file 3: "3_spatial_density_distribution_predation.csv"
The data in the different columns represent:
sampling_station - id of sampling station
plot - factor indicating which plot the data were collected; ("A", "B", or "I")
predation - factor indicating predation "treatment"; "yes" indicates a predation plot, and "no" indicates the reference plot
sampling_occassion - factor indicating the sampling occasion; "before" indicates initial sampling, and "post_pred" indicates final sampling
X_m - the X-coordinate of the sampling station in meters
Y_m - the Y-coordinate of the sampling station in meters
cockles_n - the number of cockles < 16 mm in the sampling core