Data from: Impacts of warming revealed by linking resource growth rates with consumer functional responses

Warming global temperatures are driving changes in species distributions, growth and timing, but much uncertainty remains regarding how climate change will alter species interactions. Consumer-Resource interactions in particular can be strongly impacted by changes to the relative performance of interacting species. While consumers generally gain an advantage over their resources with increasing temperatures, nonlinearities can change this relation near temperature extremes. We use an experimental approach to determine how temperature changes between 5 and 30 °C will alter the growth of the algae Scenedesmus obliquus and the functional responses of the small bodied Daphnia ambigua and the larger D. pulicaria. The impact of warming generally followed expectations, making both Daphnia species more effective grazers, with the increase in feeding rates outpacing the increases in algal growth rate. At the extremes of our temperature range, however, warming resulted in a decrease in Daphnia grazing effectiveness. Between 25 and 30°C both species of Daphnia experienced a precipitous drop in feeding rates, while algal growth rates remained high, increasing the likelihood of algal blooms in warming summer temperatures. D. pulicaria performed significantly better at cold temperatures than D. ambigua, but by 20°C there was no significant difference between the two species and at 25°C D. ambigua out-performed D. pulicaria. Warming summer temperatures will favor the smaller D. ambigua, but only over a narrow temperature range and warming beyond 25°C could open D. ambigua to invasion from tropical species. By fitting our results to temperature dependent functions we develop a temperature and density dependent model which produces a metric of grazing effectiveness, quantifying the grazer density necessary to halt algal growth. This approach should prove useful for tracking the transient dynamics of other density dependent consumer-resource interactions, such as agricultural pests and biological control agents.Algal growth time seriesDensity of algal cultures through time across 6 different temperaturesAlgal density.xlsFunctional Response dataResults of the functional response experiments. For each replicate the species, number of Daphnia, time elapsed in the feeding trial, initial density of Scenedesmus obliquus and final density of S. obliquus is provided