Direct and indirect anthropogenic effects on biodiversity of the Sardinian seas

All organisms modify their environment, and humans are no exception. Many ecosystems including marine ones are dominated directly by humanity. This thesis considers sea-based (first part) and land-based (second part) anthropogenic and natural influences and attempts to analyse the effects on two different ecosystems the demersal and pelagic, by means of two different “biological indicators”. Has also been considered the impacts of traditional fishing practices on the quality of the bluefin tuna, destined to human consumption. The First Part considers the impact of fishing on demersal resources (Chapters 1 and 2) in increasing fishing effort areas and the influence of natural dynamics on shaping deep-sea assemblages in a submarine canyon (Chapter 3). Classical biodiversity indexes, statistical simulation and multivariate analysis ordination techniques were used in order to carry out the investigations. The main aim was to propose a new method able to provide information about environmental stress due to fishery, and to analyse the diversity of canyon assemblages related to depth and time. The second part considers the patterns of tuna catch variability to test the influence of a land-based source of anthropic perturbation, via time series analysis, BACI design and DFA (Chapter 4). Moreover is analysed the impact that the traditional tuna fishery may have on the final quality of the product (Chapter 5), by means of tuna’s body temperature measurements.