Meeting Abstract

P1.72  Sunday, Jan. 4  Non-Esterified Fatty Acid Concentrations in Galápagos Marine Iguanas during a Mild El Niño Year PRENTICE, N.E.*; WIKELSKI, M.; ROMERO, L.M.; FLORANT, G.L.; Colorado State University; Princeton University; Tufts University; Colorado State University nicpren@simla.colostate.edu

The Galápagos marine iguana (Amblyrhynchus cristatus) undergoes long periods of fasting during an El Niño year. How these animals are able to survive periods when food is scarce is unclear. During a fast, we predicted that these animals mobilize endogenous fat stores to meet metabolic energy requirements. Plasma concentrations of non-esterified fatty acids (NEFA) are generally indicative of fat metabolism in fasting animals. We investigated plasma NEFA concentrations in marine iguanas collected in January of 2007, which was a mild El Niño year. Blood samples from both female and male marine iguanas were analyzed in this study. We also determined body mass (g) and body condition index ((_{body mass/snout-vent length}3) x ₁₀6) of the same animals in order to correlate NEFA concentrations with body condition. We hypothesized that the animals with a low body condition index would have low plasma NEFA levels and would be less likely to survive. Our data suggest that in female iguanas there is a positive correlation between body mass and snout-vent length (SVL) (_R2 = 0.34; n = 19) and a positive correlation for body condition index vs. plasma NEFA concentrations (_R2 = 0.33). Male iguanas did show a positive correlation between body mass and SVL (_R2 = 0.32; n = 70), but did not show any correlation between body condition index and NEFA concentrations. Overall, we conclude that female iguanas in 2007 were in better condition to survive a long fast compared to male iguanas.