Multi source data analysis for improving striped dolphin distribution modelling at a regional scale

The relationship between a species and its habitat is complex but it is essential to study the distribution and habitat use of a protected species in order to identify regions where human activities and disturbances are likely to impact its population. The Marine Strategy Framework Directive informs that studies focusing on spatial and temporal species distribution and ecosystem variations (including links between habitats and species of marine mammals) are recommended to achieve Good Environmental Status (GES) of the EU's marine water by 2020. However, the current level of information on the spatial-temporal distribution of marine mammals is often lacking. The striped dolphin is the most abundant cetacean of the Mediterranean Sea; nevertheless its Mediterranean population is listed as "vulnerable" by IUCN experts. In order to investigate the spatial distribution of striped dolphin within the Adriatic-Ionian Region, a cooperative project among different research groups was set up and a multi-source data approach was employed. Presence data collected during monitoring activity carried out from 2008 to 2018 were analysed by means of Maxent. Main topographic variables as bathymetry, slope and distance from coastline were considered and five distribution models were performed to highlight suitable areas for striped dolphin within the entire study area. Models are presented and discussed. The results of this study show that to investigate the distribution of a species at a regional scale it is necessary to monitor area with different environmental characteristics. In this regards, cooperative regional projects represent an opportunity for pooling together data that taken singularly would not necessarily reflect the distribution of species at a larger scale, but that analysed together would allow to acquire information on suitable habitats at a regional level.