Disturbance, resource supply, and food‐web architecture in streams

Abstract

We studied food webs comprising fish, macroinvertebrates, and algae (identified to species or morphospecies) in small streams using a consistent methodology at the same spatial and temporal scales. Our aim was to test a priori hypotheses derived from dynamic‐demographic and energetics models concerning the effects of disturbance and resource availability on food‐web attributes. The regime of bed disturbance affecting the organisms in the webs was measured in 10 streams. We also derived measures of the supply of resources for animals in the webs in terms of algal primary productivity and detritus standing crop. Both web size and number of links per species were significantly negatively related to mean intensity of bed disturbance. Mean chain length had a significant positive relationship with algal primary productivity but not disturbance. No food‐web attribute was related to detritus standing crop.