DOI: 10.5061/dryad.x3ffbg7v5
title: Data from: Enhanced conspicuousness of prey in warmer water mitigates the constraint of turbidity for predators

description: Changes in environmental conditions impact predator-prey interactions by
 altering behaviour through sensory and non-sensory (e.g., metabolic or
 cognitive) pathways. Elevated water temperature and turbidity are known to
 alter activity levels and anti-predator responses in prey fish, and are
 increasing globally as a result of anthropogenic activities. Less is known
 about how temperature and turbidity impact predators’ ability to detect
 prey directly, or indirectly via changes to prey behaviour. We quantified
 the detectability of Trinidadian guppies (Poecilia reticulata)
 free-swimming in a large arena from the perspective of a stationary visual
 predator (simulated as an underwater camera). We used a fully factorial
 experimental design testing the independent and combined effects of
 increased temperature and turbidity. We found that both stressors had a
 strong influence on the appearance of prey (objectively quantified as the
 mean magnitude of the optical flow in the videos). As expected, turbidity
 reduced the frequency of detection between the guppies and the simulated
 predator, i.e., the magnitude of optical flow exceeded the threshold for a
 ‘detection event’ more often in clear water. Events were also shorter in
 duration in turbid water, reducing the time available for a predator to
 detect the prey. However, during an event, prey were more detectable in
 warmer water (i.e., the mean magnitude was greater). Although we found no
 evidence of interactive effects of turbidity and temperature on the
 response variables, their cumulative main effects suggest an antagonistic
 effect between the two stressors on the predator-prey dynamic overall.
description: Data files included: #### **1. Final_data.csv** This data file includes
 all averaged variables used in the statistical analysis described in the
 Methods section * VideoFile: Unique trial identifier. Video files are not
 included in this repository. Available on request by contacting the first
 author CZ directly on cos.zanghi@bristol.ac.uk or cos.zan@gmail.com. -
 MeanMagnitude MaxMagnitude: mean and max average magnitude of optical flow
 for each trial * Trail_N: Unique Trial Number 1-96 - Guppy_tub: Number of
 holding tanks of origin 1-4 * Guppy_group : number of group tested each
 day 1-6 - Guppy_N : number of individual guppies within each group *
 Rep_Testing : Repeated testing 1-4 - Min_from_Midnight: minutes passed
 from midnight when trial commenced * SqrMean SqrMax : Square root
 transformations of mean and max magnitude - Treatment : categorical
 variable * Temp : categorical variable, H = Hot, W = Warm - Turb :
 categorical variable, C = Clear, T = Turbid * Proportion_Yes99
 Proportion_Yes95 Proportion_Yes90 Proportion_Yes80 Proportion_Yes70 :
 Proportion of detection events for each of the 5 thresholds -
 Mean_Magnitude_Yes99 Mean_Magnitude_Yes95 Mean_Magnitude_Yes90
 Mean_Magnitude_Yes80 Mean_Magnitude_Yes70 : Mean Magnitude for each of the
 5 thresholds * Mean_Event_Duration99 Mean_Event_Duration95
 Mean_Event_Duration90 Mean_Event_Duration80 Mean_Event_Duration70 : Mean
 duration of events for each of the 5 thresholds - encounters99
 encounters95 encounters90 encounters80 encounters70 : Number of events for
 each of the 5 thresholds Scripts included: **1. CH_3_stats_v.4.R** This
 script describes the final steps of data manipulation: where values of
 mean magnitude were used to calculated further metrics (i.e.  Proportion
 of events, Number of events and Duration of events). Preliminary data for
 these steps are available on request. Then, under the ### STATS ###
 heading, the analysis to support the finding reported in the paper is
 reported.