Acoustic Ecology of Greater Caribbean Manatees (Trichechus manatus manatus)

Understanding the acoustic ecology of manatees is essential for their conservation and rehabilitation. Anthropogenic noise, stemming from recreational and industrial activities, increasingly infiltrates manatee habitats, potentially affecting their behavior and communication. This dissertation investigates the auditory abilities of Greater Caribbean manatees (Trichechus manatus manatus) and examines noise levels in a human-care rehabilitation facility compared to a protected natural environment. The research aims to address critical gaps in our knowledge of manatee hearing physiology and determine the acoustic suitability of their rehabilitation environments, providing actionable insights for conservation efforts. The study employed Bone Conduction Auditory Brainstem Response (BC-ABR) to assess the hearing sensitivity of six Greater Caribbean manatees (T. manatus manatus). Results indicated that BC-ABR is a viable method for estimating manatee auditory thresholds, aligning closely with previous behavioral studies on Florida manatees (T. manatus latirostris). This innovative approach facilitates minimally invasive and efficient auditory testing, offering a valuable tool for monitoring hearing in rehabilitated manatees. These findings contribute to understanding the auditory range and sensitivity of Greater Caribbean manatees, shedding light on their capacity to perceive environmental and anthropogenic sounds. Additionally, this research assessed noise levels at the Caribbean Manatee Conservation Center (CMCC) and a protected natural habitat, Laguna del Condado in Puerto Rico. Noise monitoring revealed there was no significant difference between noise levels of human-care and natural environments. The overarching goals of this dissertation are to advance auditory testing methods for manatees and establish guidelines for acoustically suitable rehabilitation environments. By combining hearing assessments and noise monitoring, this research provides a comprehensive framework for enhancing the care of manatees in Rescue, Rehabilitation, and Release programs. Furthermore, it highlights the need for proactive conservation strategies to mitigate human-induced noise in manatee habitats. The implications of this work equip rehabilitation practitioners and conservationists with practical tools and data to optimize manatee care and ensure the preservation of their natural soundscapes.