cases in order to identify the main ecological strategies of adaptation to a particular environment such as the deep batial: one belonging to the infraclass Teleosts, Alepocephalus rostratus (Risso, 1820) and the other one belonging to the class Chondrichthyes, Galeus melastomus (Rafinesque, 1810). This general objective has been achieved through the deepen analysis of some important biological characteristics such as the identification of the type of growth and the analysis of the type of exploitation and the distribution of the trophic resources of the species.For both species, the trophic ecology was also analyzed through the analysis of the stable isotopes of Carbon and Nitrogen (δ13C and δ15N), to implement the previous analysis. Furthermore, the reproductive aspects were considered through the analysis of the main demographic components of fitness. In this study we also analyzed the biochemical composition (in terms of proteins, carbohydrates and lipids) and the caloric content of the muscles of the two species with the aim of identifying the variations with depth, size (length), maturation stage and sex.