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

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 augmentation of the terrestrial invertebrates that enter stream (i.e., peak timing of June-August vs. August-October), keeping constant the total amounts of the invertebrates entered.

We found large increases in the individual growth rate and population biomass of the cutthroat trout, in response to the early resource pulse, but not to the late pulse. This timing-dependent consumer response cascaded down to reduce benthic invertebrates and leaf break-down rate, and increased water nutrient concentrations. Furthermore, the early resource pulse resulted in higher maturity rate of the cutthroat trout in the following spring, demonstrating the importance of the subsidy timing on long-term community dynamics via the consumer's numerical response.

Our results emphasize the need to acknowledge timing-dependent consumer responses in understanding the effects of subsidies on communities and ecosystem processes. Elucidating the mechanisms by which consumers effectively exploit pulsed subsidies is an important avenue to better understand community dynamics in spatially coupled ecosystems. Usage notes trout_stomach Stomach contents of trout in each season in each treatment reach trout_growth Specific growth rate of individual trout in each season in each treatment reaches trout_nexcretion N excretion by individual trout in each season in each treatment trout_pexcretion P excretion by individual trout in each season in each treatment trout_maturity Maturation of trout in the spawning season benthics Biomasses of benthic invertebrates in each season in each treatment benthic algae Biomass of benthic algae in each season in each treatment reaches leaf_breakdown Leaf break-down rate in each season in each treatment streamwater_nutrients NH3-N and SRP concentrations in stream water in each season in each treatment reaches