DOI: 10.5061/dryad.4j0zpc8kp
title: Opposing life history strategies allow grass shrimp parasites to avoid a conflict of interest

description: A conflict of interest occurs when parasites manipulate the behavior of
 their host in contradictory ways to achieve different goals. In grass
 shrimp (Palaemonetes pugio), trematode parasites that use shrimp as an
 intermediate host cause the shrimp to be more active than usual around
 predators, whereas bopyrid isopod parasites that use shrimp as a final
 host elicit the opposite response. Since these parasites are altering the
 host’s behavior in opposing directions, a conflict of interest would occur
 in co-infected shrimp. Natural selection should favor attempts to resolve
 this conflict through avoidance, killing, or sabotage. In a field survey
 of shrimp populations in four tidal creeks in the Cape Fear River, we
 found a significant negative association between the two parasites.
 Parasite abundance was negatively correlated in differently sized hosts,
 suggesting avoidance as a mechanism. Subsequent mortality experiments
 showed no evidence of early death of co-infected hosts. In behavior
 trials, co-infected shrimp did not show significantly different behavior
 from singly infected or uninfected shrimp, suggesting that neither
 parasite sabotages the manipulation of the other. Taken together, our
 results suggest that rather than sabotaging or killing one another,
 bopyrid and trematode parasites tend to infect differently sized hosts,
 thus avoiding a conflict and confirming the importance of testing
 assumptions in natural contexts.
description: # Opposing life history strategies allow grass shrimp parasites to avoid a
 conflict of interest Oecologia Special Issue: Parasites in Aquatic Ecology
 [https://doi.org/10.1007/s00442-024-05520-3](https://doi.org/10.1007/s00442-024-05520-3) ## Summary The data presented in this paper is split into three distinct parts, Behavior study, Field Survey, and Survival Study. Data and Software files are named in accordance. The Behavior study was an analysis of the frequency of certain behaviors performed by grass shrimp with various parasite infections when exposed to a predator or not. The Field Survey was simple survey of grass shrimp parasite populations in four local tidal creeks. The Survival Study measured survival of grass shrimp with varying parasite infections. See the full publication for further methodological detail. ## DataFiles ###### BehaviorData - csv of main behavior data sheet, compiled from the raw data trial - individual number of trial (order that they were performed in) date - date of trial being performed time - time of video trial taking place (all times are PM) length - length of grass shrimp in millimeters numTrem - number of trematode metacercaria in the individual shrimp pred - whether a mummichog predator was included in the trial (Y) or not (N) bop - whether the shrimp was infected with a bopyrid parasite (Y) or not (N) trem - whether the shrimp was infected with over 10 trematode cysts (Y) or not (N) infection - category of shrimp parasite infection (uninf = N Bop, N Trem; Bop = Y Bop, N trem; Trem = N Bop, Y Trem; Double = Y Bop, Y Trem) swimhovdef - percentage of time budget where shrimp was swimming, hovering, or defensive swimhov - percentage of time budget where shrimp was hovering or swimming (more obvious) defense per - percent of budget where a defense activity occurred at a time stamp defense - number of time stamps where a defensive behavior was occurring (used to calculate percentage) swim - percentage of time spent swimming alone active - percentage of time where shrimp was swimming, walking, or defensive activeper - active * 100 (percentage instead of decimal) defense - number of instances where grass shrimp showed a defensive behavior such as jabbing or backward thrusting (note: this is any instance of defensive behavior, not only during the 30 sec time stamps) captive - approximate time that the grass shrimp individual spent in captivity before being used in the trial title - title of video of trial predOrigin - collection site of the mummichog predator (if present) fish.length - length of the mummichog predator in millimeters (averaged from fish sharing a tank so as to reduce instances of stress on fish); trials that did not include a fish have 'n/a' listed for fish.length approxDate - approximate date of collection of the grass shrimp shrimpOrigin - which sampling collection trip the grass shrimp were collected during notes - misc notes on out of the ordinary happenings in videos ###### BehaviorDataRaw\.xlsx Excel sheet with multiple pages, shows shrimp activity for each trial video. Sheets titled after videos (i.e. 420_Double_N) are breakdowns of activity budgets for each video (type of activity at each time), note: time is not the timestamp of the video, instead it is measured from the "start" which is specified under "Timestamp". Column 1 'Timestamp' only has two entries, recording when the 'time' began on the video, and when behavior types were recorded. Defensive behaviors are recorded in cells that approximate the time when they occurred with actual time included in parenthesis. Blank cells indicate no defensive behavior occurring at that time. A table is included after a blank column, used to record instances of each type of behavior, used to calculate percentages. Time is recorded in minutes. ###### FieldSurveyData.csv date - date when sample was collected (2021) Month- month of sampling (each site was collected from each month 'grouping', the grouping usually but not always corresponded with the month it was sampled, i.e. if sites were sampled late in the month, Mott Creek's sample may have been collected on the first of the next month instead site - tidal creek location where sample was collected from (TW = Town, ML = Mallory, LP = Lilliput, MT = Mott) Obs- individual number of shrimp sampled from each site each month Length (mm) - measure of grass shrimp host length in mm from rostrum to telson Bopyrid - number of bopyrid infections in the individual shrimp Trematode - number of trematode cysts in each individual shrimp Microsporidia - number of trematode cysts infected with *Haplosporidia Opacity? - whether shrimp was opaque or not, difficult to see-through broken - whether shrimp rostrum was broken, or if other parts were shortened (impact length) Disease - signs of other illness, i.e. "rust disease" Gravid - if shrimp was gravid (had visible signs of carrying eggs) or not Notes - misc notes for individual shrimp temp (Celsius) - from metadata, for each collection event sal (ppt) - from metadata, for each collection event DO - from metadata, for each collection event DoPer - from metadata, for each collection event Researcher - which researcher processed the individual shrimp Other Obs - scored data from collections with sample size that was too low, these observations were not included in data analysis ###### FieldSurveyTripSummary.xlsx Collection Date - Date of the collection trip Site - Tidal creek where shrimp were collected from Acronym - acronym for each tidal creek location Water Temp (C) - temperature in Celsius of the water taken from the boat at the time of collection Salinity (ppt) - salinity of the water in the tidal creek at the time of collection DO - dissolved oxygen measure from the creek at time of collection, '-' indicate times when no measure was taken DO Percent - percent dissolved oxygen from the creek at time of collection, '-' indicate times when no measure was taken Number Collected - number of grass shrimp total collected during the sampling trip Number Processed - number of grass shrimp that were available to be processed (did not die before processing began) Date Processed - Date on which the collected sample was scored, n/a used when no processing occured Collected By - who collected the shrimp from the boat Processed By - who scored the sample, n/a used when no processing occured Notes - misc notes, includes number dead, or qualitative assessment of sites during collection ###### SurvivalData.csv Jar # - 5 shrimp of each infection status (see below) were included in the first block, 3 of each in the second. Each shrimp was placed in a jar and labelled with the date they started (block), infection status, and number Inf Status - Refers to the category each shrimp was placed into, based on which parasites it was infected with. Uninf = Uninfected (neither parasite), Bop = infected with only the bopyrid, trem = infected with more than 10 trematode metacercaria, Double = infected with bopyrid and more than 10 trematode metacercaria bop - whether shrimp had a bopyrid (1) or not (0) trem - number of trematode metacercaria in each shrimp length - length of shrimp host from rostrum to telson in mm status - used in coxph, alive (0) or dead (1) at 'time'; all shrimp died time - days from the beginning of the trial to death for all shrimp Start Date - shrimp were placed into the trial in two blocked starting dates, 5 of each infection status began on 31-May 2022, 3 of each were placed into the trial on 12-Jun Death Date - date when grass shrimp was found dead Water Changes - dates when water changes were performed (shrimp were fed for ~30 minutes before water changes) Extra Columns with Uninf/Bop/etc. - show number of trematode metacercaria and host, were used to perform ANOVA and t-tests in excel ## SoftwareFiles BehaviorCode.R R code for processing data and generating figures for the behavior study using BehaviorData.csv FieldSurveyCode.R R code for processing data and generating figures for the field survey using FieldSurveyData.csv SurvivalCode.R R code for processing data and generating figures for the mortality study using SurvivalData.csv