Resource quality controls detritivore consumption, growth, survival and body condition recovery of reproducing females

Although the effect of resource quality on density, biomass, growth rate and secondary production of consumers has been frequently documented, the direct repercussion of resource quality on reproduction has been less investigated. Here we tested the hypothesis that resource quality can limit body-condition recovery of reproducing individuals. For this, we reared ovigerous females of the freshwater amphipod Echinogammarus berilloni in the laboratory and fed them with leaves differing in quality (native Alnus, Quercus, or the exotic Eucalyptus) conditioned in three streams differing in the concentration of dissolved nutrients. Both consumption and growth rate, as well as the length-corrected mass and protein content of females after the release of the eggs, were negatively related to the C : N and C : P ratios of the resource. Survival was significantly lower with the exotic eucalypt leaf litter compared to native alder and oak, a result likely explained by the toxicity of the leaves. The conditioning of the leaves in the different streams did not affect the measured variables, although it interacted with survival. The present study suggests that resource quality can affect the recovery of body condition of reproducing females and shape the population structure of iteroparous species.