Meeting Abstract

48.9  Jan. 6  Hematology of pinniped pups: implications for developing divers BURNS, J.M.*; RICHMOND, J.P.; CLARK, C.A.; LESTYK, K.C.; Univ. Alaska, Anchorage; Univ. Connecticut; Alaska Dept Fish Game; Univ. Alaska, Anchorage afjmb4@uaa.alaska.edu

Blood is the major oxygen storage site for most marine mammals, holding 50-70% of oxygen reserves in adults, with muscle storing most of the remaining reserves. However, due to very low myoglobin content in juvenile muscles, blood is a much more important oxygen reserve in younger animals. Despite this importance, mass specific blood oxygen stores do not increase linearly as pups grow, but instead decline during the lactation period, reaching adult values only near, or after, the onset of independent foraging. We investigated the changes in HCT, Hb, blood volume and blood oxygen reserves in developing phocids (harbor, harp, and hooded seals) and otariids (Steller sea lions), and correlated observed changes with measured iron stores, binding capacity, and erythropoietin (EPO) levels. In phocids, serum ferritin was lower and saturation rates and EPO levels higher in pups than in adults, suggesting that iron kinetics may influence red cell production and the development of oxygen reserves during the nursing period, perhaps due to limited iron intake in milk. In contrast, age related differences in blood oxygen stores persisted in otariids well past the time when iron stores and EPO levels were similar to those of adults, suggesting that other factors may be important in regulating hematological development when growth proceeds at a slower pace. Remarkably, both phocid and otariid pups begin independent foraging only once mass-specific oxygen reserves reach ~2/3 those of adults.