How Might Climate Change Affect the Ethology and Behavioral Ecology of Dugongs and Manatees?

Abstract

Climate change stressors are already affecting the subtropical and tropical coastal, estuarine, and riverine habitats of sirenians with consequential changes to their ethology and behavioral ecology. Climate change is causing temperature increases, sea level rise, changes in water chemistry and quality , increase in the intensity and nature of extreme weather events, and changes in rainfall patterns. These stressors are predicted to increase over the coming decades and will be exacerbated by co-stressors including harmful algal blooms, dam construction, hardening coastlines, phasing out coastal power plants, land clearing, and human food insecurity. The cumulative impacts on all sirenian habitats will be locally variable but changes in habitat extent and continuity are likely to be widespread. Important features of some key manatee habitats such as warm water refuges, freshwater sources, and navigable migration routes are expected to be reduced or lost. Foraging and movement behaviors of all species will change in response to alterations in community composition of feeding habitats, and the temporary loss of such habitats resulting from the increased intensity of extreme events, including the expansion of polar vortices, marine heatwaves, tropical cyclones, floods, droughts, and harmful algal blooms. These extreme events are expected to increase sirenian mortality and reduce fecundity, local population size , and genetic diversity. The locations of essential resources and the cues triggering the timing of movements are expected to alter rapidly as the climate changes . Some coastal habitats may become unsuitable for manatees because of the salinization of sources of fresh water for drinking . The capacity of sirenians to alter their behavior in response to climate change will be essential to their survival.