Effects of Climate Change on Arctic Marine Mammal Health: A Veterinary Perspective

The health of an individual animal is the result of complex interactions among immune status, body condition, disease agent pathogenicity / toxicity, and environmental conditions. Population health status is affected by these factors but assessed in a different manner. Climate change will affect these interactions in several ways including direct effects due to loss of the sea ice, elevations of water and air temperature, changes in levels of ozone and increased occurrence of severe weather. Indirect effects of climate change on animal health include alterations in pathogen  presence, abundance and transmission pathways, changes in body condition and nutrient availability due to shifts in the prey base, changes in toxin and environmental contaminant exposures, and adverse effects of increased human habitation in the Arctic such as, chemical and pathogen pollution due to run-off, increased ship traffic with the attendant increased risks of ship strike, oil spills, introduction of invasive species through ballast, and possibly acoustic injury.  Since few talks focus on the changes that will and are occurring with pathogen transmission and biotoxins exposures, this talk with focus on this aspect of climate change effects. Alterations in disease transmission and prevalence are already attributed to climate change due to vector and host range extensions, changes in host densities, and increased survival of pathogens.  Emergence and consequences of harmful algal blooms are recognized throughout the world, with significant impacts documented in marine mammals. Climate changes can result in increased micronutrients run off of from the land and airborne deposits due to desertification, increased water temperature and decreased salinity, all of which may contribute to the increase in harmful algal blooms.  The extent to which climate change will impact marine mammal health will vary among species, with some species more sensitive to these factors than others and perhaps some benefiting from the predicted changes. Current baseline data on marine mammal health along with matching data on population trends and climate changes are needed.