Exploring the biodiversity of cetacean communities along the western North Atlantic Ocean shelf-break.

Abstract

Declining biodiversity is a global issue that encompasses reduced species abundance and changing distributions. Observing community groups can reveal spatial patterns and identify shifts in presence over time, providing information to support conservation of biodiversity and ecosystem services. Passive acoustic monitoring (PAM) is a tool for observing ocean environments, and coupled with species-specific detectors and classifiers can provide information about cetacean communities. This study analysed data collected by 10 PAM recorders deployed along the western North Atlantic shelf break between April 2016 and June 2019. Relative acoustic presence of 13 specific cetacean species and a grouped category for delphinid species was evaluated using biodiversity metrics to compare dissimilarity of community composition across the sampling locations. In all years, presence of Gervais' beaked whale (Mesoplodon europaeus) was the primary distinguishing factor in grouping sites, while detections of other beaked whale species were of secondary importance, followed by other odontocetes. The presence of mysticetes also varied by site and season, and co-occurrence comparisons revealed distinctive communities at each site. This study highlights the significance of identifying beaked whales to species rather than grouping them, providing insights into the dynamics of cetacean populations to inform management and conservation of these important species.