Diet of bluefin tuna (Thunnus thynnus) and swordfish (Xhipias gladius) in the Adriatic Sea

The present issue analyses bluefin tuna (Thynnus thunnus) and swordfish (Xiphias glaudis) diet, caught by professional long-line fishing in the middle Adriatic Sea (Pomo pit). These species represent apex predators in pelagic environment that may play key roles in determining food web structure and ecosystem dynamics. The studies about their feedings habits, based upon stomach contents analysis, are important for the comprehension of biological and ecological interaction. Over the years, many studies have been performed on the diet of tuna and swordfish in the Mediterranean Sea. This research is based on a fairly wide number of analyzed stomach contents, in comparison with the previous ones. In this work, the analysis of 340 stomach contents of bluefin tuna caught by long-line in the central Adriatic sea confirms in general the opportunistic behaviour of this species. Finding support the hypothesis that Adriatic tuna and swordfish chase their food over a wide bathymetric zone and probably near the surface at night. No indication of food preference respect to size of predator or sample season are found. It seems that the two species are able to cohabit because their trophic niche are not overlapped, changing during the time and the vertical and horizontal space.

La città di Bologna e la sua storia: diffusione e condivisione delle conoscenze attraverso Webgis open source e Web Mapping

To understand a city and its urban structure it is necessary to study its history. This is feasible through GIS (Geographical Information Systems) and its by-products on the web. Starting from a cartographic view they allow an initial understanding of, and a comparison between, present and past data together with an easy and intuitive access to database information. The research done led to the creation of a GIS for the city of Bologna. It is based on varied data such as historical map, vector and alphanumeric historical data, etc.. After providing information about GIS we thought of spreading and sharing the collected data on the Web after studying two solutions available on the market: Web Mapping and WebGIS. In this study we discuss the stages, beginning with the development of Historical GIS of Bologna, which led to the making of a WebGIS Open Source (MapServer and Chameleon) and the Web Mapping services (Google Earth, Google Maps and OpenLayers).