Seafloor geomorphic features as an alternative approach into modelling the distribution of cetaceans

Abstract

Bathymetric proxies tend to indicate the relationships between the distribution of cetaceans and the seafloor in species distribution models (SDMs). Usually, seafloor features are described arbitrary to explain these relationships. Currently, a global seafloor geomorphic features dataset is available, with an objective identification and full representation for each seafloor geomorphic feature. Models based on common bathymetric proxies were compared with models with seafloor predictors, by a standardized ensemble SDM framework. Occurrences of two species with different foraging strategies and relationships with the seabed were selected: the sperm whale (Physeter macrocephalus) and the striped dolphin (Stenella coeruleoalba).. For sperm whales, GLM models had a significant better performance with seageomorphic features than with the common bathymetric proxies. In GAM and MARS models, the performance was similar for both seabed features and bathymetric proxies' models. In relation to striped dolphins, all models obtained had a significant better performance with seafloor features than with bathymetric proxies, regardless the modelling technique. The models showed preference of sperm whales for areas distant from the continental shelf and continental rise areas which consists of submarine canyons with adjacent submarine fans. Striped dolphins showed a clear preference for continental slope areas. The modelling based on seafloor geomorphic features support the hypothesis that the use of this type of predictors can improve the modelling performance and provide a complementary understanding of the relationship between cetaceans and the seafloor.