Meeting Abstract
Fatty acid oxidation provides approximately 90% of energetic requirements in northern elephant seals (NES), yet little is known about the composition of their skeletal muscle fatty acids (FAs). Here, we report the skeletal muscle FA composition of NES within different age classes (adults {AD}, 1-year olds {1YR}, weaned pups {WP}) and sex. We analyzed 136 samples, spanning from 2012-2016, via GC-FID. A subset of 15 FAs, accounting for ~96% of FAs, were normalized and transformed. Saturated fatty acids (SFAs, ~65%) dominated muscle tissue in all age classes, monounsaturated fatty acids (MUFAs, ~19%) were the second most abundant and polyunsaturated fatty acids (PUFAs, ~11%) were the least abundant. Muscle tissue was predominantly composed of five FAs, C16:0, C16:1, C18:0, C18:1n9c and C20:2 (81% total FA). Multivariate analysis (MANOVA) of FA groups (SFA, MUFA, PUFA) indicated a significant effect of age class (F[4,248]= 14.40 p<0.0001) but not sex. A significant effect for age class (F[4,388]=31.22,p<0.001) and sex (F[2,194]= 8.92, p<0.0001) was reported within the 15 FAs. Univariate statistics revealed WP significantly differed from both AD/1YR across FA groups (p<0.0001 for all ANOVA/Tukeys; no sig. dif. for AD*1YR). Weaned pups drove the model sex effects (ANOVA, F[1,1138]=1.21,p<0.0001) and differed from AD/1YR for 8 FAs (5 SFAs, 2 MUFAs, 1 PUFA) and from 1YR for 4 FAs (1 SFA, 2 MUFAs, 1 PUFA). These results suggest there may be a developmental difference in NES skeletal muscle FAs, possibly relating to the period of diving development that occurs between weaning and becoming a deep diving NES.
