Identification of cetacean hotspots in the Gulf of Mexico based on niche models

Mario Rafael Ramírez-León1, María Concepción García-Aguilar2, Oscar Sosa-Nishizaki3, Alfonsina Eugenia Romo-Curiel2, Zurisaday Ramírez-Mendoza2 and Arturo Fajardo-Yamamoto2, (1)Center for Scientific Research and Higher Education at Ensenada, Biological Oceanography, Ensenada, BJ, Mexico, (2)Center for Scientific Research and Higher Education at Ensenada, Department of Biological Oceanography, Ensenada, BJ, Mexico, (3)CICESE, Biological Oceanography, Ensenada, BJ, Mexico
The geographical distribution of a species reflects its ecology and evolutionary history and is determined by both abiotic and biotic factors that operate at different temporal and spatial scales. Niche models are powerful tools that allow projecting habitat suitability for a species and its potential distribution. The overlay of the potential distributions of a group of species facilitates the identification of hotspots. Twenty-one resident cetaceans inhabit in the Gulf of Mexico, and the objective of this study was to identify their hotspots. We implement the maximum entropy algorithm (MAXENT) to model the potential distribution of 11 species: the sperm whale (Physeter macrocephalus), the dwarf sperm whale (Kogia sima), the short-finned pilot whale (Globicephala macrorhynchus), the Risso’s dolphin (Grampus griseus), the rough-tooth dolphin (Steno bredanensis), the pantropical spotted dolphin (Stenella attenuata), the Atlantic spotted dolphin (Stenella frontalis), the Clymene dolphin (Stenella clymene), striped dolphin (Stenella coeruleoalba), the spinner dolphin (Stenella longirostris), and the bottlenose dolphin (Tursiops truncatus). Based on depth, we found a spatial partition in the distribution of the Gulf of Mexico cetaceans: 1) species that distribute on the continental shelf (< 200 m depth); 2) species associated to the continental slope (200 to 3000 m depth); and 3) oceanic species (˃ 3,000 m depth). Hotspots were defined as those regions where the potential distribution of at least seven species overlapped. According to this definition, the northern and western continental slope regions of the Gulf of Mexico are potential cetacean hotspots of cetaceans.