The raw data used in this analysis are presented in Table 1. All datasets in this study include measured concentrations of trace elements (TEs), reported in nanograms per liter (ng/L) in Table 1, used as response variables. Samples were collected at four distinct nests (N1 to N4), each with three sampling points, and each point was sampled at two depths (S = Shallow and D = Deep). The nest variable is treated as a categorical grouping factor, while sampling dates (June, July, August 2023) and sampling depths serve as predictor variables, with dates treated as temporal variables and depths as categorical variables.

To visualize the concentration of trace elements across all nests, box and whisker plots (Fig. 7) were prepared for each sampling date. These allowed the detection for errors or outliers in the data, which could be attributed to errors during data collection, data entry, or instrument errors.  The y-axis shows the concentrations (log scale) of the TEs shown on the x-axis.  

Boxplots were also used to visualize the concentrations of trace elements at Nest 1 (Fig 4), and to visualize the depth as main effect, a boxplot for select trace elements is shown in Fig 5.  These boxplots also allow us to visually assess trends, distributions, and potential outliers in the dataset across the variables and years.