Determinación de un modelo funcional de uso del espacio del delfín común (Delphinus delphis) y delfín listado (Stenella coeruleoalba) en el estrecho de Gibraltar mediante análisis multifractal e índices de similitud estructural (ssim)

Resumo

Up to 4 species of resident cetaceans can be observed in the Strait of Gibraltar. Between them we can find the common dolphin (Delphinus delphis) and the triped dolphin (Stenella coeruleoalba). Data from both species have been collected during twelve years from opportunistic platforms of whale watching, obtaining 436 records of common dolphin and 1138 records of striped dolphin. Kernel functions have been determined and have been rasterized with a resolution of 0.01 decimal degrees. Both raster images were analyzed by the structural similarity index, resulting in a value of 0.9999 ~ 1.0, indicating an absolute association between both species. On the other hand, through an analysis of the semivariance, the minimum sampling area (spatial use of maximum variance) has been determined, which has resulted in 2.92 meters for the common dolphin and 3.47 meters for the striped dolphin. A multifractal analysis shows the fractals (Dq) related to the relative density (moments q) between -10 and +10, indicating that the common dolphin shows high complexity (bigger Dq) in areas of high density, Both the common dolphin and the striped dolphin use the same space but do not use the territory in the same way. Probably the common dolphin feed more concentrated prey, may be diversified in size, although there is also the possibility of a commensal relationship in which individuals of common dolphin take advantage of the large groups of striped dolphins to find food in the Strait