Despite tremendous advances in our understanding of marine mammals over the past several decades, numerous unanswered questions remain. These include fundamental questions in every biological discipline as well as other areas of science, including basic and applied chemistry and physics. Current studies of marine mammals reflect major improvements in technology as well as equally large changes in the ocean environment. Contributions for this Special Issue were invited in all areas of marine mammal research, especially those focusing on one (or both) of two themes: changing technological advances and changes in ocean habitats affecting marine mammals (including but not limited to changes in climate/temperature
ocean acidification
noise, plastic, or chemical pollution
vessel traffic and ship strikes
pathogenic viruses and microbes
trophic and salinity changes
fisheries impacts
habitat destruction
and related topics). The five articles published in this Special Issue focus on diverse areas of marine mammal research and health, including ecology, conservation, population biology and management, behavior, habitat and distribution, genetics, evolution, physiology, anatomy, acoustics, effects of noise and pollution, and new technologies.