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.”