Quantifying stress in marine mammals: Measuring biologically active cortisol in cetaceans and pinnipeds
Abstract
In marine mammals, anthropogenic disturbances may cause chronic stress that affect both individual health and population viability. Virtually all researchers that have studied stress in these mammals and have been able to get blood samples, have used plasma cortisol levels as one of the metrics to quantify the ‘stress’ these animals are experiencing. Cortisol is the key adrenal glucocorticoid released in marine mammals in response to stressors. However, these studies have relied almost exclusively on measuring the TOTAL amount of cortisol per unit of plasma. This is incorrect as it is only the FREE cortisol that is biologically active. Thus TOTAL cortisol may not give us the insight needed to assess the true impact of human and natural stressors on marine mammals. The proposed research will quantify two key measures needed to determine FREE cortisol levels: the binding affinity of the key blood carrier protein – corticosteroid binding globulin (CBG) -? and the CBG capacity of plasma in a sample of individuals within a species. These will be determined in as many marine species as possible. All ONR-?supported scientists will contribute plasma from the species they study and they will also obtain plasma from other species that they have access to. In addition, other scientists throughout the US and Canada will also contribute samples from their species. The proposed research will result in a broad comparative benchmark paper that can then be used in future studies examining blood-?based measures to quantify free cortisol in marine mammals and thus more rigorously assess the stress they are experiencing. In addition, the CBG and FREE levels will be determined in the large scale marine mammal health studies supported by ONR to given insight into the stress/health status of the animals in the different treatments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512214
Entities
People
- Rudy Boonstra
Organizations
- Office of Naval Research
- United States Navy
- University of Toronto