**2.4 Stomach content analyses**

All stomach contents were collected and identified to the lowest possible taxonomic level based on published keys (Abbott and Hollenberg, 1976; Riosmena-Rodríguez, 1999). Entire sample volume and the relative sample volume of each plant species were calculated by the procedure of water displacement in a graduated cylinder. Voucher material was housed in Herbario Ficológico of the Universidad Autónoma de Baja California Sur (UABCS), La Paz, México.

#### **2.5 Laboratory analyses**

Tissue and plant samples (0.5 g) were dried in an oven at 70 °C until a dry weight was obtained. Dried samples were digested in acid-washed Teflon tubes with concentrated nitric acid in a microwave oven (CEM modelMars 5X, Matthews, NC). Samples were analyzed by atomic absorption (GBC Scientific equipment, model AVANTA, Dandenong, Australia) using an air-acetylene flame. The certified standard reference material, TORT-2 (National Research Council of Canada, Ottawa) was used to verify accuracy, and that the analytical values were within the range of certified values. All recoveries of metals analyzed were over 95%. Detection limits were: Zinc=0.0008, Cadmium = 0.0009, Mn= 0.002, Cu= 0.0025, Ni = 0.004, Fe=0.005, Pb=0.006 μg/g.

#### **2.6 Quantitative analyses**

We analyzed the data based on taxonomic group (red algae, green algae, and seagrass), season, spatial area, and dominant species. Reported statistics are medians (nN2) and ranges in μg/g on a dry weight basis. The Mann–Whitney test was used for conducting two-tailed sample comparisons of tissues for each metal separately and for comparing metals in marine plants collected in Magdalena Bay with those found in the stomach contents. The Kruskal– Wallis test was used to compare the median metal concentration across all plant species. The null hypothesis was rejected if p≤0.05. The influence of concentration differences among samples was removed by converting data to the percent contribution of each metal to the total metal signature of the individual sample. Fe was removed from these analyses because of its high Concentration and dominance of the metal signature profile. Principal Components Analysis (PCA) of the percent contribution of the metals in plants and turtle tissues. Additionally, factorial analysis was used to determine trends in the presence of heavy metals in the seaweed samples and the relative spatial and/or temporal variation. All analysis was conducted using the Statgraphics Plus software program (Version 5, Rockville, MD).

#### **2.7 Prescence of fibropapiloms and epibionts**

Monthly sampling has been develop in the Estero Banderitas and more recently in Estero San Buto as part of the monitoring efforts in was the prescence of fibropapiloms and epibionts by a physical inspection of each animal by region as head, neck, carapace, front or back fins, anus or tail. Comparative analysis was done of the proportion of animals with fibropapiloms and epibionts using the database and literature described in Lara-Uc (2011) in relation to the Bahía Madalena population information (Hinojosa-Arango unpublished data).
