Predator size structure fails to alter nonconsumptive effects in streams

Predator population size structure varies over space and time, mediating the top-down, consumptive effects of predators on ecosystems. Yet the role of predator size variation in governing nonconsumptive predator effects has received little targeted research attention. We manipulated stonefly (Acroneuria abnormis) predator size structure and feeding ability and measured effects on the benthic invertebrate prey community in a headwater stream. Field enclosures retained stonefly predators but allowed smaller prey to emigrate as a behavioral avoidance response. Stoneflies caused a ~30% reduction in total prey abundance regardless of whether or not they could feed, indicating a major role for nonconsumptive effects in determining the overall predator effect. This pattern was consistent across two different stonefly predator size structures with equivalent total biomass, as well as most prey responses measured at both the community level and the individual taxon level. Our study demonstrates ..., , # Predator size structure fails to alter nonconsumptive effects in streams

Dataset DOI: [10.5061/dryad.905qfttzs](https://doi.org/10.5061/dryad.905qfttzs)

## Description of the data and file structure

We ran an experiment testing the effects of stonefly predator size structure (small vs. large) and mouthpart gluing (unglued vs. glued) on prey community structure in streams. Our experiment crossed these factors resulting in 4 unique treatments and we additionally conducted a no-stonefly control. We considered effects of experimental factors on aspects of prey community structure (measured through abundance data) as well as prey size structure (measured using prey head width data). 

### Files and variables

#### File: Enclosure_experiment_data_10-15-25.csv

**Description:** Data are in a CSV format and are viewable in MS Excel. Each row in this data set represents a single prey individual that was sampled from an experimental enclosure. Some prey head width data are missing due to dam...,