Data and code associated with "Seasonal differences in predation risk among seagrass epifauna species stabilize community-level predation over time"
Data files
Mar 17, 2026 version files 409.08 KB
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MurphyStachowicz_ECY25-1455.xlsx
406 KB
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README.md
3.08 KB
Abstract
Predation risk varies through space and time due to changing refuge quality, predator communities, and prey traits. Despite this, ecological research is often focused on measuring average predation risk at the community level. While this can give important information about overall trophic transfer and ecological efficiency, it ignores differences in predation risk among prey species within a community, which may be important determinants of species coexistence and local diversity. We used crustaceans associated with temperate seagrass in Northern California to explore the relationship between seasonal variation in among-species and community-level predation risk for a community of morphologically distinct prey. We measured predation risk of the four most abundant and widespread prey species at six field sites every two to six weeks for one year. At the community level, sites differed significantly in their annual variation in predation risk, and these differences were correlated with the amount of variation in the among-species predation risk. When there was more within-year variation in predation risk among the four prey species, predation risk at the community level was more stable across the year. On the other hand, when each prey species in the community had similar levels of predation risk throughout the year, predation as a community-level process was much more seasonal and variable. Variation in predation risk also changed across a gradient of seagrass cover, a proxy for refuge quality. Sites with greater seagrass cover had less annual variation in community-level predation risk and more variation in predation risk among the four species at any given time point. In contrast, at sites with less eelgrass, all species were consumed at the same rate throughout the year, suggesting previously demonstrated differences in antipredator strategies among species are less relevant in the absence of habitat-forming species. We suggest that larger species-specific differences in predation risk throughout a year result in a more stable level of predation risk for the whole community, and that this may be driven by increased refuge provided by seagrass habitat mediating different prey species’ relative levels of susceptibility to predation.
https://doi.org/10.5061/dryad.0000000d5
Description of the data and file structure
This data (found in the file "MurphyStachowicz_ECY25-1455.xlsx") represents predation risk, abundance, and habitat data for 4 common seagrass epifaunal species (Pentidotea resecata, Ampithoe valida, Ampithoe lacertosa, and Caprella californica) at 6 sites in Bodega Harbor and Tomales Bay, California, USA.
Predation data was collected by deploying 20 tethers for each of the 4 species at each of the 6 sites 16 times across a year (April 2023 - March 2024). Ampithoe valida was only deployed in Tomales Bay, as it's not currently found in Bodega Harbor. Each tether was 0.5 meters apart from each other, in an order that alternated between the species. Assays were conducted at the same transects during each survey. We retrieved the tethers after 24 hours and recorded if each species was consumed, or if it was still on the tether, whether or not it was alive or dead.
Abundance data for each of the prey species was collected at each site concurrent with the predation assays. One person conducted 15 minute visual surveys along each transect, searching through the seagrass and algae and counting the number of each of the 4 species that was found.
Habitat data is percent cover and shoot density data from each of the sites, collected in the year prior to the predation and abundance data. 5 evenly spaced 0.5 m x 0.5 m quadrats were used to record percent cover of seagrass, macroalgae, sessile invertebrates, and bare ground, and shoot density of vegetative and flowering Zostera marina shoots along the same transects that were used for the predation assays. These surveys were done 11 times between March 2023 and April 2024.
Files and variables
File: MurphyStachowicz_ECY25-1455.xlsx
Description: The first sheet is metadata, defining the columns and variables in each of the following sheets. The second sheet is the predation data, the third sheet is the abundance data, the fourth sheet is the percent cover data, and the fifth sheet is the shoot density data.
For descriptions, definitions, and possible values for each variable, see the first sheet of the Excel file titled "metadata."
Missing values across all datasets were recorded as blank cells.
Code/software
One R script is included in this submission. It was written in R version 4.3.1.
MurphyStachowicz_ECY25-1455.R is an R script used to analyze the data and create the figures described in the manuscript "Habitat cover reduces seasonal variation in predation risk and abundance in a seagrass-associated crustacean community." It looks at between variation in predation risk, habitat amount, and variation in prey community abundance.
It requires the following packages:
tidyverse (version 2.0.0)
readxl (version 1.4.3)
vegan (version 2.6.4)
cowplot (version 1.1.1)
Methods for data collection can be found in the manuscript "Seasonal differences in predation risk among seagrass epifauna species stabilize community-level predation over time" by Claire Murphy & Jay Stachowicz in Ecology.