Cetacean distribution in São Miguel (Azores) : influence of environmental variables at different spatial and temporal scales

• Main Author: Gonzalez Garcia, Laura
• Other Authors: Torres Palenzuela, Jesus Manuel
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Física aplicada 2019
• Subjects: 2510.07 Oceanografía Física; 2510.01 Oceanografía Biológica; 2401.06 Ecología Animal; baleen whale; baleen whales; Killer Whale; north atlantic current; North Atlantic; Sperm whale
• Online Access: http://hdl.handle.net/11093/1218

The strategic location of the Azores Islands in the middle of the Atlantic makes them an oceanic paradise for pelagic species, including whales and dolphins. The dynamic oceanography of the region, influenced by the North Atlantic Current and the Azores Front/Current System, interacts with the steep bathymetry of the archipelago. It favours the increase of primary production, and therefore, improves the existent conditions for upper trophic levels to occur. Due to the economic and logistic constraints of dedicated cetacean surveys, studies with opportunistic data are increasingly common. In the Azores, whale watching companies have continuously increased since early 90’s. Data they gathered present limitations, but advantages such as regular spatial cover or long-term series, together with the low cost of the data collection, make them an essential source to improve cetacean knowledge in the Azores nowadays. The main aim of this thesis is to study the spatial and temporal distribution of the sighted cetacean species in São Miguel (Azores). We use occurrence data recorded between 2008 and 2014 by a whale watching company off São Miguel. Environmental variables such as depth, slope, chlorophyll concentration, ocean altimetry and sea surface temperature were processed into two spatial scales (low and high resolution) and three temporal (daily, weekly and monthly). Accounting for the different scales we aimed to capture long-term or persistent oceanographic features such as the spring bloom, as well as more ephemeral short-term ones such as eddies or filaments. We analyze the habitat preferences of the three most sighted baleen whale species (blue, fin and sei whales) applying Generalized Additive Models (GAMs) with the different considered scales in the environmental variables. Along the seven years of study, we recorded 20 of the 28 cetacean species listed for the Azores: six species of mysticetes or baleen whales, five of beaked whales, five of dolphins, sperm whale, killer whale, false killer whale or pilot ...