Dottorato in BIOLOGIA AMBIENTALE ED EVOLUZIONISTICA

Titolo della tesi: New insights on the ecology and conservation of Mediterranean sharks: the contribution of Citizen Science networks and novel analysis approaches, with a particular attention to the Mediterranean White Shark

It is undoubtful that we are facing a strong biodiversity loss crisis. This crisis is particularly harsh in the marine environment, where over-exploitation, habitat loss, Global Change, and pollution impact natural communities as never before. These drivers of change are particularly effective on apex predators, such as sharks, which are naturally less resilient due to their life-history traits. Given its millenarian history of exploitation and the actual strong anthropogenic pressure, the Mediterranean area is particularly prone to favor the biodiversity loss and this condition is reflected, for example, by the worst elasmobranchs’ conservation status worldwide. However, even if this situation is, for sure, the result of the human pressure on the ecosystems, it is also reinforced by a general lack of ecological data on Mediterranean elasmobranchs, which produces considerable uncertainty in the regional conservation status assessment and poor effectiveness of the conservation measures. Citizen science initiatives are always more common in conservation studies, and they are proving to be a valuable alternative source of information when conventional data are scarce or inconsistent. However, a portion of the scientific community is still skeptical about the usability of opportunistic data due to essential biases affecting them and the absence of robust approaches to correct them. In this context, my Ph.D. thesis has two primary targets: 1) to demonstrate how citizen science initiatives can produce informative ecological insights on marine species, in particular for rare and elusive species (i.e., sharks), also boosting the data collection with different substantially costless strategies. 2) to describe different approaches capable of handling and standardizing opportunistic data to produce robust analysis, also allowing to harmonize them with more conventional data to perform a real integrated modeling approach. These approaches will be illustrated with different case studies. These objectives are explored within the chapters of the thesis through both published papers and paper drafts that still need some refinement before submission to a journal. Despite these two primary targets, other minor goals will be treated in the thesis, such as: - a deep analysis of the elasmobranchs biodiversity in the Mediterranean sea, which investigates the major biodiversity patterns and tries to solve some taxonomic issues. - the use of life-history traits to estimate the rebound potential of Mediterranean sharks and rays. - the demonstration that proper analyses of opportunistic datasets can inform field-work activities in the Mediterranean Sea.