The effect of cold-induced increased metabolic rate on the rate of 13C and 15N incorporation in house sparrows (Passer domesticus)

Abstract

Animals with high metabolic rates are believed to have high rates of carbon and nitrogen isotopic incorporation. We hypothesized that (1) chronic exposure to cold, and hence an increase in metabolic rate, would increase the rate of isotopic incorporation of both 13C and 15N into red blood cells; and (2) that the rate of isotopic incorporation into red blood cells would be allometrically related to body mass. Two groups of sparrows were chronically exposed to either 5 or 22 degrees C and switched from a 13C-depleted C3-plant diet to a more 13C-enriched C4-plant one. We used respirometry to estimate the resting metabolic rate (VO2) of birds exposed chronically to our two experimental temperatures. The allometric relationship between the rate of 13C incorporation into blood and body mass was determined from published data. The (VO2) of birds at 5 degrees C was 1.9 times higher than that of birds at 22 degrees C. Chronic exposure to a low temperature did not have an effect on the rate of isotopic incorporation of 15N save for a very small effect on the incorporation of 13C. The isotopic incorporation rate of 13C was 1.5 times faster than that of 15N. The fractional rate of 13C incorporation into avian blood was allometrically related to body mass with an exponent similar to -1/4. We conclude that the relationship between metabolic rate and the rate of isotopic incorporation into an animal's tissues is indirect. It is probably mediated by protein turnover and thus more complex than previous studies have assumed.

Resource partitioning within a tropical seabird community: new information from stable isotopes

“…Secondly, isotopic signature is dependent of carbon and nitrogen turnover rates that are, in turn, dependent on tissue type and body size. Using allometric equations between body mass and carbon half-life in avian red blood cells (Carleton & Martinez del Rio 2005), half-lives in seabird blood was estimated to range from 14 d (sooty tern) to 23 d (great frigatebird), thus indicating that almost all carbon (93%, corresponding to 4 half-lives) was renewed within 55 to 92 d for all the species. Hence, the trophic structure of the community during breeding was investigated over the medium term, i.e.…”

Assignment of nesting loggerhead turtles to their foraging areas in the Northwest Atlantic using stable isotopes

“…Epidermis samples reflect the turtle's dietary history over a long period of time (i.e., up to 4 months) based on studies conducted on juvenile loggerheads (Reich et al 2008). An even longer foraging history is probable in adult loggerheads because rates of isotopic incorporation slow with reduced growth rates (Reich et al 2008) and increasing body mass (Carleton and Martínez del Rio 2005).…”

Climate affects food availability to planktivorous least auklets Aethia pusilla through physical processes in the southeastern Bering Sea

“…We used red blood cells which turn over every 15 to 17 d, so that the carbon they contain came from diets during the previous 2 to 3 wk (Carleton & del Rio 2005), to gain information about the origin of auklet diet before the onset of sampling, which was especially important for 2008 to 2009 when sampling started at late incubation. Red blood cells were freeze-dried and analyzed with continuous flow isotope ratio mass spectrometry (CF-IRMS) using a Costech Elemental Ana lyzer (Model ECS 4010), a Thermo Finnigan C).…”