Atmospheric CO2 enrichment alters leaf detritus: impacts on foraging decisions of crayfish (Orconectes virilis)

Abstract

AbstractMany tree species demonstrate altered foliar chemical composition when grown under elevated CO2 conditions, decreasing the nutritional quality of leaves for herbivores and detritivores. Leaf litter comprises a substantial portion of the organic input into some headwater stream ecosystems, so changes in the chemistry of leaf detritus may affect the food-selection behavior of organisms, such as crayfish, that feed on it. Detritus from trembling aspen (Populus tremuloides) was produced under either the current CO2 concentration of 360 ppm (ambient, AMB) or twice the current concentration, 720 ppm (elevated, ELEV). A Y-maze was used to determine crayfish preference for AMB or ELEV detritus. Experimental conditions consisted of: 1) fresh detritus, 2) detritus that had been leached in water for 24 h, and 3) leachate from detritus (dissolved organic matter, DOM) made into a slow-releasing gelatin block. Pairwise combinations of stimuli (AMB, ELEV, and a no-stimulus control, CON) were compared within each...