Meeting Abstract
66.5 Sunday, Jan. 6 The utilization of pulsed resources by a grasshopper community as quantified from breath δ13C using tunable diode laser absorption spectroscopy ENGEL, S.*; MCDOWELL, N. G.; WOLF, B. O.; Univ. of New Mexico sengel@unm.edu
Isotopic breath analysis can be used to determine the diet recently consumed by animals. We measured the δ13C of expired �breath� CO2 of a grasshopper community from the Sevilleta LTER in central New Mexico using tunable diode laser absorption spectroscopy. This approach allowed us to quantify the utilization of specific plant functional groups, as defined by photosynthetic pathway (C3 or C4), by grasshoppers and to determine its variation over the course of a season. Measurements of breath δ13C show that resource use by the grasshopper community and its temporal variability is diverse. We found species that fed only on C4 grasses, on a mix of C3 and C4 plants, and a specialist that fed only on C3 plant resources. In the Sevilleta LTER, the relative contribution of C4 and C3 plants varies over the growing season with annual or perennial C3 plants depending mostly on winter rains and C4 grasses responding strongly to the summer monsoon. Accordingly, the contribution of C4 resources to the diet of some grasshopper species increased over the season. Other species were more constant in their reliance on one or the other functional group. Plant physiology and thus primary production are tightly coupled to a variety of climate drivers, both in the short and long-term, therefore our approach provides researchers with a tool to directly link consumer nutritional ecology and population dynamics to climate dynamics and explore the influence of these drivers on entire food webs in real-time in the field.
