DOI: 10.7291/d1xm4q
title: Mussel bed community data for: Intraspecific variation in a marine predator changes intertidal community through effects on a foundation species

description: Intraspecific variation is an important form of biodiversity that can
 alter community and ecosystem properties. Recent work demonstrates the
 community effects of intraspecific variation in predators via altering
 prey communities and in foundation species via shaping habitat attributes.
 However, tests of the community effects of intraspecific trait variation
 in predators acting on foundation species are lacking despite the fact
 that consumption of foundation species can have strong community effects
 by shaping habitat structure. Here we tested the hypothesis that
 intraspecific foraging differences among populations of mussel-drilling
 dogwhelk predators (Nucella) differentially alter intertidal communities
 through effects on foundational mussels. We conducted a nine-month field
 experiment where we exposed intertidal mussel bed communities to predation
 from three Nucella populations that exhibit differences in
 size-selectivity and consumption time for mussel prey. At the end of the
 experiment, we measured mussel bed structure, species diversity, and
 community composition. While exposure to Nucella originating from
 different populations did not significantly alter overall community
 diversity, we found that differences in Nucella mussel selectivity
 significantly altered foundational mussel bed structure, which in turn
 altered the biomass of shore crabs and periwinkle snails. Our study
 extends the emerging paradigm of the ecological importance of
 intraspecific variation to include the effects of intraspecific variation
 in predators of foundation species.
description: The dataset was collected after the completion of a nine-month
 intertidal mussel bed experiment in the mid-intertidal zone testing the
 effects of intraspecific variation in dogwhelk predators in the genus
 <em>Nucella</em>. In the experiment, there were 32 plastic
 Vexar mesh intertidal cages bolted to a relatively flat area of rock, and
 each contained California mussel bed communities. The cages were treated
 with dogwhelk predators from three different populations. The goal was to
 test the effects of differential predation by the dogwhelk populations on
 the mussel bed physical structure and ecological community. At the
 completion of the experiment, each cage was photographed from above. Then,
 the entire community in each cage was removed by hand and frozen for later
 analysis. The frozen samples were then sorted by species (or as close as
 we could get to species), classified, weighed, and measured by hand in a
 laboratory. Dogwhelk data refers to the populations, sizes, and masses of
 dogwhelk predators used as treatments in the cages. Drilled mussel data
 refers to the sizes of mussels found with at least one drill hole by the
 end of the experiment. Remaining mussel data refers to the sizes of
 mussels found still alive at the end of the experiment. Community data
 refers to the identification and mass (except algae, which is measured in
 percent cover instead of mass) of all organisms living in the mussel beds
 at the end of the experiment. 
description: The comma separated values (.csv) files can be opened by free
 software such as Google Sheets or Open Office. The R script can be opened
 using R statistical software or RStudio/Posit, which are also
 free.
description: # Intraspecific variation in a predator changes intertidal community
 through effects on a foundation species *** These four datasets were
 collected after the completion of a nine-month intertidal mussel bed
 experiment in the mid-intertidal zone. In the experiment, there were 32
 plastic Vexar mesh intertidal cages bolted to a relatively flat area of
 rock, and each contained California mussel bed communities. The cages were
 treated with dogwhelk predators from three different populations. The goal
 was to test the effects of differential predation by the dogwhwelk
 populations on the mussel bed physical structure and ecological community.
 The entire community in each cage was removed by hand at the completion of
 the experiment, then frozen for later analysis. The frozen samples were
 then sorted, classified, and measured by hand in a laboratory. Dogwhelk
 data refers to the populations, sizes, and masses of dogwhelk predators
 used as treatments in the cages. Drilled mussel data refers to the sizes
 of mussels found with at least one drill hole by the end of the
 experiment. Remaining mussel data refers to the sizes of mussels found
 still alive at the end of the experiment. Community data refers to the
 identification and mass of all organisms living in the mussel beds at the
 end of the experiment. ## Description of the data and file structure
 Contolini\_Palkovacs\_dogwhelk\_data.csv describes the dogwhelk predators
 applied to cages. “site” indicates the site or population from which each
 dogwhelk originated; “cage” inidicates the cage it was assigned to during
 the experiment; “start.length” its starting length in millimeters from
 anterior canal to spire; “start.wetmass.nolabel” its starting wetmass in
 grams before a label was applied to its shell; “start.wetmass.label” its
 starting wetmass in grams after a label was applied to its shell;
 “end.length” its ending length in millimeters; “end.wetmass” its ending
 wet mass in grams; “dead” whether or not it died during the experiment (0
 indicates it did not die; 1 indicates it did die); “replacement” whether
 or not the dogwhelk was replaced (0 indicates it was not replaced; 1
 indicates it was replaced), and notes. Missing values indicate we were not
 able to obtain the data, for example because the snail was lost or its
 shell was broken, or the data were lost.
 Contolini\_Palkovacs\_drilled\_mussel\_data.csv describes drilled mussels.
 “plot” indicates the cage ID in which the mussel was located;
 “mussel.number” indicates the number it was in that cage (i.e., I counted
 how many per cage, but as counts are easily calculated in R, I did not
 always complete this numbering in the data file, which does not affect any
 R code or analyses); “trtmnt” indicates the population origin of dogwhelk
 added to the cage; “mussel.length” indicates the length of the shell in
 millimeters; “loose” indicates whether the mussel was loose (i.e.,
 unattached) in the cage; “drilled” indicates whether the mussel had a
 drill hole; and “complete” indicates whether the drill hole was complete.
 Only rows where drilled = TRUE were used in analyses of drilled mussels.
 Missing values indicate the mussel was unmeasurable (e.g., it was broken)
 or the data were lost. Contolini\_Palkovacs\_remaining\_mussel\_data.csv
 describes undrilled mussels that remained in the experiment by the end.
 “plot” indicates the cage ID in which the mussel was located;
 “mussel.number” indicates the number it was in that cage (i.e., I counted
 how many per cage); “trtmnt” indicates the population origin of dogwhelk
 added to the cage; “mussel.length” indicates the length of the shell in
 millimeters from anterior canal to spire; “drilled” indicates whether the
 mussel had a drill hole; “complete” indicates whether the drill hole was
 complete; “epi.spp” inidicates species of epibionts found on the shell and
 is not complete was and not used in analyses; “epi.spp.n” indicates the
 number of individuals of a given epibiont species and is not complete and
 was not used in analyses; “tot.mussels” indicates the total number of
 mussels found in a given cage; “block” indicates the randomized block
 designation for the cage; and “dogwhelk” indicates whether dogwhelks were
 present in the cage, i.e., whether or not it was a control treatment
 without dogwhelks. Contolini\_Palkovacs\_community\_data.csv describes the
 biomass (or for algae, percent cover) of species found in the mussel beds
 at the end of the experiment. “cage” indicates the cage ID; “trtmnt”
 indicates the population origin of dogwhelk added to the cage; all other
 columns are specific taxa found in the cage, and cell values indicate dry
 biomass in g (with the exception of algae, where the cells indicate
 percent cover as measured in photographs of the tops of the mussel beds in
 each cage). ## Code/Software Contolini\_Palkovacs\_EE\_2023\_v6.R is an R
 script that will reproduce all analyses and most figures in the article,
 “Intraspecific variation in a predator changes intertidal community
 through effects on a foundation species” by G M Contolini and E P
 Palkvoacs published in Ecology and Evolution in 2023 using the datasets
 described above. The script was created using R Studio v. 2023.03.0+386
 and R version 4.2.1 (2022-06-23) -- "Funny-Looking Kid.”