DOI: 10.5061/dryad.9ghx3fftk
title: Global warming affects foraging efficiency of fish by influencing mutual interference

description: Predator-prey interactions underpin ecological dynamics from population to
 ecosystem scales, affecting population growth and influencing community
 stability. One of the classic methods to study these relationships is the
 functional response (FR) approach, measuring resource use across resource
 densities. Global warming is known to strongly mediate consumer-resource
 interactions, but the relevance of prey and predator densities remains
 largely unknown. Elevated temperature could increase consumer energy
 expenditure, which needs to be compensated by greater foraging activity.
 However, such greater activity may concurrently result in a higher
 encounter rate with other consumers, which potentially affects their total
 pressure on resource population because of synergistic or antagonistic
 effects among multiple predators. We performed a laboratory experiment
 using three densities of a fish predator (pumpkinseed, Lepomis gibbosus)
 (one, two, and four specimens), two temperatures (25 and 28 oC), and six
 prey densities. Using the FR approach, we investigated the combined
 effects of elevated temperature and predator and prey density on
 consumer’s foraging efficiency. We observed a reduced maximum feeding rate
 at the higher temperature for single predators. The foraging efficiency of
 predators in groups was generally associated with antagonistic
 interactions, whose strength was greater for higher predator densities,
 but was further mediated by the temperature. Specifically, we observed a
 general decrease in antagonistic interactions in elevated compared to the
 ambient water temperature for multiple predator groupings. Irrespective of
 temperature, antagonistic multiple predator effects increased with
 predator density and peaked unimodally at intermediate prey densities,
 indicating multiple dimensions of density-dependence which interact to
 supersede the effects of warming. This study shows that increasing
 temperature affects the per capita performance of predators, but that this
 effect is dampened with increasing predator densities. Their adaptive
 response to temperature consists of limited food intake and further
 reduced intraspecific interactions. Including conspecifics as food
 competitors may thus offer more realistic outcomes compared to widely-used
 experiments with only single predator individuals, which could
 overestimate the effect of increasing temperature.
description: # Global warming affects foraging efficiency of fish by influencing mutual
 interference
 [https://doi.org/10.5061/dryad.9ghx3fftk](https://doi.org/10.5061/dryad.9ghx3fftk) ## Description of the data and file structure The authors collected all data included during the experiment. The compressed .zip file contains .csv files with the raw data and additional data necessary to recreate all the statistical analyses related to the study. It also includes the code prepared in R open software. ### Files and variables #### File: Augustyniak\_et\_al.\_Global\_warming\_affects\_mutual\_interference.zip **Description:**  **exp.csv** - the file contains raw data collected during the experiment. Variables: Tank ID - experimental unit identifier Species - fish species used, for clarity Temperature - water temperature (degrees Celsius): "Current (25)" represents the ambient temperature scenario, "Elevated (28)" represents the warming scenario Predator density - number of predator individuals placed in particular experimental unit Day - test day (experiment last 6 days in total) Initial prey density - initial density of prey individuals (gammarids) provided at the start of the experiment (6 prey densities were offered for each predator density) No. alive prey left - number of prey individuals left alive after 1 hour of the experiment No. prey eaten - number of prey individuals eaten during the experiment (the difference between Initial prey density and No. alive prey left) **size.csv** - the file contains fish size measurements. Variables: Fish_id - fish identifier temp - water temperature: "ambient" correspond to 25 degrees Celsius, "warming" to 28 degrees Celsius sl - fish standard length, in mm **size difference.csv** - the file contains differences in standard length between fish placed in the same experimental unit (did not contain experimental units with one predator individual). Variables: tank_id - experimental unit identifier temp - water temperature: "ambient" correspond to 25 degrees Celsius, "warming" to 28 degrees Celsius difference - difference in standard length between the biggest and the smallest fish in the same tank, in mm **exp_param.csv** - Functional response parameters obtained via the statistical analyses. Variables: Estimate - parameter (a or h, explained in "parameters" variable) estimate, modelled via equation (1) (random predator equation) in the manuscript Std.Error - standard error of the estimate from the model parameters - parameter of interest: "a" is the attack rate, "h" is the handling time Predator - treatment identificator: "amb" and "war" correspond to "ambient" and "warming" temperature, respectively, and following numbers inidicate predator density (1, 2 or 4) CI - confidence intervals for parameter estimates, calculated as 1.96 x Std.Error **ISNT.csv** - data to estimate the non-trophic interactions strength. Variables: IS - interaction strength, calculated using the equation (3) in the manuscript (prey eaten/initial prey density from exp.csv) P - the predicted consumption for each density from the population dynamic model, used to determine ISP in the same way as IS ISP - predicted interaction strength using the equation (3) in the manuscript, with P as preay eaten ISNT - non-trophic interaction strength, the difference between IS and ISP **Global warming affect mutual interference.R** - Rcode necessary to recreate all the statistical analyses used ## Code/software Rcode is provided in "Global warming affects mutual interference.R" file. It was created and used with R open software, ver 4.2.1. The list of packages needed is provided at the beginning of the code.