A test of the effects of timing of a pulsed resource subsidy on stream ecosystems

Spatial resource subsidies can alter bottom-up and top-down forces of community regulation across ecosystem boundaries. Most subsidies are temporally variable, and recent theory has suggested that consumer-resource dynamics can be stabilized if the peak timing of a subsidy is desynchronized with that of prey productivity in the recipient ecosystem. However, magnitude of consumer responses per se could depend on the subsidy timing, which may be a critical component for community dynamics and ecosystem processes. The aim of this study was to test (1) whether a recipient consumer (cutthroat trout) responds differently to a resource subsidy occurring early in its growing season than to a subsidy occurring late in the season, and, if this is the case, (2) whether the timing-dependent consumer response has cascading effects on communities and ecosystem functions in streams. To test those hypotheses, we conducted a large-scale field experiment, in which we directly manipulated the timing of au...