Meeting Abstract
P3.212 Sunday, Jan. 6 The effect of temperature on respiration rates of four key aquatic insect taxa in California riverine food webs. ALLEN, TR*; NGUYEN, JV; FAY, SA; POWER, ME; STILLMAN, JH; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley scott.a.fay@gmail.com
Predicting changes in trophic ecology of riverine systems in the face of future climate warming requires an understanding of the thermal performance of aquatic insect larvae. Larvae that differ in key trophic traits (i.e., armored vs. unarmored, grazer vs. predator) may also differ in the efficiency with which they use energy under various thermal regimes. Metabolic energy efficiency is maximized at optimal temperatures and declines at higher temperatures due to an increase in fermentative metabolism as metabolic rates outstrip oxygen delivery and an induction of stress responses to cope with thermal or oxidative damage. We compared thermal performance curves of four key aquatic insect taxa (Pteronarcys californica, Calinueria californica, Hesperoperla pacifica and Dicosmoecus gilvipes) from the South fork of the Eel River in Mendocino County, CA, by determining their respiration rates over a range of temperatures, 4-40° C using optode spots (PreSens). Respiration rate of P. californica, C. californica, and D. gilvipes peaked near 30°C, while the respiration of H. pacifica peaked near 20°C. Respiration rates among individuals within a species at a given temperature were highly variable. At peak temperature P. californica had an average respiration rate of 330±250 μmolO2/min/g, C. californica, 580±230, D. gilvipes, 250±80, and H. pacifica, 70±10. There was considerable intraspecific variation among individuals of the species tested, which could not be explained by effects of organismal handling or experimental light exposure. Our performance curves will be used to guide further work on molecular mechanisms of thermal response in trophically significant river insect larvae.
