Continuing research - Unlocking the mysteries of myoglobin
Developing the ability to breath hold and dive is undoubtedly a key benchmark for maturing mammals. Myoglobin, an oxygen carrying compound that is found in the muscles of marine mammals, provides a crucial additional store of oxygen that allows adult cetaceans to dive and stay at depth for extended periods of time.
In young marine mammals, the available evidence suggests that myoglobin levels are very low and this may be a key constraint in the development of diving capacity. Staying at the surface is costly. During the very early stages of life, it increases the energy required for swimming and reduces the length of time that the young animal can nurse. As the animal matures, diving proficiency is an important requirement for foraging ?as such the development of myoglobin supplies within the muscles can have extended impact on the success of young marine mammals, from birth, through to weaning.
Using samples of muscle tissue collected from strandings, we are investigating the rates at which myoglobin levels accumulate in young marine mammals. Findings from early animal behavior studies, and more recent studies of human exercise physiology indicate that exercise may be a key factor that ¡°turns on ?myoglobin production. In young marine mammals this is maternally driven, and indeed in our results, we documented high levels of activity in our youngest humpback whale calves. Through our research we hope to determine what role this may play in the control and ontogeny of myoglobin production.
Andrew Wilson and Bonnie Rodgers, students at CSUCI working along with Dr. Cartwright, recently completed the first round of their study, comparing levels of myoglobin in neonates of different species of cetacea. Their early results suggest widely differing trends in mysticete vs. odontocetes.
As this research continues, Dr. Sackerson will be looking to determine the molecular pathway that controls myoglobin, leading from the animals?behavior to the molecular changes that enable diving. As climate changes, our oceans warm and our existing fish stocks face ever greater stresses, the ability to grow quickly to independence and to develop the abilities required to forage successfully, will become increasingly important to the survival and fitness of our marine mammal stocks. Current evidence suggests that recent and dramatic declines in Stellar sea lions in the Gulf of Alaska are closely linked to diving constraints on juveniles, making herring stocks inaccessible to them.This research will lead to a better understanding of the processes that control maturation and development of diving capabilities of cetaceans in general and as such will help in the informed management of our marine mammal stocks and the natural resources that they depend upon.