Modeling Fine-Scale Cetaceans’ Distributions in Oceanic Islands: Madeira Archipelago as a Case Study

Abstract

Species distributional estimates are an essential tool to improve and implement effective conservation and management measures. Nevertheless, obtaining accurate distributional estimates remains a challenge in many cases, especially when looking at the marine environment, mainly due to the species mobility and habitat dynamism. Ecosystems surrounding oceanic islands are highly dynamic and constitute a key actor on pelagic habitats, congregating biodiversity in their vicinity. The main objective of this study was to obtain accurate fine-scale spatio-temporal distributional estimates of cetaceans in oceanic islands, such as the Madeira archipelago, using a long-term opportunistically collected dataset. Ecological Niche Models (ENM) were built using cetacean occurrence data collected on-board commercial whale watching activities and environmental data from 2003 to 2018 for 10 species with a diverse range of habitat associations. Models were built using two different datasets of environmental variables with different temporal and spatial resolutions for comparison purposes. State-of-the-art techniques were used to iterate, build and evaluate the MAXENT models constructed. Models built using the long-term opportunistic dataset successfully described distribution patterns throughout the study area for the species considered. Final models were used to produce spatial grids of species average and standard deviation suitability monthly estimates. Results provide the first fine-scale (both in the temporal and spatial dimension) cetacean distributional estimates for the Madeira archipelago and reveal seasonal/annual distributional patterns, thus providing novel insights on species ecology and quantitative data to implement better dynamic management actions.

Behavioural Ecology Traits of Elusive Deep-Diver Whales Unravel a Complex Social Structure Influenced by Female Philopatry and Defence Polygyny

“…This study provides an analysis of the social structure of Blainville's beaked whales in insular oceanic ecosystems, which are characterised by specific topographic and oceanographic variables that are known to influence predators' habits, such as cetaceans (Abecassis et al, 2015;Fernandez et al, 2021). The analysis of a longitudinal dataset on individual associations in relationship to age class, sex, residency status, and spatiotemporal patterns showed a social structure modulated by adult females.…”

“…Photographic data of Blainville's beaked whales were collected in the southern waters of Madeira Island (Portugal, 32 • N 017 • W), in a core area covering about 1,000 km 2 up to 15 km off the coast (see Fernandez et al, 2021). The study area is surrounded by warm-temperate Atlantic waters and is characterised by a narrow continental shelf and steep submarine canyons (Geldmacher et al, 2000;Martins et al, 2007).…”

“…The study area is surrounded by warm-temperate Atlantic waters and is characterised by a narrow continental shelf and steep submarine canyons (Geldmacher et al, 2000;Martins et al, 2007). These characteristics offer a privileged access to the pelagic environment where the target species commonly occurs throughout the year (Alves et al, 2018;Fernandez et al, 2021) and where some individuals are likely island-associated (Dinis et al, 2017). The data were collected year-round through whale-watching platforms (see Acknowledgments; procedures detailed in Alves et al, 2018) and in research trips, between 2011 and 2019 (Table 1 and Supplementary Table 1).…”

Seasonal variation in microplastics and zooplankton abundances and characteristics: The ecological vulnerability of an oceanic island system

“…The diet of these species is based mainly on epipelagic fishes, such as blue jack mackerel (Trachurus picturatus) and Atlantic chub mackerel (Scomber colias) (Romero et al, 2021b). Other large predators, such as delphinids and baleen whales, which feed mainly on small pelagic fishes, also occur in the area in high numbers during these months (Alves et al, 2018;Fernandez et al, 2021). Although the consequences of microplastics ingestion on marine organisms are still far from being fully understood, their harmful effects, especially linked with the presence of plastic additives or absorbed toxic compounds, have been largely proved (Mallik et al, 2021).…”

Priorities for ecological research on cetaceans in the Galápagos Islands

“…Such multiplatform data collection is increasingly being used to generate predictive habitat suitability maps (e.g., Thorne et al, 2012;Bouchet et al, 2015;Tobeña et al, 2016;Tardin et al, 2017;Fiedler et al, 2018;Tardin et al, 2019;Correia et al, 2021;Fernandez et al, 2021), even with short-term efforts (months to years). In the long term (years to decades), the accumulation of such data will increase the coverage, reliability, and scope of these maps and help refine the characterization of species-specific hotspots of occurrence and their fluctuations in response to environmental variation such as El Niño Southern Oscillation and climate change (e.g., Llapapasca et al, 2018;Becker et al, 2019;Becker et al, 2022).…”