AUTHOR=Pace Daniela Silvia , Panunzi Greta , Arcangeli Antonella , Moro Stefano , Jona-Lasinio Giovanna , Martino Sara 

TITLE=Seasonal distribution of an opportunistic apex predator (Tursiops truncatus) in marine coastal habitats of the Western Mediterranean Sea

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.939692

DOI=10.3389/fmars.2022.939692

ISSN=2296-7745

ABSTRACT=Assessing the distribution of marine apex-predators is pivotal to understanding community interactions and defining management goals. However, several challenges arise in both estimates and predictions considering the distinctive and mutable biological/ecological requirements of these species and the influence of human activities. Thus, efforts to study apex-predators spatial distribution patterns must deal with inherent uncertainty. 
Relying on different data sources (research programs and social media reports), physiographic and environmental covariates (depth, slope, surface temperature and chlorophyll-a), and specific source-related detection functions, this study applied a Spatial Log-Gaussian Cox Process to model the distribution patterns of an opportunistic apex-predator, the common bottlenose dolphin (Tursiops truncatus), over 14 years (2008−2021) in the central Mediterranean Sea (Italy) using a total of 955 encounters.
Both depth and slope showed a significant reduction effect in the encounters when deeper and steeper, respectively. Surface temperature did not seem to have a significant effect, while greater chlorophyll-a values were associated with higher encounter intensities. The estimated posterior mean and the coefficient of variation surfaces for the intensity by season showed higher intensity in summer nearby the Tiber River estuary than other regions. Almost homogeneous predictions were observed in winter, with slightly higher intensities where lower temperatures and significant chlorophyll-a concentration were recorded. The relatively low variance was predicted in the more coastal parts of the study area within each season, while higher uncertainty was instead revealed in the southernmost offshore area. 
This study highlighted the general persistent presence of the common bottlenose dolphin in the study area over the study period, with a coherent seasonal and geographical distribution, and rare transient occurrences in deeper waters (where uncertainty in predictions increases). Thanks to its ecological and behavioral plasticity, the species seems to well adapt to changing conditions, despite the variability and the different seasonal effects related to anthropogenic pressures.