Meeting Abstract
P2.174 Saturday, Jan. 5 Oxygen storage capacity of a primary locomotor muscle in two similarly-sized, pelagic dolphins ARTHUR, L. H.*; VELTEN, B. P.; KINSEY, S. T.; MCLELLAN, W. A.; PABST, D. A.; Univ. of North Carolina Wilmington lha8694@uncw.edu
Diving marine mammals must store oxygen (O2) within their bodies to power metabolism when submerged. Three body compartments – muscle, blood, and lungs – are sites of O2 storage. A muscle’s O2 storage capacity is dependent upon its myoglobin concentration ([Mb]) and mass. We compared epaxial locomotor muscle O2 stores in common (Delphinus delphis) (n=8) and striped (Stenella coeruleoalba) (n=7) dolphins. These two similarly-sized dolphins have overlapping distributions, but diet analyses suggest striped dolphins are deeper divers. Thus, we hypothesized that striped dolphins would have higher muscle O2 stores than common dolphins. Striped dolphins possessed higher [Mb], locomotor muscle mass (as % of total body mass) and muscle O2 capacity than did common dolphins (8.15±0.80 vs. 5.01±0.54 g Mb/100g muscle; 44.82±4.68 vs. 36.26±1.64 %; and 106.75±9.31 vs. 67.1±7.21 ml O2/ kg muscle). We calculated the aerobic dive limit (cADL) of each species using their muscle O2 stores, and blood and lung O2 stores estimated from published, mass-specific relationships. ADL was calculated as total body O2 stores divided by diving metabolic rate (here assumed to be basal metabolic rate, based upon Kleiber). The cADL of striped dolphins (23.21±0.76 min) was 1.6 times longer than that of common dolphins (14.35±1.34 min). These results support diet analyses and suggest that striped dolphins can dive to greater depths than can common dolphins. The cADL for both species are higher than those measured for common and other similarly-sized dolphins (2-8 min), likely due to the assumed low diving metabolic rate. The difference in cADL suggests that striped dolphins can routinely achieve greater depths, with longer dive duration or higher swim speeds, than can common dolphins.
