Cetacean distribution in relation to environmental parameters between Drake Passage and northern Antarctic Peninsula

Abstract

The Drake Passage (DP) is a dynamic oceanographic region influenced by the main frontal systems of the Southern Ocean, with little information about cetacean distribution and their relationship with environmental parameters. This study explored the use of generalized additive models (GAMs) to model the relationships of some cetacean species according to sea surface temperature (SST) and a suite of physiographic variables adjacent to the Antarctic Peninsula and DP during the austral summer. The results suggest that SST and distances from oceanographic boundaries, mainly the Southern Antarctic Circumpolar Current Front (SACCF) and Polar Front (PF), were the most significant parameters related to the presence/absence of cetaceans. SST showed an effect on humpback whale (Megaptera novaeangliae) presence around lower temperatures and sei whale (Balaenoptera borealis) and hourglass dolphin (Lagenorhynchus cruciger) at warmer waters. Four species of baleen whales prefer areas near SACCF and Elephant Island and two odontocetes in waters near the PF. Clustering analysis reflected three major groupings based on distances from oceanic fronts and coast: cetaceans that occurred in the northern sector of the DP but with the PF as the southernmost range; a second group with species occurring along the DP and not preferring Antarctic waters further south of the SACCF; and the third group, mainly baleen whales, mostly occupying Antarctic waters southern of the SACCF. We encourage further dedicated cetacean surveys in this particular dynamic region, based on in situ oceanographic data and krill acoustic sampling, and either taking into consideration cetacean species density or abundance.